The DNA Repair Protein yKu80 Regulates the Function of Recombination Enhancer during Yeast Mating Type Switching

Abstract

Recombination enhancer (RE) is essential for regulating donor preference during yeast mating type switching. In this study, by using minichromosome affinity purification (MAP) and mass spectrometry, we found that yeast Ku80p is associated with RE in MAT a cells. Chromatin immunoprecipitation assays confirmed its occupancy in vivo. Deletion of YKU80 results in altered chromatin structure in the RE region and more importantly causes a dramatic decrease of HML usage in MAT a cells. We also detect directional movement of yKu80p from the RE towards HML during switching. These results indicate a novel function of yeast Ku80p in regulating mating type switching.

ACKNOWLEDGMENTS

We acknowledge J. Haber and S. Ercan for providing yeast strains. We are grateful to C. Ducker for initial help on the minichromosome purification procedure. All members of the Simpson lab, Workman lab, and the Penn State gene regulation group are thanked for instructive advice and discussion.

These studies were funded by grant R01 GM-52908 to R.T.S from the National Institute of General Medical Sciences and the Stowers Institute.