The IDOL-UBE2D complex mediates sterol-dependent degradation of the LDL receptor
The IDOL-UBE2D complex mediates sterol-dependent degradation of the LDL receptor
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DOI：
10.1101/gad.2056211
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发表时间：
2011-06-15
影响因子：
10.5
通讯作者：
Schwabe, John W. R.
中科院分区：
文献类型：
--
作者：
Zhang, Li;Fairall, Louise;Schwabe, John W. R.
我们以前确定E3泛素连接酶IDOL作为LDL受体（LDLR）的固醇依赖性调节剂。然而，IDOL作用的分子途径仍有待确定。在这里，我们报告的鉴定和生化和结构表征的E2-E3泛素连接酶复合物的LDLR降解。我们确定UBE 2D家族（UBE 2D 1 -4）作为IDOL的E2伴侣，在无细胞系统中支持LDLR的autoubiquitination和IDOL依赖性泛素化。IDOL RING结构域-UBE 2D 1复合物的NMR化学位移图和2.1埃晶体结构揭示了二聚体IDOL蛋白和E2酶之间的关键相互作用。对IDOL-UBE 2D 1界面的分析还确定了IDOL对UBE 2Ds的选择性超过其他E2连接酶的立体化学基础。抑制IDOL二聚化或IDOL-UBE 2D相互作用的基于结构的突变阻断IDOL依赖性LDLR泛素化和降解。此外，显性阴性UBE 2D酶的表达抑制IDOL降解细胞中LDLR的能力。这些结果将IDOL-UBE 2D复合物确定为LDLR活性的重要决定因素，并提供了对胆固醇摄取调节的分子机制的深入了解。
We previously identified the E3 ubiquitin ligase IDOL as a sterol-dependent regulator of the LDL receptor (LDLR). The molecular pathway underlying IDOL action, however, remains to be determined. Here we report the identification and biochemical and structural characterization of an E2-E3 ubiquitin ligase complex for LDLR degradation. We identified the UBE2D family (UBE2D1-4) as E2 partners for IDOL that support both autoubiquitination and IDOL-dependent ubiquitination of the LDLR in a cell-free system. NMR chemical shift mapping and a 2.1 angstrom crystal structure of the IDOL RING domain-UBE2D1 complex revealed key interactions between the dimeric IDOL protein and the E2 enzyme. Analysis of the IDOL-UBE2D1 interface also defined the stereochemical basis for the selectivity of IDOL for UBE2Ds over other E2 ligases. Structure-based mutations that inhibit IDOL dimerization or IDOL-UBE2D interaction block IDOL-dependent LDLR ubiquitination and degradation. Furthermore, expression of a dominant-negative UBE2D enzyme inhibits the ability of IDOL to degrade the LDLR in cells. These results identify the IDOL-UBE2D complex as an important determinant of LDLR activity, and provide insight into molecular mechanisms underlying the regulation of cholesterol uptake.