利用基因重組酵母菌穩定生產cholesta-5,7,24-trienol

Abstract

Cholesta-5,7,24-trienol is a metabolic intermediate of cholesterol biosynthetic pathway in animal cell, which is the initial compound of calcifediol synthesis in industry, and supplying for calcitriol synthesis. Calcitriol is the vitamin D3 with the highest activity, human body can obtain calcitriol by 7-dehydrocholesterol in skin. During exposure to sunlight, 7-dehydrocholesterol in epidermal and dermal cells absorbs ultraviolet B (UVB), it was then metabolized by liver and kidney; finally, we got active calcitriol. In the past, vitamin D was considered to regulate in calcium absorption and metabolism in intestine, kidney and skeleton. It can prevent osteoporosis. In recent years, more and more studies found that vitamin D not only can decrease the incidence of heart disease, diabetes, depression, demen-tia, chronicpain, cancer and asthma, but increase the immunity against diseases. It is very important to intake amount of vitamin D for people without enough sunlight and vitamin D. The purpose of this research is to produce a large quantity of cholesta-5,7,24-trienol by metabolic engineering. This research utilized erg5-erg6 double-mutant yeast, which can accumulate cholesta-5,7,24-trienol and transformed a plasmid which carrying the sequence of catalytic domain of HMG-CoA reductase to improve the activity of HMG-CoA reductase who are rate-limiting step of cholesta-5,7,24-trienol biosynthesis. The quantitative result verifies that the production of cholesta-5,7,24-trienol has significant increase, showing that the percentage of dry weight reach 0.86%, which is higher than the non-transformed yeast. This result strongly suggested that the gene-modified yeast can be applied in domestic vitamin D industry, increasing competition in international marketing.