Current Genetics

, Volume 28, Issue 1, pp 1–11

Functional analysis of the ABF1-binding sites within the Ya regions of the MATa and HMRa loci of Saccharomyces cerevisiae

  • Linda D. B. McBroom
  • Paul D. Sadowski
Original Paper

DOI: 10.1007/BF00311875

Cite this article as:
McBroom, L.D.B. & Sadowski, P.D. Curr Genet (1995) 28: 1. doi:10.1007/BF00311875


Cell type in the yeast Saccharomyces cerevisiae is determined by information present at the MAT locus. Cells can switch mating types when cell-type information located at a silent locus, HML or HMR, is transposed to the MAT locus. The HML and HMR loci are kept silent through the action of a number of proteins, one of which is the DNA-binding protein, ABF1. We have identified a binding site for ABF1 within the Ya region of MATa and HMRa. In order to examine the function of this ABF1-binding site, we have constructed strains that lack the site in the MATa or HMRa loci. Consistent with the idea that ABF1 plays a redundant role in silencing, it was found that a triple deletion of the ABF1-binding sites at HMRE, Ya and I did not permit the expresion of HMRa. We have also shown that chromosomal deletion of the binding site at MATYa had no effect on the level of cutting by the HO endonuclease nor on the amount of mating-type switching observed. Similarly, chromosomal deletion of all three ABF1-binding sites at HMRa had no effect on the directionality of mating-type switching.

Key words

ABF1Mating-type switchingSilencing

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Linda D. B. McBroom
    • 1
  • Paul D. Sadowski
    • 1
  1. 1.Department of Molecular and Medical GeneticsUniversity of TorontoTorontoCanada