PLASMID REGULATION AND TEMPERATURE-SENSITIVE BEHAVIOR OF THE YERSINIA-PESTIS PENICILLIN-BINDING PROTEINS

Six major bands corresponding to penicillin-binding proteins (PBPs) wi th molecular weights ranging from 43,000 to 97,000 were detected in ce ll envelopes of Yersinia pestis EV76 grown at 28 degrees C. When cells were transferred to 37 degrees C and incubated for extended periods o f time, the amounts of all PBPs, except for PBP2, were gradually reduc ed in cell envelopes of a strain carrying a 75-kb virulence-associated plasmid (as measured by penicillin-binding capacity), whereas in a st rain cured of the plasmid, all PBPs were stable. The results indicated that the stability and/or the expression of Y. pestis PBPs is affecte d by a temperature-inducible pathway associated with the virulence-ass ociated plasmid.