Oxaloacetate decarboxylase of Archaeoglobus fulgidus: cloning of genes and expression in Escherichia coli.

Archaeoglobus fulgidus harbors three consecutive and one distantly located gene with similarity to the oxaloacetate decarboxylase Na+ pump of Klebsiella pneumoniae (KpOadGAB). The water-soluble carboxyl transferase (AfOadA) and the biotin protein (AfOadC) were readily synthesized in Escherichia coli, but the membrane-bound subunits AfOadB and AfOadG were not. AfOadA was affinity purified from inclusion bodies after refolding and AfOadC was affinity purified from the cytosol. Isolated AfOadA catalyzed the carboxyl transfer from [4-14C]-oxaloacetate to the prosthetic biotin group of AfOadC or the corresponding biotin domain of KpOadA. Conversely, the carboxyl transferase domain of KpOadA exhibited catalytic activity not only with its pertinent biotin domain but also withAfOadC.