Margolis-Clark E, Hunt I, Espinosa S, Bowman B J
Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, CA 95064, USA.
Fungal Genet Biol. 2001 Jul;33(2):127-35. doi: 10.1006/fgbi.2001.1273.
Mutations at the pmg locus in Neurospora crassa cause a deficiency in a transport system for a broad range of amino acids. We have isolated a gene that encodes a protein with a high degree of sequence similarity to the GAP1 general amino acid permease in Saccharomyces cerevisiae. Our data indicate that this is the gene at the pmg locus. It encodes a 572-residue protein with a molecular mass of 62,649 Da. The predicted secondary structure has 12 membrane-spanning regions, a feature characteristic of a superfamily of permease proteins. Inactivation of the gene yielded a mutant strain with the same phenotype as the pmg- strain, and a cosmid containing a functional copy of the gene rescued the pmg- strain. Although the pmg- strain has previously been assayed in a genetic background that contains mutations in genes for two other amino acid transport systems, we have found conditions in which the pmg- strain has an identifiable phenotype in an otherwise wild-type genetic background.
粗糙脉孢菌中pmg位点的突变会导致多种氨基酸转运系统出现缺陷。我们分离出了一个基因，该基因编码的蛋白质与酿酒酵母中的GAP1通用氨基酸通透酶具有高度的序列相似性。我们的数据表明，这就是pmg位点的基因。它编码一个由572个残基组成的蛋白质，分子量为62649道尔顿。预测的二级结构有12个跨膜区域，这是通透酶蛋白超家族的一个特征。该基因的失活产生了一个与pmg-菌株具有相同表型的突变菌株，并且一个含有该基因功能拷贝的黏粒拯救了pmg-菌株。尽管之前在一个包含另外两个氨基酸转运系统基因突变的遗传背景中对pmg-菌株进行了检测，但我们发现，在其他方面为野生型的遗传背景下，pmg-菌株在某些条件下具有可识别的表型。
