The enzyme from Acidaminococcus fermentans is a biotinyl-protein, requires Na+, and acts as a sodium pump. Prior to the Na+-dependent decarboxylation, the carboxylate is transferred to biotin in a Na+-independent manner. The conserved lysine, to which biotin forms an amide bond, is located 34 amino acids before the C-terminus, flanked on both sides by two methionine residues, which are conserved in every biotin-dependent enzyme.
Buckel, W.S. and Semmler, R. Purification, characterisation and reconstitution of glutaconyl-CoA decarboxylase, a biotin-dependent sodium pump from anaerobic bacteria. Eur. J. Biochem.136 (1983) 427–434. [PMID: 6628393]