The nuclease a-inhibitor complex is characterized by a novel metal ion bridge.

ABSTRACT: Nonspecific, extracellular nucleases have received enhanced attention recently as a consequence of the critical role that these enzymes can play in infectivity by overcoming the host neutrophil defense system. The activity of the cyanobacterial nuclease NucA, a member of the betabetaalpha Me superfamily, is controlled by the specific nuclease inhibitor, NuiA. Here we report the 2.3-A resolution crystal structure of the NucA-NuiA complex, showing that NucA inhibition by NuiA involves an unusual divalent metal ion bridge that connects the nuclease with its inhibitor. The C-terminal Thr-135(NuiA) hydroxyl oxygen is directly coordinated with the catalytic Mg(2+) of the nuclease active site, and Glu-24(NuiA) also extends into the active site, mimicking the charge of a scissile phosphate. NuiA r

SUBMITTER: Ghosh M 

PROVIDER: S-EPMC2072808 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature