title: Structural basis for catalytic activation of a serine recombinase.
abstract: Sin resolvase is a site-specific serine recombinase that is normally controlled by a complex regulatory mechanism. A single mutation, Q115R, allows the enzyme to bypass the entire regulatory apparatus, such that no accessory proteins or DNA sites are required. Here, we present a 1.86 Å crystal structure of the Sin Q115R catalytic domain, in a tetrameric arrangement stabilized by an interaction between Arg115 residues on neighboring subunits. The subunits have undergone significant conformational changes from the inactive dimeric state previously reported. The structure provides a new high-resolution view of a serine recombinase active site that is apparently fully assembled, suggesting roles for the conserved active site residues. The structure also suggests how the dimer-tetramer transition is coupled to assembly of the active site. The tetramer is captured in a different rotational substate than that seen in previous hyperactive serine recombinase structures, and unbroken crossover site DNA can be readily modeled into its active sites.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: Ross A
authors.initials: RA
authors.lastname: Keenholtz
authors.forename: Sally-J
authors.initials: SJ
authors.lastname: Rowland
authors.forename: Martin R
authors.initials: MR
authors.lastname: Boocock
authors.forename: W Marshall
authors.initials: WM
authors.lastname: Stark
authors.forename: Phoebe A
authors.initials: PA
authors.lastname: Rice
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004254:DNA Nucleotidyltransferases / Q000737:chemistry* / Q000235:genetics; D004789:Enzyme Activation; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D020125:Mutation, Missense; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D013211:Staphylococcus aureus / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D009841:Oligonucleotides; D004254:DNA Nucleotidyltransferases; C086893:sin protein, Staphylococcus aureus