MOLECULAR-CLONING, DNA-SEQUENCE, AND GENE-EXPRESSION OF THE OXALYL-COENZYME-A DECARBOXYLASE GENE, OXC, FROM THE BACTERIUM OXALOBACTER-FORMIGENES

Oxalic acid, a highly toxic by-product of metabolism, is catabolized by a limited number of bacterial species by an activation-decarboxylation reaction which yields formate and CO2. oxc, the gene encoding the oxalic acid-degrading enzyme oxalyl-coenzyme A decarboxylase, was cloned from the bacterium Oxalobacter formigenes. The DNA sequence revealed a single open reading frame of 1,704 bp capable of encoding a 568-amino-acid protein with a molecular weight of 60,691. The identification of a presumed promoter region and a rho-independent termination sequence indicates that this gene is not part of a polycistronic operon. A PCR fragment encoding the open reading frame, when overexpressed in Escherichia coli, produced a product which cross-reacted antigenically with native enzyme on Western blots (immunoblots), appeared to form homodimers spontaneously, and exhibited enzymatic activity similar to that of the purified native enzyme.