title: ORF157 from the archaeal virus Acidianus filamentous virus 1 defines a new class of nuclease.
abstract: Acidianus filamentous virus 1 (AFV1) (Lipothrixviridae) is an enveloped filamentous virus that was characterized from a crenarchaeal host. It infects Acidianus species that thrive in the acidic hot springs (>85 degrees C and pH <3) of Yellowstone National Park, WY. The AFV1 20.8-kb, linear, double-stranded DNA genome encodes 40 putative open reading frames whose sequences generally show little similarity to other genes in the sequence databases. Because three-dimensional structures are more conserved than sequences and hence are more effective at revealing function, we set out to determine protein structures from putative AFV1 open reading frames (ORF). The crystal structure of ORF157 reveals an alpha+beta protein with a novel fold that remotely resembles the nucleotidyltransferase topology. In vitro, AFV1-157 displays a nuclease activity on linear double-stranded DNA. Alanine substitution mutations demonstrated that E86 is essential to catalysis. AFV1-157 represents a novel class of nuclease, but its exact role in vivo remains to be determined.
authors.affiliation: Architecture et Fonction des Macromolcéules Biologiques, CNRS and Universités d'Aix-Marseille I & II, Marseille, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Goulet
authors.forename: Mery
authors.initials: M
authors.lastname: Pina
authors.forename: Peter
authors.initials: P
authors.lastname: Redder
authors.forename: David
authors.initials: D
authors.lastname: Prangishvili
authors.forename: Laura
authors.initials: L
authors.lastname: Vera
authors.forename: Julie
authors.initials: J
authors.lastname: Lichière
authors.forename: Nicolas
authors.initials: N
authors.lastname: Leulliot
authors.forename: Herman
authors.initials: H
authors.lastname: van Tilbeurgh
authors.forename: Miguel
authors.initials: M
authors.lastname: Ortiz-Lombardia
authors.forename: Valérie
authors.initials: V
authors.lastname: Campanacci
authors.forename: Christian
authors.initials: C
authors.lastname: Cambillau
mesh_terms: D041541:Acidianus / Q000821:virology*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D004252:DNA Mutational Analysis; D003851:Deoxyribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D045482:Hot Springs / Q000382:microbiology; D023643:Lipothrixviridae / Q000737:chemistry* / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D014764:Viral Proteins; D004247:DNA; D003851:Deoxyribonucleases