title: Implications of structures of synaptic tetramers of gamma delta resolvase for the mechanism of recombination.
abstract: The structures of two mutants of the site-specific recombinase, gammadelta resolvase, that form activated tetramers have been determined. One, at 3.5-A resolution, forms a synaptic intermediate of resolvase that is covalently linked to two cleaved DNAs, whereas the other is of an unliganded structure determined at 2.1-A resolution. Comparisons of the four known tetrameric resolvase structures show that the subunits interact through the formation of a common core of four helices. The N-terminal halves of these helices superimpose well on each other, whereas the orientations of their C termini are more variable. The catalytic domains of resolvase in the unliganded structure are arranged asymmetrically, demonstrating that their positions can move substantially while preserving the four-helix core that forms the tetramer. These results suggest that the precleavage synaptic tetramer of gammadelta resolvase, whose structure is not known, may be formed by a similar four-helix core, but differ in the relative orientations of its catalytic and DNA-binding domains.
authors.affiliation: Departments of Molecular Biophysics, and Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA.
authors.forename: Satwik
authors.initials: S
authors.lastname: Kamtekar
authors.forename: Roger S
authors.initials: RS
authors.lastname: Ho
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Cocco
authors.forename: Weikai
authors.initials: W
authors.lastname: Li
authors.forename: Sandra V C T
authors.initials: SV
authors.lastname: Wenwieser
authors.forename: Martin R
authors.initials: MR
authors.lastname: Boocock
authors.forename: Nigel D F
authors.initials: ND
authors.lastname: Grindley
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Steitz
mesh_terms: D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D004254:DNA Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D006801:Humans; D050506:Mutant Chimeric Proteins / Q000737:chemistry / Q000502:physiology; D011995:Recombination, Genetic / Q000502:physiology*; D045564:Transposon Resolvases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
chemical_list: D050506:Mutant Chimeric Proteins; D004247:DNA; D004254:DNA Nucleotidyltransferases; C059997:Hin recombinase; D045564:Transposon Resolvases; C473494:gamma delta resolvase