Requirement of protein and RNA synthesis for lambda repressor inactivation by tif-1: effects of chloramphenicol, neomycin and rifampicin.

The inactivation of lambda repressor was followed by the specific DNA binding assay during the course of lysogenic induction provoked by incubation at 42 degrees C of an E. coli tif-1 lysogenic strain. The presence of up to 400 microgram/ml chloramphenicol during the inducing treatment did not impair the loss of repressor binding activity, whilst concentrations of 200 microgram/ml neomycin and 100 microgram/ml rifampicin effectively inhibited the inactivation of lambda repressor. Residual protein synthesis in the presence of chloramphenicol, neomycin and rifampicin was 5%, 5% and 27% respectively of that observed in the drug-free control. This residual synthesis did not appear to involve amplification of the X-protein. These results suggest that tif-mediated inactivation of the lambda repressor requires the activation of some specific gene(s), the translation of which appears to be resistant to chloramphenicol.