347 results on '"Koji Nakayama"'
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2. Colony spreading of the gliding bacterium Flavobacterium johnsoniae in the absence of the motility adhesin SprB
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Keiko Sato, Masami Naya, Yuri Hatano, Yoshio Kondo, Mari Sato, Yuka Narita, Keiji Nagano, Mariko Naito, Koji Nakayama, and Chikara Sato
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Medicine ,Science - Abstract
Abstract Colony spreading of Flavobacterium johnsoniae is shown to include gliding motility using the cell surface adhesin SprB, and is drastically affected by agar and glucose concentrations. Wild-type (WT) and ΔsprB mutant cells formed nonspreading colonies on soft agar, but spreading dendritic colonies on soft agar containing glucose. In the presence of glucose, an initial cell growth-dependent phase was followed by a secondary SprB-independent, gliding motility-dependent phase. The branching pattern of a ΔsprB colony was less complex than the pattern formed by the WT. Mesoscopic and microstructural information was obtained by atmospheric scanning electron microscopy (ASEM) and transmission EM, respectively. In the growth-dependent phase of WT colonies, dendritic tips spread rapidly by the movement of individual cells. In the following SprB-independent phase, leading tips were extended outwards by the movement of dynamic windmill-like rolling centers, and the lipoproteins were expressed more abundantly. Dark spots in WT cells during the growth-dependent spreading phase were not observed in the SprB-independent phase. Various mutations showed that the lipoproteins and the motility machinery were necessary for SprB-independent spreading. Overall, SprB-independent colony spreading is influenced by the lipoproteins, some of which are involved in the gliding machinery, and medium conditions, which together determine the nutrient-seeking behavior.
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- 2021
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3. Effect of Porphyromonas gingivalis infection on gut dysbiosis and resultant arthritis exacerbation in mouse model
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Yuta Hamamoto, Kazuhisa Ouhara, Syuichi Munenaga, Mikio Shoji, Tatsuhiko Ozawa, Jyunzo Hisatsune, Isamu Kado, Mikihito Kajiya, Shinji Matsuda, Toshihisa Kawai, Noriyoshi Mizuno, Tsuyoshi Fujita, Shintaro Hirata, Kotaro Tanimoto, Koji Nakayama, Hiroyuki Kishi, Eiji Sugiyama, and Hidemi Kurihara
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Porphyromonas gingivalis ,Rheumatoid arthritis ,Periodontitis ,Citrullinated protein ,Dysbiosis ,Diseases of the musculoskeletal system ,RC925-935 - Abstract
Abstract Background Porphyromonas gingivalis (Pg) infection causes periodontal disease and exacerbates rheumatoid arthritis (RA). It is reported that inoculation of periodontopathogenic bacteria (i.e., Pg) can alter gut microbiota composition in the animal models. Gut microbiota dysbiosis in human has shown strong associations with systemic diseases, including RA, diabetes mellitus, and inflammatory bowel disease. Therefore, this study investigated dysbiosis-mediated arthritis by Pg oral inoculation in an experimental arthritis model mouse. Methods Pg inoculation in the oral cavity twice a week for 6 weeks was performed to induce periodontitis in SKG mice. Concomitantly, a single intraperitoneal (i.p.) injection of laminarin (LA) was administered to induce experimental arthritis (Pg-LA mouse). Citrullinated protein (CP) and IL-6 levels in serum as well as periodontal, intestinal, and joint tissues were measured by ELISA. Gut microbiota composition was determined by pyrosequencing the 16 s ribosomal RNA genes after DNA purification of mouse feces. Fecal microbiota transplantation (FMT) was performed by transferring Pg-LA-derived feces to normal SKG mice. The effects of Pg peptidylarginine deiminase (PgPAD) on the level of citrullinated proteins and arthritis progression were determined using a PgPAD knockout mutant. Results Periodontal alveolar bone loss and IL-6 in gingival tissue were induced by Pg oral infection, as well as severe joint destruction, increased arthritis scores (AS), and both IL-6 and CP productions in serum, joint, and intestinal tissues. Distribution of Deferribacteres and S24-7 was decreased, while CP was significantly increased in gingiva, joint, and intestinal tissues of Pg-inoculated experimental arthritis mice compared to experimental arthritis mice without Pg inoculation. Further, FMT from Pg-inoculated experimental arthritis mice reproduced donor gut microbiota and resulted in severe joint destruction with increased IL-6 and CP production in joint and intestinal tissues. The average AS of FMT from Pg-inoculated experimental arthritis was much higher than that of donor mouse. However, inoculation of the PgPAD knockout mutant inhibited the elevation of arthritis scores and ACPA level in serum and reduced CP amount in gingival, joint, and intestinal tissues compared to Pg wild-type inoculation. Conclusion Pg oral infection affected gut microbiota dysbiosis and joint destruction via increased CP generation.
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- 2020
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4. Key Amino Acids for Transferase Activity of GDSL Lipases
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Takanori Yamashiro, Akira Shiraishi, Koji Nakayama, and Honoo Satake
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Tanacetum cinerariifolium ,GDSL lipase ,transferase ,in silico ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The Gly-Asp-Ser-Leu (GDSL) motif of esterase/lipase family proteins (GELPs) generally exhibit esterase activity, whereas transferase activity is markedly preferred in several GELPs, including the Tanacetum cinerariifolium GDSL lipase TciGLIP, which is responsible for the biosynthesis of the natural insecticide, pyrethrin I. This transferase activity is due to the substrate affinity regulated by the protein structure and these features are expected to be conserved in transferase activity-exhibiting GELPs (tr-GELPs). In this study, we identified two amino acid residues, [N/R]208 and D484, in GELP sequence alignments as candidate key residues for the transferase activity of tr-GELPs by two-entropy analysis. Molecular phylogenetic analysis demonstrated that each tr-GELP is located in the clusters for non-tr-GELPs, and most GELPs conserve at least one of the two residues. These results suggest that the two conserved residues are required for the acquisition of transferase activity in the GELP family. Furthermore, substrate docking analyses using ColabFold-generated structure models of both natives and each of the two amino acids-mutated TciGLIPs also revealed numerous docking models for the proper access of substrates to the active site, indicating crucial roles of these residues of TciGLIP in its transferase activity. This is the first report on essential residues in tr-GELPs for the transferase activity.
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- 2022
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5. Draft Genome of Tanacetum Coccineum: Genomic Comparison of Closely Related Tanacetum-Family Plants
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Takanori Yamashiro, Akira Shiraishi, Koji Nakayama, and Honoo Satake
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Tanacetum coccineum ,draft genome ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The plant Tanacetum coccineum (painted daisy) is closely related to Tanacetum cinerariifolium (pyrethrum daisy). However, T. cinerariifolium produces large amounts of pyrethrins, a class of natural insecticides, whereas T. coccineum produces much smaller amounts of these compounds. Thus, comparative genomic analysis is expected to contribute a great deal to investigating the differences in biological defense systems, including pyrethrin biosynthesis. Here, we elucidated the 9.4 Gb draft genome of T. coccineum, consisting of 2,836,647 scaffolds and 103,680 genes. Comparative analyses of the draft genome of T. coccineum and that of T. cinerariifolium, generated in our previous study, revealed distinct features of T. coccineum genes. While the T. coccineum genome contains more numerous ribosome-inactivating protein (RIP)-encoding genes, the number of higher-toxicity type-II RIP-encoding genes is larger in T. cinerariifolium. Furthermore, the number of histidine kinases encoded by the T. coccineum genome is smaller than that of T. cinerariifolium, suggesting a biological correlation with pyrethrin biosynthesis. Moreover, the flanking regions of pyrethrin biosynthesis-related genes are also distinct between these two plants. These results provide clues to the elucidation of species-specific biodefense systems, including the regulatory mechanisms underlying pyrethrin production.
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- 2022
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6. Type IX Secretion System Cargo Proteins Are Glycosylated at the C Terminus with a Novel Linking Sugar of the Wbp/Vim Pathway
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Paul D. Veith, Mikio Shoji, Richard A. J. O’Hair, Michael G. Leeming, Shuai Nie, Michelle D. Glew, Gavin E. Reid, Koji Nakayama, and Eric C. Reynolds
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Porphyromonas gingivalis ,Tannerella forsythia ,glycoprotein ,type IX secretion system ,lipopolysaccharide ,Microbiology ,QR1-502 - Abstract
ABSTRACT Porphyromonas gingivalis and Tannerella forsythia use the type IX secretion system to secrete cargo proteins to the cell surface where they are anchored via glycolipids. In P. gingivalis, the glycolipid is anionic lipopolysaccharide (A-LPS), of partially known structure. Modified cargo proteins were deglycosylated using trifluoromethanesulfonic acid and digested with trypsin or proteinase K. The residual modifications were then extensively analyzed by tandem mass spectrometry. The C terminus of each cargo protein was amide-bonded to a linking sugar whose structure was deduced to be 2-N-seryl, 3-N-acetylglucuronamide in P. gingivalis and 2-N-glycyl, 3-N-acetylmannuronic acid in T. forsythia. The structures indicated the involvement of the Wbp pathway to produce 2,3-di-N-acetylglucuronic acid and a WbpS amidotransferase to produce the uronamide form of this sugar in P. gingivalis. The wbpS gene was identified as PGN_1234 as its deletion resulted in the inability to produce the uronamide. In addition, the P. gingivalis vimA mutant which lacks A-LPS was successfully complemented by the T. forsythia vimA gene; however, the linking sugar was altered to include glycine rather than serine. After removal of the acetyl group at C-2 by the putative deacetylase, VimE, VimA presumably transfers the amino acid to complete the biosynthesis. The data explain all the enzyme activities required for the biosynthesis of the linking sugar accounting for six A-LPS-specific genes. The linking sugar is therefore the key compound that enables the attachment of cargo proteins in P. gingivalis and T. forsythia. We propose to designate this novel linking sugar biosynthetic pathway the Wbp/Vim pathway. IMPORTANCE Porphyromonas gingivalis and Tannerella forsythia, two pathogens associated with severe gum disease, use the type IX secretion system (T9SS) to secrete and attach toxic arrays of virulence factor proteins to their cell surfaces. The proteins are tethered to the outer membrane via glycolipid anchors that have remained unidentified for more than 2 decades. In this study, the first sugar molecules (linking sugars) in these anchors are identified and found to be novel compounds. The novel biosynthetic pathway of these linking sugars is also elucidated. A diverse range of bacteria that do not have the T9SS were found to have the genes for this pathway, suggesting that they may synthesize similar linking sugars for utilization in different systems. Since the cell surface attachment of virulence factors is essential for virulence, these findings reveal new targets for the development of novel therapies.
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- 2020
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7. Correction: Por Secretion System-Dependent Secretion and Glycosylation of Porphyromonas gingivalis Hemin-Binding Protein 35.
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Mikio Shoji, Keiko Sato, Hideharu Yukitake, Yoshio Kondo, Yuka Narita, Tomoko Kadowaki, Mariko Naito, and Koji Nakayama
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Medicine ,Science - Abstract
[This corrects the article DOI: 10.1371/journal.pone.0021372.].
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- 2018
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8. A human genotyping trial to estimate the post-feeding time from mosquito blood meals.
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Yuuji Hiroshige, Masaaki Hara, Atsushi Nagai, Tomoyuki Hikitsuchi, Mitsuo Umeda, Yumi Kawajiri, Koji Nakayama, Koichi Suzuki, Aya Takada, Akira Ishii, and Toshimichi Yamamoto
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Medicine ,Science - Abstract
Mosquitoes occur almost worldwide, and females of some species feed on blood from humans and other animals to support ovum maturation. In warm and hot seasons, such as the summer in Japan, fed mosquitoes are often observed at crime scenes. The current study attempted to estimate the time that elapsed since feeding from the degree of human DNA digestion in mosquito blood meals and also to identify the individual human sources of the DNA using genotyping in two species of mosquito: Culex pipiens pallens and Aedes albopictus. After stereomicroscopic observation, the extracted DNA samples were quantified using a human DNA quantification and quality control kit and were genotyped for 15 short tandem repeats using a commercial multiplexing kit. It took about 3 days for the complete digestion of a blood meal, and genotyping was possible until 2 days post-feeding. The relative peak heights of the 15 STRs and DNA concentrations were useful for estimating the post-feeding time to approximately half a day between 0 and 2 days. Furthermore, the quantitative ratios derived from STR peak heights and the quality control kit (Q129/Q41, Q305/Q41, and Q305/Q129) were reasonably effective for estimating the approximate post-feeding time after 2-3 days. We suggest that this study may be very useful for estimating the time since a mosquito fed from blood meal DNA, although further refinements are necessary to estimate the times more accurately.
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- 2017
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9. Retraction Note: Temporal activation of anti- and pro-apoptotic factors in human gingival fibroblasts infected with the periodontal pathogen, Porphyromonas gingivalis: potential role of bacterial proteases in host signalling
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Sonya Urnowey, Toshihiro Ansai, Vira Bitko, Koji Nakayama, Tadamichi Takehara, and Sailen Barik
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Microbiology ,QR1-502 - Abstract
The Editor has retracted this article [1] following an investigation by the University of South Alabama which found:
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- 2019
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10. Structural Insights into the PorK and PorN Components of the Porphyromonas gingivalis Type IX Secretion System.
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Dhana G Gorasia, Paul D Veith, Eric G Hanssen, Michelle D Glew, Keiko Sato, Hideharu Yukitake, Koji Nakayama, and Eric C Reynolds
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
The type IX secretion system (T9SS) has been recently discovered and is specific to Bacteroidetes species. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilizes the T9SS to transport many proteins including the gingipain virulence factors across the outer membrane and attach them to the cell surface via a sortase-like mechanism. At least 11 proteins have been identified as components of the T9SS including PorK, PorL, PorM, PorN and PorP, however the precise roles of most of these proteins have not been elucidated and the structural organization of these components is unknown. In this study, we purified PorK and PorN complexes from P. gingivalis and using electron microscopy we have shown that PorN and the PorK lipoprotein interact to form a 50 nm diameter ring-shaped structure containing approximately 32-36 subunits of each protein. The formation of these rings was dependent on both PorK and PorN, but was independent of PorL, PorM and PorP. PorL and PorM were found to form a separate stable complex. PorK and PorN were protected from proteinase K cleavage when present in undisrupted cells, but were rapidly degraded when the cells were lysed, which together with bioinformatic analyses suggests that these proteins are exposed in the periplasm and anchored to the outer membrane via the PorK lipid. Chemical cross-linking and mass spectrometry analyses confirmed the interaction between PorK and PorN and further revealed that they interact with the PG0189 outer membrane protein. Furthermore, we established that PorN was required for the stable expression of PorK, PorL and PorM. Collectively, these results suggest that the ring-shaped PorK/N complex may form part of the secretion channel of the T9SS. This is the first report showing the structural organization of any T9SS component.
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- 2016
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11. New Short Term Prediction Method for Chemical Carcinogenicity by Hepatic Transcript Profiling Following 28-Day Toxicity Tests in Rats
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Hiroshi Matsumoto, Yoshikuni Yakabe, Fumiyo Saito, Koichi Saito, Kayo Sumida, Masaru Sekijima, Koji Nakayama, Hideki Miyaura, Masanori Otsuka, and Tomoyuki Shirai
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Published
- 2011
12. Discrimination of Carcinogens by Hepatic Transcript Profiling in Rats Following 28-day Administration
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Hiroshi Matsumoto, Yoshikuni Yakabe, Koichi Saito, Kayo Sumida, Masaru Sekijima, Koji Nakayama, Hideki Miyaura, Fumiyo Saito, Masanori Otsuka, and Tomoyuki Shirai
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
This study aimed at discriminating carcinogens on the basis of hepatic transcript profiling in the rats administrated with a variety of carcinogens and non-carcinogens. We conducted 28-day toxicity tests in male F344 rats with 47 carcinogens and 26 non- carcinogens, and then investigated periodically the hepatic gene expression profiles using custom microarrays. By hierarchical cluster analysis based on significantly altered genes, carcinogens were clustered into three major groups (Group 1 to 3). The formation of these groups was not affected by the gene sets used as well as the administration period, indicating that the grouping of carcinogens was universal independent of the conditions of both statistical analysis and toxicity testing. Seventeen carcinogens belonging to Group 1 were composed of mainly rat hepatocarcinogens, most of them being mutagenic ones. Group 2 was formed by three subgroups, which were composed of 23 carcinogens exhibiting distinct properties in terms of genotoxicity and target tissues, namely nonmutagenic hepatocarcinogens, and mutagenic and nonmutagenic carcinogens both of which are targeted to other tissues. Group 3 contained 6 carcinogens including 4 estrogenic substances, implying the group of estrogenic carcinogens. Gene network analyses revealed that the significantly altered genes in Group 1 included Bax, Tnfrsf6, Btg2, Mgmt and Abcb1b, suggesting that p53-mediated signaling pathway involved in early pathologic alterations associated with preceding mutagenic carcinogenesis. Thus, the common transcriptional signatures for each group might reflect the early molecular events of carcinogenesis and hence would enable us to identify the biomarker genes, and then to develop a new assay for carcinogenesis prediction.
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- 2009
13. Por secretion system-dependent secretion and glycosylation of Porphyromonas gingivalis hemin-binding protein 35.
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Mikio Shoji, Keiko Sato, Hideharu Yukitake, Yoshio Kondo, Yuka Narita, Tomoko Kadowaki, Mariko Naito, and Koji Nakayama
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Medicine ,Science - Abstract
The anaerobic Gram-negative bacterium Porphyromonas gingivalis is a major pathogen in severe forms of periodontal disease and refractory periapical perodontitis. We have recently found that P. gingivalis has a novel secretion system named the Por secretion system (PorSS), which is responsible for secretion of major extracellular proteinases, Arg-gingipains (Rgps) and Lys-gingipain. These proteinases contain conserved C-terminal domains (CTDs) in their C-termini. Hemin-binding protein 35 (HBP35), which is one of the outer membrane proteins of P. gingivalis and contributes to its haem utilization, also contains a CTD, suggesting that HBP35 is translocated to the cell surface via the PorSS. In this study, immunoblot analysis of P. gingivalis mutants deficient in the PorSS or in the biosynthesis of anionic polysaccharide-lipopolysaccharide (A-LPS) revealed that HBP35 is translocated to the cell surface via the PorSS and is glycosylated with A-LPS. From deletion analysis with a GFP-CTD[HBP35] green fluorescent protein fusion, the C-terminal 22 amino acid residues of CTD[HBP35] were found to be required for cell surface translocation and glycosylation. The GFP-CTD fusion study also revealed that the CTDs of CPG70, peptidylarginine deiminase, P27 and RgpB play roles in PorSS-dependent translocation and glycosylation. However, CTD-region peptides were not found in samples of glycosylated HBP35 protein by peptide map fingerprinting analysis, and antibodies against CTD-regions peptides did not react with glycosylated HBP35 protein. These results suggest both that the CTD region functions as a recognition signal for the PorSS and that glycosylation of CTD proteins occurs after removal of the CTD region. Rabbits were used for making antisera against bacterial proteins in this study.
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- 2011
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14. Coincidence between transcriptome analyses on different microarray platforms using a parametric framework.
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Tomokazu Konishi, Fumikazu Konishi, Shigeru Takasaki, Kohei Inoue, Koji Nakayama, and Akihiko Konagaya
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Medicine ,Science - Abstract
A parametric framework for the analysis of transcriptome data is demonstrated to yield coincident results when applied to data acquired using two different microarray platforms. Microarrays are widely employed to acquire transcriptome information, and several platforms of chips are currently in use. However, discrepancies among studies are frequently reported, particularly among those performed using different platforms, casting doubt on the reliability of collected data. The inconsistency among observations can be largely attributed to differences among the analytical frameworks employed for data analysis. The existing frameworks are based on different philosophies and yield different results, but all involve normalization against a standard determined from the data to be analyzed. In the present study, a parametric framework based on a strict model for normalization is applied to data acquired using several slide-glass-type chips and GeneChip. The model is based on a common statistical characteristic of microarray data, and each set of chip data is normalized on the basis of a linear relationship with this model. In the proposed framework, the expressional changes observed and genes selected are coincident between platforms, achieving superior universality of data compared to other frameworks.
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- 2008
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15. A Puncturing Device that Mimics the Mechanism of Mosquito's Proboscis and Labium - Verification of the Effect of Skin Deformation / Needle Buckling Prevention Mechanism and Puncture Experiment on Artificial Skin and Experimental Animals -.
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Shunki Yamamoto, Seiji Aoyagi, Masahiro Yamada, Tomokazu Takahashi, Masato Suzuki, Toshio Nagashima, Atsushi Kunugi, Makoto Chiyonobu, Takeshi Kuroiwa, Ryota Hosomi, Kenji Fukunaga, Daisuke Uta, Tomonori Takazawa, Tomoyuki Hikitsuchi, Yumi Kawajiri, and Koji Nakayama
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- 2020
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16. 10 kV SiC thyristor for High Voltage Pulsed Power Generators
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Koji Nakayama, Yasunori Tanaka, Tomohisa Kato, Kazutoshi Kojima, Mitsuru Sometani, and Yoshiyuki Yonezawa
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- 2023
17. Porphyromonas gingivalis Gingipains Induce Cyclooxygenase-2 Expression and Prostaglandin E2 Production via ERK1/2-Activated AP-1 (c-Jun/c-Fos) and IKK/NF-κB p65 Cascades
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Masaaki Nakayama, Mariko Naito, Kazuhiro Omori, Shintaro Ono, Koji Nakayama, and Naoya Ohara
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Immunology ,Immunology and Allergy - Abstract
Porphyromonas gingivalis is commonly known as one of the major pathogens contributing to periodontitis, and its persistent infection may increase the risk for the disease. The proinflammatory mediators, including IL-6, TNF-α, and cyclooxygenase-2 (COX-2)/PGE2, are closely associated with progression of periodontitis. In this study, we focused on the cysteine protease “gingipains,” lysine-specific gingipain, arginine-specific gingipain (Rgp) A, and RgpB, produced by P. gingivalis, and used the wild-type strain and several gene-deletion mutants (rgpA, rgpB, kgp, and fimA) to elucidate the involvement of gingipains in COX-2 expression and PGE2 production. We infected human monocytes, which are THP-1 cells and primary monocytes, with these bacterial strains and found that gingipains were involved in induction of COX-2 expression and PGE2 production. We have shown that the protease activity of gingipains was crucial for these events by using gingipain inhibitors. Furthermore, activation of ERK1/2 and IκB kinase was required for gingipain-induced COX-2 expression/PGE2 production, and these kinases activated two transcription factors, c-Jun/c-Fos (AP-1) and NF-κB p65, respectively. In particular, these data suggest that gingipain-induced c-Fos expression via ERK is essential for AP-1 formation with c-Jun, and activation of AP-1 and NF-κB p65 plays a central role in COX-2 expression/PGE2 production. Thus, we show the (to our knowledge) novel finding that gingipains with the protease activity from P. gingivalis induce COX-2 expression and PGE2 production via activation of MEK/ERK/AP-1 and IκB kinase/NF-κB p65 in human monocytes. Hence it is likely that gingipains closely contribute to the inflammation of periodontal tissues.
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- 2022
18. Report on the practice of 'Goal Achievement Seminar' using Mandala Charts
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Kazuki, Nomakawauchi, Koji, Nakayama, Kazuya, Yamasaki, 岡山理科大学教育推進機構教育開発センター, 岡山理科大学教育推進機構基盤教育センター, 岡山理科大学大学院マネジメント研究科, and Center for Fundamental Education, Institute for the Advancement of Higher Education, Okayama University of Science
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- 2022
19. Insertional Inactivation and Gene Complementation of Prevotella intermedia Type IX Secretion System Reveals Its Indispensable Roles in Black Pigmentation, Hemagglutination, Protease Activity of Interpain A, and Biofilm Formation
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Mariko Naito, Mikio Shoji, Keiko Sato, and Koji Nakayama
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Base Composition ,Pigmentation ,Virulence Factors ,Hemagglutination ,Sequence Analysis, DNA ,Microbiology ,Prevotella intermedia ,Bacterial Proteins ,Cysteine Proteases ,Biofilms ,RNA, Ribosomal, 16S ,Humans ,Molecular Biology ,Bacterial Secretion Systems ,Phylogeny ,Research Article - Abstract
Prevotella intermedia, a Gram-negative oral anaerobic bacterium, is frequently isolated from the periodontal pockets of patients with chronic periodontitis. In recent years, the involvement of the bacterium in respiratory tract infections as well as in oral infections has been revealed. P. intermedia possesses several potent virulence factors, such as cysteine proteinase interpain A encoded by the inpA gene. The genome of P. intermedia carries genes of the type IX secretion system (T9SS), which enables the translocation of virulence factors across the outer membrane in several pathogens belonging to the phylum Bacteroidetes; however, it is still unclear whether the T9SS is functional in this microorganism. Recently, we performed targeted mutagenesis in the strain OMA14 of P. intermedia. Here, we successfully obtained mutants deficient in inpA and the T9SS component genes porK and porT. None of the mutants exhibited protease activity of interpain A. The porK and porT mutants, but not the inpA mutant, showed defects in colony pigmentation, hemagglutination, and biofilm formation. We also obtained a complemented strain for the porK gene that recovered all the above abilities. These results indicate that T9SS functions in P. intermedia and that interpain A is one of the T9SS cargo proteins. IMPORTANCE The virulence factors of periodontal pathogens such as Prevotella intermedia have not been elucidated. Using our established procedure, we succeeded in generating type IX secretion system mutants and gene complementation strains that might transfer virulence factors to the bacterial surface. The generated strains clearly indicate that T9SS in P. intermedia is essential for colonial pigmentation, hemagglutination, and biofilm formation. These results indicated that interpain A is a T9SS cargo protein.
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- 2022
20. A Multi-Rail Structure in the Cell Envelope for the Bacteroidetes Gliding Machinery
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Satoshi Shibata, Yuhei O. Tahara, Eisaku Katayama, Akihiro Kawamoto, Takayuki Kato, Yongtao Zhu, Daisuke Nakane, Keiichi Namba, Makoto Miyata, Mark J. McBride, and Koji Nakayama
- Abstract
Many bacteria belonging to the phylum Bacteroidetes move on solid surfaces, which is called gliding motility. In our previous study with the Bacteroidetes gliding bacterium Flavobacterium johnsoniae, we proposed a helical loop track model, where adhesive SprB filaments are propelled along a left-handed closed helical loop on the cell surface. Attachment of SprB to the substratum results in cell movement. In this study, we observed the gliding cell rotating counterclockwise about its axis when viewed from the rear to the advancing direction of the cell, which was consistent with the helical loop track model. Total internal reflection fluorescence microscopy of SprB on a gliding cell revealed that one labeled SprB focus sometimes overtook and passed another SprB focus that was moving in the same direction, suggesting the presence of multiple lanes in the helical loop track. Several electron microscopic analyses revealed the presence of a multi-rail structure underneath the outer membrane, which was associated with SprB filaments and contained GldJ protein. A similar structure was observed in the distantly related marine gliding Bacteroidetes Saprospira grandis. These results provide new insights into the mechanism of Bacteroidetes gliding motility, in which the SprB filaments are propelled along the multi-rails underneath the outer membrane.
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- 2022
21. Colony spreading of the gliding bacterium Flavobacterium johnsoniae in the absence of the motility adhesin SprB
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Koji Nakayama, Mari Sato, Yuka Narita, Chikara Sato, Yuri Hatano, Keiko Sato, Mariko Naito, Masami Naya, Yoshio Kondo, and Keiji Nagano
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0301 basic medicine ,food.ingredient ,Gliding motility ,Molecular biology ,Lipoproteins ,Movement ,Science ,030106 microbiology ,Cell ,Motility ,Microbiology ,Flavobacterium ,Article ,03 medical and health sciences ,food ,Bacterial Proteins ,Soft agar ,medicine ,Agar ,Adhesins, Bacterial ,Flavobacterium johnsoniae ,Multidisciplinary ,biology ,Chemistry ,biology.organism_classification ,Cell biology ,Bacterial adhesin ,030104 developmental biology ,medicine.anatomical_structure ,Mutation ,Medicine ,Bacteria - Abstract
Colony spreading of Flavobacterium johnsoniae is shown to include gliding motility using the cell surface adhesin SprB, and is drastically affected by agar and glucose concentrations. Wild-type (WT) and ΔsprB mutant cells formed nonspreading colonies on soft agar, but spreading dendritic colonies on soft agar containing glucose. In the presence of glucose, an initial cell growth-dependent phase was followed by a secondary SprB-independent, gliding motility-dependent phase. The branching pattern of a ΔsprB colony was less complex than the pattern formed by the WT. Mesoscopic and microstructural information was obtained by atmospheric scanning electron microscopy (ASEM) and transmission EM, respectively. In the growth-dependent phase of WT colonies, dendritic tips spread rapidly by the movement of individual cells. In the following SprB-independent phase, leading tips were extended outwards by the movement of dynamic windmill-like rolling centers, and the lipoproteins were expressed more abundantly. Dark spots in WT cells during the growth-dependent spreading phase were not observed in the SprB-independent phase. Various mutations showed that the lipoproteins and the motility machinery were necessary for SprB-independent spreading. Overall, SprB-independent colony spreading is influenced by the lipoproteins, some of which are involved in the gliding machinery, and medium conditions, which together determine the nutrient-seeking behavior., Scientific Reports, 11(1), art.no.967; 2021
- Published
- 2021
22. Team YowAI-2001 Description.
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Koji Nakayama and Ikuo Takeuchi
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- 2001
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23. PorM, a core component of bacterial type IX secretion system, forms a dimer with a unique kinked-rod shape
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Keiko Sato, Kodai Okada, Katsumi Imada, and Koji Nakayama
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Models, Molecular ,0301 basic medicine ,Dimer ,Biophysics ,Crystallography, X-Ray ,Biochemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Bacterial Proteins ,Protein Domains ,Humans ,Inner membrane ,Protein Interaction Domains and Motifs ,Secretion ,Amino Acid Sequence ,Protein Structure, Quaternary ,Bacterial Secretion Systems ,Molecular Biology ,Porphyromonas gingivalis ,Sequence Homology, Amino Acid ,biology ,Protein Stability ,Chemistry ,Core component ,Cell Biology ,Periplasmic space ,biology.organism_classification ,Gingipain ,030104 developmental biology ,Genes, Bacterial ,030220 oncology & carcinogenesis ,Mutation ,Bacterial outer membrane - Abstract
Porphyromonas gingivalis, which is a major pathogen of the periodontal disease, secrets virulence factors such as gingipain proteases via the type IX secretion system (T9SS). T9SS consists of a trans-periplasmic core complex, the outer membrane translocon complex and the cell-surface complex attached on the outer membrane. PorM is a major component of the trans-periplasmic core complex and is believed to connect the outer membrane component with the inner membrane component. Recent structural studies have revealed that the periplasmic region of GldM, a PorM homolog of a gliding bacterium, consist of four domains and forms a dimer with a straight rod shape. However, only fragment structures are known for PorM. Moreover, one of the PorM fragment structure shows a kink. Here we show the structure of the entire structure of the periplasmic region of PorM (PorMp) at 3.7 A resolution. PorMp is made up of four domains and forms a unique dimeric structure with an asymmetric, kinked-rod shape. The structure and the following mutational analysis revealed that R204 stabilizes the kink between the D1 and D2 domains and is essential for gingipains secretion, suggesting that the kinked structure of PorM is important for the functional T9SS formation.
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- 2020
24. Effect of Porphyromonas gingivalis infection on gut dysbiosis and resultant arthritis exacerbation in mouse model
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Syuichi Munenaga, Isamu Kado, Mikio Shoji, Toshihisa Kawai, Hidemi Kurihara, Yuta Hamamoto, Eiji Sugiyama, Kotaro Tanimoto, Noriyoshi Mizuno, Jyunzo Hisatsune, Kazuhisa Ouhara, Koji Nakayama, Tsuyoshi Fujita, Shintaro Hirata, Shinji Matsuda, Tatsuhiko Ozawa, Mikihito Kajiya, and Hiroyuki Kishi
- Subjects
0301 basic medicine ,medicine.medical_specialty ,lcsh:Diseases of the musculoskeletal system ,Arthritis ,Gut flora ,Inflammatory bowel disease ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Animals ,Rheumatoid arthritis ,Periodontitis ,Porphyromonas gingivalis ,030203 arthritis & rheumatology ,biology ,business.industry ,medicine.disease ,biology.organism_classification ,Arthritis, Experimental ,Rheumatology ,030104 developmental biology ,Immunology ,Protein-Arginine Deiminases ,Dysbiosis ,Citrullinated protein ,lcsh:RC925-935 ,business ,Research Article - Abstract
Background Porphyromonas gingivalis (Pg) infection causes periodontal disease and exacerbates rheumatoid arthritis (RA). It is reported that inoculation of periodontopathogenic bacteria (i.e., Pg) can alter gut microbiota composition in the animal models. Gut microbiota dysbiosis in human has shown strong associations with systemic diseases, including RA, diabetes mellitus, and inflammatory bowel disease. Therefore, this study investigated dysbiosis-mediated arthritis by Pg oral inoculation in an experimental arthritis model mouse. Methods Pg inoculation in the oral cavity twice a week for 6 weeks was performed to induce periodontitis in SKG mice. Concomitantly, a single intraperitoneal (i.p.) injection of laminarin (LA) was administered to induce experimental arthritis (Pg-LA mouse). Citrullinated protein (CP) and IL-6 levels in serum as well as periodontal, intestinal, and joint tissues were measured by ELISA. Gut microbiota composition was determined by pyrosequencing the 16 s ribosomal RNA genes after DNA purification of mouse feces. Fecal microbiota transplantation (FMT) was performed by transferring Pg-LA-derived feces to normal SKG mice. The effects of Pg peptidylarginine deiminase (PgPAD) on the level of citrullinated proteins and arthritis progression were determined using a PgPAD knockout mutant. Results Periodontal alveolar bone loss and IL-6 in gingival tissue were induced by Pg oral infection, as well as severe joint destruction, increased arthritis scores (AS), and both IL-6 and CP productions in serum, joint, and intestinal tissues. Distribution of Deferribacteres and S24-7 was decreased, while CP was significantly increased in gingiva, joint, and intestinal tissues of Pg-inoculated experimental arthritis mice compared to experimental arthritis mice without Pg inoculation. Further, FMT from Pg-inoculated experimental arthritis mice reproduced donor gut microbiota and resulted in severe joint destruction with increased IL-6 and CP production in joint and intestinal tissues. The average AS of FMT from Pg-inoculated experimental arthritis was much higher than that of donor mouse. However, inoculation of the PgPAD knockout mutant inhibited the elevation of arthritis scores and ACPA level in serum and reduced CP amount in gingival, joint, and intestinal tissues compared to Pg wild-type inoculation. Conclusion Pg oral infection affected gut microbiota dysbiosis and joint destruction via increased CP generation.
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- 2020
25. Biogenesis of Type V pili
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Satoshi Shibata, Mariko Naito, Mikio Shoji, Koji Nakayama, and Takayuki Sueyoshi
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Proteases ,Protein Conformation ,Lipoproteins ,Immunology ,Fimbria ,Crystallography, X-Ray ,Microbiology ,Pilus ,03 medical and health sciences ,Virology ,Periodontitis ,Porphyromonas gingivalis ,030304 developmental biology ,0303 health sciences ,lipoprotain ,biology ,030306 microbiology ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Cell biology ,Protein Transport ,periodontal pathogen ,Lipoprotein transport ,Pilin ,Fimbriae, Bacterial ,bacterial components ,biology.protein ,bacteria ,pili ,Fimbriae Proteins ,Bacterial outer membrane ,Bacteria - Abstract
Pili or fimbriae, which are filamentous structures present on the surface of bacteria, were purified from a periodontal pathogen, Porphyromonas gingivalis, in 1980s. The protein component of pili (stalk pilin), which is its major component, was named FimA; it has a molecular weight of approximately 41 kDa. Because the molecular weight of the pilin from P. gingivalis is twice that of pilins from other bacterial pili, the P. gingivalis Fim pili were suggested to be formed via a novel mechanism. In earlier studies, we reported that the FimA pilin is secreted on the cell surface as a lipoprotein precursor, and the subsequent N-terminal processing of the FimA precursor by arginine-specific proteases is necessary for Fim pili formation. The crystal structures of FimA and its related proteins were determined recently, which show that Fim pili are formed by a protease-mediated strand-exchange mechanism. The most recent study conducted by us, wherein we performed cryoelectron microscopy of the pilus structure, provided evidence in support of this mechanism. As the P. gingivalis Fim pili are formed through novel transport and assembly mechanisms, such pili are now designated as Type V pili. Surface lipoproteins, including the anchor pilin FimB of Fim pili that are present on the outer membrane, have been detected in certain Gram-negative bacteria. Here, we describe the assembly mechanisms of pili, including those of Type V and other pili, as well as the lipoprotein transport mechanisms., Microbiology and Immunology, 64(10), pp.643-656; 2020
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- 2020
26. 20 kV-Class Ultra-High Voltage 4H-SiC n-IE-IGBTs
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Koji Nakayama, Akihiro Koyama, Yuji Kiuchi, Atsuko Kimoto, Tomohisa Kato, Kensuke Takenaka, Tomonori Mizushima, Yoshiyuki Yonezawa, Hitoshi Ishimori, Mitsuru Sometani, Hajime Okumura, Shinichiro Matsunaga, and Manabu Takei
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010302 applied physics ,Class (computer programming) ,Materials science ,business.industry ,Mechanical Engineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Ultra high voltage ,Mechanics of Materials ,0103 physical sciences ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
We demonstrate 20 kV-class 4H-SiC n-channel implantation and epitaxial (IE)-IGBTs having both low on-state voltage and high blocking characteristics. We fabricated n-IE-IGBTs on a (0001) silicon face with free-standing epitaxial layers. Effective carrier lifetime increased significantly from 0.9 μs to 9.6 μs by a lifetime enhancement process. We used the IE structure to suppress an increase of the surface p+-well concentration, reduce implantation damage at the p+-well, and reduce junction field effect transistor (JFET) region resistance by ion implantation as a counter doping. The n-IE-IGBT at 100 A/cm2 on-state voltage and specific differential on-resistance was 8.2 V and 36.9 mΩcm2, respectively, at room temperature with a 30 V gate voltage. The blocking voltage was 26.8 kV at 45.7 μA.
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- 2020
27. Structure of polymerized type V pilin reveals assembly mechanism involving protease-mediated strand exchange
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Satoshi Shibata, Hideyuki Matsunami, Mikio Shoji, Kodai Okada, Koji Nakayama, Matthias Wolf, Katsumi Imada, and Melissa M. Matthews
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Models, Molecular ,Microbiology (medical) ,Protein Conformation ,Protein subunit ,Immunology ,Crystallography, X-Ray ,Cleavage (embryo) ,Applied Microbiology and Biotechnology ,Microbiology ,Pilus ,Structure-Activity Relationship ,03 medical and health sciences ,Protein structure ,Genetics ,Amino Acid Sequence ,Porphyromonas gingivalis ,030304 developmental biology ,0303 health sciences ,biology ,030306 microbiology ,Chemistry ,C-terminus ,Cryoelectron Microscopy ,Biofilm ,Cell Biology ,biology.organism_classification ,Pilin ,Biophysics ,biology.protein ,Fimbriae Proteins ,Protein Multimerization ,Peptide Hydrolases ,Protein Binding - Abstract
Bacterial adhesion is a general strategy for host–microbe and microbe–microbe interactions. Adhesive pili are essential for colonization, biofilm formation, virulence and pathogenesis of many environmental and pathogenic bacteria1,2. Members of the class Bacteroidia have unique type V pili, assembled by protease-mediated polymerization3. Porphyromonas gingivalis is the main contributor to periodontal disease and its type V pili are a key factor for its virulence4. However, the structure of the polymerized pilus and its assembly mechanism are unknown. Here we show structures of polymerized and monomeric states of FimA stalk pilin from P. gingivalis, determined by cryo-electron microscopy and crystallography. The atomic model of assembled FimA shows that the C-terminal strand of a donor subunit is inserted into a groove in the β-sheet of an acceptor subunit after N-terminal cleavage by the protease RgpB. The C terminus of the donor strand is essential for polymerization. We propose that type V pili assemble via a sequential polar assembly mechanism at the cell surface, involving protease-mediated strand exchange, employed by various Gram-negative species belonging to the class Bacteroidia. Our results reveal functional surfaces related to pathogenic properties of polymerized FimA. These insights may facilitate development of antibacterial drugs.
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- 2020
28. ウンドウノウ ノ ケイトウジュ セイメイ ノ ケイトウジュ ニオケル ウンドウ システム シンカ ニツイテノ テイアン
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Azuma Taoka, Tohru Minamino, Isil Tulum, Yoshiaki Kinosita, Kentaro Kato, Robert Robinson, Kazuo Inaba, Hirofumi Wada, Hiroyuki Mori, Seiji Kojima, Ken-ichi Wakabayashi, Shuichi Nakamura, Chikara Kaito, Masayoshi Nishiyama, Katsuya Shimabukuro, Shin Haruta, Koji Nakayama, Yosuke Tashiro, Shun ichi Fukushima, Masatada Tamakoshi, Yoshihiro Fukumori, Taro Q.P. Uyeda, Masahiro Ito, Tsuyoshi Kenri, Michio Homma, Satoshi Shibata, Daisuke Nakane, and Makoto Miyata
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three domains ,Dynein ,Mollicutes ,Motility ,Kinesins ,Context (language use) ,appendage ,Review Article ,Flagellum ,Biology ,peptidoglycan ,Myosins ,Motor protein ,Evolution, Molecular ,03 medical and health sciences ,motor protein ,Cell Movement ,Myosin ,Genetics ,Animals ,Humans ,Actin ,Phylogeny ,030304 developmental biology ,0303 health sciences ,Bacteria ,モリクテス綱 ,べん毛 ,Dyneins ,cytoskeleton ,Cell Biology ,Biological Evolution ,Cell biology ,Actin Cytoskeleton ,Flagella ,モータータンパク質 ,ペプチドグリカン層 ,Kinesin ,細胞骨格 ,membrane remodeling - Abstract
Motility often plays a decisive role in the survival of species. Five systems of motility have been studied in depth: those propelled by bacterial flagella, eukaryotic actin polymerization and the eukaryotic motor proteins myosin, kinesin and dynein. However, many organisms exhibit surprisingly diverse motilities, and advances in genomics, molecular biology and imaging have showed that those motilities have inherently independent mechanisms. This makes defining the breadth of motility nontrivial, because novel motilities may be driven by unknown mechanisms. Here, we classify the known motilities based on the unique classes of movement‐producing protein architectures. Based on this criterion, the current total of independent motility systems stands at 18 types. In this perspective, we discuss these modes of motility relative to the latest phylogenetic Tree of Life and propose a history of motility. During the ~4 billion years since the emergence of life, motility arose in Bacteria with flagella and pili, and in Archaea with archaella. Newer modes of motility became possible in Eukarya with changes to the cell envelope. Presence or absence of a peptidoglycan layer, the acquisition of robust membrane dynamics, the enlargement of cells and environmental opportunities likely provided the context for the (co)evolution of novel types of motility., The known motilities are classified based on the unique classes of movement‐producing protein architectures. Based on this criterion, the current total of independent motility systems stands at 18 types. Presence or absence of a peptidoglycan layer, the acquisition of robust membrane dynamics, the enlargement of cells and environmental opportunities likely provided the context for the (co)evolution of novel types of motility.
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- 2020
29. Draft genome of Tanacetum cinerariifolium, the natural source of mosquito coil
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Koji Nakayama, Akira Shiraishi, Honoo Satake, and Takanori Yamashiro
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0106 biological sciences ,0301 basic medicine ,Transposable element ,Pyrethrum ,lcsh:Medicine ,Genes, Plant ,01 natural sciences ,Genome ,Article ,Plant evolution ,03 medical and health sciences ,chemistry.chemical_compound ,Pyrethrins ,Pyrethrin ,Animals ,lcsh:Science ,Gene ,Phylogeny ,Plant Proteins ,Whole genome sequencing ,Genetics ,Chrysanthemum cinerariifolium ,Multidisciplinary ,biology ,Phylogenetic tree ,lcsh:R ,biology.organism_classification ,White (mutation) ,Culicidae ,030104 developmental biology ,chemistry ,DNA Transposable Elements ,lcsh:Q ,Secondary metabolism ,Genome, Plant ,010606 plant biology & botany - Abstract
Pyrethrum (Tanacetum cinerariifolium), which is a perennial Asteraceae plant with white daisy-like flowers, is the original source of mosquito coils and is known for the biosynthesis of the pyrethrin class of natural insecticides. However, the molecular basis of the production of pyrethrins by T. cinerariifolium has yet to be fully elucidated. Here, we present the 7.1-Gb draft genome of T. cinerariifolium, consisting of 2,016,451 scaffolds and 60,080 genes predicted with high confidence. Notably, analyses of transposable elements (TEs) indicated that TEs occupy 33.84% of the genome sequence. Furthermore, TEs of the sire and oryco clades were found to be enriched in the T. cinerariifolium-specific evolutionary lineage, occupying a total of 13% of the genome sequence, a proportion approximately 8-fold higher than that in other plants. InterProScan analysis demonstrated that biodefense-related toxic proteins (e.g., ribosome inactivating proteins), signal transduction-related proteins (e.g., histidine kinases), and metabolic enzymes (e.g., lipoxygenases, acyl-CoA dehydrogenases/oxygenases, and P450s) are also highly enriched in the T. cinerariifolium genome. Molecular phylogenetic analysis detected a variety of enzymes with genus-specific multiplication, including both common enzymes and others that appear to be specific to pyrethrin biosynthesis. Together, these data identify possible novel components of the pyrethrin biosynthesis pathway and provide new insights into the unique genomic features of T. cinerariifolium.
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- 2019
30. Utilization of SiC Avalanche Diode as a Solid-State Snubber
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Kunio Koseki, Yasunori Tanaka, Koji Nakayama, and Masayuki Yamamoto
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- 2021
31. Initiation of Shockley Stacking Fault Expansion in 4H-SiC P-i-N Diodes
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Akihiro Goryu, Koji Nakayama, Chiharu Ota, Tomohisa Kato, Yoshiyuki Yonezawa, Aoi Okada, Ryosuke Iijima, Johji Nishio, and Hajime Okumura
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010302 applied physics ,Thesaurus (information retrieval) ,Materials science ,Mechanical Engineering ,P i n diode ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Engineering physics ,Search engine ,Mechanics of Materials ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,Science, technology and society ,Current density ,Stacking fault ,Diode - Abstract
To understand the effects of temperature and injection current density on expansion of Shockley stacking faults (SSFs) from basal-plane dislocations in 4H-SiC p-i-n diodes, the threshold current density for SSF expansion was investigated at eight temperatures by electroluminescence image observation. The threshold injection current density was found to decrease at lower temperatures and to increase at higher temperatures. We identified the origin of this temperature dependence and found that the limiting factor for expansion differed depending on the temperature.
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- 2019
32. PGN_0297 is an essential component of the type IX secretion system (T9SS) in Porphyromonas gingivalis : Tn-seq analysis for exhaustive identification of T9SS-related genes
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Takashi Tominaga, Mikio Shoji, Mariko Naito, and Koji Nakayama
- Subjects
DNA, Bacterial ,Transposable element ,Candidate gene ,Virulence Factors ,Immunology ,Mutant ,Virulence ,Microbiology ,03 medical and health sciences ,Tn-seq analysis ,Bacterial Proteins ,Virology ,Adhesins, Bacterial ,Bacterial Secretion Systems ,Porphyromonas gingivalis ,Gene ,Sequence Deletion ,030304 developmental biology ,Genetics ,0303 health sciences ,biology ,Pigmentation ,030306 microbiology ,colony pigmentation ,Hemagglutination ,Tn‐seq analysis ,Bacteriology ,Original Articles ,Gene Expression Regulation, Bacterial ,biology.organism_classification ,Gingipain ,Cysteine Endopeptidases ,Genes, Bacterial ,DNA Transposable Elements ,Gingipain Cysteine Endopeptidases ,Original Article ,Bacterial outer membrane ,type IX secretion system ,Bacterial Outer Membrane Proteins ,Peptide Hydrolases - Abstract
The type IX secretion system (T9SS) was originally discovered in Porphyromonas gingivalis, one of the pathogenic bacteria associated with periodontal disease and is now known to be present in many members of the phylum Bacteroidetes. The T9SS secretes a number of potent virulence factors,including the highly hydrolytic proteases called gingipains, across the outer membrane in P.gingivalis. To understand the entire machinery of T9SS, an exhaustive search for T9SS-related genes in P. gingivalis using the mariner family transposon (Tn) and Tn-seq analysis was performed. Seven hundred and two Tn insertion sites in Tn mutants with no colony pigmentation that is associated with Lys-gingipain (Kgp) defectiveness were determined, and it was found that the Tn was inserted in the kgp gene and 54 T9SS-related candidate genes. Thirty-three out of the 54 genes were already known as T9SS-related genes. Furthermore, deletion mutant analysis of the remaining 21 genes revealed that they were not related to the T9SS. The 33 T9SS-related genes include a gene for PGN_0297, which was found to be associated with the T9SS components PorK and PorN. A PGN_0297 gene deletion mutant was constructed, and it was found that the mutant showed no colony pigmentation, hemagglutination or gingipain activities, indicating that PGN_0297 was an essential component of the T9SS. The 33 genes did not include the six genes (gppX, omp17, porY, rfa, sigP and wzx) that were also reported as T9SS-related genes. gppX deletion and insertion mutants were constructed, and it was found that they did not show deficiency in the T9SS., Microbiology and Immunology, 63(1), pp.11-20; 2019
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- 2019
33. Type IX Secretion System Cargo Proteins Are Glycosylated at the C Terminus with a Novel Linking Sugar of the Wbp/Vim Pathway
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Michael G. Leeming, Paul D. Veith, Richard A. J. O'Hair, Shuai Nie, Eric C. Reynolds, Michelle D. Glew, Koji Nakayama, Mikio Shoji, and Gavin E. Reid
- Subjects
Lipopolysaccharides ,glycoprotein ,Molecular Biology and Physiology ,Glycosylation ,Microbiology ,Mass Spectrometry ,Serine ,03 medical and health sciences ,chemistry.chemical_compound ,Virology ,Tannerella forsythia ,Secretion ,Porphyromonas gingivalis ,Bacterial Secretion Systems ,030304 developmental biology ,chemistry.chemical_classification ,0303 health sciences ,biology ,030306 microbiology ,Chemistry ,lipopolysaccharide ,biology.organism_classification ,QR1-502 ,Amino acid ,Biosynthetic Pathways ,stomatognathic diseases ,Protein Transport ,Biochemistry ,Bacterial outer membrane ,Glycoprotein ,Sugars ,Research Article ,type IX secretion system - Abstract
Porphyromonas gingivalis and Tannerella forsythia, two pathogens associated with severe gum disease, use the type IX secretion system (T9SS) to secrete and attach toxic arrays of virulence factor proteins to their cell surfaces. The proteins are tethered to the outer membrane via glycolipid anchors that have remained unidentified for more than 2 decades. In this study, the first sugar molecules (linking sugars) in these anchors are identified and found to be novel compounds. The novel biosynthetic pathway of these linking sugars is also elucidated. A diverse range of bacteria that do not have the T9SS were found to have the genes for this pathway, suggesting that they may synthesize similar linking sugars for utilization in different systems. Since the cell surface attachment of virulence factors is essential for virulence, these findings reveal new targets for the development of novel therapies., Porphyromonas gingivalis and Tannerella forsythia use the type IX secretion system to secrete cargo proteins to the cell surface where they are anchored via glycolipids. In P. gingivalis, the glycolipid is anionic lipopolysaccharide (A-LPS), of partially known structure. Modified cargo proteins were deglycosylated using trifluoromethanesulfonic acid and digested with trypsin or proteinase K. The residual modifications were then extensively analyzed by tandem mass spectrometry. The C terminus of each cargo protein was amide-bonded to a linking sugar whose structure was deduced to be 2-N-seryl, 3-N-acetylglucuronamide in P. gingivalis and 2-N-glycyl, 3-N-acetylmannuronic acid in T. forsythia. The structures indicated the involvement of the Wbp pathway to produce 2,3-di-N-acetylglucuronic acid and a WbpS amidotransferase to produce the uronamide form of this sugar in P. gingivalis. The wbpS gene was identified as PGN_1234 as its deletion resulted in the inability to produce the uronamide. In addition, the P. gingivalis vimA mutant which lacks A-LPS was successfully complemented by the T. forsythia vimA gene; however, the linking sugar was altered to include glycine rather than serine. After removal of the acetyl group at C-2 by the putative deacetylase, VimE, VimA presumably transfers the amino acid to complete the biosynthesis. The data explain all the enzyme activities required for the biosynthesis of the linking sugar accounting for six A-LPS-specific genes. The linking sugar is therefore the key compound that enables the attachment of cargo proteins in P. gingivalis and T. forsythia. We propose to designate this novel linking sugar biosynthetic pathway the Wbp/Vim pathway.
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- 2020
34. Surge absorption by the 430V mesa-structured SiC avalanche diode
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Masayuki Yamamoto, Kunio Koseki, Yasunori Tanaka, Shigeki Nishiyama, and Koji Nakayama
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Materials science ,Avalanche diode ,business.industry ,Inductor ,Avalanche breakdown ,law.invention ,law ,MOSFET ,Optoelectronics ,Resistor ,business ,Absorption (electromagnetic radiation) ,Current density ,Diode - Abstract
We evaluate the surge absorption capability of the 430V SiC avalanche diode at the switched current 100A, corresponding to the current density 35.4kA/cm2 for the diode with the diameter 0.6mm. It is shown that, even at such a huge current density, the surge absorption has been successfully achieved with no device damage. We also investigate the effect of an additional stray inductor as well as a gate resistor of a MOSFET. It is found that the reduction of the stray inductance between a switching device and the SiC avalanche diode by, e.g., the co-pack configuration, is essential to realize an excellent surge absorption performance at a high speed turn-off event. The characteristics after the avalanche breakdown at 200$^{\circ}C$ implies that the surge absorption performance is not affected by a high ambient temperature.
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- 2020
35. Transport and Polymerization of Porphyromonas gingivalis Type V Pili
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Mariko Naito, Koji Nakayama, Satoshi Shibata, and Mikio Shoji
- Subjects
0303 health sciences ,biology ,030306 microbiology ,Chemistry ,Protein subunit ,Fimbria ,biology.organism_classification ,Pilus ,03 medical and health sciences ,Biochemistry ,Polymerization ,Pilin ,biology.protein ,Gene ,Porphyromonas gingivalis ,Bacteria ,030304 developmental biology - Abstract
Adhesive pili (or fimbriae) in bacteria are classified into five types, among which type V pili have been most recently described. Type V pili differ from other pili types with respect to transport mechanism, structure, and pilin synthesis. Genes of type V pili are restricted to the phylum Bacteroidetes. Protein subunits that compose type V pili are transported to the cell surface as lipoprotein precursors and then polymerized into a pilus through a strand-exchange mechanism, which is demonstrated by several experiments, including palmitic acid labeling and Cys-Cys cross-linking analysis. Here, we describe the use of these methods to analyze type V pili.
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- 2020
36. Effect of Porphyromonas gingivalis infection on gut dysbiosis and arthritis exacerbation in mouse model
- Author
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Yuta Hamamoto, Kazuhisa Ouhara, Syuichi Munenaga, Mikio Shoji, Tatsuhiko Ozawa, Jyunzo Hisatsune, Isamu Kado, Mikihito Kajiya, Shinji Matsuda, Toshihisa Kawai, Noriyoshi Mizuno, Tsuyoshi Fujita, Shintaro Hirata, Kotaro Tanimoto, Koji Nakayama, Hiroyuki Kishi, Eiji Sugiyama, and Hidemi Kurihara
- Abstract
Background: Porphyromonas gingivalis (Pg) infection causes periodontal disease and is involved in the exacerbation of rheumatoid arthritis (RA). Gut microbiota dysbiosis has shown strong associations with systemic diseases, including RA, diabetes mellitus, and inflammatory bowel disease, and inoculation of periodontopathogenic bacteria (i.e. Pg) can alter gut microbiota composition. Therefore, this study investigated dysbiosis-mediated arthritis exacerbation by Pg oral inoculation in an experimental arthritis model mouse.Methods: Pg inoculation in the oral cavity twice a week for 6 weeks was performed to induce periodontitis in SKG mice. Concomitantly, a single intraperitoneal (i.p.) injection of laminarin (LA) was administered to induce experimental arthritis (Pg-LA mouse). Citrullinated protein (CP) and IL-6 levels in periodontal, intestinal, and joint tissues, and serum were measured by ELISA. Gut microbiota composition was determined by sequencing the bacterial 16S rRNA after DNA purification of mouse feces. Fecal microbiota transplantation (FMT) was performed by transferring Pg-RA-derived feces to normal SKG mice. The effect of the Pg peptidylarginine deaminase (PgPAD) on the level of citrullinated proteins and arthritis progression were determined using PgPAD knockout mutant.Results: Periodontal alveolar bone loss and IL-6 in gingival tissue were induced by Pg oral infection, as well as severe joint destruction, increased arthritis scores (AS), and IL-6 and CP production in serum, joint, and intestinal tissues. Distribution of Deferribacteres and S24-7 was decreased, while CP was significantly increased in gingival, joint, and intestinal tissues of Pg-inoculated experimental arthritis mice compared to experimental arthritis mice without Pg inoculation. Further, FMT from Pg-inoculated experimental arthritis mice showed the reproduction of donor gut microbiota and resulted in severe joint destruction with increased IL-6 and CP production in joint and intestinal tissues. The avarage AS of FMT from Pg-inoculated experimental arthritis was much higher than that of donor mouse. However, inoculation of the PgPAD knockout mutant inhibited the elevation of arthritis scores, ACPA level in serum and reduced CP amount in gingival, joint, and intestinal tissues compared to Pg wild type inoculation .Conclusion: Pg oral infection affected gut microbiota dysbiosis and joint destruction via increased CP generation.
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- 2020
37. Effect of Porphyromonas gingivalis infection on gut dysbiosis and arthritis exacerbation in 1 mouse model
- Author
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Yuta Hamamoto, Kazuhisa Ouhara, Syuichi Munenaga, Mikio Shoji, Tatsuhiko Ozawa, Jyunzo Hisatsune, Isamu Kado, Mikihito Kajiya, Shinji Matsuda, Toshihisa Kawai, Noriyoshi Mizuno, Tsuyoshi Fujita, Shintaro Hirata, Kotaro Tanimoto, Koji Nakayama, Hiroyuki Kishi, Eiji Sugiyama, and Hidemi Kurihara
- Abstract
Background : Porphyromonas gingivalis (Pg) infection causes periodontal disease and is one of the causative bacteria of rheumatoid arthritis (RA) exacerbation. Gut microbiota dysbiosis has shown strong associations with systemic diseases, including RA, diabetes mellitus, and inflammatory bowel disease, and inoculation of periodontopathogenic bacteria (i.e. Pg) can alter gut microbiota composition. Therefore, this study investigated dysbiosis-mediated arthritis exacerbation by Pg oral inoculation in an experimental arthritis model mouse.Methods : Pg inoculation in the oral cavity twice a week for 6 weeks was performed to induce periodontitis in SKG mice. Concomitantly, a single intraperitoneal (i.p.) injection of laminarin (LA) was administered to induce experimental arthritis (Pg-LA mouse). Citrullinated protein (CP) and IL-6 levels in periodontal, intestinal, and joint tissues, and serum were measured by ELISA. Gut microbiota composition was determined by Miseq after DNA purification of mouse feces. Fecal microbiota transplantation (FMT) was performed by transferring Pg-RA-derived feces to normal mice. The effect of the Pg peptidylarginine deaminase (PgPAD) in arthritis progression was determined using PgPAD knockout mutant.Results : Periodontal alveolar bone loss and IL-6 in gingival tissue were induced by Pg oral infection, as well as severe joint destruction, increased arthritis scores (AS), and IL-6 and CP production in serum, joint, and intestinal tissues. Distribution of Deferribacteres and S24-7 was decreased, while CP was significantly increased in gingival, joint, and intestinal tissues of Pg-inoculated experimental arthritis mice compared to experimental arthritis mice without Pg inoculation. Further, FMT from Pg-inoculated experimental arthritis mice showed the reproduction of donor gut microbiota and resulted in severe joint destruction with increased IL-6 and CP production in joint and intestinal tissues. The maximum AS of FMT from Pg-inoculated experimental arthritis was much higher than that of donor mouse. However, inoculation of the PgPAD knockout mutant inhibited the elevation of arthritis scores, ACPA level in serum and reduced CP amount in gingival, joint, and intestinal tissues compared to Pg wild type inoculation .Conclusion : Pg oral infection exacerbated gut microbiota dysbiosis and joint destruction via increased CP generation.
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- 2020
38. Immunoglobulin‐like domains of the cargo proteins are essential for protein stability during secretion by the type IX secretion system
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Hideharu Yukitake, Koichi Hiratsuka, Mamoru Suzuki, Keiko Sato, Daisuke Nakane, Katsuki Takebe, Mikio Shoji, Shinji Kakuda, Mariko Naito, Yoshimitsu Abiko, Yoshio Kondo, Koji Nakayama, and Yuka Narita
- Subjects
0301 basic medicine ,Signal peptide ,Proteases ,medicine.medical_treatment ,030106 microbiology ,Biology ,Crystallography, X-Ray ,Microbiology ,Domain (software engineering) ,03 medical and health sciences ,Bacterial Proteins ,Sequence Analysis, Protein ,medicine ,Secretion ,Adhesins, Bacterial ,Bacterial Secretion Systems ,Molecular Biology ,chemistry.chemical_classification ,Protease ,Protein Stability ,Caseins ,Recombinant Proteins ,Cell biology ,Amino acid ,Gingipain ,Cysteine Endopeptidases ,chemistry ,Gingipain Cysteine Endopeptidases ,Muramidase ,Immunoglobulin Domains ,Serine Proteases ,Thioredoxin ,Porphyromonas gingivalis - Abstract
The periodontal pathogen Porphyromonas gingivalis secretes many potent virulence factors using the type IX secretion system (T9SS). T9SS cargo proteins that have been structurally determined by X-ray crystallography are composed of a signal peptide, functional domain(s), an immunoglobulin (Ig)-like domain and a C-terminal domain. Role of the Ig-like domains of cargo proteins in the T9SS has not been elucidated. Gingipain proteases, which are cargo proteins of the T9SS, were degraded when their Ig-like domains were lacking or truncated. The degradation was dependent on the activity of a quality control factor, HtrA protease. Another T9SS cargo protein, HBP35, which has a thioredoxin domain as a functional domain, was analyzed by X-ray crystallography, revealing that HBP35 has an Ig-like domain after the thioredoxin domain and that the hydrophobic regions of the thioredoxin domain and the Ig-like domain face each other. HBP35 with substitution of hydrophobic amino acids in the Ig-like domain was degraded depending on HtrA. These results suggest that the Ig-like domain mediates stability of the cargo proteins in the T9SS.
- Published
- 2018
39. Biogenesis of Type V pili
- Author
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Mikio, Shoji, Satoshi, Shibata, Takayuki, Sueyoshi, Mariko, Naito, Koji, Nakayama, Mikio, Shoji, Satoshi, Shibata, Takayuki, Sueyoshi, Mariko, Naito, and Koji, Nakayama
- Abstract
Pili or fimbriae, which are filamentous structures present on the surface of bacteria, were purified from a periodontal pathogen, Porphyromonas gingivalis, in 1980s. The protein component of pili (stalk pilin), which is its major component, was named FimA; it has a molecular weight of approximately 41 kDa. Because the molecular weight of the pilin from P. gingivalis is twice that of pilins from other bacterial pili, the P. gingivalis Fim pili were suggested to be formed via a novel mechanism. In earlier studies, we reported that the FimA pilin is secreted on the cell surface as a lipoprotein precursor, and the subsequent N‐terminal processing of the FimA precursor by arginine‐specific proteases is necessary for Fim pili formation. The crystal structures of FimA and its related proteins were determined recently, which show that Fim pili are formed by a protease‐mediated strand‐exchange mechanism. The most recent study conducted by us, wherein we performed cryoelectron microscopy of the pilus structure, provided evidence in support of this mechanism. As the P. gingivalis Fim pili are formed through novel transport and assembly mechanisms, such pili are now designated as Type V pili. Surface lipoproteins, including the anchor pilin FimB of Fim pili that are present on the outer membrane, have been detected in certain Gram‐negative bacteria. Here, we describe the assembly mechanisms of pili, including those of Type V and other pili, as well as the lipoprotein transport mechanisms., source:https://onlinelibrary.wiley.com/doi/full/10.1111/1348-0421.12838
- Published
- 2020
40. Involvement of PorK, a component of the type IX secretion system, inPrevotella melaninogenicapathogenicity
- Author
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Tomonori Hoshino, Keiji Nagano, Taku Fujiwara, Keiko Sato, Miyuki Nishiguchi, Yoshio Kondo, and Koji Nakayama
- Subjects
0301 basic medicine ,Proteases ,biology ,030106 microbiology ,Immunology ,Mutant ,Virulence ,biology.organism_classification ,Microbiology ,Prevotella melaninogenica ,03 medical and health sciences ,030104 developmental biology ,Virology ,Secretion ,Pathogen ,Porphyromonas gingivalis ,Bacteria - Abstract
Prevotella melaninogenica is a gram-negative anaerobic commensal bacterium that resides in the human oral cavity and is isolated as a pathogen of suppurative diseases both inside and outside the mouth. However, little is known about the pathogenic factors of P. melaninogenica. The periodontal pathogens Porphyromonas gingivalis and Tanerella forsythia secrete virulence factors such as protease and bacterial cell surface proteins via a type IX secretion system (T9SS) that are involved in pathogenicity. P. melaninogenica also possesses all known orthologs of T9SS. In this study, a P. melaninogenica GAI 07411 mutant deficient in the orthologue of the T9SS-encoding gene, porK, was constructed. Hemagglutination and biofilm formation were decreased in the porK mutant. Furthermore, following growth on skim milk-containing medium, the diameters of the halos surrounding the porK mutant were smaller than those of the wild-type strain, suggesting a decrease in secretion of proteases outside the bacterium. To investigate this in detail, culture supernatants of wild-type and porK mutant strains were purified and compared by two-dimensional electrophoresis. In the mutant strain, fewer spots were detected, indicating fewer secreted proteins. In infection experiments, the mortality rate of mice inoculated with the porK mutant strain was significantly lower than in the wild-type strain. These results suggest that P. melaninogenica secretes potent virulence factors via the T9SS that contribute to its pathogenic ability.
- Published
- 2018
41. Photoreactivities of the Antiseptics Dehydroacetic Acid and Sodium Dehydroacetate Used in Cosmetics
- Author
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Kazuhiro Nojima, Takuya Izawa, Noritaka Uchida, and Koji Nakayama
- Subjects
Free Radicals ,Molecular Structure ,Photoisomerization ,010405 organic chemistry ,Radical ,Sodium dehydroacetate ,Cosmetics ,General Chemistry ,General Medicine ,Dehydroacetic acid ,Photochemical Processes ,010402 general chemistry ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Dieldrin ,chemistry.chemical_compound ,chemistry ,Pyrones ,Drug Discovery ,Anti-Infective Agents, Local ,Quantum Theory ,Aldrin ,Irradiation ,Isomerization - Abstract
Dehydroacetic acid (1) was found to induce photoisomerization, converting aldrin (3) and dieldrin (4) into photoaldrin (5) and photodieldrin (6), respectively, not only when irradiated with artificial light at wavelengths longer than 290 nm in air but also when exposed to sunlight in air. By contrast, sodium dehydroacetate (2) induced both photoisomerization, primarily converting 3 to 5 and photoepoxidation, partially forming 6. Thus, because 2 is usually used as a water-soluble antiseptic, photo-erethism might occur due to the isomerization and epoxidation properties of this compound. The difference between the photoreactivity of 1 and that of 2 might be attributed to the spin density of the odd electron on the carbon atom in the respective radicals that were formed after photo-excited 1 and 2 caused H-abstraction.
- Published
- 2018
42. Ability Development Measured by the Fundamental Competencies for Working Persons and Effectiveness of Forest Volunteer Activities: Case Study of Forest Volunteer Activities of University Students in Niimi City, Okayama Prefecture
- Author
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Koji Nakayama and Naoto Matsumura
- Subjects
0106 biological sciences ,Medical education ,Higher education ,business.industry ,Sociology ,010501 environmental sciences ,business ,01 natural sciences ,Volunteer ,010606 plant biology & botany ,0105 earth and related environmental sciences - Published
- 2018
43. Ability Development Measured by the Fundamental Competencies for Working Persons and Effectiveness of Forest Environmental Education
- Author
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Naoto Matsumura and Koji Nakayama
- Subjects
060104 history ,Medical education ,Environmental education ,business.industry ,05 social sciences ,050501 criminology ,0601 history and archaeology ,06 humanities and the arts ,Sociology ,Rural area ,Project-based learning ,business ,0505 law - Published
- 2018
44. 13 kV SiC-DMOSFETs and body diodes for HVDC MMC converters
- Author
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Hiroshi Yamaguchi, Koji Nakayama, and Takeharu Kuroiwa
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,General Engineering ,General Physics and Astronomy ,Optoelectronics ,Converters ,business ,Diode - Abstract
Power electronics utilizing SiC power devices will become key components in next-generation power systems based on renewable energy, which are becoming an urgent issue worldwide. In this study, the on-characteristics and switching characteristics of 13 kV SiC-double-implanted metal-oxide-semiconductor field-effect transistors (DMOSFETs) and their body diodes were measured. In particular, the carrier lifetime, which has a significant effect on electrical characteristics, was estimated from the dynamic characteristics of the body diodes. The short carrier lifetime resulted in a large on-state voltage and a small reverse recovery loss of the body diode. Moreover, a conceptual design of a modular multilevel converter-based high-voltage, large-capacity, and self-excited AC/DC converter with 13 kV SiC-DMOSFETs was conducted, and its characteristics were investigated. When the 13 kV SiC-DMOSFETs were applied, the ratio of the total device loss to the electricity power of the converter was 1.10%, which is a significant reduction of 50% compared with 2.17% when 6.5 kV Si-insulated gate bipolar transistors were used.
- Published
- 2021
45. Identification of genes encoding glycosyltransferases involved in lipopolysaccharide synthesis inPorphyromonas gingivalis
- Author
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Mariko Naito, Koji Nakayama, Hideharu Yukitake, Yuko Sasaki, Mikio Shoji, Keiko Sato, and Arihide Kamaguchi
- Subjects
Lipopolysaccharides ,0301 basic medicine ,Microbiology (medical) ,030106 microbiology ,Immunology ,Mutant ,Virulence ,medicine.disease_cause ,Microbiology ,03 medical and health sciences ,Bacterial Proteins ,Glycosyltransferase ,Escherichia coli ,medicine ,Amino Acid Sequence ,General Dentistry ,Gene ,Porphyromonas gingivalis ,chemistry.chemical_classification ,biology ,Pigmentation ,Escherichia coli Proteins ,Glycosyltransferases ,Oligosaccharide ,biology.organism_classification ,Molecular biology ,Amino acid ,Hexosyltransferases ,Biochemistry ,chemistry ,Genes, Bacterial ,Glucosyltransferases ,Mutation ,biology.protein ,lipids (amino acids, peptides, and proteins) - Abstract
Porphyromonas gingivalis can synthesize both A-LPS and O-LPS lipopolysaccharides, which contain anionic O-polysaccharides and conventional O-polysaccharides, respectively. A-LPS can anchor virulence proteins to the cell surface, so elucidating the mechanism of A-LPS synthesis is important for understanding the pathogenicity of this bacterium. To identify the genes involved in LPS synthesis, we focused on uncharacterized genes encoding the glycosyltransferases, PGN_0361, PGN_1239, PGN_1240 and PGN_1668, which were tentatively named gtfC, gtfD, gtfE and gtfF, respectively, and characterized their mutants. We found that disruption of gtfC and gtfF resulted in A-LPS deficiency. In addition, a gtfD mutant had abnormal A-LPS synthesis, and a gtfE mutant exhibited a rough-type LPS that possesses a short oligosaccharide with lipid A-core. We then constructed a gtfC and gtfD double mutant, because their amino acid sequences were very similar, and this mutant similarly possessed a rough-type LPS. Cross-complementation analysis revealed that the GtfD protein is a functional homologue of the Escherichia coli WbbL protein, which is a rhamnosyltransferase. These results suggested that the GtfE protein is essential for the synthesis of both O-LPS and A-LPS, and that GtfC and GtfD proteins may work together to synthesize the two kinds of LPS. In addition, the GtfF protein was essential for A-LPS synthesis, although this may be achieved in a strain-specific manner.
- Published
- 2017
46. The type IX secretion system and the type V pilus in the phylum Bacteroidetes
- Author
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Koji Nakayama
- Subjects
0301 basic medicine ,biology ,030106 microbiology ,Fimbria ,Bacteroidetes ,General Medicine ,Porphyromonas ,biology.organism_classification ,Pilus ,Microbiology ,Gingipain ,03 medical and health sciences ,stomatognathic system ,Secretion ,Porphyromonas gingivalis ,Bacteria - Abstract
Many bacteria symbiotic and parasitic in humans are included in the genera Bacteroides, Prevotella, Porphyromonas and others, which belong to the phylum Bacteroidetes. We have been studying gingipain, a major secretory protease of Porphyromonas gingivalis which is a periodontopathogenic bacterium belonging to the genus Porphyromonas, and pili which contribute to host colonization in the bacterium. In the process, it was found that gingipain was secreted by a system not reported previously. Furthermore, this secretion system was found to exist widely in the Bacteroidetes phylum bacteria and closely related to the gliding motility of bacteroidete bacteria, and it was named the Por secretion system (later renamed the type IX secretion system). Regarding P. gingivalis pili, it was found that the pilus protein is transported as a lipoprotein to the cell surface, and the pilus formation occurs due to degradation by arginine-gingipain. Pili with this novel formation mechanism was found to be widely present in bacteria belonging to the class Bacteroidia in the phylum Bacteroidetes and was named the type V pili.
- Published
- 2017
47. Facile and Accurate Analysis of Sodium Dehydroacetate in Cosmetic Powders After Extraction by Na2CO3-Methanol-H2O and Derivatization with 4-Nitrophenylhydrazine∙HCl
- Author
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Kazuhiro Nojima, Hisaaki Itoh, Koji Nakayama, Masaru Niitsu, Takuya Izawa, and Yuuji Kurosawa
- Subjects
0301 basic medicine ,030207 dermatology & venereal diseases ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,Chromatography ,chemistry ,Extraction (chemistry) ,Sodium dehydroacetate ,General Medicine ,Methanol ,Derivatization - Published
- 2017
48. Effect of Simultaneity of Emergence on Simultaneous Flowering of Tomato Grown under Low Node-order Pinching and High-density Planting
- Author
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Yoshikazu Kiriiwa, Katsumi Suzuki, Koji Nakayama, Akira Nukaya, and Masakazu Nakayama
- Subjects
Simultaneity ,Order (business) ,Node (networking) ,Statistics ,General Engineering ,General Earth and Planetary Sciences ,Sowing ,High density ,04 agricultural and veterinary sciences ,0405 other agricultural sciences ,040501 horticulture ,General Environmental Science ,Mathematics - Published
- 2017
49. Tenascin XB Is a Novel Diagnostic Marker for Malignant Mesothelioma
- Author
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Rintaro Noro, Kuniko Matsuda, Masahiro Seike, Susumu Takeuchi, Koji Nakayama, Kaoru Kubota, Akihiko Gemma, and Shinobu Kunugi
- Subjects
TENASCIN XB ,Mesothelioma ,Cancer Research ,Pathology ,medicine.medical_specialty ,Lung Neoplasms ,Adenocarcinoma ,Sensitivity and Specificity ,Diagnosis, Differential ,03 medical and health sciences ,0302 clinical medicine ,Cell Line, Tumor ,Gene expression ,medicine ,Biomarkers, Tumor ,Humans ,RNA, Small Interfering ,Cell Proliferation ,Lung ,business.industry ,Gene Expression Profiling ,Mesothelioma, Malignant ,Tenascin ,General Medicine ,medicine.disease ,Immunohistochemistry ,medicine.anatomical_structure ,Oncology ,030220 oncology & carcinogenesis ,Calbindin 2 ,Calretinin ,Differential diagnosis ,business - Abstract
Background/aim Malignant mesothelioma (MM) is an aggressive tumor with poor prognosis. The establishment of a new diagnostic and therapeutic approach for MM is expected. This study investigated the diagnostic significance of tenascin XB (TNXB) for MM. Materials and methods TNXB gene expression was found to be significantly higher in MM tumor tissues compared to paired normal tissues, as assessed by the Gene Expression Omnibus database. The inhibition of TNXB using small interfering RNAs suppressed the proliferation and colony formation of MM cells. Expression of TNXB and calretinin, a current diagnostic marker of MM, was evaluated by immunohistochemistry. Results The sensitivity and specificity of TNXB for MM were 80.0% and 69.5%, respectively. When the detection of TNXB was combined with that of calretinin, 83.3% of MM cases were detected. Conclusion These findings suggest that TNXB is a novel diagnostic biomarker for MM. A combination of detecting TNXB and calretinin may be useful for the differential diagnosis of MM from lung adenocarcinoma.
- Published
- 2018
50. Progress in High and Ultrahigh Voltage Silicon Carbide Device Technology
- Author
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K. Koseki, T. Kimoto, Shinsuke Harada, Yoshiyuki Yonezawa, Ryoji Kosugi, Koji Nakayama, Hajime Okumura, and Kunihiro Sakamoto
- Subjects
010302 applied physics ,Materials science ,business.industry ,Bipolar junction transistor ,Hardware_PERFORMANCEANDRELIABILITY ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry.chemical_compound ,Oxide semiconductor ,chemistry ,Hardware_GENERAL ,Power electronics ,0103 physical sciences ,Hardware_INTEGRATEDCIRCUITS ,Silicon carbide ,Optoelectronics ,Field-effect transistor ,Current (fluid) ,0210 nano-technology ,business ,Hardware_LOGICDESIGN ,Degradation (telecommunications) ,Voltage - Abstract
The current developments in silicon carbide (SiC) device technology in various voltage ranges are introduced. These developments correspond to, in particular, next-generation high to ultrahigh-voltage devices, SiC super-junction metal oxide semiconductor field effect transistors, SiC insulated gate bipolar transistors, and the fundamental bipolar degradation suppression technology. We expect that these next generation devices will trigger a paradigm shift in power electronics.
- Published
- 2018
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