Disease relevance of Carboxybiotin

• The membrane-bound beta-subunit of oxaloacetate decarboxylase from Klebsiella pneumoniae catalyzes the decarboxylation of carboxybiotin, which is coupled to Na(+) translocation and consumes a periplasmically derived proton [1].

High impact information on Carboxybiotin

• The Gcdalpha catalyses the transfer of carbon dioxide from glutaconyl-CoA to a biotin carrier (Gcdgamma) that subsequently is decarboxylated by the carboxybiotin decarboxylation site within the actual Na(+) pump (Gcdbeta) [2].
• Molecular structure and intermolecular interactions of N1'-methoxycarbonylbiotin methyl ester: a model for carboxybiotin [3].
• Sodium ion binding from the cytoplasm to both sites elicits decarboxylation of carboxybiotin, and a conformational switch exposes the bound Na+ ions toward the periplasm [4].
• In seeking a connection between bound CO2 and proton transfer in the histidine decarboxylase reaction, one is reminded of the carboxybiotin enzymes also known for an invariant stereochemistry of retention and for the requirement that the biotin be in the carboxylated form for H-exchange to occur [5].
• The carboxybiotin complex of chicken liver pyruvate carboxylase. A kinetic analysis of the effects of acetyl-CoA, Mg2+ ions and temperature on its stability and on its reaction with 2-oxobutyrate [6].

Biological context of Carboxybiotin

• The membrane-bound beta-subunit is responsible for the decarboxylation of carboxybiotin and the coupled translocation of Na+ ions across the membrane [7].
• The results are consistent with the hypothesis that the location of the carboxybiotin in the active site is determined by the presence of Mg2+, acetyl-CoA and the oxo acid substrate [8].
• The kinetics of the decay of the enzyme-[14C] carboxybiotin complex at 0 degree C in the absence of substrates are similar to the reaction with pyruvate except that the carboxybiotin is also unstable in the first sub-site, to some degree [9].
• Biotin assay excluded potential contamination by traces of biotin as a cause of the observed ATP hydrolysis, and this was confirmed by the findings that carboxybiotin did not accumulate and that avidin was uninhibitory [10].
• In many sequenced genomes from Bacteria and Archaea homologues of the carboxybiotin decarboxylase from A. fermentans with up to 80% sequence identity have been detected [11].

Associations of Carboxybiotin with other chemical compounds

• The model predicts that asp203 in its dissociated form binds Na+ and promotes its translocation, while the protonated residue transfers the proton to the acid-labile carboxybiotin which initiates its decarboxylation [7].
• Recently it has been shown that the proton required for the decarboxylation of carboxybiotin is taken up from the side to which Na+ ions are pumped, and a membrane-embedded aspartate residue that is probably involved both in Na+ and in H+ transport was identified [12].

Gene context of Carboxybiotin

• The carboxybiotin complex of pyruvate carboxylase. A kinetic analysis of the effects of Mg2+ ions on its stability and on its reaction with pyruvate [9].
• MadB is the integral membrane-bound carboxybiotin protein decarboxylase, MadC and MadD are the two subunits of the carboxyltransferase, MadE is the acyl carrier protein and MadF is the biotin protein [13].

References