Figure 3.

Disulfide bond formation is impaired in the dsbB R48C and R48H mutants under anaerobic conditions but not under aerobic conditions. Strains HK205 (wild type; lane 1), HK207 (dsbB C41Y; lane 2), HK209 (dsbB R48C; lane 3), HK211 (dsbB R48H; lane 4), HK227 (dsbB∷Kan; lane 5), and HK229 (dsbA∷Kan; lane 6) were transformed with pUC18 carrying bla, and were grown aerobically (A) or anaerobically (B) at 30°C. Portions of exponentially growing cultures were harvested and alkylated with AMS. The AMS-modified proteins were separated by native SDS/PAGE and subjected to Western blotting with anti-β-lactamase antibody to detect oxidized (oxi) and reduced (red) β-lactamase.