文摘
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Summary
Replication protein A (RPA) is an essential eukaryotic single-stranded DNA binding protein with a central role in DNA metabolism. RPA directly participates in DNA double-strand break repair by stimulating 5¡ä-3¡ä end resection by the Sgs1/BLM helicase and Dna2 endonuclease in?vitro. Here we investigated the role of RPA in end resection in?vivo, using a heat-inducible degron system that allows rapid conditional depletion of RPA in Saccharomyces cerevisiae. We found that RPA depletion eliminated both the Sgs1-Dna2- and Exo1-dependent extensive resection pathways and synergized with mre11¦¤ to prevent end resection. The short single-stranded DNA tails formed in the absence of RPA were unstable due to 3¡ä strand loss and the formation of fold-back hairpin structures that required resection initiation?and Pol32-dependent DNA synthesis. Thus, RPA is required to generate ssDNA, and also to protect ssDNA from degradation and inappropriate annealing that could lead to genome rearrangements.
