DNA sequence alignment by microhomology sampling during homologous recombination.
Cell
; 160(5): 856-869, 2015 Feb 26.
Article
en En
| MEDLINE
| ID: mdl-25684365
ABSTRACT
Homologous recombination (HR) mediates the exchange of genetic information between sister or homologous chromatids. During HR, members of the RecA/Rad51 family of recombinases must somehow search through vast quantities of DNA sequence to align and pair single-strand DNA (ssDNA) with a homologous double-strand DNA (dsDNA) template. Here, we use single-molecule imaging to visualize Rad51 as it aligns and pairs homologous DNA sequences in real time. We show that Rad51 uses a length-based recognition mechanism while interrogating dsDNA, enabling robust kinetic selection of 8-nucleotide (nt) tracts of microhomology, which kinetically confines the search to sites with a high probability of being a homologous target. Successful pairing with a ninth nucleotide coincides with an additional reduction in binding free energy, and subsequent strand exchange occurs in precise 3-nt steps, reflecting the base triplet organization of the presynaptic complex. These findings provide crucial new insights into the physical and evolutionary underpinnings of DNA recombination.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Saccharomyces cerevisiae
/
Proteínas de Saccharomyces cerevisiae
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Recombinasa Rad51
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Recombinación Homóloga
Idioma:
En
Revista:
Cell
Año:
2015
Tipo del documento:
Article
País de afiliación:
Estados Unidos