Smc5/6, an atypical SMC complex with two RING-type subunits

Abstract

Smc5/6, an atypical SMC complex with two RING-type subunits Roger Solé-Soler ; Jordi Torres-Rosell Crossmark: Check for Updates Biochem Soc Trans (2020) 48 (5): 2159-2171. https://doi.org/10.1042/BST20200389 Article history Share Icon Share Cite Icon Cite Get Permissions The Smc5/6 complex plays essential roles in chromosome segregation and repair, by promoting disjunction of sister chromatids. The core of the complex is constituted by an heterodimer of Structural Maintenance of Chromosomes (SMC) proteins that use ATP hydrolysis to dynamically associate with and organize chromosomes. In addition, the Smc5/6 complex contains six non-SMC subunits. Remarkably, and differently to other SMC complexes, the Nse1 and Nse2 subunits contain RING-type domains typically found in E3 ligases, pointing to the capacity to regulate other proteins and complexes through ubiquitin-like modifiers. Nse2 codes for a C-terminal SP-RING domain with SUMO ligase activity, assisting Smc5/6 functions in chromosome segregation through sumoylation of several chromosome-associated proteins. Nse1 codes for a C-terminal NH-RING domain and, although it has been proposed to have ubiquitin ligase activity, no Smc5/6-dependent ubiquitylation target has been described to date. Here, we review the function of the two RING domains of the Smc5/6 complex in the broader context of SMC complexes as global chromosome organizers of the genome.

Work in the J.T.-R. lab is supported by grant and PGC2018-097796-B-I00 from Ministerio de Ciencia, Innovación y Universidades and grant 2017-SGR-569 from AGAUR-Generalitat de Catalunya. R.S.-S. is a recipient of an FPU16/07021 fellowship from Ministerio de Ciencia, Innovación y Universidades. The IRBLLEIDA Institute is part of CERCA Programme/Generalitat de Catalunya