Structural adaptation of vertebrate endonuclease G for 5-hydroxymethylcytosine recognition and function.

Autor:	Vander Zanden CM; Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA., Czarny RS; Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA., Ho EN; Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA., Robertson AB; Department of Molecular Microbiology, Oslo University Hospital, Sognsvannsveien 20, NO-0027 Oslo, Norway., Ho PS; Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
Jazyk:	angličtina
Zdroj:	Nucleic acids research [Nucleic Acids Res] 2020 Apr 17; Vol. 48 (7), pp. 3962-3974.
DOI:	10.1093/nar/gkaa117
Abstrakt:	Modified DNA bases functionally distinguish the taxonomic forms of life-5-methylcytosine separates prokaryotes from eukaryotes and 5-hydroxymethylcytosine (5hmC) invertebrates from vertebrates. We demonstrate here that mouse endonuclease G (mEndoG) shows specificity for both 5hmC and Holliday junctions. The enzyme has higher affinity (>50-fold) for junctions over duplex DNAs. A 5hmC-modification shifts the position of the cut site and increases the rate of DNA cleavage in modified versus unmodified junctions. The crystal structure of mEndoG shows that a cysteine (Cys69) is positioned to recognize 5hmC through a thiol-hydroxyl hydrogen bond. Although this Cys is conserved from worms to mammals, a two amino acid deletion in the vertebrate relative to the invertebrate sequence unwinds an α-helix, placing the thiol of Cys69 into the mEndoG active site. Mutations of Cys69 with alanine or serine show 5hmC-specificity that mirrors the hydrogen bonding potential of the side chain (C-H < S-H < O-H). A second orthogonal DNA binding site identified in the mEndoG structure accommodates a second arm of a junction. Thus, the specificity of mEndoG for 5hmC and junctions derives from structural adaptations that distinguish the vertebrate from the invertebrate enzyme, thereby thereby supporting a role for 5hmC in recombination processes. (© The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu