Crystal structure and functional analysis of the SurE protein identify a novel phosphatase family

Homologs of the Escherichia coli surE gene are present in many eubacteria a nd archaea. Despite the evolutionary conservation, little information is av ailable on the structure and function of their gene products. We have deter mined the crystal structure of the SurE protein from Thermotoga maritima. T he structure reveals the dimeric arrangement of the subunits and an active site around a bound metal ion. We also demonstrate that the SurE protein ex hibits a divalent metal ion-dependent phosphatase activity that is inhibite d by vanadate or tungstate. In the vanadate- and tungstate-complexed struct ures, the inhibitors bind adjacent to the divalent metal ion. Our structura l and functional analyses identify the SurE proteins as a novel family of m etal ion-dependent phosphatases.