Fig. 4.

The PK resistance of OmpLA arginine mutants in a degP- strain is due to membrane integration. JMR352 transformed with pMDG2 or a pMDG2 derivative encoding the indicated OmpLA mutant were pulse labeled and subjected to a 20 min chase after the addition of IPTG. In (A) the OM was then permeabilized and equal portions of each sample were left untreated, treated with PK or treated with PK after the addition of DDM. In (B) cells were disrupted by sonication. After a portion of the total cell extract (T) was set aside, membranes (Memb) were separated from soluble proteins (Sol) by centrifugation. Equal portions of the membrane fractions were then left untreated, treated with PK or treated with PK after the addition of DDM. Immunoprecipitations were conducted using an anti-OmpLA antiserum.