Applied Force Provides Insight into Transcriptional Pausing and Its Modulation by Transcription Factor NusA
| Autor: | Kook Sun Ha, Steven M. Block, Robert Landick, Jing Zhou, Arthur La Porta |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
DNA
Bacterial Optical Phenomena Optical Tweezers Transcription Genetic Biology Article chemistry.chemical_compound Tandem repeat RNA polymerase Escherichia coli A-DNA Molecular Biology Transcription factor Genetics Regulation of gene expression Escherichia coli Proteins DNA-Directed RNA Polymerases Gene Expression Regulation Bacterial Templates Genetic Cell Biology Peptide Elongation Factors Cell biology Elongation factor Kinetics chemistry Tandem Repeat Sequences Transcriptional Elongation Factors Elongation DNA Plasmids Transcription Factors |
| Zdroj: | Molecular Cell. 44:635-646 |
| ISSN: | 1097-2765 |
| Popis: | Transcriptional pausing by RNA polymerase (RNAP) plays an essential role in gene regulation. Pausing is modified by various elongation factors, including prokaryotic NusA, but the mechanisms underlying pausing and NusA function remain unclear. Alternative models for pausing invoke blockade events that precede translocation (on-pathway), enzyme backtracking (off-pathway), or isomerization to a non-backtracked, elemental pause state (off-pathway). We employed an optical-trapping assay to probe the motions of individual RNAP molecules transcribing a DNA template carrying tandem repeats encoding the his pause, subjecting these enzymes to controlled forces. NusA significantly decreased the pause-free elongation rate of RNAP while increasing the probability of entry into short- and long-lifetime pauses, in a manner equivalent to exerting a ~19 pN force opposing transcription. The effects of force and NusA on pause probabilities and lifetimes support a reaction scheme where non-backtracked, elemental pauses branch off the elongation pathway from the pre-translocated state of RNAP. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|