Biochemical Analyses of Human IST1 and Its Function in Cytokinesis
Biochemical Analyses of Human IST1 and Its Function in Cytokinesis
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DOI：
10.1091/mbc.e08-05-0475
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发表时间：
2009-03-01
影响因子：
3.3
通讯作者：
Sundquist, Wesley I.
中科院分区：
文献类型：
--
作者：
Bajorek, Monika;Morita, Eiji;Sundquist, Wesley I.
新描述的酵母内体分选复合物运输所需的（ESCRT）蛋白增加钠耐受性-1（Ist 1 p）结合晚期作用ESCRT蛋白Did 2 p/带电MVB蛋白（CHMP）1和Vps 4p，并在与Vta 1 p/LIP 5-Vps 60 p/CHMP 5复合物中的突变结合时表现出合成空泡蛋白分选缺陷。在这里，我们报告说，人类的IST 1也在ESCRT途径的功能，并在HeLa细胞胞质分裂过程中有效的分裂所需的。表征了IST 1与VPS 4、CHMP 1、LIP 5和ESCRT-1的结合相互作用，并详细研究了IST 1-VPS 4相互作用。突变和NMR光谱研究显示，IST 1末端包含两个不同的MIT相互作用基序（MIM 1和MIM 2），它们缠绕并结合在MIT螺旋束的不同格罗夫斯中。IST 1、CHMP 1和VPS 4被募集到分裂细胞的中间体，并且耗尽IST 1或CHMP 1蛋白阻断VPS 4募集和释放。相比之下，IST 1耗竭并不能抑制人类免疫缺陷病毒-1的出芽。因此，IST 1和CHMP 1共同作用以募集和调节细胞分裂最后阶段所需的特定VPS 4活性。
The newly described yeast endosomal sorting complexes required for transport (ESCRT) protein increased sodium tolerance-1 (Ist1p) binds the late-acting ESCRT proteins Did2p/charged MVB protein (CHMP) 1 and Vps4p and exhibits synthetic vacuolar protein sorting defects when combined with mutations in the Vta1p/LIP5-Vps60p/CHMP5 complex. Here, we report that human IST1 also functions in the ESCRT pathway and is required for efficient abscission during HeLa cell cytokinesis. IST1 binding interactions with VPS4, CHMP1, LIP5, and ESCRT-I were characterized, and the IST1-VPS4 interaction was investigated in detail. Mutational and NMR spectroscopic studies revealed that the IST1 terminus contains two distinct MIT interacting motifs (MIM1 and MIM2) that wrap around and bind in different groves of the MIT helical bundle. IST1, CHMP1, and VPS4 were recruited to the midbodies of dividing cells, and depleting either IST1 or CHMP1 proteins blocked VPS4 recruitment and abscission. In contrast, IST1 depletion did not inhibit human immunodeficiency virus-1 budding. Thus, IST1 and CHMP1 act together to recruit and modulate specific VPS4 activities required during the final stages of cell division.