Linked Life Data

9201945

Source:http://linkedlifedata.com/resource/pubmed/id/9201945

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
1997-7-21
pubmed:abstractText
The kinetics of the ATP-dependent RNA-DNA helicase activity of Escherichia colitranscription termination factor rho have been analyzed. Helicase substrates were assembled using 255 nt and 391 nt RNA sequences from the trp t' RNA transcript of E. coli. These RNA sequences each carry a rho "loading site" at a position near the 5'-end, and a rho-dependent terminator sequence at the 3'-end to which complementary approximately 20 nt DNA oligonucleotides have been annealed. A rapid ( approximately 30 s) pre-steady-state burst of helicase activity (DNA oligomer release), followed by a slow linear phase, is observed in reactions carried out at low salt concentrations (50 mM KCl). Using poly(rC) or poly(dC) as traps for the rho that is released after one round of activity, we have shown that the first (burst) phase of the reaction represents the processive translocation of prebound rho hexamers from the rho loading site to the 3'-end of the RNA molecule. The slow phase of the reaction is complex and represents a combination of many different processes, including the slow release of RNA from rho, the reannealing of complementary DNA oligonucleotides to the RNA substrate, and the recycling of rho hexamers onto additional RNA molecules. Reactions carried out at higher salt concentrations (150 mM KCl) consist of only one phase, since under these conditions rho dissociates more rapidly from the RNA, with an amplitude corresponding to several DNA oligomers removed per rho hexamer. Thus, rho can recycle and function as a catalytic helicase under reaction conditions resembling those found in the cell.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7980-92
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Kinetics of the RNA-DNA helicase activity of Escherichia coli transcription termination factor rho. 1. Characterization and analysis of the reaction.
pubmed:affiliation
Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't