6tuw
human XPG-DNA, Complex 1
Structural highlights
DiseaseERCC5_HUMAN Xeroderma pigmentosum complementation group G;COFS syndrome. The disease is caused by mutations affecting the gene represented in this entry. FunctionERCC5_HUMAN Single-stranded structure-specific DNA endonuclease involved in DNA excision repair. Makes the 3'incision in DNA nucleotide excision repair (NER). Acts as a cofactor for a DNA glycosylase that removes oxidized pyrimidines from DNA. May also be involved in transcription-coupled repair of this kind of damage, in transcription by RNA polymerase II, and perhaps in other processes too. Publication Abstract from PubMedNucleotide excision repair (NER) is an essential pathway to remove bulky lesions affecting one strand of DNA. Defects in components of this repair system are at the ground of genetic diseases such as xeroderma pigmentosum (XP) and Cockayne syndrome (CS). The XP complementation group G (XPG) endonuclease cleaves the damaged DNA strand on the 3' side of the lesion coordinated with DNA re-synthesis. Here, we determined crystal structures of the XPG nuclease domain in the absence and presence of DNA. The overall fold exhibits similarities to other flap endonucleases but XPG harbors a dynamic helical arch that is uniquely oriented and defines a gateway. DNA binding through a helix-2-turn-helix motif, assisted by one flanking alpha-helix on each side, shows high plasticity, which is likely relevant for DNA scanning. A positively-charged canyon defined by the hydrophobic wedge and beta-pin motifs provides an additional DNA-binding surface. Mutational analysis identifies helical arch residues that play critical roles in XPG function. A model for XPG participation in NER is proposed. Our structures and biochemical data represent a valuable tool to understand the atomic ground of XP and CS, and constitute a starting point for potential therapeutic applications. The crystal structure of human XPG, the xeroderma pigmentosum group G endonuclease, provides insight into nucleotide excision DNA repair.,Gonzalez-Corrochano R, Ruiz FM, Taylor NMI, Huecas S, Drakulic S, Spinola-Amilibia M, Fernandez-Tornero C Nucleic Acids Res. 2020 Aug 21. pii: 5895332. doi: 10.1093/nar/gkaa688. PMID:32821917[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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