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Crystal structure of the modification-dependent SRA-HNH endonuclease TagI.

Kisiala, Marlena and Copelas, Alyssa and Czapinska, Honorata and Xu, Shuang-yong and Bochtler, Matthias (2018) Crystal structure of the modification-dependent SRA-HNH endonuclease TagI. Nucleic Acids Research, 46 (19). pp. 10489-10503. ISSN 0305-1048

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Official URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC62127...

Abstract

TagI belongs to the recently characterized SRA-HNH family of modification-dependent restriction endonucleases (REases) that also includes ScoA3IV (Sco5333) and TbiR51I (Tbis1). Here, we present a crystal structure of dimeric TagI, which exhibits a DNA binding site formed jointly by the nuclease domains, and separate binding sites for modified DNA bases in the two protomers. The nuclease domains have characteristic features of HNH/ββα-Me REases, and catalyze nicks or double strand breaks, with preference for /RY and RYN/RY sites, respectively. The SRA domains have the canonical fold. Their pockets for the flipped bases are spacious enough to accommodate 5-methylcytosine (5mC) or 5-hydroxymethylcytosine (5hmC), but not glucosyl-5-hydroxymethylcytosine (g5hmC). Such preference is in agreement with the biochemical determination of the TagI modification dependence and the results of phage restriction assays. The ability of TagI to digest plasmids methylated by Dcm (C5mCWGG), M.Fnu4HI (G5mCNGC) or M.HpyCH4IV (A5mCGT) suggests that the SRA domains of the enzyme are tolerant to different sequence contexts of the modified base.

Item Type:Article
Subjects:Q Science > Q Science (General)
Divisions:Department of Bioinformatics
ID Code:1784
Deposited By: Prof. Matthias Bochtler
Deposited On:06 Dec 2019 09:10
Last Modified:06 Dec 2019 09:10

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