Effects of chlorpromazine on the cell envelope proteins of Escherichia coli.

Chlorpromazine (CPZ), at a concentration of 60 micrograms/ml of medium completely inhibited the replication of Escherichia coli. At concentrations below this MIC, CPZ caused transient induction of filamentation, such that by the end of 5 h, all of the cells were filaments, and by the end of 24 h, only rod-shaped E. coli were present. The reversion to normal morphology in the presence of CPZ was not due to either the degradation of CPZ or the selection of CPZ-resistant mutants. The electrophoretic pattern of proteins extracted from isolated cell envelopes of CPZ-induced filaments as well as from E. coli that reverted to normal morphology was distinctly different from that of the controls.