Regulation of Mu Transposition. II. The Escherichia Coli HimD Protein Positively Controls Two Repressor Promoters and the Early Promoter of Bacteriophage Mu

Two leftward Pc promoters for the repressor gene of bacteriophage Mu have been localized by fusions of the promoter region to the structural galK gene and by S1 nuclease mapping. Transcription initiated at the left-end-proximal promoter (Pc-1) starts 23 bp ahead of the c gene. The second promoter (Pc-2) is located 200 bp from the translation start codon of gene c. The RNA initiated from Pc-2 overlaps 35 bp with the rightward transcript from the early Mu promoter (Pe). The expression from Pe and both repressor promoters is positively regulated by the Escherichia coli HimD (Hip) protein, probably acting as a subunit of the integration host factor (IHF). Two overlapping sequences matching the consensus for the IHF binding site (ihf) are found between Pe and Pc-1.