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首页> 外文学位 >Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent carbon dioxide fixation through ribulose carboxylase/oxygenase (RubisCO) in Methanococcus jannaschii.
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Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent carbon dioxide fixation through ribulose carboxylase/oxygenase (RubisCO) in Methanococcus jannaschii.

机译：发现了在詹氏甲烷球菌中产生核糖1,5-二磷酸核糖并随后通过核糖羧化酶/加氧酶（RubisCO）固定二氧化碳的生化途径。

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摘要

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) catalyzes the biological reduction and assimilation of carbon dioxide gas to organic carbon. Until recently it was believed that there were only two forms of RubisCO, form I and form II. However, recent completion of several genome-sequencing projects uncovered open reading frames resembling RubisCO in the third domain of life, the archaea. Previous work and homology comparisons, suggest that these enzymes represent a third form of RubisCO, form III. While earlier work had indicated that two structurally distinct recombinant archaeal RubisCO proteins catalyzed bona fide RubisCO reactions, it was not established that the rbcL genes of anaerobic archaea could be transcribed and translated to an active enzyme in the native organisms.; This study provides evidence that RubisCO in Methanococcus jannaschii, Archaeoglobus fulgidus, Methanosarcina acetivorans, and Methanosarcina barkeri accumulates in an active form under normal growth conditions. In addition, the form III RubisCO gene (rbcL) from M. acetivorans complemented RubisCO deletion strains of Rhodobacter capsulatus and Rhodobacter sphaeroides such that both photoheterotrophic and photoautotrophic growth occurred. These studies thus, for the first time, indicated that archaeal form III RubisCO can fix enough CO2 to support cellular growth. Furthermore, recombinant M. jannaschii, M. acetivorans, and A. fulgidus RubisCO possess unique properties with respect to quaternary structure, temperature optima, and activity in the presence of molecular oxygen.; To complete the Calvin-Benson-Bassham (CBB) cycle in M. jannaschii , phosphoribulokinase (PRK) would be required to produce RuBP, the substrate for the RubisCO reaction. However, homology searches as well as direct enzymatic assays in M. jannaschii failed to reveal the presence of this enzyme. The apparent lack of PRK raised the possibility that either an alternative pathway to generate RuBP was present or that RubisCO might use an alternative substrate in vivo. This study provided evidence for a previously uncharacterized pathway for RuBP synthesis from 5-phosphoribose-1-pyrophosphate (PRPP) in M. jannaschii, in which protein Mj0601 was shown to catalyze a novel and key reaction.
机译：核糖1,5-双磷酸羧化酶/加氧酶（RubisCO）催化二氧化碳气体向有机碳的生物还原和同化作用。直到最近，人们仍认为只有两种形式的RubisCO，即形式I和形式II。但是，最近完成的几个基因组测序项目发现了在生活的第三领域古细菌中类似于RubisCO的开放阅读框。先前的工作和同源性比较表明，这些酶代表RubisCO的第三种形式，即III型。虽然较早的工作表明两种结构上不同的重组古细菌RubisCO蛋白可催化真正的RubisCO反应，但尚不能确定厌氧古细菌的rbcL基因是否可以被转录并翻译成天然生物中的活性酶。这项研究提供的证据表明，在正常生长条件下，詹氏甲烷球菌，古生弧菌，醋酸拟甲烷单胞菌和巴氏甲烷八叠球菌中的RubisCO会以活性形式积累。另外，来自乙酸食单胞菌的III型RubisCO基因（rbcL）补充了荚膜红细菌和球形红细菌的RubisCO缺失菌株，从而发生了光异养和光自养生长。因此，这些研究首次表明，古细菌III型RubisCO可以固定足够的CO2以支持细胞生长。此外，重组的詹氏甲烷八叠球菌，乙酰腐氏甲烷八叠球菌和fulfulusdus RubisCO在分子氧存在下具有四级结构，最佳温度和活性方面的独特性能。为了在詹氏甲烷球菌中完成Calvin-Benson-Bassham（CBB）循环，将需要磷酸核糖激酶（PRK）来产生RuBP，RuBP是反应RubisCO的底物。然而，在詹氏甲烷球菌中的同源性搜索以及直接的酶法测定未能揭示该酶的存在。 PRK的明显缺乏增加了存在替代途径产生RuBP或RubisCO可能在体内使用替代底物的可能性。这项研究为詹氏甲烷球菌中5-磷酸核糖-1-焦磷酸（PRPP）合成RuBP的以前未知的途径提供了证据，其中Mj0601蛋白被证明可催化新的关键反应。

著录项

  • 作者

    Finn, Michael W.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 162 p.
  • 总页数 162
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 微生物学;
  • 关键词

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