Abstract: The effects of overexpression of three key enzyme genes involved in the purine synthesis pathway on cAMP product with highly efficient cyclic adenosine monophosphate (cAMP)-producing Saccharomyces cerevisiae strains were studied. Saccharomyces cerevisae episomal plasmid YEplac195 and the promoter (PGK1p) and terminator (PGK1t) of phosphoglycerate kinase were used to construct single gene expression vectors containing PRS1, PRS3, ADE4 and ADK1, respectively, which were transferred to the cAMP-producing strain GA125. The recombinant strains generated with shake flask fermentation improved cAMP production performance with various degrees. With addition of adenine, the cAMP yield with PRS1, PRS3 and ADE4 was increased by 4.17%, 9.03% and 6.06%, respectively, but that with ADK1 decreased by 3.85%, compared with strain GA125.

Key words: Saccharomyces cerevisae, cyclic adenosine monophosphate, adenine, phosphoribosylpyrophosphate

摘要： 研究了环磷酸腺苷(cAMP)合成途径中的3个关键酶基因(磷酸核糖焦磷酸合成酶基因PRS1和PRS3、磷酸核糖焦磷酸氨基转移酶基因ADE4、腺苷酸激酶基因ADK1)过量表达对重组酿酒酵母(Saccharomyces cerevisiae)发酵向胞外分泌cAMP的影响，利用酿酒酵母游离型质粒YEplac195和磷酸甘油酸激酶PGK的强启动子PGK1p及终止子PGK1t构建含PRS1, PRS3, ADE4和ADK1的单基因表达载体，分别转入cAMP生产菌GA125，通过摇瓶发酵实验考察重组菌株与对照菌株的生长、cAMP生产及胞外腺嘌呤消耗情况. 结果表明，在外加腺嘌呤条件下，与对照菌株相比，PRS1, PRS3和ADE4基因过表达菌株的cAMP产量分别提高4.17%, 9.03%和6.06%，而ADK1过表达菌株的cAMP产量降低3.85%.

关键词: 酿酒酵母, 环磷酸腺苷, 腺嘌呤, 磷酸核糖焦磷酸