Reverter David, Lima Christopher D
Structural Biology Program, Sloan-Kettering Institute, New York, New York 10021, USA.
Nat Struct Mol Biol. 2006 Dec;13(12):1060-8. doi: 10.1038/nsmb1168. Epub 2006 Nov 12.
SUMO processing and deconjugation are essential proteolytic activities for nuclear metabolism and cell-cycle progression in yeast and higher eukaryotes. To elucidate the mechanisms used during substrate lysine deconjugation, SUMO isoform processing and SUMO isoform interactions, X-ray structures were determined for a catalytically inert SENP2 protease domain in complex with conjugated RanGAP1-SUMO-1 or RanGAP1-SUMO-2, or in complex with SUMO-2 or SUMO-3 precursors. Common features within the active site include a 90 degrees kink proximal to the scissile bond that forces C-terminal amino acid residues or the lysine side chain toward a protease surface that appears optimized for lysine deconjugation. Analysis of this surface reveals SENP2 residues, particularly Met497, that mediate, and in some instances reverse, in vitro substrate specificity. Mutational analysis and biochemistry provide a mechanism for SENP2 substrate preferences that explains why SENP2 catalyzes SUMO deconjugation more efficiently than processing.
SUMO修饰和去共轭作用是酵母和高等真核生物中核代谢及细胞周期进程所必需的蛋白水解活性。为阐明底物赖氨酸去共轭、SUMO亚型修饰及SUMO亚型相互作用过程中所涉及的机制，我们测定了与共轭的RanGAP1-SUMO-1或RanGAP1-SUMO-2形成复合物，或与SUMO-2或SUMO-3前体形成复合物的催化惰性SENP2蛋白酶结构域的X射线结构。活性位点内的共同特征包括在可裂解键近端有一个90度的扭结，该扭结将C末端氨基酸残基或赖氨酸侧链推向一个似乎为赖氨酸去共轭作用而优化的蛋白酶表面。对该表面的分析揭示了介导体外底物特异性的SENP2残基，特别是Met497，在某些情况下还能逆转底物特异性。突变分析和生物化学研究为SENP2底物偏好性提供了一种机制，解释了为什么SENP2催化SUMO去共轭作用比修饰作用更有效。
