Structural highlights
FunctionT2D1_STRR6 Recognizes the double-stranded and methylated sequence G(Me)ATC and cleaves after A-2. Publication Abstract from PubMedDNA methylation-dependent restriction enzymes have many applications in genetic engineering and in the analysis of the epigenetic state of eukaryotic genomes. Nevertheless, high-resolution structures have not yet been reported, and therefore mechanisms of DNA methylation-dependent cleavage are not understood. Here, we present a biochemical analysis and high-resolution DNA co-crystal structure of the N(6)-methyladenine (m6A)-dependent restriction enzyme R.DpnI. Our data show that R.DpnI consists of an N-terminal catalytic PD-(D/E)XK domain and a C-terminal winged helix (wH) domain. Surprisingly, both domains bind DNA in a sequence- and methylation-sensitive manner. The crystal contains R.DpnI with fully methylated target DNA bound to the wH domain, but distant from the catalytic domain. Independent readout of DNA sequence and methylation by the two domains might contribute to R.DpnI specificity or could help the monomeric enzyme to cut the second strand after introducing a nick. Crystal structure and mechanism of action of the N6-methyladenine-dependent type IIM restriction endonuclease R.DpnI.,Siwek W, Czapinska H, Bochtler M, Bujnicki J, Skowronek K Nucleic Acids Res. 2012 May 18. PMID:22610857[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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