title: The bacteriophage T4 late-transcription coactivator gp33 binds the flap domain of Escherichia coli RNA polymerase.
abstract: Transcription of bacteriophage T4 late genes requires concomitant DNA replication. T4 late promoters, which consist of a single 8-bp -10 motif, are recognized by a holoenzyme containing Escherichia coli RNA polymerase core and the T4-encoded promoter specificity subunit, gp55. Initiation of transcription at these promoters by gp55-holoenzyme is inefficient, but is greatly activated by the DNA-loaded DNA polymerase sliding clamp, gp45, and the coactivator, gp33. We report that gp33 attaches to the flap domain of the Escherichia coli RNA polymerase beta-subunit and that this interaction is essential for activation. The beta-flap also mediates recognition of -35 promoter motifs by binding to sigma(70) domain 4. The results suggest that gp33 is an analogue of sigma(70) domain 4 and that gp55 and gp33 together constitute two parts of the T4 late sigma. We propose a model for the role of the gp45 sliding clamp in activation of T4 late-gene transcription.
authors.affiliation: Division of Biological Sciences and Center for Molecular Genetics, University of California at San Diego, La Jolla, CA 92093-0634, USA. netchaev@biomail.ucsd.edu
authors.forename: Sergei
authors.initials: S
authors.lastname: Nechaev
authors.forename: Masood
authors.initials: M
authors.lastname: Kamali-Moghaddam
authors.forename: Estelle
authors.initials: E
authors.lastname: André
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Léonetti
authors.forename: E Peter
authors.initials: EP
authors.lastname: Geiduschek
mesh_terms: D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000235:genetics / Q000378:metabolism; D001667:Binding, Competitive; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C078876:AsiA protein, Enterobacteria phage T4; D014764:Viral Proteins; C085859:gene 33 protein, Enterobacteria phage T4; D012321:DNA-Directed RNA Polymerases