Multivesicular body-ESCRT components function in pH response regulation in Saccharomyces cerevisiae and Candida albicans.
Multivesicular body-ESCRT components function in pH response regulation in Saccharomyces cerevisiae and Candida albicans.
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DOI：
10.1091/mbc.e04-08-0666
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发表时间：
2004-09
影响因子：
3.3
通讯作者：
Wenjie Xu;F. J. Smith;R. Subaran;A. Mitchell
中科院分区：
文献类型：
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作者：
Wenjie Xu;F. J. Smith;R. Subaran;A. Mitchell
ESCRT-I， -II和-III蛋白复合物的功能是产生多泡体（MVBs），用于分选运往溶酶体或液泡的蛋白质。先前对酿酒酵母的研究表明，ESCRT-III蛋白Snf7p与MVB通路蛋白Bro1p及其同源蛋白Rim20p相互作用。Rim20p在MVB的形成中没有作用，但在Rim101p的ph反应途径中起作用；Rim20p与转录因子Rim101p相互作用，是c端蛋白水解裂解激活Rim101p所必需的。我们在这里报道了ESCRT-III蛋白Snf7p和Vps20p以及所有ESCRT-I和-II蛋白都是酿酒葡萄球菌中Rim101p蛋白水解激活所必需的。突变分析表明，Rim20p的n端区域与Snf7p相互作用，而在Rim20p“Bro1结构域”中的插入消除了这种相互作用，这是通过双杂交分析确定的。通过影响非escrt蛋白的突变破坏MVB通路不会损害Rim101p加工。MVB途径和Rim101p途径之间的关系在白色念珠菌中是保守的，因为四个ESCRT亚基基因的突变消除了碱性ph诱导的丝化，这是以前在rim101和rim20突变体中发现的表型。这种缺陷被c端截断的Rim101-405p的表达所抑制，正如预期的那样，突变阻断了Rim101p的蛋白水解激活。这些结果表明，ESCRT复合物控制着特定的信号转导途径，并提示MVB途径可能提供调节ph响应转录的信号。
The ESCRT-I, -II, and -III protein complexes function to create multivesicular bodies (MVBs) for sorting of proteins destined for the lysosome or vacuole. Prior studies with Saccharomyces cerevisiae have shown that the ESCRT-III protein Snf7p interacts with the MVB pathway protein Bro1p as well as its homolog Rim20p. Rim20p has no role in MVB formation, but functions in the Rim101p pH-response pathway; Rim20p interacts with transcription factor Rim101p and is required for the activation of Rim101p by C-terminal proteolytic cleavage. We report here that ESCRT-III proteins Snf7p and Vps20p as well as all ESCRT-I and -II proteins are required for Rim101p proteolytic activation in S. cerevisiae. Mutational analysis indicates that the Rim20p N-terminal region interacts with Snf7p, and an insertion in the Rim20p "Bro1 domain" abolishes this interaction, as determined with two-hybrid assays. Disruption of the MVB pathway through mutations affecting non-ESCRT proteins does not impair Rim101p processing. The relationship between the MVB pathway and Rim101p pathway is conserved in Candida albicans, because mutations in four ESCRT subunit genes abolish alkaline pH-induced filamentation, a phenotype previously seen for rim101 and rim20 mutants. The defect is suppressed by expression of C-terminally truncated Rim101-405p, as expected for mutations that block Rim101p proteolytic activation. These results indicate that the ESCRT complexes govern a specific signal transduction pathway and suggest that the MVB pathway may provide a signal that regulates pH-responsive transcription.