Promoter Escape by Escherichia coli RNA Polymerase

EcoSal Plus ◽  
2008 ◽  
Vol 3 (1) ◽  
Author(s):  
Lilian M. Hsu
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Promoter Escape

scholarly journals Mechanism of transcription initiation and promoter escape byE.coliRNA polymerase

2017 ◽  
Vol 114 (15) ◽  
pp. E3032-E3040 ◽  
Author(s):  
Kate L. Henderson ◽  
Lindsey C. Felth ◽  
Cristen M. Molzahn ◽  
Irina Shkel ◽  
Si Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Free Energy ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Initial Phase ◽  
Rna Synthesis ◽  
Quantitative Model ◽  
Ternary Complexes ◽  
Promoter Escape ◽  
Abortive Cycling

To investigate roles of the discriminator and open complex (OC) lifetime in transcription initiation byEscherichia coliRNA polymerase (RNAP; α2ββ’ωσ70), we compare productive and abortive initiation rates, short RNA distributions, and OC lifetime for the λPRand T7A1 promoters and variants with exchanged discriminators, all with the same transcribed region. The discriminator determines the OC lifetime of these promoters. Permanganate reactivity of thymines reveals that strand backbones in open regions of long-lived λPR-discriminator OCs are much more tightly held than for shorter-lived T7A1-discriminator OCs. Initiation from these OCs exhibits two kinetic phases and at least two subpopulations of ternary complexes. Long RNA synthesis (constrained to be single round) occurs only in the initial phase (<10 s), at similar rates for all promoters. Less than half of OCs synthesize a full-length RNA; the majority stall after synthesizing a short RNA. Most abortive cycling occurs in the slower phase (>10 s), when stalled complexes release their short RNA and make another without escaping. In both kinetic phases, significant amounts of 8-nt and 10-nt transcripts are produced by longer-lived, λPR-discriminator OCs, whereas no RNA longer than 7 nt is produced by shorter-lived T7A1-discriminator OCs. These observations and the lack of abortive RNA in initiation from short-lived ribosomal promoter OCs are well described by a quantitative model in which ∼1.0 kcal/mol of scrunching free energy is generated per translocation step of RNA synthesis to overcome OC stability and drive escape. The different length-distributions of abortive RNAs released from OCs with different lifetimes likely play regulatory roles.

scholarly journals Stringent control in Escherichia coli applies also to transcription by T7 RNA polymerase.

1987 ◽  
Vol 262 (9) ◽  
pp. 3940-3943
Author(s):  
M. Yamagishi ◽  
J.R. Cole ◽  
M. Nomura ◽  
F.W. Studier ◽  
J.J. Dunn
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
T7 Rna Polymerase ◽  
Stringent Control
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