PMID: 30194838
Authors:
Zagorskaite E, Manakova E, Sasnauskas G
Title:
Recognition of modified cytosine variants by the DNA binding domain of methyl-directed endonuclease McrBC.
Journal:
FEBS Lett. 2018 Sep 8. doi: 10.1002/1873-3468.13244.
Abstract:
Cytosine modifications expand the information content of genomic DNA in both eukaryotes and prokaryotes, providing means for epigenetic regulation and self versus non-self discrimination. For example, the methyl-directed restriction endonuclease McrBC recognizes and cuts invading bacteriophage DNA containing 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and N4-methylcytosine (4mC), leaving unmodified host DNA intact. Here, we present co-crystal structures of McrB-N bound to DNA oligoduplexes containing 5hmC, 5-formylcytosine (5fC) and 4mC, and characterise the relative affinity of McrB-N to various cytosine variants. We find that McrB-N flips out modified bases into a protein pocket and binds cytosine derivatives in the order of descending affinity: 4mC>5mC>5hmC>>5fC. We also show that pocket mutations alter the relative preference of McrB-N to 5mC, 5hmC and 4mC. This article is protected by copyright. All rights reserved.