More complexity to the Bloom's syndrome complex

Bloom's syndrome is caused by mutations in the BLM gene. The BLM gene product, BLM helicase, forms a complex with two other proteins, DNA topoisomerase III alpha and RMI1. In this issue of Genes & Development, Wang and colleagues (pp. 2843 - 2855) and Meetei and colleagues (pp. 2856 - 2868) report the discovery of a fourth component of this complex called RMI2. RMI2 may be a representative of a new family of OB-fold-containing proteins that are important for complex stabilization and checkpoint response.