Structure/function analysis of four core ESCRT-III proteins reveals common regulatory role for extreme C-terminal domain
Structure/function analysis of four core ESCRT-III proteins reveals common regulatory role for extreme C-terminal domain
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DOI：
10.1111/j.1600-0854.2007.00584.x
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发表时间：
2007-08-01
期刊：
影响因子：
4.5
通讯作者：
Hanson, Phyllis I.
中科院分区：
文献类型：
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作者：
Shim, Soomin;Kimpler, Lisa A.;Hanson, Phyllis I.
转运蛋白III所需的内体分选复合物（ESCRT-III）是由参与多泡体生物发生的相关ESCRT-III蛋白构建的大型复合物。关于这个复合体的结构和功能知之甚少。在这里，我们比较了四种人ESCRT-III蛋白-hVps 2 -1/CHMP 2a，hVps 24/CHMP 3，hVps 20/CHMP 6和hSnf 7 -1/CHMP 4a-彼此，研究删除预测的α-螺旋结构域对其在转染细胞中的行为的影响。令人惊讶的是，从每种蛋白质的C末端去除大约40个氨基酸，揭示了与内体膜结合并组装成大型聚合物复合物的共同能力。在培养的细胞中表达这些截短的ESCRT-III蛋白会导致泛素化货物在扩大的内体上积累并抑制病毒出芽，而表达全长蛋白则不会。缺少其C-末端42个氨基酸的hVps 2 -1/CHMP 2a进一步不能结合AAA+腺苷三磷酸酶VPS 4 B/SKD 1，表明C-末端序列对于ESCRT-III蛋白与VPS 4的相互作用是重要的。总的来说，我们的研究支持一个模型，其中ESCRT-III蛋白在默认的“关闭”状态和激活的“开放”状态之间循环，其C-末端序列和相关因子的控制下。
Endosomal sorting complex required for transport-III (ESCRT-III) is a large complex built from related ESCRT-III proteins involved in multivesicular body biogenesis. Little is known about the structure and function of this complex. Here, we compare four human ESCRT-III proteins - hVps2-1/CHMP2a, hVps24/CHMP3, hVps20/CHMP6, and hSnf7-1/CHMP4a - to each other, studying the effects of deleting predicted alpha-helical domains on their behavior in transfected cells. Surprisingly, removing similar to 40 amino acids from the C-terminus of each protein unmasks a common ability to associate with endosomal membranes and assemble into large polymeric complexes. Expressing these truncated ESCRT-III proteins in cultured cells causes ubiquitinated cargo to accumulate on enlarged endosomes and inhibits viral budding, while expressing full-length proteins does not. hVps2-1/CHMP2a lacking its C-terminal 42 amino acids further fails to bind to the AAA+ adenosine triphosphatase VPS4B/SKD1, indicating that C-terminal sequences are important for interaction of ESCRT-III proteins with VPS4. Overall, our study supports a model in which ESCRT-III proteins cycle between a default 'closed' state and an activated 'open' state under control of sequences at their C-terminus and associated factors.