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ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase
The superfamily 2 bacterial helicase, RecG, is a monomeric enzyme with a role in DNA repair by reversing stalled replication forks. The helicase must act specifically and rapidly to prevent replication fork collapse. We have shown that RecG binds tightly and rapidly to four-strand oligonucleotide ju...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368886/ https://www.ncbi.nlm.nih.gov/pubmed/22701618 http://dx.doi.org/10.1371/journal.pone.0038270 |
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author | Toseland, Christopher P. Powell, Ben Webb, Martin R. |
author_facet | Toseland, Christopher P. Powell, Ben Webb, Martin R. |
author_sort | Toseland, Christopher P. |
collection | PubMed |
description | The superfamily 2 bacterial helicase, RecG, is a monomeric enzyme with a role in DNA repair by reversing stalled replication forks. The helicase must act specifically and rapidly to prevent replication fork collapse. We have shown that RecG binds tightly and rapidly to four-strand oligonucleotide junctions, which mimic a stalled replication fork. The helicase unwinds such DNA junctions with a step-size of approximately four bases per ATP hydrolyzed. To gain an insight into this mechanism, we used fluorescent stopped-flow and quenched-flow to measure individual steps within the ATPase cycle of RecG, when bound to a DNA junction. The fluorescent ATP analogue, mantATP, was used throughout to determine the rate limiting steps, effects due to DNA and the main states in the cycle. Measurements, when possible, were also performed with unlabeled ATP to confirm the mechanism. The data show that the chemical step of hydrolysis is the rate limiting step in the cycle and that this step is greatly accelerated by bound DNA. The ADP release rate is similar to the cleavage rate, so that bound ATP and ADP would be the main states during the ATP cycle. Evidence is provided that the main structural rearrangements, which bring about DNA unwinding, are linked to these states. |
format | Online Article Text |
id | pubmed-3368886 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-33688862012-06-13 ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase Toseland, Christopher P. Powell, Ben Webb, Martin R. PLoS One Research Article The superfamily 2 bacterial helicase, RecG, is a monomeric enzyme with a role in DNA repair by reversing stalled replication forks. The helicase must act specifically and rapidly to prevent replication fork collapse. We have shown that RecG binds tightly and rapidly to four-strand oligonucleotide junctions, which mimic a stalled replication fork. The helicase unwinds such DNA junctions with a step-size of approximately four bases per ATP hydrolyzed. To gain an insight into this mechanism, we used fluorescent stopped-flow and quenched-flow to measure individual steps within the ATPase cycle of RecG, when bound to a DNA junction. The fluorescent ATP analogue, mantATP, was used throughout to determine the rate limiting steps, effects due to DNA and the main states in the cycle. Measurements, when possible, were also performed with unlabeled ATP to confirm the mechanism. The data show that the chemical step of hydrolysis is the rate limiting step in the cycle and that this step is greatly accelerated by bound DNA. The ADP release rate is similar to the cleavage rate, so that bound ATP and ADP would be the main states during the ATP cycle. Evidence is provided that the main structural rearrangements, which bring about DNA unwinding, are linked to these states. Public Library of Science 2012-06-06 /pmc/articles/PMC3368886/ /pubmed/22701618 http://dx.doi.org/10.1371/journal.pone.0038270 Text en Toseland et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Toseland, Christopher P. Powell, Ben Webb, Martin R. ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title | ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title_full | ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title_fullStr | ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title_full_unstemmed | ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title_short | ATPase Cycle and DNA Unwinding Kinetics of RecG Helicase |
title_sort | atpase cycle and dna unwinding kinetics of recg helicase |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368886/ https://www.ncbi.nlm.nih.gov/pubmed/22701618 http://dx.doi.org/10.1371/journal.pone.0038270 |
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