Biochemical and mutational analysis of EcoRII functional domains reveals evolutionary links between restriction enzymes

The archetypal Type BE restriction endonuclease EcoRII is a dimer that has a modular structure. DNA binding studies indicate that the isolated C-terminal domain dimer has an interface that binds a single cognate DNA molecule whereas the N-terminal domain is a monomer that also binds a single copy of cognate DNA. Hence, the full-length EcoRII contains three putative DNA binding interfaces: one at the C-terminal domain dimer and two at each of the N-terminal domains. Mutational analysis indicates that the C-terminal domain shares conserved active site architecture and DNA binding elements with the tetrameric restriction enzyme NgoMIV. Data provided here suggest possible evolutionary relationships between different subfamilies of restriction enzymes. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.