Five SWI genes are required for expression of the HO gene in yeast

Michael Stern, Robert Jensen, Ira Herskowitz

Research output: Contribution to journalArticlepeer-review

292 Scopus citations


High-frequency mating type interconversion in yeast requires the HO gene, which encodes a site-specific endonuclease that initiates the switching process. We have isolated and analyzed switching-defective mutants. These mutants define five complementation and linkage groups, SWI 1 to SWI 5. We have shown by two assays, Northern hybridization and β-galactosidase activity in strains containing an HO-lacZ fusion, that mutants defective any SWI gene fail to express the HO gene. In addition, all of the swi mutants exhibit other phenotypes. the most notable being the inviability of double mutants defective in SWI 4 and in either SWI 1, SWI 2 or SWI 3. These results indicate that the SWI genes function in some way as positive regulators of HO expression and have additional cellular roles.

Original languageEnglish (US)
Pages (from-to)853-868
Number of pages16
JournalJournal of molecular biology
Issue number4
StatePublished - Oct 5 1984
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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