Sec16 function in ER export and autophagy is independent of its phosphorylation in Saccharomyces cerevisiae
Sec16 function in ER export and autophagy is independent of its phosphorylation in Saccharomyces cerevisiae
复制标题
酿酒酵母中 Sec16 在内质网输出和自噬中的功能与其磷酸化无关
DOI：
10.1091/mbc.e19-08-0477
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发表时间：
2020
期刊：
影响因子：
3.3
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Yorimitsu;T.;Sato;K.
外壳蛋白复合体II(COPII)蛋白聚集在内质网出口部位(ERES)，形成囊泡载体，从内质网运输到高尔基体。Sec16在COPII组装形成ERES中起关键作用。缺失N端565个氨基酸的Sec16∆565N突变体在ERES的形成和内质网输出方面存在缺陷。一些磷酸蛋白质组学研究已经证实酿酒酵母Sec16基因有108个磷酸化的丝氨酸/苏氨酸/酪氨酸残基，其中30个残基位于Sec16∆565N的截短部分。磷酸化在Sec16功能中的确切作用仍有待确定。因此，我们分析了不可磷酸化的Sec16突变体，其中所有已鉴定的磷酸化位点都被Ala取代。这些突变体的ERES和ER输出与野生型Sec16相当，尽管不可磷酸化的突变体比野生型蛋白更有效地结合COPII亚单位Sec23。因为营养饥饿诱导的自噬依赖于Sec16，Sec16∆565N会削弱自噬，而不可磷酸化的突变体不会影响自噬。我们得出结论，Sec16的磷酸化不是其功能所必需的。
Coat protein complex II (COPII) protein assembles at the endoplasmic reticulum exit site (ERES) to form vesicle carrier for transport from the ER to the Golgi apparatus. Sec16 has a critical role in COPII assembly to form ERES. Sec16∆565Nmutant, which lacks the N-terminal 565 amino acids, is defective in ERES formation and ER export. Several phosphoproteomic studies have identified 108 phosphorylated Ser/Thr/Tyr residues in Sec16 ofSaccharomyces cerevisiae, of which 30 residues are located in the truncated part of Sec16∆565N. The exact role of the phosphorylation in Sec16 function remains to be determined. Therefore, we analyzed nonphosphorylatable Sec16 mutants, in which all identified phosphorylation sites are substituted with Ala. These mutants show ERES and ER export comparable to those of wild-type Sec16, although the nonphosphorylatable mutant binds the COPII subunit Sec23 more efficiently than the wild-type protein. Because nutrient starvation–induced autophagy depends on Sec16, Sec16∆565Nimpairs autophagy, whereas the nonphosphorylatable mutants do not affect autophagy. We conclude that Sec16 phosphorylation is not essential for its function.