Sgs1 helicase and two nucleases Dna2 and Exo1 resect DNA double-strand break ends.
Cell
; 134(6): 981-94, 2008 Sep 19.
Article
en En
| MEDLINE
| ID: mdl-18805091
ABSTRACT
Formation of single-strand DNA (ssDNA) tails at a double-strand break (DSB) is a key step in homologous recombination and DNA-damage signaling. The enzyme(s) producing ssDNA at DSBs in eukaryotes remain unknown. We monitored 5'-strand resection at inducible DSB ends in yeast and identified proteins required for two stages of resection initiation and long-range 5'-strand resection. We show that the Mre11-Rad50-Xrs2 complex (MRX) initiates 5' degradation, whereas Sgs1 and Dna2 degrade 5' strands exposing long 3' strands. Deletion of SGS1 or DNA2 reduces resection and DSB repair by single-strand annealing between distant repeats while the remaining long-range resection activity depends on the exonuclease Exo1. In exo1Deltasgs1Delta double mutants, the MRX complex together with Sae2 nuclease generate, in a stepwise manner, only few hundred nucleotides of ssDNA at the break, resulting in inefficient gene conversion and G2/M damage checkpoint arrest. These results provide important insights into the early steps of DSB repair in eukaryotes.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Saccharomyces cerevisiae
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ADN Helicasas
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Proteínas de Saccharomyces cerevisiae
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Reparación del ADN
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Exodesoxirribonucleasas
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RecQ Helicasas
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Roturas del ADN de Doble Cadena
Límite:
Animals
Idioma:
En
Revista:
Cell
Año:
2008
Tipo del documento:
Article
País de afiliación:
Estados Unidos