酿酒酵母中亚硫酸盐转运基因SSU1的分子进化分析  

Molecular evolution of the sulphite efflux gene SSU1 in Saccharomyces cerevisiae

作　　者：彭立新[1] 孙菲菲[1] 黄艳燕[1] 黎贞崇[1] 

机构地区：[1]广西科学院非粮生物质酶解国家重点实验室,国家非粮生物质能源工程技术研究中心,广西生物炼制重点实验室,南宁530007

出　　处：《遗传》2013年第11期1317-1326,共10页Hereditas（Beijing)

基　　金：广西科学院基本科研业务(编号:10YJ25SW13);广西青年基金项目(编号:2013GXNSFBA019106)资助

摘　　要：SSU1基因是涉及亚硫酸外排及SO2耐受性的重要因素之一。为了研究酿酒酵母(Saccharomyce cerevisiae)中SSU1对SO2耐受性及其分化机制,文章探讨了SSU1基因在酿酒酵母中的遗传特征及进化规律。基于SSU1基因序列的聚类分析表明,酿酒酵母群体可通过该基因分为3个亚群,且与其分离的地理位置无关;基于群体数据的McDonald-Kreitman检验表明,SSU1基因在酿酒酵母中受到适应性选择的作用;Ka/Ks检验表明,在酿酒酵母中,不同的亚群间有Ka/Ks显著大于1的值,且PAML的支系模型检验到正选择作用在群体中特定的支系上;PAML的支系-位点模型检验获得9个潜在正选择作用位点,其中有4个发生在受正选择作用的特定支系中;基于ssu1p蛋白结构的分析表明,在特定支系存在的正选择作用位点中,除345(R/K)位点上两氨基酸替换均为碱性氨基酸外,其他3个位点均是极性氨基酸/疏水性氨基酸之间替换,考虑不同区域的氨基酸pKa值对其维持正常的功能有着重要的作用,在该类位点的替换可能影响到ssu1p蛋白对SO2的转运作用。The SSU1 gene encoding a membrane sulfite pump is a main facilitator invovled in sulfite effiux. In Sac- charomyce cerevisiae, various range of resistance to sulfite was observed among strains. To explore the evolution traits of SSU1 gene, the population data of S. cerevisiae were collected and analyzed. The phylogenetie analysis indicated that S. cerevisiae population can be classified into three sub-populations, and the positive selection was detected in population by McDonald-Kreitman test. The anaylsis of Ka/Ks ratios further showed that S. cerevisiae sub-population was undergoing positive selection. This finding was also supported by PAML branch mode/. Nine potential positive selection sites were predicted by branch-site model, and four sites exclusively belong to the sub-population under positive seletion. The data from ssulp protein structure demonstrated that three sites are substitutions between polar and hydrophobic amino acids, andonly one site of substitutaion from basic amino acid to basic amino acid （345R/K）. Because amino acid pKa values are cru- cial for sulfite pump to maintain their routine function, positive selection of these amino acid substitutions might affect sul- rite effiux efficient.

关 键 词：酿酒酵母 亚硫酸盐转运蛋白 适应性进化 

分 类 号：Q93[生物学—微生物学]