A new SUMO ligase in the DNA damage response

SUMO is a small ubiquitin-like protein that is attached to target proteins, altering their localization and function. The condensin and cohesin-related Smc5/6 complex has been linked to DNA repair and checkpoint responses, but details of its molecular function have remained obscure. Recent reports show one subunit of the complex is a SUMO ligase, providing another link between protein sumoylation and DNA damage responses.