title: Hjc resolvase is a distantly related member of the type II restriction endonuclease family.
abstract: Hjc resolvase is an archaeal enzyme involved in homologous DNA recombination at the Holliday junction intermediate. However, the structure and the catalytic mechanism of the enzyme have not yet been identified. We performed database searching using the amino acid sequence of the enzyme from Pyrococcus furiosus as a query. We detected 59 amino acid sequences showing weak but significant sequence similarity to the Hjc resolvase. The detected sequences included DPN:II, HAE:II and Vsr endonuclease, which belong to the type II restriction endonuclease family. In addition, a highly conserved region was identified from a multiple alignment of the detected sequences, which was similar to an active site of the type II restriction endonucleases. We substituted three conserved amino acid residues in the highly conserved region of the Hjc resolvase with Ala residues. The amino acid replacements inactivated the enzyme. The experimental study, together with the results of the database searching, suggests that the Hjc resolvase is a distantly related member of the type II restriction endonuclease family. In addition, the results of our database searches suggested that the members of the RecB domain superfamily are evolutionarily related to the type II restriction endonuclease family.
authors.affiliation: Department of Bioinformatics and Department of Molecular Biology, Biomolecular Engineering Research Institute, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Daiyasu
authors.forename: K
authors.initials: K
authors.lastname: Komori
authors.forename: S
authors.initials: S
authors.lastname: Sakae
authors.forename: Y
authors.initials: Y
authors.lastname: Ishino
authors.forename: H
authors.initials: H
authors.lastname: Toh
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019843:Archaeal Proteins / Q000235:genetics; D016208:Databases, Factual; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics* / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D045565:Holliday Junction Resolvases; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D020027:Pyrococcus furiosus / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D019843:Archaeal Proteins; D004706:Endodeoxyribonucleases; D045565:Holliday Junction Resolvases; D015252:Deoxyribonucleases, Type II Site-Specific