Linked Life Data

9843372

Source:http://linkedlifedata.com/resource/pubmed/id/9843372

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
45
pubmed:dateCreated
1998-12-21
pubmed:abstractText
The Escherichia coli purine repressor, PurR, exists in an equilibrium between open and closed conformations. Binding of a corepressor, hypoxanthine or guanine, shifts the allosteric equilibrium in favor of the closed conformation and increases the operator DNA binding affinity by 40-fold compared to aporepressor. Glu70 and Trp147 PurR mutations were isolated which perturb the allosteric equilibrium. Three lines of evidence indicate that the allosteric equilibrium of E70A and W147A aporepressors was shifted toward the closed conformation. First, compared to wild-type PurR, these mutant repressors had a 10-30-fold higher corepressor binding affinity. Second, the mutant aporepressors bound to operator DNA with an affinity that is characteristic of the wild-type PurR holorepressor. Third, binding of guanine to wild-type PurR resulted in a near-UV circular dichroism spectral change at 297-305 nm that is attributed to the closed conformation. The circular dichroism spectrum of the E70A aporepressor at 297-305 nm was that expected for the closed conformation, and it was not appreciably altered by corepressor binding. Mutational analysis was used to identify an Arg115-Ser46' interdomain intersubunit hydrogen bond that is necessary for transmitting the allosteric transition in the corepressor binding domain to the DNA binding domain. R115A and S46G PurR mutants were defective in DNA binding in vitro and repressor function in vivo although corepressor binding was identical to the wild type. These results establish that the hydrogen bond between the side chain NH2 of Arg115 and the main chain CO of Ser46' plays a critical role in interdomain signaling.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15680-90
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Escherichia coli purine repressor: key residues for the allosteric transition between active and inactive conformations and for interdomain signaling.
pubmed:affiliation
Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907-1153, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.