Binding and activation of DNA topoisomerase III by the Rmi1 subunit.

ABSTRACT: Rmi1 is a conserved oligonucleotide and oligosaccharide binding-fold protein that is associated with RecQ DNA helicase complexes from humans (BLM-TOP3 alpha) and yeast (Sgs1-Top3). Although human RMI1 stimulates the dissolution activity of BLM-TOP3 alpha, its biochemical function is unknown. Here we examined the role of Rmi1 in the yeast complex. Consistent with the similarity of top3Delta and rmi1Delta phenotypes, we find that a stable Top3.Rmi1 complex can be isolated from yeast cells overexpressing these two subunits. Compared with Top3 alone, this complex displays increased superhelical relaxation activity. The isolated Rmi1 subunit also stimulates Top3 activity in reconstitution experiments. In both cases elevated temperatures are required for optimal relaxation unless the substrate c

SUBMITTER: Chen CF 

PROVIDER: S-EPMC2804875 | biostudies-literature | 2007 Sep

REPOSITORIES: biostudies-literature