Identification of a target gene for the bE-bW homeodomain protein complex in Ustilago maydis

Mol Microbiol. 2000 Jul;37(1):54-66. doi: 10.1046/j.1365-2958.2000.01978.x.


In the phytopathogenic fungus Ustilago maydis, sexual and pathogenic development are controlled by the multiallelic b mating type locus. The b locus encodes a pair of unrelated homeodomain proteins termed bE and bW that form a heterodimeric complex when both proteins originate from different alleles. The heterodimer is presumed to be the central regulator for pathogenicity genes. Here, we show that a translational fusion protein comprising specific domains of bE1 and bW2 remains biologically active and binds to a sequence motif in the promoter of lga2, a gene located in the a mating type locus. This b binding sequence 1 (bbs1) is also recognized by the native bE1-bW2 heterodimer in vivo and mediates the b-dependent regulation of the lga2 gene. Our data demonstrate that the bE-bW heterodimer can act as a positive transcriptional regulator.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Binding Sites
  • DNA, Fungal / genetics*
  • DNA, Fungal / metabolism*
  • Dimerization
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Gene Expression Regulation, Fungal
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism*
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transcription, Genetic
  • Two-Hybrid System Techniques
  • Ustilago / genetics
  • Ustilago / physiology*


  • DNA, Fungal
  • Fungal Proteins
  • Homeodomain Proteins
  • Recombinant Fusion Proteins