Novel Function of Rad27 (FEN-1) in Restricting Short-Sequence Recombination

Abstract

Saccharomyces cerevisiae mutants lacking the structure-specific nuclease Rad27 display an enhancement in recombination that increases as sequence length decreases, suggesting that Rad27 preferentially restricts recombination between short sequences. Since wild-type alleles of both RAD27 and its human homologue FEN1 complement the elevated short-sequence recombination (SSR) phenotype of a rad27-null mutant, this function may be conserved from yeast to humans. Furthermore, mutant Rad27 and FEN-1 enzymes with partial flap endonuclease activity but without nick-specific exonuclease activity partially complement the SSR phenotype of the rad27-null mutant. This suggests that the endonuclease activity of Rad27 (FEN-1) plays a role in limiting recombination between short sequences in eukaryotic cells.

ACKNOWLEDGMENTS

This work was supported by U.S. Public Health Service grants GM57484 to A.M.B. and CA73764 to B.S. and by an APRC suppplemental grant (CA85344) to B.S. and A.M.B. from the National Institutes of Health, as well as by funds from the Beckman Research Institute of the City of Hope and the City of Hope National Medical Center.

We thank J. McDonald for yeast strain W1011-3B and D. Garfinkel, J. Wilson, and several anonymous reviewers for comments on the manuscript. We also thank J. Termini, T. Krontiris, R. J. Lin, J. Haber, D. Gordenin, S. Rosenberg, G. Smith, R. Rothstein, D. Botstein, and the members of the Bailis and Shen laboratories for stimulating discussions.