Identification of a target gene for the bE-bW homeodomain protein complex in Ustilago maydis.
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.
Institut für Genetik und Mikrobiologie, Ludwig-Maximilians-Universität München, Maria-Ward-Strasse 1a, D-80638 München, Germany.
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Romeis
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Brachmann
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Kahmann
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Kämper
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004271:DNA, Fungal / Q000235:genetics* / Q000378:metabolism*; D019281:Dimerization; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014588:Ustilago / Q000235:genetics / Q000502:physiology*
D004271:DNA, Fungal; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D011993:Recombinant Fusion Proteins