Mrr superfamily of homologous genes in microbial genomes restricts modified DNA in vivo. However, their biochemical properties in vitro have remained obscure. Here, we report the experimental characterization of MspJI, a remote homolog of Escherichia coli’s Mrr and show it is a DNA modification-dependent restriction endonuclease. Our results suggest MspJI recognizes mCNNR (R = G/A) sites and cleaves DNA at fixed distances (N12/N16) away from the modified cytosine at the 3′ side (or N9/N13 from R). Besides 5-methylcytosine, MspJI also recognizes 5-hydroxymethylcytosine but is blocked by 5-glucosylhydroxymethylcytosine. Several other close homologs of MspJI show similar modification-dependent endonuclease activity and display substrate preferences different from MspJI. A unique feature of these modification-dependent enzymes is that they are able to extract small DNA fragments containing modified sites on genomic DNA, for example ∼32 bp around symmetrically methylated CG sites and ∼31 bp around methylated CNG sites. The digested fragments can be directly selected for high-throughput sequencing to map the location of the modification on the genomic DNA. The MspJI enzyme family, with their different recognition specificities and cleavage properties, provides a basis on which many future methods can build to decode the epigenomes of different organisms.
A unique family of Mrr-like modification-dependent restriction endonucleases
Yu Zheng,Devora Cohen-Karni,Derrick Xu,H. Chin,G. Wilson,S. Pradhan,R. Roberts
Published 2010 in Nucleic Acids Research
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- Publication year
2010
- Venue
Nucleic Acids Research
- Publication date
2010-05-05
- Fields of study
Biology, Medicine
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Semantic Scholar, PubMed
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