Breeding of efficient strains of saccharomyces cerevisiae to produce heterologous gene product.

对外源基因产物高效菌株的选育进行了研究。以KZLwvem“S”马氏链霉菌编码的多聚半乳糖醛酸酶(PG)基因为标记，从酿酒酵母中分离到一株导致外源基因产物高产的突变体。突变株(SSM5-2)的PG产量是出发菌株的10~30倍。(2)突变株细胞膜脂质含量与出发菌株不同，制备感受态细胞的条件也与出发菌株不同。(3)SSM5-2为温度敏感型致死突变体，其生长受阻于PG的产生，证实为G2期停滞。G_2期停滞被Ca~(2+)和Gt~(2+)恢复。(4)在马尾藻PG基因的上游区域发现了一个促进PG产生的基因(PGPPF)。测定了PGPPF的碱基序列。

The research on breeding of efficient strains to produce heterologous gene product have been done. A mutant responsible for an overproduction phenotype on heterologous gene product in S. cerevisiae has been isolated, using the gene coding for polygalacturonase (PG) from KZLwvem"s marxianus as a marker.The results obtained are as follows :(1) A mutant responsible for an oversecretion of PG was obtained. The mutant (SSM5-2) produced PG by 10- to 30-fold in parent strain.(2) Contents of lipids in the cell membrane of the mutant was different from those of parent strain, and the conditions for preparing competent cell were also different from parent strain. A simple and efficient method for transformation with plasmids was established.(3) SSM5-2 was temperature-sensitive lethal mutant and it growth was arrested with the production of PG, and it was confirmed to be G2 arrest. The G2 arrest was found to be recovered by Ca^<2+>.(4) A gene which promote the PG production (PGPPF) was found on upstream region of PG gene of K. marxianus. The base sequence of PGPPF was determined.