Structural insight into the ESCRT-I/-II link and its role in MVB trafficking
Structural insight into the ESCRT-I/-II link and its role in MVB trafficking
复制标题
DOI：
10.1038/sj.emboj.7601501
复制
发表时间：
2007-01-24
期刊：
影响因子：
11.4
通讯作者：
Williams, Roger L.
中科院分区：
文献类型：
--
作者：
Gill, David J.;Teo, Hsiangling;Williams, Roger L.
ESCRT（转运所需的内体分选复合物）复合物通过多泡体（MVB）协调泛素化跨膜受体有效分选至溶酶体。酵母ESCRT-I和ESCRT-II在体外直接相互作用，然而，这种关联在酵母胞质溶胶中未检测到。为了了解这种联系的分子机制，我们表征了ESCRT-I/-II超复合物并确定了其界面的晶体结构。该连接通过液泡蛋白分选（Vps）28 C-末端（ESCRT-I）以纳摩尔亲和力结合至Vps 36-NZF-N锌指结构域（ESCRT-II）而形成。Vps 28-CT四螺旋束上的疏水补丁接触Vps 36-NZF-N的疏水关节。ESCRT-I/-II连接的突变导致酵母中的货物分选缺陷。有趣的是，两个Vps 36 NZF结构域，NZF-N和NZF-C，尽管具有相同的核心折叠，使用不同的表面结合ESCRT-I或泛素化货物。我们还表明，ESCRT-I，Mvb 12（YGR 206 W）的一个新的组件，从事ESCRT-I直接与纳摩尔亲和力，形成1：1：1：1异四聚体。Mvb 12在体外不影响ESCRT-I对ESCRT-II的亲和力。我们的数据表明，在酵母中的ESCRT-I/-II连接的复杂的调节机制。
ESCRT (endosomal sorting complex required for transport) complexes orchestrate efficient sorting of ubiquitinated transmembrane receptors to lysosomes via multivesicular bodies (MVBs). Yeast ESCRT-I and ESCRT-II interact directly in vitro; however, this association is not detected in yeast cytosol. To gain understanding of the molecular mechanisms of this link, we have characterised the ESCRT-I/-II supercomplex and determined the crystal structure of its interface. The link is formed by the vacuolar protein sorting (Vps) 28 C-terminus (ESCRT-I) binding with nanomolar affinity to the Vps36-NZF-N zinc-finger domain (ESCRT-II). A hydrophobic patch on the Vps28-CT four-helix bundle contacts the hydrophobic knuckles of Vps36-NZF-N. Mutation of the ESCRT-I/-II link results in a cargo-sorting defect in yeast. Interestingly, the two Vps36 NZF domains, NZF-N and NZF-C, despite having the same core fold, use distinct surfaces to bind ESCRT-I or ubiquitinated cargo. We also show that a new component of ESCRT-I, Mvb12 (YGR206W), engages ESCRT-I directly with nanomolar affinity to form a 1: 1: 1: 1 heterotetramer. Mvb12 does not affect the affinity of ESCRT-I for ESCRT-II in vitro. Our data suggest a complex regulatory mechanism for the ESCRT-I/-II link in yeast.