Effect of the heat shock reaction on the phenotypic manifestation of mutations in rifampicin resistance affecting the gene of the RNA polymerase beta-subunit under the control of the lactose promotor

Plasmids bearing the rifampicin-resistant RNA polymerase beta-subunit gene under control of the lac promoter failed to provide Escherichia coli cells with resistance to rifampicin, despite the accumulation of large quantities of the resistant subunit. The effect proved to be connected with the aggregation of the plasmid-borne subunit. Conditions that induce synthesis of heat-shock proteins make the plasmid-containing cells resistant to rifampicin. This finding suggests that heat-shock proteins prevent the formation of protein aggregates.