一种新的酸性磷酸酯酶基因在酿酒酵母中的表达

Expression of A New Acid Phosphatase Gene of Kluveromyces fragilis in Saccharomyces cerevisiae

脆壁克鲁维酵母(Kluyveromyces fragilis)的酸性磷酸酯酶的基因曾被克隆到酿酒酵母(S.cerevisiae),并进行核酸顺序测定和分析,导出对应的氨基酸序列,发现其与酿酒酵母的Ph03和Ph05酸性磷酸酯酶及E.coli的碱性磷酸酯酶没有同源性,而被认为属于一种新的基因系。

In our privious work, we cloned an acid phosphatase gene of Kluveromyces fragilis in S.cerevisiae.The amino acid sequence had no homology to those of acid phosphatase of a closely related S.cerevisiae.To know the substrate specificity of the K.fragilis acid phosphatase,several efficient expression systems for the cloned gene in E. coli and S. cerevisine were tested. In E.coli system, the acid phosphatase gene clonend on a multicopy plasmid was tried to be expressed under the control of tac or phoA promoter with varied distance between SD and the initiation codon or the sequehce of signal peptide. Exprected proteins and activities, however, were not detected in any trial. Then we tested an expression system of S.cerevisiae.The acid phosphatase gene was placed downstream of GAL7 promoter and subcloned on a YEp24 derived plasmid. S.cerevisiae (pho3, pho5) transformed with the plasmid secreted a distinct amount of acid phosphatase in the periplasm only when galactose was added as an inducer.