Urban M, Kahmann R, Bölker M
Institut für Genetik and Mikrobiologie, Universität München, Germany.
Mol Gen Genet. 1996 Apr 24;251(1):31-7. doi: 10.1007/BF02174341.
The a mating type locus of Ustilago maydis contains the structural genes for a pheromone-based cell recognition system that governs fusion of haploid cells. Binding of pheromone to its cognate receptor includes mating competence in haploid cells and stimulates filamentous growth of the dikaryon. We have analyzed transcription of genes located in the a locus and demonstrate that all genes are induced by pheromone. Transcriptional stimulation is mediated by a 9 bp DNA element (ACAAAGGGA) that occurs in multiple copies in both alleles of the a locus. By fusing multimers containing this 9 bp sequence to the pheromone gene promoter and to a heterologous promoter we demonstrate that this sequence acts as a pheromone response element. In addition, we show that expression of the b genes, which regulate pathogenic development of the dikaryon, is also stimulated by pheromone. Pheromone-inducible genes can be divided into three classes depending on whether their expression is reduced, maintained, or increased after cell fusion. These differences may suggest some regulatory cross-talk between the a and b loci.
玉米黑粉菌的a交配型位点包含基于信息素的细胞识别系统的结构基因，该系统控制单倍体细胞的融合。信息素与其同源受体的结合包括单倍体细胞中的交配能力，并刺激双核体的丝状生长。我们分析了位于a位点的基因的转录，并证明所有基因均由信息素诱导。转录刺激由一个9 bp的DNA元件（ACAAAGGGA）介导，该元件在a位点的两个等位基因中均有多个拷贝。通过将包含此9 bp序列的多聚体与信息素基因启动子和异源启动子融合，我们证明该序列作为信息素反应元件起作用。此外，我们表明，调节双核体致病发育的b基因的表达也受到信息素的刺激。根据细胞融合后其表达是降低、维持还是增加，信息素诱导的基因可分为三类。这些差异可能表明a和b位点之间存在一些调节性相互作用。
