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293 results on '"Obata, Hitoshi"'

3. Biochemical and genetic analysis of the [gamma]-resorcylate (2,6-dihydroxybenzoate) catabolic pathway in Rhizobium sp. strain MTP-10005: identification and functional analysis of its gene cluster

Author

Yoshida, Masahiro, Oikawa, Tadao, Obata, Hitoshi, Abe, Katsumasa, Mihara, Hisaaki, and Esaki, Nobuyoshi

Subjects
Rhizobium -- Genetic aspects, Rhizobium -- Research, Escherichia coli -- Genetic aspects, Escherichia coli -- Research, Genetic transcription -- Identification and classification, Genetic transcription -- Research, Biological sciences
Abstract

We identified a gene cluster that is involved in the [gamma]-resorcylate (2,6-dihydroxybenzoate) catabolism of the aerobic bacterium Rhizobium sp. strain MTP-10005. The cluster consists of the graRDAFCBEK genes, and graA, graB, graC, and graD were heterologously expressed in Escherichia coli. Enzymological studies showed that graD, graA, graC, and graB encode the reductase (GraD) and oxygenase (GraA) components of a resorcinol hydroxylase (EC 1.14.13.x), a maleylacetate reductase (GraC) (EC 1.3.1.32), and a hydroxyquinol 1,2-dioxygenase (GraB) (EC 1.13.11.37). Bioinformatic analyses suggested that graE, graR, and graK encode a protein with an unknown function (GraE), a MarR-type transcriptional regulator (GraR), and a benzoate transporter (GraK). Quantitative reverse transcription-PCR of graF, which encodes [gamma]-resorcylate decarboxylase, revealed that the maximum relative mRNA expression level ([5.93 [+ or -] 0.82] x [10.sup.-4]) of graF was detected in the total RNA of the cells after one hour of cultivation when [gamma]-resorcylate was used as the sole carbon source. Reverse transcription-PCR of graDAFCBE showed that these genes are transcribed as a single mRNA and that the transcription of the gene cluster is induced by [gamma]-resorcylate. These results suggested that the graDAFCBE genes are responsible as an operon for the growth of Rhizobium sp. strain MTP-10005 on [gamma]-resorcylate and are probably regulated by GraR at the transcriptional level. This is the first report of the [gamma]-resorcylate catabolic pathway in an aerobic bacterium.

Published
2007

5. Cloning and expression of afpA, a gene encoding an antifreeze protein from the Arctic plant growth-promoting rhizobacterium Pseudomonas putida GR12-27

Author

Muryoi, Naomi, Sato, Mika, Kaneko, Shoji, Kawahara, Hidehisa, Obata, Hitoshi, Yaish, Mahmoud W.F., Griffith, Marilyn, and Glick, Bernard R.

Subjects
Rhizobium -- Research, Rhizobium -- Risk factors, Pseudomonas putida -- Research, Pseudomonas putida -- Risk factors, Gene expression -- Research, Cloning -- Research, Biological sciences
Abstract

The Arctic plant growth-promoting rhizobacterium Pseudomonas putida GR12-2 secretes an antifreeze protein (AFP) that promotes survival at subzero temperatures. The AFP is unusual in that it also exhibits a low level of ice nucleation activity. A DNA fragment with an open reading frame encoding 473 amino acids was cloned by PCR and inverse PCR using primers designed from partial amino acid sequences of the isolated AFP. The predicted gene product, AfpA, had a molecular mass of 47.3 kDa, a pI of 3.51, and no previously known function. Although AfpA is a secreted protein, it lacked an N-terminal signal peptide and was shown by sequence analysis to have two possible secretion systems: a hemolysin-like, calcium-binding secretion domain and a type V autotransporter domain found in gram-negative bacteria. Expression of afpA in Escherichia coli yielded an intracellular 72-kDa protein modified with both sugars and lipids that exhibited lower levels of antifreeze and ice nucleation activities than the native protein. The 164-kDa AFP previously purified from P. putida GR12-2 was a lipoglycoprotein, and the carbohydrate was required for ice nucleation activity. Therefore, the recombinant protein may not have been properly posttranslationally modified. The AfpA sequence was most similar to cell wall-associated proteins and less similar to ice nucleation proteins (INPs). Hydropathy plots revealed that the amino acid sequence of AfpA was more hydrophobic than those of the INPs in the domain that forms the ice template, thus suggesting that AFPs and INPs interact differently with ice. To our knowledge, this is the first gene encoding a protein with both antifreeze and ice nucleation activities to be isolated and characterized.

Published
2004

15. Cloning of three ZIP/Nramp transporter genes from a Ni hyperaccumulator plant thlaspi japonicum and their Ni²⁺ transport abilities

Author

Mizuno, Takahumi, Usui, Koji, Horie, Kenji, Nosaka, Shiro, Mizuno, Naoharu, and Obata, Hitoshi

Subjects
inorganic chemicals, Thlaspi japonicum, TjNRAMP4, histidine-rich domain, hyperaccumulator, Ni-transport, TjZNT1, TjZNT2
Abstract

Ni homeostasis is essential for plant cell activity, but the mechanisms of Ni-transport and delivery are unknown. To elucidate the role of ZIP and NRAMP metal-transporters for Ni²⁺-transport and homeostasis, we cloned their homologous genes from the Ni hyperaccumulator Thlaspi japonicum, and investigated their Ni-transporting abilities by expression in yeast. The deduced amino acid sequences of the two Zip transporter genes (TjZnt1, TjZnt2) and one Nramp transporter gene cloned had high homologies with TcZNT1 and TcZNT2 of Thlaspi caerulescens and AtNRAMP4 of Arabidopsis thaliana, respectively, and were predicted as integral membrane proteins with 6 or 12 transmembrane domains. TjZNT1 and TjZNT2 had two long histidine-rich domains in the putative cytoplasmic domain between transmembrane domains III and IV. TjNRAMP4 conserved a consensus transporter motif between transmembrane domains VIII and IX. The yeast transformed with TjZNT1 or TjZNT2 showed a marked increase in Ni²⁺ tolerance with the gene expression. In contrast, the expression of TjNramp4 caused elevation of Ni²⁺ sensitivity and Ni²⁺ concentration. These data suggest that ZIP/NRAMP transporters participate in Ni²⁺ homeostasis of Ni hyperaccumulator plants. TjZNT1 had Zn²⁺-, Cd²⁺- and Mn²⁺-transporting abilities and TjZNT2 also had Zn²⁺- and Mn²⁺-transporting abilities, but TjNRAMP4 could transport Ni²⁺ but not Zn²⁺, Cd²⁺ or Mn²⁺., 重金属汚染土壌の浄化と重金属資源の回収技術開発に関する研究

Published
2005

16. 和歌山県産南高梅の梅干加工工程におけるミネラル及び有機酸含量の変化

Author

Furuichi, Yukio, Mizuno, Takafumi, Yamashita, Yoshinobu, Suzuki, Atsushi, Obata, Hitoshi, and Umemiya, Yoshiaki

Abstract

Changes in mineral components during the processing of umeboshi was investigated using ripened Nanko mume fruit as raw material. Calcium and Magnesium contents were increased or almost equal by pickling in salt, and potassium was decreased, Among the trace elements, iron showed remarkable increase by salting, Furthermore, mineral component of salt used for pickling was recognized to reflect in the content of these elements in salted mume fruits. Sodium content in edible part of Umeboshi was decreased with desalting and following pickling in seasoning solution, but those of calcium and magnesium did not changed. Potassium was also decreased but large part of potassium remained in edible part, suggesting that a function of Umebosshi as an alkaline food remained after hypochloric treatment. Contents of all minerals investigated showed smaller change in kernel than those in pulp. Many parts of organic acid in edible part remained after Umeboshi processing, and it was speculated that resulting low pH condition effected on the mineral composition in Umeboshi.

Published
2005

17. カー時空における光の軌道の3次元的な図示について

Author

岸本, 功, 小畑, 仁, 近藤, 悠太, Kishimoto, Isao, Obata, Hitoshi, Kondo, Yuta, 岸本, 功, 小畑, 仁, 近藤, 悠太, Kishimoto, Isao, Obata, Hitoshi, and Kondo, Yuta

Abstract

真空のアインシュタイン方程式の解として, 回転するブラックホールを表すカー時空が知られている. ここでは, このカー時空において, 光の軌道を表すヌル測地線を具体的に調べ, 図示する. 赤道面内の軌道だけでなく, カーター定数が値をもち軌道が平面内におさまらないようなものについても計算し, 3 次元的なプロットを行う. 特に, 無限遠からやって来て再び無限遠に去っていくような, ホライズンの外側の光の軌道の湾曲の様子を調べる.

Published
2016

18. Continual pH lowering and manganese dioxide solubilization in the rhizosphere of Mn-hypereccumulator plant Chengiopanax sciadophylloides.

Author

Graduate School of Bioresources, Mie University, Mizuno, Takahumi, Hirano, Kenji, Hosono, Atsuko, Kato, Shinta, Obata, Hitoshi, Graduate School of Bioresources, Mie University, Mizuno, Takahumi, Hirano, Kenji, Hosono, Atsuko, Kato, Shinta, and Obata, Hitoshi

Abstract

The Japanese woody plant Chengiopanax sciadophylloides is well known for its extraordinary accumulation of manganese (Mn), and is used as a model for studying Mn uptake and utilization by plants. To clarify the role of manganese dioxide (MnO_2) solubilization for Mn acquisition and further Mn hyperaccumulation in this plant, we examined the lowering of pH in the rhizosphere and Mn accumulation of this plant using regenerated plants. Plants regenerated from C. sciadophylloides calli lowered the pH of the culture broth continuously and simultaneously solubilized MnO_2 added to the medium. The Mn content of the plant increased up to 1,300 mg kg^<-1> within 4 weeks of culture. Release of protein or specific organic acid from the roots was not observed. The medium used for plant culture maintained MnO_2 solubilization ability after removal of the plant; however, this ability was lost by adjustment to the same medium pH of pre-culture conditions. In addition, pH lowering and MnO_2 solubilization were suppressed by adding 1 mmol L^<-1> of the plasma H^+-ATPase inhibitor Na_3VO_4 to the medium, and completely inhibited when 5 mmol L^<-1> of Na_3VO_4 was added. These results suggested that H^+ leaking from plasma H^+-ATPase plays an important role in MnO_2 solubilization in the rhizosphere of C. sciadophylloides and in Mn accumulation in this plant.

Published
2007

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