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Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent CO2 fixation through ribulose carboxylase/oxygenase (rubisco) in methanococcus jannaschii

Finn, Michael Wehren

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Microbiology.

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.

Fred Tabita (Advisor)
162 p.

Recommended Citations

Citations

  • Finn, M. W. (2004). Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent CO2 fixation through ribulose carboxylase/oxygenase (rubisco) in methanococcus jannaschii [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1077915999

    APA Style (7th edition)

  • Finn, Michael. Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent CO2 fixation through ribulose carboxylase/oxygenase (rubisco) in methanococcus jannaschii. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1077915999.

    MLA Style (8th edition)

  • Finn, Michael. "Discovery of a biochemical pathway to generate ribulose 1,5-bisphosphate and subsequent CO2 fixation through ribulose carboxylase/oxygenase (rubisco) in methanococcus jannaschii." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1077915999

    Chicago Manual of Style (17th edition)