FIG. 4.

Presence of the CcaR protein and cephamycin C biosynthetic enzymes in ccaR mutant strains. (A) Wild-type and ccaR::apr insertion strains; (B) wild-type and ΔccaR::tsr deletion strains; (C) wild-type and Δcob::tsr deletion strains. Ten micrograms of cell extract protein from each strain, harvested after 72 h of growth unless otherwise noted, was separated by SDS-PAGE (10% gel) and transferred to PVDF membranes. The resulting Western blots were developed with polyclonal antibodies specific for the CcaR, LAT, IPNS, and DAOCS proteins. Each strain’s ability to produce cephamycin (Ceph) C was determined by bioassay, and the results were scored as + (production) and − (lack of production).