Ferrous-iron-dependent Uptake of<scp>L</scp>-Glutamate by a Mesophilic, Mixotrophic Iron-oxidizing Bacterium Strain OKM-9

• INOUE Takao

  <i>Division of Science and Technology for Energy Conversion, Graduate School of Natural Science and Technology, Okayama University</i>

• KAMIMURA Kazuo

  <i>Division of Science and Technology for Energy Conversion, Graduate School of Natural Science and Technology, Okayama University</i>

• SUGIO Tsuyoshi

  <i>Division of Science and Technology for Energy Conversion, Graduate School of Natural Science and Technology, Okayama University</i>

書誌事項

タイトル別名

• Ferrous-iron-dependent Uptake of L-Glutamate by a Mesophilic, Mixotrophic Iron-oxidizing Bacterium Strain OKM-9.

抄録

  Strain OKM-9 is a mesophilic, mixotrophic iron-oxidizing bacterium that absolutely requires ferrous iron as its energy source and L-amino acids (including L-glutamate) as carbon sources for growth. The properties of the L-glutamate transport system were studied with OKM-9 resting cells, plasma membranes, and actively reconstituted proteoliposomes. L-Glutamate uptake into resting cells was totally dependent on ferrous iron that was added to the reaction mixture. Potassium cyanide, an iron oxidase inhibitor, completely inhibited the activity at 1 mM. The optimum pH for Fe²⁺-dependent uptake activity of L-glutamate was 3.5-4.0. Uptake activity was dependent on the concentration of the L-glutamate. The K_m and V_max for L-glutamate were 0.4 mM and 11.3 nmol•min⁻¹•mg⁻¹, respectively. L-Aspartate, D-aspartate, D-glutamate, and L-cysteine strongly inhibited L-glutamate uptake. L-Aspartate competitively inhibited the activity, and the apparent K_i for this amino acid was 75.9 μM. 2,4-Dinitrophenol, carbonyl cyanide m-chlorophenylhydrazone, gramicidin D, valinomycin, and monensin did not inhibit Fe²⁺-dependent L-glutamate uptake. The OKM-9 plasma membranes had approximately 40% of the iron-oxidizing activity of the resting cells and approximately 85% of the Fe²⁺-dependent uptake activity. The glutamate transport system was solubilized from the membranes with 1% n-octyl-β-D-glucopyranoside and reconstituted into a lecithin liposome. The L-glutamate transport activity of the reconstituted proteoliposomes was 8-fold than that of the resting cells. The Fe²⁺-dependent L-glutamate uptake observed here seems to explain the mixotrophic nature of this strain, which absolutely requires Fe²⁺ oxidation when using amino acids as carbon sources.<br>

収録刊行物

• Ｂｉｏｓｃｉｅｎｃｅ，　Ｂｉｏｔｅｃｈｎｏｌｏｇｙ，　ａｎｄ　Ｂｉｏｃｈｅｍｉｓｔｒｙ

  Ｂｉｏｓｃｉｅｎｃｅ，　Ｂｉｏｔｅｃｈｎｏｌｏｇｙ，　ａｎｄ　Ｂｉｏｃｈｅｍｉｓｔｒｙ 66 (10), 2030-2035, 2002

  公益社団法人 日本農芸化学会

キーワード

• iron-oxidizing bacterium
• mixotroph
• <small>L</small>-glutamate uptake system
• iron oxidase
• <small>L</small>-glutamate transporter

詳細情報

• CRID: 1390001206475548032
• NII論文ID: 110002693514
• NII書誌ID: AA10824164
• DOI: 10.1271/bbb.66.2030
• COI: 1:CAS:528:DC%2BD38XosVKjsbg%3D
• ISSN: 13476947
• ISSN: 09168451
• NDL書誌ID: 6346173
• PubMed: 12450111
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6346173
• Web Site: http://www.tandfonline.com/doi/pdf/10.1271/bbb.66.2030
• 本文言語コード: en
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • PubMed
  • CiNii Articles
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