Linked Life Data

14604986

Source:http://linkedlifedata.com/resource/pubmed/id/14604986

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2004-1-26
pubmed:abstractText
Single-molecule measurements of the activities of a variety of enzymes show that rates of catalysis may vary markedly between different molecules in putatively homogeneous enzyme preparations. We measured the rate at which purified Escherichia coli RNA polymerase moves along a approximately 2650-bp DNA during transcript elongation in vitro at 0.5 mm nucleoside triphosphates. Individual molecules of a specifically biotinated RNA polymerase derivative were tagged with 199-nm diameter avidin-coated polystyrene beads; enzyme movement along a surface-linked DNA molecule was monitored by observing changes in bead Brownian motion by light microscopy. The DNA was derived from a naturally occurring transcription unit and was selected for the absence of regulatory sequences that induce lengthy pausing or termination of transcription. With rare exceptions, individual enzyme molecules moved at a constant velocity throughout the transcription reaction; the distribution of velocities across a population of 140 molecules was unimodal and was well fit by a Gaussian. However, the width of the Gaussian, sigma = 6.7 bp/s, was considerably larger than the precision of the velocity measurement (1 bp/s). The observations show that different transcription complexes have differences in catalytic rate (and thus differences in structure) that persist for thousands of catalytic turnovers. These differences may provide a parsimonious explanation for the complex transcription kinetics observed in bulk solution.
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
30
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3292-9
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:14604986-Avidin, pubmed-meshheading:14604986-Biotinylation, pubmed-meshheading:14604986-Catalysis, pubmed-meshheading:14604986-DNA, pubmed-meshheading:14604986-DNA-Directed RNA Polymerases, pubmed-meshheading:14604986-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:14604986-Escherichia coli, pubmed-meshheading:14604986-Kinetics, pubmed-meshheading:14604986-Models, Biological, pubmed-meshheading:14604986-Models, Statistical, pubmed-meshheading:14604986-Normal Distribution, pubmed-meshheading:14604986-RNA Polymerase II, pubmed-meshheading:14604986-Templates, Genetic, pubmed-meshheading:14604986-Terminator Regions, Genetic, pubmed-meshheading:14604986-Time Factors, pubmed-meshheading:14604986-Transcription, Genetic, pubmed-meshheading:14604986-Transcriptional Elongation Factors
pubmed:year
2004
pubmed:articleTitle
Diversity in the rates of transcript elongation by single RNA polymerase molecules.
pubmed:affiliation
Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.