Bidirectional transcription in the mom promoter region of bacteriophage Mu.
Transcription of the Mu mom operon requires activation by the phage gene product, C, a site-specific DNA binding protein. Previous in vivo and in vitro footprinting studies showed that Escherichia coli RNA polymerase (Esigma70=RNAP) bound the wild-type (wt) mom promoter (Pmom) region in the absence of C; this site, now designated momP2 (-11 to -64), is slightly upstream of, but overlapping with, momP1 (+16 to -49), the functional binding site for mom operon (rightward) transcription. The location/distribution of KMnO4-sensitive sites on the two DNA strands suggested that RNAP bound at momP2 was in an open-complex, but that transcription was in the opposite direction. Here, we used both runoff transcription and reverse transcriptase-primer extension sequencing to provide direct evidence that in the absence of C protein, RNAP carries out leftward transcription from momP2 both in vitro and in vivo. In addition, the 5' ends of these transcripts were mapped to the same upstream initiation site, -58G, relative to the initiation site of C-activated rightward transcription. We also present evidence that leftward transcription from momP2 requires RNAP recognition of an UP-element by the carboxyl-terminal domain of the alpha subunit.
Sun
W
W
Department of Biology, University of Rochester, Rochester, NY, 14627-0211, USA.
Hattman
S
S
D010583:Bacteriophage mu / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D014764:Viral Proteins
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C090591:C protein, Bacteriophage Mu; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D012367:RNA, Viral; D015534:Trans-Activators; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases