title: The structure of Escherichia coli RusA endonuclease reveals a new Holliday junction DNA binding fold.
abstract: Holliday junction resolution performed by a variety of structure-specific endonucleases is a key step in DNA recombination and repair. It is believed that all resolvases carry out their reaction chemistries in a similar fashion, utilizing a divalent cation to facilitate the hydrolysis of the phosphodiester backbone of the DNA, but their architecture varies. To date, with the exception of bacteriophage T4 endonuclease VII, each of the known resolvase enzyme structures has been categorized into one of two families: the integrases and the nucleases. We have now determined the structure of the Escherichia coli RusA Holliday junction resolvase, which reveals a fourth structural class for these enzymes. The structure suggests that dimer formation is essential for Mg(2+) cation binding and hence catalysis and that like the other resolvases, RusA distorts its Holliday junction target upon binding. Key residues identified by mutagenesis experiments are well positioned to interact with the DNA.
authors.affiliation: Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom. j.rafferty@sheffield.ac.uk
authors.forename: John B
authors.initials: JB
authors.lastname: Rafferty
authors.forename: Edward L
authors.initials: EL
authors.lastname: Bolt
authors.forename: Tatyana A
authors.initials: TA
authors.lastname: Muranova
authors.forename: Svetlana E
authors.initials: SE
authors.lastname: Sedelnikova
authors.forename: Philip
authors.initials: P
authors.lastname: Leonard
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pasquo
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Baker
authors.forename: David W
authors.initials: DW
authors.lastname: Rice
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Sharples
authors.forename: Robert G
authors.initials: RG
authors.lastname: Lloyd
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002412:Cations; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004260:DNA Repair; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry*; D014644:Genetic Variation; D045565:Holliday Junction Resolvases / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D002412:Cations; D029968:Escherichia coli Proteins; D004247:DNA; D045565:Holliday Junction Resolvases; C112057:RusA protein, E coli; D008274:Magnesium