title: Acetyl-CoA carboxylase activity in Helicobacter pylori and the requirement of increased CO2 for growth.
abstract: A biotinylated acetyl-CoA carboxylase from the microaerophilic bacterium Helicobacter pylori was partially purified and characterized. The approximate molecular mass of the native enzyme was estimated at 235 kDa by native PAGE. A single band corresponding to approximately 24 kDa was detected by SDS-PAGE, suggesting that the native enzyme is a multi-protein complex. The protein was isolated from the soluble fraction of the cell. Catalytic activity was acetyl-CoA-dependent and inhibited by avidin but unaffected by avidin pretreated with excess biotin. The end-product of the reaction was identified as malonyl-CoA and the reaction was shown to be reversible by NMR spectroscopy. The activity of the enzyme was 0.29 mumol min-1 (mg protein)-1. The Vmax for bicarbonate was calculated at 0.73 mumol min-1 (mg protein)-1, and the affinity of the enzyme for this substrate was relatively low, with an apparent Km of 16.6 mM. These data provide the first evidence of a possible physiological role for the requirement of high levels of CO2 for growth in vitro of this bacterium.
authors.affiliation: School of Microbiology, University of New South Wales, Sydney, Australia.
authors.forename: B P
authors.initials: BP
authors.lastname: Burns
authors.forename: S L
authors.initials: SL
authors.lastname: Hazell
authors.forename: G L
authors.initials: GL
authors.lastname: Mendz
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D016480:Helicobacter pylori / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008316:Malonyl Coenzyme A / Q000378:metabolism; D008970:Molecular Weight; D012995:Solubility; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide; D008316:Malonyl Coenzyme A; D000103:Acetyl-CoA Carboxylase