Linked Life Data

16285918

Source:http://linkedlifedata.com/resource/pubmed/id/16285918

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2005-11-15
pubmed:abstractText
We investigated the binding of E. coli RNA polymerase holoenzymes bearing sigma70, sigma(S), sigma32, or sigma54 to the ribosomal RNA operons (rrn) in vivo. At the rrn promoter, we observed "holoenzyme switching" from Esigma70 to Esigma(S) or Esigma32 in response to environmental cues. We also examined if sigma factors are retained by core polymerase during transcript elongation. At the rrn operons, sigma70 translocates briefly with the elongating polymerase and is released stochastically from the core polymerase with an estimated half-life of approximately 4-7 s. Similarly, at gadA and htpG, operons that are targeted by Esigma(S) and Esigma32, respectively, we find that sigma(S) and sigma32 also dissociate stochastically, albeit more rapidly than sigma70, from the elongating core polymerase. Up to approximately 70% of Esigma70 (the major vegetative holoenzyme) in rapidly growing cells is engaged in transcribing the rrn operons. Thus, our results suggest that at least approximately 70% of cellular holoenzymes release sigma70 during transcript elongation. Release of sigma factors during each round of transcription provides a simple mechanism for rapidly reprogramming polymerase with the relevant sigma factor and is consistent with the occurrence of a "sigma cycle" in vivo.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1097-2765
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
357-66
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Holoenzyme switching and stochastic release of sigma factors from RNA polymerase in vivo.
pubmed:affiliation
Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural