Closely related form I ribulose bisphosphate carboxylase/oxygenase molecules that possess different CO2/O2 substrate specificities.
The deduced primary sequence (cbbL and cbbS) of form I ribulose 1, 5-bisphosphate carboxylase/oxygenase (rubisco) from Bradyrhizobium japonicum places this enzyme within the Type IC subgroup of red-like rubisco enzymes. In addition, B. japonicum appears to organize most of the structural genes of the Calvin-Benson-Bassham (CBB) pathway in at least one major operon. Functional expression and characterization of the B. japonicum and Xanthobacter flavus enzymes from this group revealed that these molecules exhibit diverse kinetic properties despite their relatively high degree of sequence relatedness. Of prime importance was the fact that these closely related enzymes exhibited CO2 and O2 substrate specificities that varied from relatively low values [tau = (VcKo)/(VoKc) = 45] to values that approximated those obtained for higher plants (tau = 75). These results, combined with the metabolic and genetic versatility of the organisms from which these enzymes were derived, suggest a potential rich resource for future biological selection and structure-function studies aimed at elucidating structural features that govern key enzymological properties of rubisco.
Horken
K M
KM
Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210-1292, USA.
Tabita
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FR
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D020369:Bradyrhizobium / Q000201:enzymology / Q000235:genetics; D002245:Carbon Dioxide / Q000378:metabolism*; D004789:Enzyme Activation / Q000235:genetics; D005798:Genes, Bacterial; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D013379:Substrate Specificity
D001426:Bacterial Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen