Synthesis of catalytically active form III ribulose 1,5-bisphosphate carboxylase/oxygenase in archaea.
Ribulose 1,5 bisphosphate carboxylase/oxygenase (RubisCO) catalyzes the biological reduction and assimilation of carbon dioxide gas to organic carbon; it is the key enzyme responsible for the bulk of organic matter found on earth. Until recently it was believed that there are only two forms of RubisCO, form I and form II. However, the 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 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 can be transcribed and translated to an active enzyme in the native organisms. In this report, it is shown not only that Methanococcus jannaschii, Archaeoglobus fulgidus, Methanosarcina acetivorans, and Methanosarcina barkeri possess open reading frames with the residues required for catalysis but also that the RubisCO protein from these archaea accumulates in an active form under normal growth conditions. In addition, the form III RubisCO gene (rbcL) from M. acetivorans was shown to complement RubisCO deletion strains of Rhodobacter capsulatus and Rhodobacter sphaeroides under both photoheterotrophic and photoautotrophic growth conditions. These studies thus indicate for the first time that archaeal form III RubisCO functions in a physiologically significant fashion to fix CO(2). 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 compared to the previously described Thermococcus kodakaraensis and halophile proteins.
Finn
Michael W
MW
Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, USA.
Tabita
F Robert
FR
D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015153:Blotting, Western; D002245:Carbon Dioxide / Q000378:metabolism; D002384:Catalysis; D002455:Cell Division / Q000502:physiology; D004789:Enzyme Activation; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000235:genetics / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D019843:Archaeal Proteins; D011994:Recombinant Proteins; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase