Linked Life Data

10644772

Source:http://linkedlifedata.com/resource/pubmed/id/10644772

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2000-2-29
pubmed:abstractText
The gamma complex of the Escherichia coli DNA polymerase III holoenzyme assembles the beta sliding clamp onto DNA in an ATP hydrolysis-driven reaction. Interactions between gamma complex and primer/template DNA are investigated using fluorescence depolarization to measure binding of gamma complex to different DNA substrates under steady-state and presteady-state conditions. Surprisingly, gamma complex has a much higher affinity for single-stranded DNA (K(d) in the nM range) than for a primed template (K(d) in the microM range) under steady-state conditions. However, when examined on a millisecond time scale, we find that gamma complex initially binds very rapidly and with high affinity to primer/template DNA but is converted subsequently to a much lower affinity DNA binding state. Presteady-state data reveals an effective dissociation constant of 1.5 nM for the initial binding of gamma complex to DNA and a dissociation constant of 5.7 microM for the low affinity DNA binding state. Experiments using nonhydrolyzable ATPgammaS show that ATP binding converts gamma complex from a low affinity "inactive" to high affinity "active" DNA binding state while ATP hydrolysis has the reverse effect, thus allowing cycling between active and inactive DNA binding forms at steady-state. We propose that a DNA-triggered switch between active and inactive states of gamma complex provides a two-tiered mechanism enabling gamma complex to recognize primed template sites and load beta, while preventing gamma complex from competing with DNA polymerase III core for binding a newly loaded beta.DNA complex.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
275
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3006-15
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
A model for Escherichia coli DNA polymerase III holoenzyme assembly at primer/template ends. DNA triggers a change in binding specificity of the gamma complex clamp loader.
pubmed:affiliation
Department of Chemistry, Arizona State University, Tempe, Arizona 85287-1604, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.