期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 101, 期 50, 页码 17365-17370出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0408028101
关键词
RNA polymerase structure; sliding clamp; transcription-replication coupling
Transcription of bacteriophage T4 late genes requires concomitant DNA replication. T4 late promoters, which consist of a single 8-by -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.
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