Kües U, Tymon A M, Richardson W V, May G, Gieser P T, Casselton L A
Department of Plant Sciences, University of Oxford, UK.
Mol Gen Genet. 1994 Oct 17;245(1):45-52. doi: 10.1007/BF00279749.
We have identified the seven genes that constitute the A43 mating-type factor of Coprinus cinereus and compare the organisation of A43 with the previously characterised A42 factor. In both, the genes that trigger clamp cell development, the so-called specificity genes, are separated into alpha and beta loci by 7 kb of noncoding sequence and are flanked by homologous genes alpha-fg and beta-fg. The specificity genes are known to encode two classes of dissimilar homeodomain (HD1 and HD2) proteins and have different allelic forms which show little or no cross-hybridisation. By partial sequencing we identified a divergently transcribed HD1 (a1-2) and HD2 (a2-2) gene in the A43 alpha locus. a2-2 failed to elicit clamp cell development in three different hosts, suggesting that it is non-functional. a1-2 elicited clamp cells in an A42 host that has only an HD2 gene (a2-1) in its alpha locus, thus demonstrating that the compatible A alpha mating interaction is between an HD1 and an HD2 protein. The A43 beta locus contains three specificity genes, the divergently transcribed HD1 and HD2 genes b1-2 and b2-2 and a third HD1 gene (d1-1) that was shown by hybridisation and transformation analyses to be functionally equivalent to d1-1 in A42. An untranscribed footprint of a third A42 HD1 gene, c1-1, was detected between the A43 b2-2 and d1-1 genes by Southern hybridisation.
我们已经鉴定出构成灰盖鬼伞A43交配型因子的7个基因，并将A43的基因组织与先前已表征的A42因子进行了比较。在这两种因子中，触发锁状细胞发育的基因，即所谓的特异性基因，被7 kb的非编码序列分隔为α和β位点，两侧是同源基因α-fg和β-fg。已知特异性基因编码两类不同的同源异型域（HD1和HD2）蛋白，并且具有不同的等位基因形式，这些等位基因形式几乎没有或没有交叉杂交。通过部分测序，我们在A43的α位点鉴定出一个反向转录的HD1（a1-2）和HD2（a2-2）基因。a2-2在三种不同宿主中均未引发锁状细胞发育，表明它无功能。a1-2在其α位点仅具有HD2基因（a2-1）的A42宿主中引发了锁状细胞，从而证明兼容的Aα交配相互作用发生在HD1和HD2蛋白之间。A43的β位点包含三个特异性基因，反向转录的HD1和HD2基因b1-2和b2-2，以及第三个HD1基因（d1-1），通过杂交和转化分析表明其在功能上等同于A42中的d1-1。通过Southern杂交在A43的b2-2和d1-1基因之间检测到第三个A42 HD1基因c1-1的未转录足迹。
