A novel RING finger protein complex essential for a late step in protein transport to the yeast vacuole
A novel RING finger protein complex essential for a late step in protein transport to the yeast vacuole
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DOI：
10.1091/mbc.8.11.2307
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发表时间：
1997-11-01
影响因子：
3.3
通讯作者：
Emr, SD
中科院分区：
文献类型：
--
作者：
Rieder, SE;Emr, SD
酵母中蛋白质运输到溶酶体样空泡的途径有多种，包括液泡水解酶的生物合成途径、内吞途径和自噬途径。在酿酒酵母空泡蛋白分选(VPS)所需的40多个基因中，四个C类VPS基因的突变导致了最严重的空泡蛋白分选和形态缺陷。在这里，我们提供了互补的遗传和生化证据，证明C类VPS基因产物(Vps18p、Vps11p、Vps16p和Vps33p)在物理和功能上相互作用，介导蛋白质运输到液泡的后期步骤。化学交联实验表明，Vps11p和Vps18p都含有环指锌结合结构域，是包括Vps16p和Sec1p同源物Vps33p的异源低聚蛋白复合体的组成部分。C类VPs蛋白复合体与空泡膜共定位，有明显的致密膜组分。对含有温度条件vps18等位基因(vps18(TSF))的细胞的分析表明，Vps18p功能是生物合成、内吞和自噬蛋白运输到液泡所必需的。此外，vps18(TSF)细胞积聚了多泡小体、自噬小体和其他似乎代表受阻的运输中间产物的膜室。Vps16p或Vam3p空泡合成素同源物的过度生产抑制了与vps18(TSF)突变细胞相关的缺陷，表明C类VPs蛋白和Vam3p可能在功能上相互作用。因此，我们认为C类VPS蛋白是异寡聚体蛋白复合体的组成部分，该复合体介导多种运输中间产物向液泡的运输。
Protein transport to the lysosome-like vacuole in yeast is mediated by multiple pathways, including the biosynthetic routes for vacuolar hydrolases, the endocytic pathway, and autophagy. Among the more than 40 genes required for vacuolar protein sorting (VPS) in Saccharomyces cerevisiae, mutations in the four class C VPS genes result in the most severe vacuolar protein sorting and morphology defects. Herein, we provide complementary genetic and biochemical evidence that the class C VPS gene products (Vps18p, Vps11p, Vps16p, and Vps33p) physically and functionally interact to mediate a late step in protein transport to the vacuole. Chemical cross-linking experiments demonstrated that Vps11p and Vps18p, which both contain RING finger zinc-binding domains, are components of a hetero-oligomeric protein complex that includes Vps16p and the Sec1p homologue Vps33p. The class C Vps protein complex colocalized with vacuolar membranes and a distinct dense membrane fraction. Analysis of cells harboring a temperature-conditional vps18 allele (vps18(tsf)) indicated that Vps18p function is required for the biosynthetic, endocytic, and autophagic protein transport pathways to the vacuole. In addition, vps18(tsf) cells accumulated multivesicular bodies, autophagosomes, and other membrane compartments that appear to represent blocked transport intermediates. Overproduction of either Vps16p or the vacuolar syntaxin homologue Vam3p suppressed defects associated with vps18(tsf) mutant cells, indicating that the class C Vps proteins and Vam3p may functionally interact. Thus we propose that the class C Vps proteins are components of a hetero-oligomeric protein complex that mediates the delivery of multiple transport intermediates to the vacuole.