EcoRV endonuclease recognition site

Although they often share little sequence similarity and have quite different specificiities, many restriction enzymes have similar three-dimensional structures as well as mechanisms of action. This is true for the EcoRI, BamHl (Fig. 26-5),83/90 EcoRV,91/91a and C/r 101 enzymes,84 and presumably many others. The specifically shaped and tightly packed active sites in the enzyme-substrate complexes ensure specificity. For example, the EcoRV endonuclease cleaves DNA at its recognition site at least a million times faster than at any other DNA sequence.91 As mentioned in Chapter 12, restriction endonucleases require a metal ion, preferably Mg2+, and probably act via a hydroxyl ion generated from Mg2+-OH2 at the active site. Three conserved active site residues, Asp 91, Glu 111, and Lys 113, in the EcoRI endonuclease interact with the DNA near the cleavage site. Lys 113 is replaced by Glu 113 in the BamHl enzyme.83 90... 

Fig. 13.2. Cleavage of the specific recognition sites by the type II restriction endonucleases EcoRV, EcoRI and Bg/I The cleavage reaction, which requires Mg2+ as cofactor, leads to 5 phosphate and 3 OH ends. While EcoRV cleavage results in blunt ends, EcoRI and Bg/I generate sticky ends with a 5 and 3 overhang, respectively.

The recognition sequence for EcoRV endonuclease (left) and the sites of methylation (right) in DNA protected from the catalytic action of the enzyme. 

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