Structural basis for the recognition of N-end rule substrates by the UBR box of ubiquitin ligases
Structural basis for the recognition of N-end rule substrates by the UBR box of ubiquitin ligases
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DOI：
10.1038/nsmb.1907
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发表时间：
2010-10-01
影响因子：
16.8
通讯作者：
Song, Hyun Kyu
中科院分区：
文献类型：
--
作者：
Choi, Woo Suk;Jeong, Byung-Cheon;Song, Hyun Kyu
N-末端规则途径是一种受调节的蛋白水解系统，其靶向含有不稳定的N-末端残基（N-降解决定子）的蛋白，用于真核生物中的泛素化和蛋白酶体降解。1型底物的N-降解决定子含有被E3泛素连接酶UBR 1的UBR盒结构域识别的N-末端碱性残基。我们描述了酿酒酵母UBR 1的UBR盒的结构，以及与N-降解决定子肽的复合物，包括粘附素亚基Scc 1的结构，该粘附素亚基Scc 1在中期-后期过渡期被切割并靶向降解。结构揭示了一个以前未知的蛋白质折叠，是稳定的一个新的双核锌中心。N-降解决定子的N-末端精氨酸、赖氨酸或组氨酸侧链在多特异性结合口袋中配位。出乎意料的是，结构与我们的体外生物化学和体内脉冲追踪分析一起揭示了N-降解决定子2位残基对结合特异性的先前未知的调节。
The N-end rule pathway is a regulated proteolytic system that targets proteins containing destabilizing N-terminal residues (N-degrons) for ubiquitination and proteasomal degradation in eukaryotes. The N-degrons of type 1 substrates contain an N-terminal basic residue that is recognized by the UBR box domain of the E3 ubiquitin ligase UBR1. We describe structures of the UBR box of Saccharomyces cerevisiae UBR1 alone and in complex with N-degron peptides, including that of the cohesin subunit Scc1, which is cleaved and targeted for degradation at the metaphase-anaphase transition. The structures reveal a previously unknown protein fold that is stabilized by a novel binuclear zinc center. N-terminal arginine, lysine or histidine side chains of the N-degron are coordinated in a multispecific binding pocket. Unexpectedly, the structures together with our in vitro biochemical and in vivo pulse-chase analyses reveal a previously unknown modulation of binding specificity by the residue at position 2 of the N-degron.