Fatty acid production in Schizochytrium sp.:: Involvement of a polyunsaturated fatty acid synthase and a type I fatty acid synthase
Fatty acid production in Schizochytrium sp.:: Involvement of a polyunsaturated fatty acid synthase and a type I fatty acid synthase
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DOI：
10.1007/s11745-006-5025-6
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发表时间：
2006-08-01
期刊：
影响因子：
1.9
通讯作者：
Metz, J. G.
中科院分区：
文献类型：
--
作者：
Hauvermale, A.;Kuner, J.;Metz, J. G.
Schizochytrium sp.是一种海洋微生物，已被开发为二十二碳六烯酸（DHA，C22：6 omega-3）、富集生物质和油的商业来源。先前的研究表明，DHA以及在裂殖壶菌中积累的二十二碳五烯酸（DPA，C22：5 omega-6）是多亚基多不饱和脂肪酸（PUFA）合酶的产物（1）。在这里，我们显示的数据来支持这一观点，也提供了在这种生物体的脂肪酸合成的其他方面的信息。从基因组DNA中分离出三个编码PUFA合酶亚基的基因，并在大肠杆菌中与编码磷酸泛酰巯基乙胺基转移酶（PPTase）的必需辅助基因一起沿着表达。所得转化体积累DHA和DPA两者。DHA与DPA的比率与在裂殖壶菌中观察到的比率大致相同。用一定水平的浅蓝菌素处理裂殖壶菌细胞导致14 C乙酸盐掺入短链脂肪酸的抑制，而不影响PUFA的标记，表明不同的生物合成途径。一个单一的大基因编码推定的短链脂肪酸合成酶（FAS）的克隆和测序。基于序列同源性和结构域组织，裂殖壶菌FAS类似于真菌FAS β和α亚基的融合。
Schizochytrium sp. is a marine microalga that has been developed as a commercial source for docosahexaenoic acid (DHA, C22:6 omega-3), enriched biomass, and oil. Previous work suggested that the DHA, as well as docosapentaenoic acid (DPA, C22:5 omega-6), that accumulate in Schizochytrium are products of a multi-subunit polyunsaturated fatty acid (PUFA) synthase (1). Here we show data to support this view and also provide information on other aspects of fatty acid synthesis in this organism. Three genes encoding subunits of the PUFA synthase were isolated from genomic DNA and expressed in E coli along with an essential accessory gene encoding a phosphopantetheinyl transferase (PPTase). The resulting transformants accumulated both DHA and DPA. The ratio of DHA to DPA was approximately the same as that observed in Schizochytrium. Treatment of Schizochytrium cells with certain levels of cerulenin resulted in inhibition of 14 C acetate incorporation into short chain fatty acids without affecting labeling of PUFAs, indicating distinct biosynthetic pathways. A single large gene encoding the presumed short chain fatty acid synthase (FAS) was cloned and sequenced. Based on sequence homology and domain organization, the Schizochytrium FAS resembles a fusion of fungal FAS beta and alpha subunits.