LAUSR

Human cells express 3 conformationally similar structural maintenance of chromosome (SMC) complexes called cohesin, condensin, and the SMC5/6 complex [1]. The SMC5/6 complex plays an important role in chromosomal DNA repair, including repair of double-stranded DNA breaks via homologous recombination, and maintenance of replication fork stability. The SMC5/6 complex has also been reported to use ATP hydrolysis to conformationally com-pact bound DNA. In addition to SMC5 and SMC6, the SMC5/6 complex contains 6 other proteins: nonstructural maintenance of chromosomes element 1 through 4 (NSMCE1-4) and SMC5/6 localization factors 1 and 2 (SLF1 and 2). Of note, NSMCE2 has been shown to be a SUMO E3 ligase and SUMOylation of a range of protein substrates, including the SMC5/6 complex itself, is thought to play a key role in the maintenance of DNA integrity by the SMC5/ 6 complex [1].