Schulz B, Banuett F, Dahl M, Schlesinger R, Schäfer W, Martin T, Herskowitz I, Kahmann R
Institut für Genbiologische Forschung Berlin GmbH, Federal Republic of Germany.
Cell. 1990 Jan 26;60(2):295-306. doi: 10.1016/0092-8674(90)90744-y.
U. maydis is a fungal pathogen of corn with two forms: one is yeast-like and nonpathogenic; the other is filamentous and pathogenic. The b locus, with 25 different alleles, regulates this dimorphism: any combination of two different alleles triggers pathogenic development, whereas the presence of identical alleles results in the yeast-like form. We have cloned four b alleles (b1, b2, b3, and b4) and show that the b locus contains a single open reading frame (ORF) of 410 amino acids with a variable N-terminal region and a highly conserved C-terminal region (60% and 93% identity, respectively). Mutational analysis confirms that this ORF is responsible for b activity. The b polypeptides appear to be DNA binding proteins because they contain a motif related to the homeodomain in their constant region. We propose that combinatorial interactions between b polypeptides generate regulatory proteins that determine the developmental program of the fungus.
玉米黑粉菌是玉米的一种真菌病原体，有两种形态：一种是酵母样且无致病性的；另一种是丝状且有致病性的。b位点有25个不同的等位基因，调控这种二态性：任意两个不同等位基因的组合会触发致病发育，而相同等位基因的存在则导致酵母样形态。我们克隆了四个b等位基因（b1、b2、b3和b4），并表明b位点包含一个410个氨基酸的单一开放阅读框（ORF），其N端区域可变，C端区域高度保守（分别具有60%和93%的同一性）。突变分析证实该ORF负责b活性。b多肽似乎是DNA结合蛋白，因为它们在其恒定区域含有一个与同源异型域相关的基序。我们提出b多肽之间的组合相互作用产生决定真菌发育程序的调控蛋白。
