KINETICS OF RNA-POLYMERASE INITIATION AND PAUSING AT THE LAMBDA LATE GENE PROMOTER IN-VIVO

[摘要] We have measured the kinetics of-transcription initiation and pausing by Escherichia coli RNA polymerase (RNAP) at the bacteriophage lambda late promoter, p(R), in growing cells. RNAP initiating transcription from p(R) pauses after transcribing 16 or 17 nucleotides, and escape from this pause could in theory be the rate-limiting step in promoter function. We tested this hypothesis by analyzing pausing and non-pausing variants of both the p(R). promoter segment and a more active mutant version of p(R); we measured reporter gene expression and used KMnO4 footprinting to measure directly occupancy of the promoter and pause sites in growing cells. We find that RNAP paused at +16/+17 does not limit expression of p(R). However, RNAP paused at +16/+17 does limit expression from the more active promoter by impeding formation of open complex. Therefore, the activity of the late gene regulatory protein Q to suppress the early pause, in addition to its antitermination activity, is unlikely to be important in phage gene expression. (C) 1995 Academic Press Limited

[发布日期] 1995-12-15

[关键词] TRANSCRIPTION PAUSE;RNA POLYMERASE;PROMOTER ACTIVITY;ANTITERMINATOR