Allosteric mechanism for site-specific ubiquitination of FANCD2
Allosteric mechanism for site-specific ubiquitination of FANCD2
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DOI：
10.1038/s41589-019-0426-z
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发表时间：
2019-12-23
影响因子：
14.8
通讯作者：
Walden, Helen
中科院分区：
文献类型：
--
作者：
Chaugule, Viduth K.;Arkinson, Connor;Walden, Helen
DNA损伤修复是由专门的分子信号协调的蛋白质实现的。用于修复DNA链间交联的范可尼贫血（FA）途径中的一个这样的信号是FANCD 2和FANCI的位点特异性单泛素化。该信号由多蛋白FA核心复合物（FA-CC）介导，然而，精确泛素化的机制仍然难以捉摸。我们发现，FANCL，环轴承模块FA-CC，变构激活其同源泛素结合酶E2 UBE 2 T驱动位点特异性FANCD 2泛素化。与典型的RING E3连接酶不同，FANCL通过重新连接UBE 2 T的残基内网络来影响活性位点来催化泛素化。因此，UBE 2 T特有的碱性三联体在FANCD 2上的靶赖氨酸附近接合结构化的酸性补丁。FANCL诱导的E2活性位点和底物表面之间的这种三维互补性是FA途径中位点特异性单泛素化的核心。此外，UBE 2 T的变构网络可以在不影响位点特异性的情况下增强FANCL催化的FANCD 2-FANCI二单泛素化，UBE 2 T通过变构激活机制介导Fanconi贫血复合物的位点特异性泛素化。与FANCL的相互作用诱导了UBE 2 T的级联构象变化，并导致底物结合位点的暴露。
DNA-damage repair is implemented by proteins that are coordinated by specialized molecular signals. One such signal in the Fanconi anemia (FA) pathway for the repair of DNA interstrand crosslinks is the site-specific monoubiquitination of FANCD2 and FANCI. The signal is mediated by a multiprotein FA core complex (FA-CC) however, the mechanics for precise ubiquitination remain elusive. We show that FANCL, the RING-bearing module in FA-CC, allosterically activates its cognate ubiqutin-conjugating enzyme E2 UBE2T to drive site-specific FANCD2 ubiquitination. Unlike typical RING E3 ligases, FANCL catalyzes ubiquitination by rewiring the intraresidue network of UBE2T to influence the active site. Consequently, a basic triad unique to UBE2T engages a structured acidic patch near the target lysine on FANCD2. This three-dimensional complementarity, between the E2 active site and substrate surface, induced by FANCL is central to site-specific monoubiquitination in the FA pathway. Furthermore, the allosteric network of UBE2T can be engineered to enhance FANCL-catalyzed FANCD2-FANCI di-monoubiquitination without compromising site specificity.UBE2T adopts an allosteric activation mechanism to mediate site-specific ubiquitination of Fanconi anemia complex. Interaction with FANCL induces a cascade of conformational changes of UBE2T and leads to exposure of substrate-binding sites.