Linked Life Data

1856861

Source:http://linkedlifedata.com/resource/pubmed/id/1856861

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-8-27
pubmed:abstractText
This paper describes the binding interactions of Escherichia coli transcription factors sigma 70 and NusA with core RNA polymerase, both free in solution and as a part of the functional transcription complex. High pressure liquid chromatography gel filtration and fluorescence techniques have been used to monitor the binding of these factors to core polymerase in solution at salt concentrations roughly comparable to the in vivo environment (250 mM-KCl, 50 mM-potassium phosphate (pH 7.5]; under these conditions all the interacting species exist separately as protein monomers. We find that sigma 70 and NusA binds competitively to core polymerase with a 1:1 binding stoichiometry in this milieu, and that NusA does not bind to the polymerase holoenzyme. Association constants of approximately 2 x 10(9) and 1 x 10(7) M-1 have been measured for the sigma 70-core polymerase interaction and for the NusA-core polymerase interaction, respectively. These findings are consistent with the original formulation of the NusA-sigma 70 cycle put forward by Greenblatt & Li, and provide the basis for a further (and preliminary) quantitative examination of these same interactions within the transcription complex. We use a number of molecular biological techniques, together with data from the literature, to estimate these binding constants in various phases of the transcription cycle. In keeping with our results in solution, we find that the effective binding affinity of sigma 70 for core polymerase within the "open" promoter-polymerase complex is at least 500-fold greater than that of NusA. As the transcription complex moves from the initiation to the elongation phase these relative binding affinities are reversed; the average association constant of NusA for the core polymerase in the elongation complex remains practically the same as in free solution (approx. 3 x 10(7) M-1), while the affinity of sigma 70 for core polymerase in this complex drops to less than 5 x 10(5) M-1. These results are used to begin to define the basic conformational states and interaction potentials of core polymerase in the various stages of the transcription cycle.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
220
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
307-24
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:1856861-Bacterial Proteins, pubmed-meshheading:1856861-Binding, Competitive, pubmed-meshheading:1856861-Chromatography, High Pressure Liquid, pubmed-meshheading:1856861-DNA-Directed RNA Polymerases, pubmed-meshheading:1856861-Escherichia coli, pubmed-meshheading:1856861-Escherichia coli Proteins, pubmed-meshheading:1856861-Kinetics, pubmed-meshheading:1856861-Mathematics, pubmed-meshheading:1856861-Models, Theoretical, pubmed-meshheading:1856861-Osmolar Concentration, pubmed-meshheading:1856861-Peptide Elongation Factors, pubmed-meshheading:1856861-Plasmids, pubmed-meshheading:1856861-Promoter Regions, Genetic, pubmed-meshheading:1856861-Protein Binding, pubmed-meshheading:1856861-Protein Conformation, pubmed-meshheading:1856861-Sigma Factor, pubmed-meshheading:1856861-Solutions, pubmed-meshheading:1856861-Spectrometry, Fluorescence, pubmed-meshheading:1856861-Transcription, Genetic, pubmed-meshheading:1856861-Transcription Factors
pubmed:year
1991
pubmed:articleTitle
Escherichia coli sigma 70 and NusA proteins. I. Binding interactions with core RNA polymerase in solution and within the transcription complex.
pubmed:affiliation
Department of Chemistry, University of Oregon, Eugene 97403.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't