酵母糖化酶基因高效表达的剂量效应研究

通过原生质体融合和秋水仙素加倍技术，将糖化酵母的３个等效异位基因分别构建成交配型位点等痊基因纯合和糖化酶基因各自纯各加倍的纯合二倍体（ＳＴＡ１／ＳＴＡ１、ＳＴＡ２／ＳＴＡ２和ＳＴＡ３ＳＴＡ３）以及糖化酶基因相互组织加倍的组合二倍体（ＳＴＡ１／ＳＴＡ２、ＳＴＡ２／ＳＴＡ３和ＳＴＡ１／ＳＴＡ３）。研究了这３个糖化酶基因表达的剂量效及其相互关系。糖化酶酶活测定的结果表明，在交配型位点等位基因纯合状态下，

Study on Gene-dosage Effect of High Level Expression of the Yeast Glucoamylase Genes

Diploid strains homozygous for both MAT allele and STA genes (a/a. STA1/ STA1 or STA2/ STA2 or STA3/ STA3) and diploid strains homozygous for MAT allele but intercombinahve for STA genes (a / a. STA1/ STA2 or STA2/ STA3 or STA1/ STA3) were constructed by means of the protoplast fusion or the colchicine beatment.According to glucoamylase activity in YPS medium, we studied the gene-dosage effect and their interrelation of these three polymeric genes coding for glucoamylase. The results of the glucoamylase activity determination showed that the gene-dosage effect of glucoamylase is obvious in diploid and triploid strains homozygous for both MAT allele and STA gene, such as the glucoamylase achvity of a diploid strain SFY56-6 and a triploid strain SFY56-104 homozygous for both MAT allele and STA genes were respectively 2.35 and 3.18-fold as compared with that of the their parental strain IATA-Y56 that is a haploid Aaccharomyces diastaticus. Moreover, the glucoamylase achvity of diploid stains homozygous for MAT allele but intereombinative for STA genes also showed the combinative gene-dosage effect to a certain extent.