Structural maintenance of chromosomes (SMC) complexes are ring-shaped protein machines that have ubiquitous, ancient, and important roles in chromosome management (1, 2). In Bacillus subtilis, Escherichia coli, and probably most bacteria, functional SMC complexes ensure proper chromosome segregation (3–8). However, the molecular mechanisms underlying SMC action have remained elusive. On page 524 of this issue, Wang et al. elucidate these mechanisms by showing that SMC complexes direct a rapid and progressive “zip-up” of the B. subtilis chromosome arms (9).
Author: David J. Sherratt