| First Author | Vander Zanden CM | Year | 2020 |
| Journal | Nucleic Acids Res | Volume | 48 |
| Issue | 7 | Pages | 3962-3974 |
| PubMed ID | 32095813 | Mgi Jnum | J:314088 |
| Mgi Id | MGI:6810801 | Doi | 10.1093/nar/gkaa117 |
| Citation | Vander Zanden CM, et al. (2020) Structural adaptation of vertebrate endonuclease G for 5-hydroxymethylcytosine recognition and function. Nucleic Acids Res 48(7):3962-3974 |
| abstractText | 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 alpha-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. |
