Abstract
DNA repair is fundamental to genome stability and is found in all three domains of life. However many archaeal species, such as Methanopyrus kandleri, contain only a subset of the eukaryotic nucleotide excision repair (NER) homologs, and those present often contain significant differences compared to their eukaryotic homologs. To clarify the role of the NER XPG-like protein Mk0566 from M. kandleri, its biochemical activity and three-dimensional structure were investigated. Both were found to be more similar to human FEN-1 than human XPG, suggesting a biological role in replication and long-patch base excision repair rather than in NER.