Effects of inhibitors of protein synthesis on lysis of Escherichia coli induced by beta-lactam antibiotics.

The role of protein synthesis in ampicillin-induced lysis of Escherichia coli was investigated. The inhibition of protein synthesis through amino acid deprivation resulted in the rapid development of ampicillin tolerance as a consequence of the stringent response, as previously reported. In contrast, inhibition of protein synthesis by use of ribosome inhibitors such as chloramphenicol did not readily confer ampicillin tolerance and, in fact, promoted the development of both stages of the ampicillin-induced lysis process, i.e., (i) an ampicillin-dependent stage which apparently involves the interaction of penicillin-binding proteins with ampicillin and (ii) an ampicillin-independent stage which may represent the events leading to the deregulation of peptidoglycan hydrolase activity. We propose that lysis was facilitated when protein synthesis was inhibited because the production of new penicillin-binding proteins to replace those which were ampicillin inhibited was prevented under these conditions.