Xie Z, Fang M, Rivas M P, Faulkner A J, Sternweis P C, Engebrecht J A, Bankaitis V A
Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA.
Proc Natl Acad Sci U S A. 1998 Oct 13;95(21):12346-51. doi: 10.1073/pnas.95.21.12346.
Yeast phosphatidylinositol transfer protein (Sec14p) function is essential for production of Golgi-derived secretory vesicles, and this requirement is bypassed by mutations in at least seven genes. Analyses of such 'bypass Sec14p' mutants suggest that Sec14p acts to maintain an essential Golgi membrane diacylglycerol (DAG) pool that somehow acts to promote Golgi secretory function. SPO14 encodes the sole yeast phosphatidylinositol-4,5-bisphosphate-activated phospholipase D (PLD). PLD function, while essential for meiosis, is dispensable for vegetative growth. Herein, we report specific physiological circumstances under which an unanticipated requirement for PLD activity in yeast vegetative Golgi secretory function is revealed. This PLD involvement is essential in 'bypass Sec14p' mutants where normally Sec14p-dependent Golgi secretory reactions are occurring in a Sec14p-independent manner. PLD catalytic activity is necessary but not sufficient for 'bypass Sec14p', and yeast operating under 'bypass Sec14p' conditions are ethanol-sensitive. These data suggest that PLD supports 'bypass Sec14p' by generating a phosphatidic acid pool that is somehow utilized in supporting yeast Golgi secretory function.
酵母磷脂酰肌醇转移蛋白（Sec14p）的功能对于高尔基体衍生的分泌囊泡的产生至关重要，并且至少七个基因的突变可绕过这一需求。对这类“绕过Sec14p”突变体的分析表明，Sec14p的作用是维持一个必需的高尔基体膜二酰基甘油（DAG）池，该池以某种方式促进高尔基体的分泌功能。SPO14编码酵母唯一的磷脂酰肌醇 - 4,5 - 二磷酸激活的磷脂酶D（PLD）。PLD的功能虽然对减数分裂至关重要，但对营养生长却是可有可无的。在此，我们报告了一些特定的生理情况，在这些情况下，揭示了酵母营养型高尔基体分泌功能中对PLD活性的意外需求。这种PLD的参与在“绕过Sec14p”突变体中至关重要，在这些突变体中，通常依赖Sec14p的高尔基体分泌反应以不依赖Sec14p的方式发生。PLD催化活性对于“绕过Sec14p”是必要但不充分的，并且在“绕过Sec14p”条件下生长的酵母对乙醇敏感。这些数据表明，PLD通过产生一个磷脂酸池来支持“绕过Sec14p”，该池以某种方式用于支持酵母高尔基体的分泌功能。
