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Separable roles for exonuclease I in meiotic DNA double-strand break repair

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posted on 2011-01-10, 09:37 authored by Rebecca E. Keelagher, Victoria E. Cotton, Alastair S. H. Goldman, Rhona H. Borts
Exo1 is a member of the Rad2 protein family and possesses both 5' –3' exonuclease and 5 flap endonuclease activities. In addition to performing a variety of functions during mitotic growth, Exo1 is also important for the production of crossovers during meiosis. However, its precise molecular role has remained ambiguous and several models have been proposed to account for the crossover deficit observed in its absence. Here, we present physical evidence that the nuclease activity of Exo1 is essential for normal 5' –3' resection at the Spo11-dependent HIS4 hotspot in otherwise wild-type cells. This same activity was also required for normal levels of gene conversion at the locus. However, gene conversions were frequently observed at a distance beyond that at which resection was readily detectable arguing that it is not the extent of the initial DNA end resection that limits heteroduplex formation. In addition to these nuclease-dependent functions, we found that an exo1-D173A mutant defective in nuclease activity is able to maintain crossing-over at wild-type levels in a number of genetic intervals, suggesting that Exo1 also plays a nuclease-independent role in crossover promotion.

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Citation

DNA repair, 2011, 10(2), pp. 126-137.

Published in

DNA repair

Publisher

Elsevier

issn

1568-7864

Copyright date

2011

Available date

2011-01-10

Publisher version

http://www.sciencedirect.com/science/article/pii/S1568786410003356

Language

en

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