Viadiu H, Aggarwal A K
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA.
Nat Struct Biol. 1998 Oct;5(10):910-6. doi: 10.1038/2352.
Type II restriction enzymes are characterized by their remarkable specificity and simplicity. They require only divalent metals (such as Mg2+ or Mn2+) as cofactors to catalyze the hydrolysis of DNA. However, most of the structural work on endonucleases has been performed in the absence of metals, leaving unanswered questions about their mechanisms of DNA cleavage. Here we report structures of the endonuclease BamHI-DNA complex, determined in the presence of Mn2+ and Ca2+, that describe the enzyme at different stages of catalysis. Overall, the results support a two-metal mechanism of DNA cleavage for BamHI which is distinct from that of EcoRV.
II型限制酶的特点是具有显著的特异性和简单性。它们只需要二价金属（如Mg2+或Mn2+）作为辅助因子来催化DNA的水解。然而，大多数关于核酸内切酶的结构研究都是在没有金属的情况下进行的，这使得关于它们切割DNA机制的问题仍未得到解答。在这里，我们报告了在Mn2+和Ca2+存在下测定的核酸内切酶BamHI-DNA复合物的结构，这些结构描述了该酶在催化的不同阶段的情况。总体而言，结果支持BamHI切割DNA的双金属机制，这与EcoRV的机制不同。
