小柯机器人

德国马克斯普朗克生物化学研究所Brenda A. Schulman研究小组实现SCF泛素连接酶复合物的全系统拆卸和组装。2023年4月6日，《细胞》杂志在线发表了这项成果。

研究人员表示，细胞通过重塑其多蛋白复合物的库存对环境线索做出反应。细胞的SCF（SKP1-CUL1-F盒蛋白）泛素连接酶复合物介导了许多蛋白质的降解，需要CAND1在70种不同的F盒蛋白家族中分配限制性的CUL1亚单位。然而，一个单一的因子如何协调地组装许多不同的多蛋白复合物仍然是未知的。

研究人员获得了CAND1结合的SCF复合物在多种状态下的冷冻电镜结构，并将突变对结构、生物化学和细胞检测的影响联系起来。数据表明，CAND1紧紧抓住非活性SCF的闲置催化结构域，在周围滚动，并以异构方式摇动和破坏SCF的稳定性。新SCF的产生是反向进行的，通过SKP1-F盒异生破坏CAND1的稳定性。CAND1-SCF构象组合将CUL1从非活性复合物中回收，助长了SCF部分的混合和匹配，以响应底物的可用性而激活E3。这些数据揭示了一个主要的E3连接酶家族的生物生成，以及全系统多蛋白复合物组装的分子基础。

附：英文原文

Title: Systemwide disassembly and assembly of SCF ubiquitin ligase complexes

Author: Kheewoong Baek, Daniel C. Scott, Lukas T. Henneberg, Moeko T. King, Matthias Mann, Brenda A. Schulman

Issue&Volume: 2023-04-06

Abstract: Cells respond to environmental cues by remodeling their inventories of multiprotein complexes. Cellular repertoires of SCF (SKP1-CUL1-F box protein) ubiquitin ligase complexes, which mediate much protein degradation, require CAND1 to distribute the limiting CUL1 subunit across the family of ～70 different F box proteins. Yet, how a single factor coordinately assembles numerous distinct multiprotein complexes remains unknown. We obtained cryo-EM structures of CAND1-bound SCF complexes in multiple states and correlated mutational effects on structures, biochemistry, and cellular assays. The data suggest that CAND1 clasps idling catalytic domains of an inactive SCF, rolls around, and allosterically rocks and destabilizes the SCF. New SCF production proceeds in reverse, through SKP1-F box allosterically destabilizing CAND1. The CAND1-SCF conformational ensemble recycles CUL1 from inactive complexes, fueling mixing and matching of SCF parts for E3 activation in response to substrate availability. Our data reveal biogenesis of a predominant family of E3 ligases, and the molecular basis for systemwide multiprotein complex assembly.

DOI: 10.1016/j.cell.2023.02.035

Source: https://www.cell.com/cell/fulltext/S0092-8674(23)00213-1