Crystal structure of the beta beta alpha-Me type II restriction endonuclease Hpy99I with target DNA.

ABSTRACT: The beta beta alpha-Me restriction endonuclease (REase) Hpy99I recognizes the CGWCG target sequence and cleaves it with unusual stagger (five nucleotide 5'-recessed ends). Here we present the crystal structure of the specific complex of the dimeric enzyme with DNA. The Hpy99I protomer consists of an antiparallel beta-barrel and two beta 4 alpha 2 repeats. Each repeat coordinates a structural zinc ion with four cysteine thiolates in two CXXC motifs. The beta beta alpha-Me region of the second beta 4 alpha 2 repeat holds the catalytic metal ion (or its sodium surrogate) via Asp148 and Asn165 and activates a water molecule with the general base His149. In the specific complex, Hpy99I forms a ring-like structure around the DNA that contacts DNA bases on the major and minor groove sides via the

SUBMITTER: Sokolowska M 

PROVIDER: S-EPMC2699513 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature