多不饱和脂肪酸（PUFAs）在生物体内具有重要的生物学功能，巴斯德毕赤酵母是目前表达外源蛋白的理想宿主。通过气相色谱法对其胞内脂肪酸组成分析后发现，毕赤酵母不仅含有16碳棕榈酸、18碳硬脂酸饱和脂肪酸；而且还含有棕榈油酸、油酸单不饱和脂肪酸以及亚油酸、α-亚麻酸多不饱和脂肪酸。因此它不同于酿酒酵母，其体内具有相对完整的PUFAs代谢系统，是研究脂肪酸代谢理想的模式菌株。本项目拟通过在分子水平上对其体内PUFAs生物合成途径中相关脱氢酶基因的功能、基因表达变化、基因启动子顺式作用元件和基因表达潜在的调控蛋白进行研究，旨在明确该模式菌株体内PUFAs合成过程中相关基因的表达调控机制，从而为全面阐述真核生物PUFAs生物合成途径及PUFAs在生物膜中的作用奠定基础，并且为真核生物PUFAs代谢及调控通路的研究提供一个简单的模型。

PUFAs play crucial biological roles in various organisms. The methylotrophic yeast Pichia pastoris has been proved to be an excellent system for high-level expression of heterologous proteins because of many advantages. Our early analysis of fatty acid composition in P.pastoris GS115 indicated that it has a fatty acid profile which mainly includes two types of saturated fatty acids (SFAs), palmitic acid (PAM, C16:0) and stearic acid (STA, C18:0), two types of monounsaturated fatty acids (MUFAs), palmitoleic acid (C16:1n-7) and oleic acid (OLA, C18:1n-9), and two types of PUFAs, linoleic acid (LNA; C18:2n-6) and α-linolenic acid (ALA; C18:3n-3). Therefore, unlike the yeast Saccharomyces cerevisiae, which has only one desaturase (△9 FAD) encoded by OLE1 gene, P.pastoris possesses a relatively complete system of PUFAs biosynthesis. For all these reasons above, P.pastoris is a good eukaryotic model organism for studies on the metabolism and regulation mechanism of fatty acid biosynthesis. In an effort to elucidate the regulation mechanism controlling gene expression in the biosynthesis pathway of PUFAs of P.pastoris, we are willing to perform some experiments concerning the physiological role of the FAD gene product, changes in gene expression, cis-acting elements and potential regulatory protein on the molecular level. The results will facilitate a comprehensive understanding of the biosynthetic pathways and regulation mechanisms involved in the production of PUFAs and improve our understanding of their role in biofilms.