Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada. stephen_delcardayre@maxygen.com
The cdr gene encoding coenzyme A disulfide reductase (CoADR) from Staphylococcus aureus 8325-4 was cloned, sequenced, and overexpressed. The gene encodes a 438-amino acid polypeptide that has a calculated molecular weight of 49,200 and sequence similarity to the pyridine nucleotide-disulfide oxidoreductase family of flavoenzymes. The deduced primary structure contains consensus sequences for flavin adenine dinucleotide and NADPH-binding regions but lacks the catalytic disulfide signature sequence typical of the glutathione reductase family of disulfide reductases. The active site region of CoADR has only a single cysteine residue that is similar to that in the conserved SFXXC active site motif of NADH oxidase and NADH peroxidase from Enterococcus faecalis. CoADR is the first disulfide reductase reported having this active site region, and sequence comparisons of CoADR to representative members of the pyridine nucleotide-disulfide reductase superfamily placed CoADR in a distinct subfamily. CoADR was overexpressed in Escherichia coli using the pET expression system, and 5-10 mg of fully active recombinant enzyme were recovered per liter of E. coli cells.