A GENE, YAEQ, THAT SUPPRESSES REDUCED OPERON EXPRESSION CAUSED BY MUTATIONS IN THE TRANSCRIPTION ELONGATION GENE RFAH IN ESCHERICHIA-COLI AND SALMONELLA-TYPHIMURIUM

RfaH is a specialised transcription elongation protein. We isolated fr om a Salmonella typhimurium rfaH suppressor strain a gene that complem ents in trans the attenuated transcription of the hlyCABD hemolysin op eron caused by an rfaH mutation. The gene is homologous to the unchara cterised Escherichia coli gene yaeQ. YaeQ did not increase hlyCABD-enc oded hemolysin activity in the RfaH(+) wild type, nor did it increase the level of RfaH protein. YaeQ also complements a rfaH::Tn5 null muta tion, indicating that it compensates for loss of RfaH function without interaction between the two proteins.