47 results on '"Klepsch, M."'
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2. Internationale Umfrage zu dem Einsatz von virtueller Realität in der endoskopischen Weiterbildung von Ärzten und Pflegepersonal
- Author
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Engelke, M, additional, Klepsch, M, additional, Moga, T, additional, Mokrowiecka, A, additional, Furnari, M, additional, De Maria, C, additional, Murino, A, additional, Fitting, D, additional, Meining, A, additional, Seufert, T, additional, and Hann, A, additional
- Published
- 2021
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3. Wandel bei der Behandlung der Unterschenkelschaftfraktur
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Runkel, M. and Klepsch, M.
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- 1999
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4. Beyond the membrane: Characterization of the oligopeptide binding protein from Escherichia coli: C4.13
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Klepsch, M., Berntsson, R., de Gier, J.-W., and Slotboom, D.-J.
- Published
- 2010
5. G. Keiper, Biographische Studien zu den Verständigungsversuchen zwischen Deutschland und Frankreich am Vorabend des Ersten Weltkrieges, 1997
- Author
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Klepsch, M.
- Abstract
Francia, Bd. 26 Nr. 3 (1999)
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- 2019
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6. RESULTS AFTER PRIMARY UNREAMED NAILING OF TIBIAL FRACTURES WITH SEVERE OPEN OR CLOSED SOFT INJURY COMPARED TO EXTERNAL STABILISATION
- Author
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KLEPSCH, M, SEIDEL, T H, RUNKEL, M, and ROMMENS, P M
- Published
- 1999
7. Challenges in understanding air-seeding in angiosperm xylem
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Jansen, S., primary, Klepsch, M., additional, Li, S., additional, Kotowska, M.M., additional, Schiele, S., additional, Zhang, Y., additional, and Schenk, H.J., additional
- Published
- 2018
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8. Escherichia coli Peptide Binding Protein OppA Has a Preference for Positively Charged Peptides
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Klepsch, M. M., Kovermann, M., Löw, C., Balbach, J., Permentier, H. P., Fusetti, F., de Gier, J. W., Gier, Jan-Willem de, Slotboom, D. J., Berntsson, R. P. -A., Analytical Biochemistry, Medicinal Chemistry and Bioanalysis (MCB), Groningen Biomolecular Sciences and Biotechnology, and Zernike Institute for Advanced Materials
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Models, Molecular ,Salmonella typhimurium ,STRUCTURAL BASIS ,Protein Conformation ,Lipoproteins ,Immunoblotting ,Peptide binding ,Tripeptide ,Plasma protein binding ,Crystallography, X-Ray ,peptide binding protein, oligopeptide transporter, ABC transporter, Escherichia coli, substrate binding protein ,Substrate Specificity ,Protein structure ,ABC TRANSPORTERS ,Structural Biology ,Escherichia coli ,Binding site ,Molecular Biology ,SPECIFICITY ,chemistry.chemical_classification ,Oligopeptide ,Binding Sites ,OLIGOPEPTIDE PERMEASE ,COMPLEX ,Chemistry ,MEMBRANE-PROTEINS ,Escherichia coli Proteins ,oligopeptide transporter ,SALMONELLA-TYPHIMURIUM ,Isothermal titration calorimetry ,Biological Transport ,substrate binding protein ,Amino acid ,MODEL ,peptide binding protein ,Biochemistry ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,ddc:540 ,LIGAND-BINDING ,ABC transporter ,Carrier Proteins ,Oligopeptides ,Protein Binding - Abstract
The Escherichia coli peptide binding protein OppA is an essential component of the oligopeptide transporter Opp. Based on studies on its orthologue from Salmonella typhimurium, it has been proposed that OppA binds peptides between two and five amino acids long, with no apparent sequence selectivity. Here, we studied peptide binding to E. coli OppA directly and show that the protein has an unexpected preference for basic peptides. OppA was expressed in the periplasm, where it bound to available peptides. The protein was purified in complex with tightly bound peptides. The crystal structure (up to 2.0 angstrom) of OppA liganded with the peptides indicated that the protein has a preference for peptides containing a lysine. Mass spectrometry analysis of the bound peptides showed that peptides between two and five amino acids long bind to the protein and indeed hinted at a preference for positively charged peptides. The preference of OppA for peptides with basic residues, in particular lysines, was corroborated by binding studies with peptides of defined sequence using isothermal titration calorimetry and intrinsic protein fluorescence titration. The protein bound tripeptides and tetrapeptides containing positively charged residues with high affinity, whereas related peptides without lysines/arginines were bound with low affinity. A structure of OppA in an open conformation in the absence of ligands was also determined to 2.0 angstrom, revealing that the initial binding site displays a negative surface charge, consistent with the observed preference for positively charged peptides. Taken together, E. coli OppA appears to have a preference for basic peptides. (C) 2011 Elsevier Ltd. All rights reserved.
- Published
- 2011
9. HUMAN ARTD1 (PARP1) - CATALYTIC DOMAIN IN COMPLEX WITH INHIBITOR TALAZOPARIB
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Karlberg, T., primary, Thorsell, A.G., additional, Ekblad, T., additional, Klepsch, M., additional, Pinto, A.F., additional, Tresaugues, L., additional, Moche, M., additional, and Schuler, H., additional
- Published
- 2015
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10. Human PARP13 (ZC3HAV1), C-Terminal PARP Domain (H810N; N830Y variant)
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Karlberg, T., primary, Thorsell, A.G., additional, Klepsch, M., additional, and Schuler, H., additional
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- 2015
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11. Dual roles of the central domain of colicin D tRNAse in TonB-mediated import and immunity
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Mora, L., Klepsch, M., R. H., Buckingham, Heurgué-Hamard, V., Kervestin, S., Zamaroczy M., De, Régulation de l'expression génétique chez les microorganismes (REGCM), Centre National de la Recherche Scientifique (CNRS), and Gauthier, Laurence
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[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2008
12. Dual roles of the central domain of colicin D tRNAse in TonB-mediated import and in immunity
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Mora, L., Klepsch, M., R.H., Buckingham, Heugué-Hamard, V., Kervestin, S., Zamaroczy M., De, and Gauthier, Laurence
- Subjects
[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology - Published
- 2007
13. Role for Escherichia coli YidD in Membrane Protein Insertion
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Yu, Z., Laven, M., Klepsch, M., de Gier, J.W., Bitter, W., van Ulsen, J.P., Luirink, S., Yu, Z., Laven, M., Klepsch, M., de Gier, J.W., Bitter, W., van Ulsen, J.P., and Luirink, S.
- Abstract
YidC has an essential but poorly defined function in membrane protein insertion and folding in bacteria. The yidC gene is located in a gene cluster that is highly conserved in Gram-negative bacteria, the gene order being rpmH, rnpA, yidD, yidC, and trmE. Here, we show that Escherichia coli yidD, which overlaps with rnpA and is only 2 bp upstream of yidC, is expressed and localizes to the inner membrane, probably through an amphipathic helix. Inactivation of yidD had no discernible effect on cell growth and viability. However, compared to control cells, ΔyidD cells were affected in the insertion and processing of three YidC-dependent inner membrane proteins. Furthermore, in vitro cross-linking showed that YidD is in proximity of a nascent inner membrane protein during its localization in the Sec-YidC translocon, suggesting that YidD might be involved in the insertion process. © 2011, American Society for Microbiology.
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- 2011
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14. Consequences of depletion of the signal recognition particle in Escherichia coli
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Wickstrom, D., Wagner, S., Baars, L, Ytterberg, A.J., Klepsch, M., van Wijk, K.J., Luirink, J., de Gier, J.W., Wickstrom, D., Wagner, S., Baars, L, Ytterberg, A.J., Klepsch, M., van Wijk, K.J., Luirink, J., and de Gier, J.W.
- Abstract
Thus far, the role of the Escherichia coli signal recognition particle (SRP) has only been studied using targeted approaches. It has been shown for a handful of cytoplasmic membrane proteins that their insertion into the cytoplasmic membrane is at least partially SRP-dependent. Furthermore, it has been proposed that the SRP plays a role in preventing toxic accumulation of mistargeted cytoplasmic membrane proteins in the cytoplasm. To complement the targeted studies on SRP, we have studied the consequences of the depletion of the SRP component Fifty-four homologue (Ffh) in E. coli using a global approach. The steady-state proteomes and the proteome dynamics were evaluated using oneand two-dimensional gel analysis, followed by mass spectrometry-based protein identification and immunoblotting. Our analysis showed that depletion of Ffh led to the following: (i) impaired kinetics of the biogenesis of the cytoplasmic membrane proteome; (ii) lowered steady-state levels of the respiratory complexes NADH dehydrogenase, succinate dehydrogenase, and cytochrome bo
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- 2011
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15. Ion-mediated enhancement of xylem hydraulic conductivity in four Acer species: relationships with ecological and anatomical features
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Nardini, A., primary, Dimasi, F., additional, Klepsch, M., additional, and Jansen, S., additional
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- 2012
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16. Morbus Paget der proximalen Ulna - eine seltene monostotische Manifestation
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Klepsch, M., primary, Seidel, Th., additional, and Runkel, M., additional
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- 2008
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17. Structural insights into an equilibrium folding intermediate of an archaeal ankyrin repeat protein
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Low, C., primary, Weininger, U., additional, Neumann, P., additional, Klepsch, M., additional, Lilie, H., additional, Stubbs, M. T., additional, and Balbach, J., additional
- Published
- 2008
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18. Ruptur einer Echinokokkuszyste in die Gallewege
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Brück, E., primary, Gerdes, B., additional, Klepsch, M., additional, Stinner, B., additional, and Ernst, M., additional
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- 2001
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19. Streßfraktur des Schenkelhalses durch Step Aerobic - Kasuistik
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Klepsch, M., primary and Kreitner, K.-F., additional
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- 1998
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20. Morbus Paget der proximalen Ulna - eine seltene monostotische Manifestation.
- Author
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Klepsch, M., Seidel, Th., and Runkel, M.
- Published
- 1997
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21. Ion-mediated enhancement of xylem hydraulic conductivity in four Acer species: relationships with ecological and anatomical features
- Author
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Steven Jansen, Andrea Nardini, Matthias M. Klepsch, Federica Dimasi, Nardini, Andrea, Dimasi, F, Klepsch, M, and Jansen, S.
- Subjects
Physiology ,Acer monspessulanum ,Ionic bonding ,Acer ,Acer platanoides ,Plant Science ,xylem sap ,water stress ,Species Specificity ,Hydraulic conductivity ,Xylem ,Electrical resistivity and conductivity ,ionic effect ,light ,pit membranes ,vessel grouping ,Botany ,Photosynthesis ,Acer campestre ,Ions ,biology ,Ecology ,Water ,Biological Transport ,water stre ,Acer pseudoplatanus ,biology.organism_classification ,pit membrane - Abstract
The 'ionic effect', i.e., changes in xylem hydraulic conductivity (k(xyl)) due to variation of the ionic sap composition in vessels, was studied in four Acer species growing in contrasting environments differing in water availability. Hydraulic measurements of the ionic effect were performed together with measurements on the sap electrical conductivity, leaf water potential and vessel anatomy. The low ionic effect recorded in Acer pseudoplatanus L. and Acer campestre L. (15.8 and 14.7%, respectively), which represented two species from shady and humid habitats, was associated with a low vessel grouping index, high sap electrical conductivity and least negative leaf water potential. Opposite traits were found for Acer monspessulanum L. and Acer platanoides L., which showed an ionic effect of 23.6 and 23.1%, respectively, and represent species adapted to higher irradiance and/or lower water availability. These findings from closely related species provide additional support that the ionic effect could function as a compensation mechanism for embolism-induced loss of k(xyl), either as a result of high evaporative demand or increased risk of hydraulic failure.
- Published
- 2012
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22. Central Role of Sibling Small RNAs NgncR_162 and NgncR_163 in Main Metabolic Pathways of Neisseria gonorrhoeae.
- Author
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Steiner T, Zachary M, Bauer S, Müller MJ, Krischke M, Radziej S, Klepsch M, Huettel B, Eisenreich W, Rudel T, and Beier D
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- Humans, Siblings, Bacteria genetics, Metabolic Networks and Pathways genetics, RNA, Bacterial metabolism, Nucleotides metabolism, Amino Acids metabolism, Vitamins, Gene Expression Regulation, Bacterial, Neisseria gonorrhoeae genetics, Neisseria gonorrhoeae metabolism, RNA, Small Untranslated genetics, RNA, Small Untranslated metabolism
- Abstract
Small bacterial regulatory RNAs (sRNAs) have been implicated in the regulation of numerous metabolic pathways. In most of these studies, sRNA-dependent regulation of mRNAs or proteins of enzymes in metabolic pathways has been predicted to affect the metabolism of these bacteria. However, only in a very few cases has the role in metabolism been demonstrated. Here, we performed a combined transcriptome and metabolome analysis to define the regulon of the sibling sRNAs NgncR_162 and NgncR_163 (NgncR_162/163) and their impact on the metabolism of Neisseria gonorrhoeae. These sRNAs have been reported to control genes of the citric acid and methylcitric acid cycles by posttranscriptional negative regulation. By transcriptome analysis, we now expand the NgncR_162/163 regulon by several new members and provide evidence that the sibling sRNAs act as both negative and positive regulators of target gene expression. Newly identified NgncR_162/163 targets are mostly involved in transport processes, especially in the uptake of glycine, phenylalanine, and branched-chain amino acids. NgncR_162/163 also play key roles in the control of serine-glycine metabolism and, hence, probably affect biosyntheses of nucleotides, vitamins, and other amino acids via the supply of one-carbon (C
1 ) units. Indeed, these roles were confirmed by metabolomics and metabolic flux analysis, which revealed a bipartite metabolic network with glucose degradation for the supply of anabolic pathways and the usage of amino acids via the citric acid cycle for energy metabolism. Thus, by combined deep RNA sequencing (RNA-seq) and metabolomics, we significantly extended the regulon of NgncR_162/163 and demonstrated the role of NgncR_162/163 in the regulation of central metabolic pathways of the gonococcus. IMPORTANCE Neisseria gonorrhoeae is a major human pathogen which infects more than 100 million people every year. An alarming development is the emergence of gonococcal strains that are resistant against virtually all antibiotics used for their treatment. Despite the medical importance and the vanishing treatment options of gonococcal infections, the bacterial metabolism and its regulation have been only weakly defined until today. Using RNA-seq, metabolomics, and13 C-guided metabolic flux analysis, we here investigated the gonococcal metabolism and its regulation by the previously studied sibling sRNAs NgncR_162/163. The results demonstrate the regulation of transport processes and metabolic pathways involved in the biosynthesis of nucleotides, vitamins, and amino acids by NgncR_162/163. In particular, the combination of transcriptome and metabolic flux analyses provides a heretofore unreached depth of understanding the core metabolic pathways and their regulation by the neisserial sibling sRNAs. This integrative approach may therefore also be suitable for the functional analysis of a growing number of other bacterial metabolic sRNA regulators.- Published
- 2023
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23. Identification and initial characterization of a new pair of sibling sRNAs of Neisseria gonorrhoeae involved in type IV pilus biogenesis.
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Zachary M, Bauer S, Klepsch M, Wagler K, Hüttel B, Rudel T, and Beier D
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- Gene Expression Regulation, Bacterial, Humans, RNA, Bacterial genetics, Sequence Analysis, RNA, Siblings, Neisseria gonorrhoeae genetics, RNA, Small Untranslated genetics
- Abstract
Non-coding regulatory RNAs mediate post-transcriptional gene expression control by a variety of mechanisms relying mostly on base-pairing interactions with a target mRNA. Though a plethora of putative non-coding regulatory RNAs have been identified by global transcriptome analysis, knowledge about riboregulation in the pathogenic Neisseriae is still limited. Here we report the initial characterization of a pair of sRNAs of N. gonorrhoeae , TfpR1 and TfpR2, which exhibit a similar secondary structure and identical single-stranded seed regions, and therefore might be considered as sibling sRNAs. By combination of in silico target prediction and sRNA pulse expression followed by differential RNA sequencing we identified target genes of TfpR1 which are involved in type IV pilus biogenesis and DNA damage repair. We provide evidence that members of the TfpR1 regulon can also be targeted by the sibling TfpR2.
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- 2021
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24. Learning From Multiple Representations: Prior Knowledge Moderates the Beneficial Effects of Signals and Abstract Graphics.
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Vogt A, Klepsch M, Baetge I, and Seufert T
- Abstract
Multimedia learning research addresses the question of how to design instructional material effectively. Signaling and adding graphics are typical instructional means that might support constructing a mental model, particularly when learning abstract content from multiple representations. Although signals can help to select relevant aspects of the learning content, additional graphics could help to visualize mentally the subject matter. Learners' prior knowledge is an important factor for the effectiveness of both types of support: signals and added graphics. Therefore, we conducted an experimental study situated in a university course of computer science with N = 124 participants. In our 2 × 2 factorial design, we investigated the effects of signals and illustrating graphics on learning outcomes and their potential interplay. Based on our regression analysis, we revealed prior knowledge as a significant moderator. Although learners with low levels of prior knowledge can profit from all types of help but still gain rather weak learning outcomes, learners with medium levels of prior knowledge profit from the synergy of both helps. With higher levels of prior knowledge, signals were particularly hampering. To improve the understanding of these supportive or hampering effects, a more fine-grained analysis of these processes and motivational effects is necessary., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Vogt, Klepsch, Baetge and Seufert.)
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- 2020
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25. Identification of a Novel LysR-Type Transcriptional Regulator in Staphylococcus aureus That Is Crucial for Secondary Tissue Colonization during Metastatic Bloodstream Infection.
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Groma M, Horst SA, Das S, Huettel B, Klepsch M, Rudel T, Medina E, and Fraunholz M
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- Animals, Bacterial Proteins metabolism, Female, Gene Expression Regulation, Bacterial, Mice, Mice, Inbred C57BL, Specific Pathogen-Free Organisms, Transcription Factors metabolism, Transcription, Genetic, Virulence, Virulence Factors, Bacteremia microbiology, Bacterial Proteins genetics, Staphylococcal Infections microbiology, Staphylococcus aureus genetics, Staphylococcus aureus pathogenicity, Transcription Factors genetics
- Abstract
Staphylococcus aureus is a common cause of bacteremia that can lead to severe complications once the bacteria exit the bloodstream and establish infection in secondary organs. Despite its clinical relevance, little is known about the bacterial factors facilitating the development of these metastatic infections. Here, we used an S. aureus transposon mutant library coupled to transposon insertion sequencing (Tn-Seq) to identify genes that are critical for efficient bacterial colonization of secondary organs in a murine model of metastatic bloodstream infection. Our transposon screen identified a LysR-type transcriptional regulator (LTTR), which was required for efficient colonization of secondary organs such as the kidneys in infected mice. The critical role of LTTR in secondary organ colonization was confirmed using an isogenic mutant deficient in the expression of LTTR. To identify the set of genes controlled by LTTR, we used an S. aureus strain carrying the LTTR gene in an inducible expression plasmid. Gene expression analysis upon induction of LTTR showed increased transcription of genes involved in branched-chain amino acid biosynthesis, a methionine sulfoxide reductase, and a copper transporter as well as decreased transcription of genes coding for urease and components of pyrimidine nucleotides. Furthermore, we show that transcription of LTTR is repressed by glucose, is induced under microaerobic conditions, and required trace amounts of copper ions. Our data thus pinpoints LTTR as an important element that enables a rapid adaptation of S. aureus to the changing host microenvironment. IMPORTANCE Staphylococcus aureus is an important pathogen that can disseminate via the bloodstream and establish metastatic infections in distant organs. To achieve a better understanding of the bacterial factors facilitating the development of these metastatic infections, we used in this study a Staphylococcus aureus transposon mutant library in a murine model of intravenous infection, where bacteria first colonize the liver as the primary infection site and subsequently progress to secondary sites such as the kidney and bones. We identified a novel LysR-type transcriptional regulator (LTTR), which was specifically required by S. aureus for efficient colonization of secondary organs. We also determined the transcriptional activation as well as the regulon of LTTR, which suggests that this regulator is involved in the metabolic adaptation of S. aureus to the host microenvironment found in secondary infection sites., (Copyright © 2020 Groma et al.)
- Published
- 2020
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26. Is xylem of angiosperm leaves less resistant to embolism than branches? Insights from microCT, hydraulics, and anatomy.
- Author
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Klepsch M, Zhang Y, Kotowska MM, Lamarque LJ, Nolf M, Schuldt B, Torres-Ruiz JM, Qin DW, Choat B, Delzon S, Scoffoni C, Cao KF, and Jansen S
- Subjects
- Betula physiology, Laurus physiology, Liriodendron physiology, Plant Leaves anatomy & histology, Plant Leaves cytology, Plant Leaves physiology, Plant Shoots anatomy & histology, Plant Shoots cytology, Plant Shoots physiology, Trees physiology, X-Ray Microtomography, Betula anatomy & histology, Droughts, Laurus anatomy & histology, Liriodendron anatomy & histology, Trees anatomy & histology, Xylem physiology
- Abstract
According to the hydraulic vulnerability segmentation hypothesis, leaves are more vulnerable to decline of hydraulic conductivity than branches, but whether stem xylem is more embolism resistant than leaves remains unclear. Drought-induced embolism resistance of leaf xylem was investigated based on X-ray microcomputed tomography (microCT) for Betula pendula, Laurus nobilis, and Liriodendron tulipifera, excluding outside-xylem, and compared with hydraulic vulnerability curves for branch xylem. Moreover, bordered pit characters related to embolism resistance were investigated for both organs. Theoretical P50 values (i.e. the xylem pressure corresponding to 50% loss of hydraulic conductance) of leaves were generally within the same range as hydraulic P50 values of branches. P50 values of leaves were similar to branches for L. tulipifera (-2.01 versus -2.10 MPa, respectively), more negative for B. pendula (-2.87 versus -1.80 MPa), and less negative for L. nobilis (-6.4 versus -9.2 MPa). Despite more narrow conduits in leaves than branches, mean interconduit pit membrane thickness was similar in both organs, but significantly higher in leaves of B. pendula than in branches. This case study indicates that xylem shows a largely similar embolism resistance across leaves and branches, although differences both within and across organs may occur, suggesting interspecific variation with regard to the hydraulic vulnerability segmentation hypothesis.
- Published
- 2018
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27. Long Noncoding RNA SSR42 Controls Staphylococcus aureus Alpha-Toxin Transcription in Response to Environmental Stimuli.
- Author
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Horn J, Klepsch M, Manger M, Wolz C, Rudel T, and Fraunholz M
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- Bacterial Proteins genetics, Bacterial Proteins metabolism, RNA, Bacterial genetics, Transcription Factors genetics, Transcription Factors metabolism, Bacterial Toxins genetics, Gene Expression Regulation, Bacterial, Hemolysin Proteins genetics, RNA, Long Noncoding genetics, Staphylococcus aureus genetics, Transcription, Genetic
- Abstract
Staphylococcus aureus is a human pathogen causing a variety of diseases by versatile expression of a large set of virulence factors that most prominently features the cytotoxic and hemolytic pore-forming alpha-toxin. Expression of alpha-toxin is regulated by an intricate network of transcription factors. These include two-component systems sensing quorum and environmental signals as well as regulators reacting to the nutritional status of the pathogen. We previously identified the repressor of surface proteins (Rsp) as a virulence regulator. Acute cytotoxicity and hemolysis are strongly decreased in rsp mutants, which are characterized by decreased transcription of toxin genes as well as loss of transcription of a 1,232-nucleotide (nt)-long noncoding RNA (ncRNA), SSR42. Here, we show that SSR42 is the effector of Rsp in transcription regulation of the alpha-toxin gene, hla SSR42 transcription is enhanced after exposure of S. aureus to subinhibitory concentrations of oxacillin which thus leads to an SSR42-dependent increase in hemolysis. Aside from Rsp, SSR42 transcription is under the control of additional global regulators, such as CodY, AgrA, CcpE, and σ
B , but is positioned upstream of the two-component system SaeRS in the regulatory cascade leading to alpha-toxin production. Thus, alpha-toxin expression depends on two long ncRNAs, SSR42 and RNAIII, which control production of the cytolytic toxin on the transcriptional and translational levels, respectively, with SSR42 as an important regulator of SaeRS-dependent S. aureus toxin production in response to environmental and metabolic signals. IMPORTANCE Staphylococcus aureus is a major cause of life-threatening infections. The bacterium expresses alpha-toxin, a hemolysin and cytotoxin responsible for many of the pathologies of S. aureus Alpha-toxin production is enhanced by subinhibitory concentrations of antibiotics. Here, we show that this process is dependent on the long noncoding RNA, SSR42. Further, SSR42 itself is regulated by several global regulators, thereby integrating environmental and nutritional signals that modulate hemolysis of the pathogen., (Copyright © 2018 American Society for Microbiology.)- Published
- 2018
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28. Development and Validation of Two Instruments Measuring Intrinsic, Extraneous, and Germane Cognitive Load.
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Klepsch M, Schmitz F, and Seufert T
- Abstract
Cognitive Load Theory is one of the most powerful research frameworks in educational research. Beside theoretical discussions about the conceptual parts of cognitive load, the main challenge within this framework is that there is still no measurement instrument for the different aspects of cognitive load, namely intrinsic, extraneous, and germane cognitive load. Hence, the goal of this paper is to develop a differentiated measurement of cognitive load. In Study 1 ( N = 97), we developed and analyzed two strategies to measure cognitive load in a differentiated way: (1) Informed rating: We trained learners in differentiating the concepts of cognitive load, so that they could rate them in an informed way. They were asked then to rate 24 different learning situations or learning materials related to either high or low intrinsic, extraneous, or germane load. (2) Naïve rating: For this type of rating of cognitive load we developed a questionnaire with two to three items for each type of load. With this questionnaire, the same learning situations had to be rated. In the second study ( N = between 65 and 95 for each task), we improved the instrument for the naïve rating. For each study, we analyzed whether the instruments are reliable and valid, for Study 1, we also checked for comparability of the two measurement strategies. In Study 2, we conducted a simultaneous scenario based factor analysis. The informed rating seems to be a promising strategy to assess the different aspects of cognitive load, but it seems not economic and feasible for larger studies and a standardized training would be necessary. The improved version of the naïve rating turned out to be a useful, feasible, and reliable instrument. Ongoing studies analyze the conceptual validity of this measurement with up to now promising results.
- Published
- 2017
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29. Bordered pits in xylem of vesselless angiosperms and their possible misinterpretation as perforation plates.
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Zhang Y, Klepsch M, and Jansen S
- Subjects
- Gold Colloid metabolism, Magnoliopsida anatomy & histology, Magnoliopsida cytology, Wood cytology, Wood ultrastructure, Xylem anatomy & histology, Xylem cytology, Magnoliopsida ultrastructure, Xylem ultrastructure
- Abstract
Vesselless wood represents a rare phenomenon within the angiosperms, characterizing Amborellaceae, Trochodendraceae and Winteraceae. Anatomical observations of bordered pits and their pit membranes based on light, scanning and transmission electron microscopy (SEM and TEM) are required to understand functional questions surrounding vesselless angiosperms and the potential occurrence of cryptic vessels. Interconduit pit membranes in 11 vesselless species showed a similar ultrastructure as mesophytic vessel-bearing angiosperms, with a mean thickness of 245 nm (± 53, SD; n = six species). Shrunken, damaged and aspirated pit membranes, which were 52% thinner than pit membranes in fresh samples (n = four species), occurred in all dried-and-rehydrated samples, and in fresh latewood of Tetracentron sinense and Trochodendron aralioides. SEM demonstrated that shrunken pit membranes showed artificially enlarged, > 100 nm wide pores. Moreover, perfusion experiments with stem segments of Drimys winteri showed that 20 and 50 nm colloidal gold particles only passed through 2 cm long dried-and-rehydrated segments, but not through similar sized fresh ones. These results indicate that pit membrane shrinkage is irreversible and associated with a considerable increase in pore size. Moreover, our findings suggest that pit membrane damage, which may occur in planta, could explain earlier records of vessels in vesselless angiosperms., (© 2017 John Wiley & Sons Ltd.)
- Published
- 2017
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30. Chromosomal integration of HHV-6A during non-productive viral infection.
- Author
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Gulve N, Frank C, Klepsch M, and Prusty BK
- Subjects
- Base Sequence, Cell Line, Tumor, Genome, Viral, Humans, Repetitive Sequences, Nucleic Acid genetics, Telomere genetics, Chromosomes, Human virology, Herpesvirus 6, Human genetics, Roseolovirus Infections virology, Virus Integration genetics
- Abstract
Human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) are two different species of betaherpesviruses that integrate into sub-telomeric ends of human chromosomes, for which different prevalence rates of integration have been reported. It has been demonstrated that integrated viral genome is stable and is fully retained. However, study of chromosomally integrated viral genome in individuals carrying inherited HHV-6 (iciHHV-6) showed unexpected number of viral DR copies. Hence, we created an in vitro infection model and studied retention of full or partial viral genome over a period of time. We observed an exceptional event where cells retained viral direct repeats (DRs) alone in the absence of the full viral genome. Finally, we found evidence for non-telomeric integration of HHV-6A DR in both cultured cells and in an iciHHV-6 individual. Our results shed light on several novel features of HHV-6A chromosomal integration and provide valuable information for future screening techniques.
- Published
- 2017
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31. Structural basis for lack of ADP-ribosyltransferase activity in poly(ADP-ribose) polymerase-13/zinc finger antiviral protein.
- Author
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Karlberg T, Klepsch M, Thorsell AG, Andersson CD, Linusson A, and Schüler H
- Subjects
- Amino Acid Sequence, Crystallography, X-Ray, Humans, Molecular Dynamics Simulation, Molecular Sequence Data, Mutagenesis, Site-Directed, NAD metabolism, Poly(ADP-ribose) Polymerases chemistry, Poly(ADP-ribose) Polymerases genetics, Sequence Homology, Amino Acid, ADP Ribose Transferases metabolism, Poly(ADP-ribose) Polymerases metabolism, Zinc Fingers
- Abstract
The mammalian poly(ADP-ribose) polymerase (PARP) family includes ADP-ribosyltransferases with diphtheria toxin homology (ARTD). Most members have mono-ADP-ribosyltransferase activity. PARP13/ARTD13, also called zinc finger antiviral protein, has roles in viral immunity and microRNA-mediated stress responses. PARP13 features a divergent PARP homology domain missing a PARP consensus sequence motif; the domain has enigmatic functions and apparently lacks catalytic activity. We used x-ray crystallography, molecular dynamics simulations, and biochemical analyses to investigate the structural requirements for ADP-ribosyltransferase activity in human PARP13 and two of its functional partners in stress granules: PARP12/ARTD12, and PARP15/BAL3/ARTD7. The crystal structure of the PARP homology domain of PARP13 shows obstruction of the canonical active site, precluding NAD(+) binding. Molecular dynamics simulations indicate that this closed cleft conformation is maintained in solution. Introducing consensus side chains in PARP13 did not result in 3-aminobenzamide binding, but in further closure of the site. Three-dimensional alignment of the PARP homology domains of PARP13, PARP12, and PARP15 illustrates placement of PARP13 residues that deviate from the PARP family consensus. Introducing either one of two of these side chains into the corresponding positions in PARP15 abolished PARP15 ADP-ribosyltransferase activity. Taken together, our results show that PARP13 lacks the structural requirements for ADP-ribosyltransferase activity., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
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32. Nobody's perfect: can irregularities in pit structure influence vulnerability to cavitation?
- Author
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Plavcová L, Jansen S, Klepsch M, and Hacke UG
- Abstract
Recent studies have suggested that species-specific pit properties such as pit membrane thickness, pit membrane porosity, torus-to-aperture diameter ratio and pit chamber depth influence xylem vulnerability to cavitation. Despite the indisputable importance of using mean pit characteristics, considerable variability in pit structure within a single species or even within a single pit field should be acknowledged. According to the rare pit hypothesis, a single pit that is more air-permeable than many neighboring pits is sufficient to allow air-seeding. Therefore, any irregularities or morphological abnormalities in pit structure allowing air-seeding should be associated with increased vulnerability to cavitation. Considering the currently proposed models of air-seeding, pit features such as rare, large pores in the pit membrane, torus extensions, and plasmodesmatal pores in a torus can represent potential glitches. These aberrations in pit structure could either result from inherent developmental flaws, or from damage caused to the pit membrane by chemical and physical agents. This suggests the existence of interesting feedbacks between abiotic and biotic stresses in xylem physiology.
- Published
- 2013
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33. How to quantify conduits in wood?
- Author
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Scholz A, Klepsch M, Karimi Z, and Jansen S
- Abstract
Vessels and tracheids represent the most important xylem cells with respect to long distance water transport in plants. Wood anatomical studies frequently provide several quantitative details of these cells, such as vessel diameter, vessel density, vessel element length, and tracheid length, while important information on the three dimensional structure of the hydraulic network is not considered. This paper aims to provide an overview of various techniques, although there is no standard protocol to quantify conduits due to high anatomical variation and a wide range of techniques available. Despite recent progress in image analysis programs and automated methods for measuring cell dimensions, density, and spatial distribution, various characters remain time-consuming and tedious. Quantification of vessels and tracheids is not only important to better understand functional adaptations of tracheary elements to environment parameters, but will also be essential for linking wood anatomy with other fields such as wood development, xylem physiology, palaeobotany, and dendrochronology.
- Published
- 2013
- Full Text
- View/download PDF
34. Optimizing E. coli-based membrane protein production using Lemo21(DE3) and GFP-fusions.
- Author
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Hjelm A, Schlegel S, Baumgarten T, Klepsch M, Wickström D, Drew D, and de Gier JW
- Subjects
- Bioreactors, Fermentation, Gene Expression Regulation, Bacterial, Genetic Vectors genetics, Green Fluorescent Proteins chemistry, Green Fluorescent Proteins genetics, Membrane Proteins chemistry, Membrane Proteins genetics, Recombinant Fusion Proteins chemistry, Recombinant Fusion Proteins genetics, Transformation, Bacterial, Escherichia coli genetics, Escherichia coli metabolism, Green Fluorescent Proteins biosynthesis, Membrane Proteins biosynthesis, Recombinant Fusion Proteins biosynthesis
- Abstract
Optimizing the conditions for the overexpression of membrane proteins in E. coli and their subsequent purification is usually a laborious and time-consuming process. Combining the Lemo21(DE3) strain, which conveniently allows to identify the optimal expression intensity of a membrane protein using only one strain, and membrane proteins C-terminally fused to Green Fluorescent Protein (GFP) greatly facilitates the production of high-quality membrane protein material for functional and structural studies.
- Published
- 2013
- Full Text
- View/download PDF
35. Optimizing membrane protein overexpression in the Escherichia coli strain Lemo21(DE3).
- Author
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Schlegel S, Löfblom J, Lee C, Hjelm A, Klepsch M, Strous M, Drew D, Slotboom DJ, and de Gier JW
- Subjects
- Bacteriophage T7 genetics, DNA-Directed RNA Polymerases genetics, DNA-Directed RNA Polymerases metabolism, Escherichia coli metabolism, Gene Expression, Gene Expression Regulation, Bacterial, Membrane Proteins metabolism, N-Acetylmuramoyl-L-alanine Amidase genetics, Promoter Regions, Genetic, Recombinant Fusion Proteins genetics, Viral Proteins genetics, Viral Proteins metabolism, Escherichia coli genetics, Membrane Proteins biosynthesis, Membrane Proteins genetics, Recombinant Fusion Proteins biosynthesis
- Abstract
Escherichia coli BL21(DE3) is widely used to overexpress proteins. In this overexpression host, the gene encoding the target protein is located on a plasmid and is under control of the T7 promoter, which is recognized exclusively by the T7 RNA polymerase (RNAP). The T7 RNAP gene is localized on the chromosome, and its expression is governed by the non-titratable, IPTG-inducible lacUV5 promoter. Recently, we constructed the Lemo21(DE3) strain, which allows improved control over the expression of genes from the T7 promoter. Lemo21(DE3) is a BL21(DE3) strain equipped with a plasmid harboring the gene encoding T7 lysozyme, an inhibitor of the T7 RNAP, under control of the exceptionally well-titratable rhamnose promoter. The overexpression yields of a large collection of membrane proteins in Lemo21(DE3) at different concentrations of rhamnose indicated that this strain may be very suitable for optimizing the production of membrane proteins. However, insight in the mechanism by which optimized expression yields are achieved in Lemo21(DE3) is lacking. Furthermore, whether the overexpressed proteins are suitable for functional and structural studies remains to be tested. Here, we show that in Lemo21(DE3), (i) the modulation of the activity of the T7 RNAP by the T7 lysozyme is key to optimizing the ratio of membrane proteins properly inserted in the cytoplasmic membrane to non-inserted proteins; (ii) maximizing the yields of membrane proteins is accompanied by reduction of the adverse effects of membrane protein overexpression, resulting in stable overexpression; and (iii) produced membrane proteins can be used for functional and structural studies., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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36. Evaluation of a health promotion program in children: Study protocol and design of the cluster-randomized Baden-Württemberg primary school study [DRKS-ID: DRKS00000494].
- Author
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Dreyhaupt J, Koch B, Wirt T, Schreiber A, Brandstetter S, Kesztyüs D, Wartha O, Kobel S, Kettner S, Prokopchuk D, Hundsdörfer V, Klepsch M, Wiedom M, Sufeida S, Fischbach N, Muche R, Seufert T, and Steinacker JM
- Subjects
- Anthropometry, Attitude to Health, Child, Cluster Analysis, Educational Measurement, Female, Germany, Humans, Longitudinal Studies, Male, Mentors education, Outcome and Process Assessment, Health Care standards, Parents education, Program Evaluation, Prospective Studies, Research Design, Running physiology, School Health Services statistics & numerical data, Socioeconomic Factors, Health Behavior, Health Promotion methods, Obesity prevention & control, Overweight prevention & control, School Health Services standards
- Abstract
Background: Increasing prevalences of overweight and obesity in children are known problems in industrialized countries. Early prevention is important as overweight and obesity persist over time and are related with health problems later in adulthood. "Komm mit in das gesunde Boot - Grundschule" is a school-based program to promote a healthier lifestyle. Main goals of the intervention are to increase physical activity, decrease the consumption of sugar-sweetened beverages, and to decrease time spent sedentary by promoting active choices for healthy lifestyle. The program to date is distributed by 34 project delivery consultants in the state of Baden-Württemberg and is currently implemented in 427 primary schools. The efficacy of this large scale intervention is examined via the Baden-Württemberg Study., Methods/design: The Baden-Württemberg Study is a prospective, stratified, cluster-randomized, and longitudinal study with two groups (intervention group and control group). Measurements were taken at the beginning of the academic years 2010/2011 and 2011/2012. Efficacy of the intervention is being assessed using three main outcomes: changes in waist circumference, skinfold thickness and 6 minutes run. Stratified cluster-randomization (according to class grade level) was performed for primary schools; pupils, teachers/principals, and parents were investigated. An approximately balanced number of classes in intervention group and control group could be reached by stratified randomization and was maintained at follow-up., Discussion: At present, "Komm mit in das Gesunde Boot - Grundschule" is the largest school-based health promotion program in Germany. Comparative objective main outcomes are used for the evaluation of efficacy. Simulations showed sufficient power with the existing sample size. Therefore, the results will show whether the promotion of a healthier lifestyle in primary school children is possible using a relatively low effort within a school-based program involving children, teachers and parents. The research team anticipates that not only efficacy will be proven in this study but also expects many other positive effects of the program., Trial Registration: German Clinical Trials Register (DRKS), DRKS-ID: DRKS00000494.
- Published
- 2012
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37. Role for Escherichia coli YidD in membrane protein insertion.
- Author
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Yu Z, Lavèn M, Klepsch M, de Gier JW, Bitter W, van Ulsen P, and Luirink J
- Subjects
- Amino Acid Sequence, Escherichia coli genetics, Escherichia coli Proteins chemistry, Escherichia coli Proteins genetics, Membrane Proteins chemistry, Membrane Proteins genetics, Membrane Transport Proteins genetics, Membrane Transport Proteins metabolism, Microscopy, Fluorescence, Molecular Sequence Data, Protein Transport genetics, Protein Transport physiology, Sequence Homology, Amino Acid, Cell Membrane metabolism, Escherichia coli metabolism, Escherichia coli Proteins metabolism, Membrane Proteins metabolism
- Abstract
YidC has an essential but poorly defined function in membrane protein insertion and folding in bacteria. The yidC gene is located in a gene cluster that is highly conserved in Gram-negative bacteria, the gene order being rpmH, rnpA, yidD, yidC, and trmE. Here, we show that Escherichia coli yidD, which overlaps with rnpA and is only 2 bp upstream of yidC, is expressed and localizes to the inner membrane, probably through an amphipathic helix. Inactivation of yidD had no discernible effect on cell growth and viability. However, compared to control cells, ΔyidD cells were affected in the insertion and processing of three YidC-dependent inner membrane proteins. Furthermore, in vitro cross-linking showed that YidD is in proximity of a nascent inner membrane protein during its localization in the Sec-YidC translocon, suggesting that YidD might be involved in the insertion process.
- Published
- 2011
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- View/download PDF
38. Consequences of depletion of the signal recognition particle in Escherichia coli.
- Author
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Wickström D, Wagner S, Baars L, Ytterberg AJ, Klepsch M, van Wijk KJ, Luirink J, and de Gier JW
- Subjects
- Cell Membrane genetics, Cytoplasm genetics, Escherichia coli genetics, Escherichia coli Proteins genetics, Protein Transport physiology, Proteome genetics, Signal Recognition Particle genetics, Cell Membrane metabolism, Cytoplasm metabolism, Escherichia coli metabolism, Escherichia coli Proteins metabolism, Proteome metabolism, Signal Recognition Particle metabolism
- Abstract
Thus far, the role of the Escherichia coli signal recognition particle (SRP) has only been studied using targeted approaches. It has been shown for a handful of cytoplasmic membrane proteins that their insertion into the cytoplasmic membrane is at least partially SRP-dependent. Furthermore, it has been proposed that the SRP plays a role in preventing toxic accumulation of mistargeted cytoplasmic membrane proteins in the cytoplasm. To complement the targeted studies on SRP, we have studied the consequences of the depletion of the SRP component Fifty-four homologue (Ffh) in E. coli using a global approach. The steady-state proteomes and the proteome dynamics were evaluated using one- and two-dimensional gel analysis, followed by mass spectrometry-based protein identification and immunoblotting. Our analysis showed that depletion of Ffh led to the following: (i) impaired kinetics of the biogenesis of the cytoplasmic membrane proteome; (ii) lowered steady-state levels of the respiratory complexes NADH dehydrogenase, succinate dehydrogenase, and cytochrome bo(3) oxidase and lowered oxygen consumption rates; (iii) increased levels of the chaperones DnaK and GroEL at the cytoplasmic membrane; (iv) a σ(32) stress response and protein aggregation in the cytoplasm; and (v) impaired protein synthesis. Our study shows that in E. coli SRP-mediated protein targeting is directly linked to maintaining protein homeostasis and the general fitness of the cell.
- Published
- 2011
- Full Text
- View/download PDF
39. Revolutionizing membrane protein overexpression in bacteria.
- Author
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Schlegel S, Klepsch M, Gialama D, Wickström D, Slotboom DJ, and de Gier JW
- Subjects
- Bacteria genetics, Biotechnology methods, Cell-Free System, Genetic Engineering methods, Membrane Proteins genetics, Recombinant Proteins biosynthesis, Recombinant Proteins genetics, Bacteria metabolism, Gene Expression, Membrane Proteins biosynthesis
- Abstract
The bacterium Escherichia coli is the most widely used expression host for overexpression trials of membrane proteins. Usually, different strains, culture conditions and expression regimes are screened for to identify the optimal overexpression strategy. However, yields are often not satisfactory, especially for eukaryotic membrane proteins. This has initiated a revolution of membrane protein overexpression in bacteria. Recent studies have shown that it is feasible to (i) engineer or select for E. coli strains with strongly improved membrane protein overexpression characteristics, (ii) use bacteria other than E. coli for the expression of membrane proteins, (iii) engineer or select for membrane protein variants that retain functionality but express better than the wild-type protein, and (iv) express membrane proteins using E. coli-based cell-free systems., (© 2009 The Authors. Journal compilation © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.)
- Published
- 2010
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- View/download PDF
40. Comparative analysis of cytoplasmic membrane proteomes of Escherichia coli using 2D blue native/SDS-PAGE.
- Author
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Schlegel S, Klepsch M, Wickström D, Wagner S, and de Gier JW
- Subjects
- Electrophoresis, Gel, Two-Dimensional, Electrophoresis, Polyacrylamide Gel, Cell Membrane metabolism, Escherichia coli metabolism, Proteome metabolism
- Abstract
Two-dimensional blue native (2D BN)/SDS-PAGE is the method of choice for the global analysis of the subunits of complexes in membrane proteomes. In the 1st dimension complexes are separated by BN-PAGE, and in the 2nd dimension their subunits are resolved by SDS-PAGE. The currently available protocols result in the distortion of the 1st dimension BN-gel lanes during their transfer to the 2nd dimension separation gels. This leads to low reproducibility and high variation of 2D BN/SDS-gels, making 2D BN/SDS-PAGE unsuitable for comparative analysis. Here, we present a 2D BN/SDS-PAGE protocol where the 1st dimension BN-gel is cast on a GelBond PAG film. Immobilization prevents distortion of BN-gel lanes when they are transferred to the 2nd dimension, which lowers variation and greatly improves reproducibility of 2D BN/SDS-gels. The use of 2D BN/SDS-PAGE with an immobilized first dimension is illustrated by the characterization of the cytoplasmic membrane proteome of Escherichia coli cells overexpressing cytochrome bo (3).
- Published
- 2010
- Full Text
- View/download PDF
41. Immobilization of the first dimension in 2D blue native/SDS-PAGE allows the relative quantification of membrane proteomes.
- Author
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Klepsch M, Schlegel S, Wickström D, Friso G, van Wijk KJ, Persson JO, de Gier JW, and Wagner S
- Subjects
- Electrophoresis, Gel, Two-Dimensional instrumentation, Escherichia coli Proteins isolation & purification, Mass Spectrometry, Proteome analysis, Electrophoresis, Gel, Two-Dimensional methods, Immobilized Proteins, Membrane Proteins analysis, Proteomics methods
- Abstract
In biological membranes many proteins are organized in complexes. The method of choice for the global analysis of the subunits of these complexes is two-dimensional blue native (2D BN)/SDS-PAGE. In the 1st dimension complexes are separated by BN-PAGE, and in the 2nd dimension their subunits are resolved by SDS-PAGE. In the currently available protocols the 1st dimension BN gel lanes get distorted during their transfer to the 2nd dimension separation gels. This leads to low reproducibility and high variation of 2D BN/SDS-gels, rendering them unsuitable for comparative analysis. We have developed a 2D BN/SDS-PAGE protocol where the 1st dimension BN gel is cast on a GelBond PAG film. Immobilization prevents distortion of BN gel lanes, which lowers variation and greatly improves reproducibility of 2D BN/SDS-gels. 2D BN/SDS-PAGE with an immobilized 1st dimension was used for the comparative analysis of the cytoplasmic membrane proteomes of Escherichia coli cells overexpressing a membrane protein and to create a 2D BN/SDS-PAGE reference map of the E. coli cytoplasmic membrane proteome with 143 identified proteins from 165 different protein spots.
- Published
- 2008
- Full Text
- View/download PDF
42. Effects of SecE depletion on the inner and outer membrane proteomes of Escherichia coli.
- Author
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Baars L, Wagner S, Wickström D, Klepsch M, Ytterberg AJ, van Wijk KJ, and de Gier JW
- Subjects
- Bacterial Outer Membrane Proteins metabolism, Escherichia coli metabolism, Escherichia coli Proteins chemistry, Mass Spectrometry, Membrane Transport Proteins chemistry, Membrane Transport Proteins metabolism, SEC Translocation Channels, Cell Membrane metabolism, Escherichia coli genetics, Escherichia coli Proteins metabolism, Membrane Transport Proteins physiology, Proteome metabolism, Proteomics methods
- Abstract
The Sec translocon is a protein-conducting channel that allows polypeptides to be transferred across or integrated into a membrane. Although protein translocation and insertion in Escherichia coli have been studied using only a small set of specific model substrates, it is generally assumed that most secretory proteins and inner membrane proteins use the Sec translocon. Therefore, we have studied the role of the Sec translocon using subproteome analysis of cells depleted of the essential translocon component SecE. The steady-state proteomes and the proteome dynamics were evaluated using one- and two-dimensional gel analysis, followed by mass spectrometry-based protein identification and extensive immunoblotting. The analysis showed that upon SecE depletion (i) secretory proteins aggregated in the cytoplasm and the cytoplasmic sigma(32) stress response was induced, (ii) the accumulation of outer membrane proteins was reduced, with the exception of OmpA, Pal, and FadL, and (iii) the accumulation of a surprisingly large number of inner membrane proteins appeared to be unaffected or increased. These proteins lacked large translocated domains and/or consisted of only one or two transmembrane segments. Our study suggests that several secretory and inner membrane proteins can use Sec translocon-independent pathways or have superior access to the remaining Sec translocons present in SecE-depleted cells.
- Published
- 2008
- Full Text
- View/download PDF
43. Dual roles of the central domain of colicin D tRNase in TonB-mediated import and in immunity.
- Author
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Mora L, Klepsch M, Buckingham RH, Heurgué-Hamard V, Kervestin S, and de Zamaroczy M
- Subjects
- Bacteriocins genetics, Bacteriocins metabolism, Escherichia coli genetics, Escherichia coli Proteins genetics, Membrane Proteins genetics, Protein Binding physiology, Protein Structure, Secondary physiology, Protein Structure, Tertiary physiology, Protein Transport physiology, RNA, Transfer, Arg genetics, RNA, Transfer, Arg metabolism, Ribonucleases genetics, Escherichia coli metabolism, Escherichia coli Proteins metabolism, Membrane Proteins metabolism, Ribonucleases metabolism
- Abstract
Colicin D import into Escherichia coli requires an interaction via its TonB box with the energy transducer TonB. Colicin D cytotoxicity is inhibited by specific tonB mutations, but it is restored by suppressor mutations in the TonB box. Here we report that there is a second site of interaction between TonB and colicin D, which is dependent upon a 45-amino acid region, within the uncharacterized central domain of colicin D. In addition, the 8th amino acids of colicin D (a glycine) and colicin B (a valine), adjacent to their TonB boxes, are also required for TonB recognition, suggesting that high affinity complex formation involves multiple interactions between these colicins and TonB. The central domain also contributes to the formation of the immunity complex, as well as being essential for uptake and thus killing. Colicin D is normally secreted in association with the immunity protein, and this complex involves the following two interactions: a major interaction with the C-terminal tRNase domain and a second interaction involving the central domain of colicin D and, most probably, the alpha4 helix of ImmD, which is on the opposite side of ImmD compared with the major interface. In contrast, formation of the immunity complex with the processed cytotoxic domain, the form expected to be found in the cytoplasm after colicin D uptake, requires only the major interaction. Klebicin D has, like colicin D, a ribonuclease activity toward tRNAArg and a central domain, which can form a complex with ImmD but which does not function in TonB-mediated transport.
- Published
- 2008
- Full Text
- View/download PDF
44. Interaction of potassium cyanide with the [Ni-4Fe-5S] active site cluster of CO dehydrogenase from Carboxydothermus hydrogenoformans.
- Author
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Ha SW, Korbas M, Klepsch M, Meyer-Klaucke W, Meyer O, and Svetlitchnyi V
- Subjects
- Absorptiometry, Photon, Aldehyde Oxidoreductases antagonists & inhibitors, Aldehyde Oxidoreductases metabolism, Bacterial Proteins antagonists & inhibitors, Bacterial Proteins metabolism, Binding Sites, Carbon Monoxide chemistry, Carbon Monoxide metabolism, Iron metabolism, Multienzyme Complexes antagonists & inhibitors, Multienzyme Complexes metabolism, Nickel chemistry, Nickel metabolism, Oxidation-Reduction, Sulfur chemistry, Sulfur metabolism, Aldehyde Oxidoreductases chemistry, Bacterial Proteins chemistry, Clostridium enzymology, Iron chemistry, Multienzyme Complexes chemistry, Potassium Cyanide chemistry
- Abstract
The Ni-Fe carbon monoxide (CO) dehydrogenase II (CODHII(Ch)) from the anaerobic CO-utilizing hydrogenogenic bacterium Carboxydothermus hydrogenoformans catalyzes the oxidation of CO, presumably at the Ni-(micro(2)S)-Fe1 subsite of the [Ni-4S-5S] cluster in the active site. The CO oxidation mechanism proposed on the basis of several CODHII(Ch) crystal structures involved the apical binding of CO at the nickel ion and the activation of water at the Fe1 ion of the cluster. To understand how CO interacts with the active site, we have studied the reactivity of the cluster with potassium cyanide and analyzed the resulting type of nickel coordination by x-ray absorption spectroscopy. Cyanide acts as a competitive inhibitor of reduced CODHII(Ch) with respect to the substrate CO and is therefore expected to mimic the substrate. It inhibits the enzyme reversibly, forming a nickel cyanide. In this reaction, one of the four square-planar sulfur ligands of nickel is replaced by the carbon atom of cyanide, suggesting removal of the micro(2)S from the Ni-(micro(2)S)-Fe1 subsite. Upon reactivation of the inhibited enzyme, cyanide is released, and the square-planar coordination of nickel by 4S ligands is recovered, which includes the reformation of the Ni-(micro(2)S)-Fe1 bridge. The results are summarized in a model of the CO oxidation mechanism at the [Ni-4Fe-5S] active site cluster of CODHII(Ch) from C. hydrogenoformans.
- Published
- 2007
- Full Text
- View/download PDF
45. Acute pancreatitis and amaurosis after right parathyroidectomy for primary hyperparathyroidism.
- Author
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Klepsch M and Bergenfelz A
- Subjects
- Acute Disease, Adult, Female, Humans, Pancreatitis complications, Blindness etiology, Hyperparathyroidism surgery, Pancreatitis etiology, Parathyroidectomy, Postoperative Complications
- Published
- 2000
- Full Text
- View/download PDF
46. [Stress fractures of the femoral neck due to step aerobics--case report].
- Author
-
Klepsch M and Kreitner KF
- Subjects
- Adult, Female, Humans, Athletic Injuries diagnosis, Femoral Neck Fractures diagnosis, Fractures, Stress diagnosis
- Abstract
With the rising public interest in physical fitness an increasing number of stress reactions of the bone are diagnosed. Commonly known in competitive athletes, they are increasingly seen in recreational sports. Stress reactions of the bone are a disorder between the loading force and the capability to compensate. Stress fractures with displacement of the bone are more rarely diagnosed due to improved diagnostic means. Stress fractures of the medial femoral neck in young athletes are uncommon. We are reporting the case of a beginning tension type stress fracture of the medial femoral neck of a 29 year old female recreational athlete after excessive stepping and step aerobic at a fitness center.
- Published
- 1998
- Full Text
- View/download PDF
47. [Paget's disease of the proximal ulna--a rare monostotic manifestation].
- Author
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Klepsch M, Seidel T, and Runkel M
- Subjects
- Alkaline Phosphatase blood, Diagnostic Imaging, Female, Humans, Hydroxyproline urine, Middle Aged, Osteitis Deformans pathology, Osteitis Deformans diagnosis, Ulna pathology
- Abstract
Bone changes of the upper extremity are rare manifestations of the M. Paget disease. Most frequently the disease affects the lower extremities, the pelvis followed by the calvarium and others. The rare asymptomatic, monostotic manifestation of Paget's disease of the left proximal ulnae of a 59 year old woman and the way of diagnosis is described. Symptomatic skeletal lesions are detected by radiological examination, bone scintigraphy reveals asymptomatic lesions. Laboratory tests (Alkaline serum phosphatase, Hydroxyproline in urine) monitor the activity of the disease.
- Published
- 1997
- Full Text
- View/download PDF
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