Kagey Michael H, Melhuish Tiffany A, Wotton David
Department of Biochemistry and Molecular Genetics, Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA.
Cell. 2003 Apr 4;113(1):127-37. doi: 10.1016/s0092-8674(03)00159-4.
Polycomb group (PcG) proteins form large multimeric complexes (PcG bodies) which are involved in the stable repression of gene expression. The human PcG protein, Pc2, has been shown to recruit the transcriptional corepressor, CtBP, to PcG bodies. We show that CtBP is sumoylated at a single lysine. In vitro, CtBP sumoylation minimally requires the SUMO E1 and E2 (Ubc9) and SUMO-1. However, Pc2 dramatically enhances CtBP sumoylation. In vivo, this is likely due to the ability of Pc2 to recruit both CtBP and Ubc9 to PcG bodies, thereby bringing together substrate and E2, and stimulating the transfer of SUMO to CtBP. These results demonstrate that Pc2 is a SUMO E3, and suggest that PcG bodies may be sumoylation centers.
多梳蛋白家族（PcG）形成大型多聚体复合物（PcG小体），参与基因表达的稳定抑制。已表明人类PcG蛋白Pc2可将转录共抑制因子CtBP招募至PcG小体。我们发现CtBP在单个赖氨酸处发生了SUMO化修饰。在体外，CtBP的SUMO化修饰最少需要SUMO E1、E2（Ubc9）和SUMO-1。然而，Pc2可显著增强CtBP的SUMO化修饰。在体内，这可能是由于Pc2能够将CtBP和Ubc9都招募至PcG小体，从而使底物和E2聚集在一起，并刺激SUMO转移至CtBP。这些结果表明Pc2是一种SUMO E3，并提示PcG小体可能是SUMO化修饰中心。
