MODE OF PROMOTER RECOGNITION BY THE ESCHERICHIA-COLI RNA-POLYMERASE HOLOENZYME CONTAINING THE SIGMA(S) SUBUNIT - IDENTIFICATION OF THE RECOGNITION SEQUENCE OF THE FIC PROMOTER

Transcription of a number of genes during stationary phase in Escheric hia coli requires the alternative sigma factor sigma(s), encoded by th e rpoS gene. No consensus sequence for the promoters recognized by the RNA polymerase holoenzyme containing the sigma(s) subunit (E sigma(s) ) is known. To identify the E sigma(s) recognition sequence, we analys ed the promoter region of the fic gene, whose expression depends on E sigma(s) both in vivo and in vitro. By random mutagenesis, we isolated a large number of the fic promoter mutants that had defective promote r activities in an rpoS(+) strain. All such mutants contained alterati ons within the -10 region, TATACT, whereas no mutant was isolated with alterations in the -35 region. Based on further analyses including sc anning mutagenesis and DNase I footprinting assays of the fic promoter region, and in vitro transcription assays, we conclude that the -10 h examer is essential to transcription initiation from the fic promoter by E sigma(s).