title: Serine 363 of a Hydrophobic Region of Archaeal Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase from Archaeoglobus fulgidus and Thermococcus kodakaraensis Affects CO2/O2 Substrate Specificity and Oxygen Sensitivity.
abstract: Archaeal ribulose 1, 5-bisphospate carboxylase/oxygenase (RubisCO) is differentiated from other RubisCO enzymes and is classified as a form III enzyme, as opposed to the form I and form II RubisCOs typical of chemoautotrophic bacteria and prokaryotic and eukaryotic phototrophs. The form III enzyme from archaea is particularly interesting as several of these proteins exhibit unusual and reversible sensitivity to molecular oxygen, including the enzyme from Archaeoglobus fulgidus. Previous studies with A. fulgidus RbcL2 had shown the importance of Met-295 in oxygen sensitivity and pointed towards the potential significance of another residue (Ser-363) found in a hydrophobic pocket that is conserved in all RubisCO proteins. In the current study, further structure/function studies have been performed focusing on Ser-363 of A. fulgidus RbcL2; various changes in this and other residues of the hydrophobic pocket point to and definitively establish the importance of Ser-363 with respect to interactions with oxygen. In addition, previous findings had indicated discrepant CO2/O2 specificity determinations of the Thermococcus kodakaraensis RubisCO, a close homolog of A. fulgidus RbcL2. It is shown here that the T. kodakaraensis enzyme exhibits a similar substrate specificity as the A. fulgidus enzyme and is also oxygen sensitive, with equivalent residues involved in oxygen interactions.
authors.affiliation: The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210-1292, United States of America.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Kreel
authors.affiliation: The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210-1292, United States of America; Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210-1292, United States of America.
authors.forename: F Robert
authors.initials: FR
authors.lastname: Tabita
mesh_terms: D000595:Amino Acid Sequence; D019611:Archaeoglobus fulgidus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D030781:Organisms, Genetically Modified; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012694:Serine / Q000235:genetics*; D013379:Substrate Specificity / Q000235:genetics; D019712:Thermococcus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D012694:Serine; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen