MIG1 Overexpression Causes Flocculation in Saccharomyces Cerevisiae

Microbiology. 1996 Sep;142 ( Pt 9):2663-7. doi: 10.1099/00221287-142-9-2663.


MIG1, encoding a C2H2 zinc-finger repressor protein involved in carbon catabolite repression, was found to play a role in non-sexual flocculation of Saccharomyces cerevisiae. Disruption of MIG1 in a flocculent mutant strain of NCYC 227, resulted in a non-flocculent phenotype. Expression of MIG1 on a 2 mu pRS426 vector in a non-flocculent strain, YM 4134, caused flocculation; MIG1 on a high-copy-number LEU2-d plasmid caused intense flocculation in the same strain. Mutations in the SSN6 and TUP1 genes confer a flocculent phenotype in non-flocculent strains of S. cerevisiae, and it has been shown that Mig1 can tether the Ssn6p-Tup1p complex to the regulatory regions of glucose-repressible genes. Mutations in tup1 in a MIG1 background caused flocculation while double mutants of TUP1 and MIG1 did not flocculate. Based on these results, a model for the role of MIG1 in flocculation gene regulation is proposed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Northern
  • Cloning, Molecular
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • Flocculation Tests
  • Flocculation*
  • Gene Expression Regulation, Fungal*
  • Mutagenesis / radiation effects
  • Mutagenesis, Insertional
  • Plasmids
  • RNA, Messenger / isolation & purification
  • Repressor Proteins / antagonists & inhibitors
  • Repressor Proteins / biosynthesis
  • Repressor Proteins / genetics*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae Proteins


  • DNA-Binding Proteins
  • MIG1 protein, S cerevisiae
  • RNA, Messenger
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins