title: Bacterial-type DNA holliday junction resolvases in eukaryotic viruses.
abstract: Homologous DNA recombination promotes genetic diversity and the maintenance of genome integrity, yet no enzymes with specificity for the Holliday junction (HJ)-a key DNA recombination intermediate-have been purified and characterized from metazoa or their viruses. Here we identify critical structural elements of RuvC, a bacterial HJ resolvase, in uncharacterized open reading frames from poxviruses and an iridovirus. The putative vaccinia virus resolvase was expressed as a recombinant protein, affinity purified, and shown to specifically bind and cleave a synthetic HJ to yield nicked duplex molecules. Mutation of either of two conserved acidic amino acids abrogated the catalytic activity of the A22R protein without affecting HJ binding. The presence of bacterial-type enzymes in metazoan viruses raises evolutionary questions.
authors.affiliation: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, and National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Garcia
authors.forename: L
authors.initials: L
authors.lastname: Aravind
authors.forename: E V
authors.initials: EV
authors.lastname: Koonin
authors.forename: B
authors.initials: B
authors.lastname: Moss
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002846:Chromatography, Affinity; D017931:DNA Primers; D004269:DNA, Bacterial / Q000737:chemistry*; D006868:Hydrolysis; D017994:Iridovirus / Q000201:enzymology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011212:Poxviridae / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D045522:Recombinases; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D019895:Transposases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D011994:Recombinant Proteins; D045522:Recombinases; D019895:Transposases