Using Mechanical Force to Probe the Mechanism of Pausing and Arrest during Continuous Elongation by Escherichia coli RNA Polymerase

Escherichia coli RNA polymerase translocates along the DNA discontinuously during the elongation phase of transcription, spending proportionally more time at some template positions, known as pause and arrest sites, than at others. Current models of elongation suggest that the enzyme backtracks at t...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2002-09, Vol.99 (18), p.11682-11687
Main Authors: Forde, Nancy R., Izhaky, David, Woodcock, Glenna R., Gijs J. L. Wuite, Bustamante, Carlos
Format: Article
Language:English
Subjects:
Bacteria
Biochemistry
Biological Sciences
Biophysics
Coordinate systems
DNA
DNA-Directed RNA Polymerases - chemistry
DNA-Directed RNA Polymerases - metabolism
Enzymes
Escherichia coli - enzymology
Hybridity
Kinetics
Mechanical forces
Mechanics
Molecules
Ribonucleic acid
RNA
Transcription, Genetic
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Escherichia coli RNA polymerase translocates along the DNA discontinuously during the elongation phase of transcription, spending proportionally more time at some template positions, known as pause and arrest sites, than at others. Current models of elongation suggest that the enzyme backtracks at these locations, but the dynamics are unresolved. Here, we study the role of lateral displacement in pausing and arrest by applying force to individually transcribing molecules. We find that an assisting mechanical force does not alter the translocation rate of the enzyme, but does reduce the efficiency of both pausing and arrest. Moreover, arrested molecules cannot be rescued by force, suggesting that arrest occurs by a bipartite mechanism: the enzyme backtracks along the DNA followed by a conformational change of the ternary complex (RNA polymerase, DNA and transcript), which cannot be reversed mechanically.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.142417799