Force regulated dynamics of RPA on a DNA fork.
Nucleic Acids Res
; 44(12): 5837-48, 2016 07 08.
Article
em En
| MEDLINE
| ID: mdl-27016742
ABSTRACT
Replication protein A (RPA) is a single-stranded DNA binding protein, involved in most aspects of eukaryotic DNA metabolism. Here, we study the behavior of RPA on a DNA substrate that mimics a replication fork. Using magnetic tweezers we show that both yeast and human RPA can open forked DNA when sufficient external tension is applied. In contrast, at low force, RPA becomes rapidly displaced by the rehybridization of the DNA fork. This process appears to be governed by the binding or the release of an RPA microdomain (toehold) of only few base-pairs length. This gives rise to an extremely rapid exchange dynamics of RPA at the fork. Fork rezipping rates reach up to hundreds of base-pairs per second, being orders of magnitude faster than RPA dissociation from ssDNA alone. Additionally, we show that RPA undergoes diffusive motion on ssDNA, such that it can be pushed over long distances by a rezipping fork. Generally the behavior of both human and yeast RPA homologs is very similar. However, in contrast to yeast RPA, the dissociation of human RPA from ssDNA is greatly reduced at low Mg(2+) concentrations, such that human RPA can melt DNA in absence of force.
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Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
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DNA de Cadeia Simples
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Proteínas de Saccharomyces cerevisiae
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Mecanotransdução Celular
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Replicação do DNA
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Proteína de Replicação A
Limite:
Humans
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article