| Nucleotide excision by E. coli DNA polymerase I in proofreading and non-proofreading modes. | |
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MedLine Citation:
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PMID: 3061468 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Escherichia coli DNA polymerase I exists in at least two distinct kinetic forms. When it binds to a template, the proofreading activity is usually switched off. As the enzyme progresses along the template, it becomes more and more competent for excision. This phenomenon introduces a link between fidelity and processivity. Processivity is best studied when the chain-length distributions of synthesized polymers are stationary. Even then, however, one cannot avoid multiple initiations on a given template by the same molecule of the enzyme. When synthesis is initiated with primers of lengths 15 or 20, a strange phenomenon is observed. It seems that the polymerase starts by hydrolyzing the primer down to a length of 7-10 nucleotides and only then starts to add nucleotides. It does so in a low-accuracy mode, suggesting that, while the exonuclease is clearly active, it does not contribute to proofreading. The warm-up of the proofreading function is therefore reinterpreted as a switch between two modes of behaviour: a mode 1 of low accuracy in which the 3'----5' exonuclease, while active, is uncoupled from the polymerase and does not contribute to proofreading, and a mode 2 of high accuracy in which the exonuclease is kinetically linked to the polymerase activity. |
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Authors:
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P J Lecomte; J Ninio |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 951 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 1988 Dec |
Date Detail:
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Created Date: 1989-02-13 Completed Date: 1989-02-13 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 255-60 Citation Subset: IM |
Affiliation:
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Institut Jacques Monod, Paris, France. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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DNA Polymerase I
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metabolism* DNA, Bacterial / metabolism* Escherichia coli / enzymology*, genetics Exodeoxyribonuclease V Exodeoxyribonucleases / metabolism Kinetics Nucleotides / metabolism* Oligodeoxyribonucleotides / metabolism Poly A / metabolism Templates, Genetic |
| Chemical | |
Reg. No./Substance:
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0/DNA, Bacterial; 0/Nucleotides; 0/Oligodeoxyribonucleotides; 0/oligo (dT); 24937-83-5/Poly A; 25191-20-2/poly(dA); EC 2.7.7.-/DNA Polymerase I; EC 3.1.-/Exodeoxyribonucleases; EC 3.1.11.5/Exodeoxyribonuclease V |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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