Evidence for a Nonendosomal Function of the Saccharomyces cerevisiae ESCRT-III-Like Protein Chm7
Evidence for a Nonendosomal Function of the Saccharomyces cerevisiae ESCRT-III-Like Protein Chm7
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DOI：
10.1534/genetics.115.178939
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发表时间：
2015-12-01
期刊：
影响因子：
3.3
通讯作者：
Koelling, Ralf
中科院分区：
文献类型：
--
作者：
Bauer, Iva;Brune, Thomas;Koelling, Ralf
转运所需的内体分选复合体(ESCRT)蛋白参与了许多细胞过程，如内体蛋白分选、HIV萌发、胞质分裂、质膜修复和有丝分裂期间核膜的重新密封。在这里，我们探索了ESCRT-III蛋白家族的一个非规范成员的功能，即人类CHMP7的酿酒酵母同源基因。人们对这种蛋白质知之甚少。在计算机分析中预测CHM7(酵母ORF YJL049w)是ESCRT-II和ESCRT-III样结构域的融合，这可能表明在内体蛋白分选中发挥作用。然而，我们的数据反对Chm7在内体蛋白分类中的作用。CHM7缺失不影响细胞内货物蛋白Ste6的周转和羧肽酶S(CPs)的空泡蛋白分选，Chm7对Vps4功能丧失的反应也与典型的ESCRT-III蛋白截然不同。我们的数据表明，Chm7功能可能与内质网(ER)有关。与内质网的功能一致，我们观察到与核孔复合体组装有关的基因功能(APQ12)的缺失和信使RNA(MRNA)输出与CHM7缺失之间存在强烈的负遗传相互作用。APQ12缺失和ESCRT-III基因缺失之间的遗传相互作用、双杂交相互作用和mCherry融合蛋白的特异性定位的模式与Chm7作为ESCRT-III复合体的一部分在内质网发挥新功能的概念一致。
Endosomal sorting complex required for transport (ESCRT) proteins are involved in a number of cellular processes, such as endosomal protein sorting, HIV budding, cytokinesis, plasma membrane repair, and resealing of the nuclear envelope during mitosis. Here we explored the function of a noncanonical member of the ESCRT-III protein family, the Saccharomyces cerevisiae ortholog of human CHMP7. Very little is known about this protein. In silico analysis predicted that Chm7 (yeast ORF YJL049w) is a fusion of an ESCRT-II and ESCRT-III-like domain, which would suggest a role in endosomal protein sorting. However, our data argue against a role of Chm7 in endosomal protein sorting. The turnover of the endocytic cargo protein Ste6 and the vacuolar protein sorting of carboxypeptidase S (CPS) were not affected by CHM7 deletion, and Chm7 also responded very differently to a loss in Vps4 function compared to a canonical ESCRT-III protein. Our data indicate that the Chm7 function could be connected to the endoplasmic reticulum (ER). In line with a function at the ER, we observed a strong negative genetic interaction between the deletion of a gene function (APQ12) implicated in nuclear pore complex assembly and messenger RNA (mRNA) export and the CHM7 deletion. The patterns of genetic interactions between the APQ12 deletion and deletions of ESCRT-III genes, two-hybrid interactions, and the specific localization of mCherry fusion proteins are consistent with the notion that Chm7 performs a novel function at the ER as part of an alternative ESCRT-III complex.