Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
Mol Biol Cell. 2022 Jan 1;33(1):ar11. doi: 10.1091/mbc.E21-11-0558-T. Epub 2021 Nov 24.
The asymmetric distribution of phospholipids in membranes is a fundamental principle of cellular compartmentalization and organization. Phosphatidylethanolamine (PE), a nonbilayer phospholipid that contributes to organelle shape and function, is synthesized at several subcellular localizations via semiredundant pathways. Previously, we demonstrated in budding yeast that the PE synthase Psd1, which primarily operates on the mitochondrial inner membrane, is additionally targeted to the ER. While ER-localized Psd1 is required to support cellular growth in the absence of redundant pathways, its physiological function is unclear. We now demonstrate that ER-localized Psd1 sublocalizes on the ER to lipid droplet (LD) attachment sites and show it is specifically required for normal LD formation. We also find that the role of phosphatidylserine decarboxylase (PSD) enzymes in LD formation is conserved in other organisms. Thus we have identified PSD enzymes as novel regulators of LDs and demonstrate that both mitochondria and LDs in yeast are organized and shaped by the spatial positioning of a single PE synthesis enzyme.
磷脂在膜中的不对称分布是细胞区室化和组织的基本原则。磷脂酰乙醇胺（PE）是一种非双层磷脂，有助于细胞器的形状和功能，通过半冗余途径在几个亚细胞定位合成。以前，我们在芽殖酵母中证明，主要在线粒体内膜上起作用的 PE 合酶 Psd1 还被靶向到内质网。虽然内质网定位的 Psd1 对于在没有冗余途径的情况下支持细胞生长是必需的，但它的生理功能尚不清楚。我们现在证明，内质网定位的 Psd1 亚定位在内质网上的脂滴（LD）附着位点，并表明它是正常 LD 形成所必需的。我们还发现，磷脂酰丝氨酸脱羧酶（PSD）酶在 LD 形成中的作用在其他生物体中是保守的。因此，我们已经确定 PSD 酶是 LD 的新调节剂，并证明酵母中的线粒体和 LD 都是由单个 PE 合成酶的空间定位来组织和塑造的。
