How Does a Helicase Unwind DNA? Insights from RecBCD Helicase.
Bioessays
; 40(6): e1800009, 2018 06.
Article
em En
| MEDLINE
| ID: mdl-29603305
ABSTRACT
DNA helicases are a class of molecular motors that catalyze processive unwinding of double stranded DNA. In spite of much study, we know relatively little about the mechanisms by which these enzymes carry out the function for which they are named. Most current views are based on inferences from crystal structures. A prominent view is that the canonical ATPase motor exerts a force on the ssDNA resulting in "pulling" the duplex across a "pin" or "wedge" in the enzyme leading to a mechanical separation of the two DNA strands. In such models, DNA base pair separation is tightly coupled to ssDNA translocation of the motors. However, recent studies of the Escherichia coli RecBCD helicase suggest an alternative model in which DNA base pair melting and ssDNA translocation occur separately. In this view, the enzyme-DNA binding free energy is used to melt multiple DNA base pairs in an ATP-independent manner, followed by ATP-dependent translocation of the canonical motors along the newly formed ssDNA tracks. Repetition of these two steps results in processive DNA unwinding. We summarize recent evidence suggesting this mechanism for RecBCD helicase action.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA
/
DNA Helicases
Idioma:
En
Revista:
Bioessays
Assunto da revista:
BIOLOGIA
/
BIOLOGIA MOLECULAR
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA