title: Recognition and processing of the origin of transfer DNA by conjugative relaxase TrwC.
abstract: Relaxases are DNA strand transferases that catalyze the initial and final stages of DNA processing during conjugative cell-to-cell DNA transfer. Upon binding to the origin of transfer (oriT) DNA, relaxase TrwC melts the double helix. The three-dimensional structure of the relaxase domain of TrwC in complex with its cognate DNA at oriT shows a fold built on a two-layer alpha/beta sandwich, with a deep narrow cleft that houses the active site. The DNA includes one arm of an extruded cruciform, an essential feature for specific recognition. This arm is firmly embraced by the protein through a beta-ribbon positioned in the DNA major groove and a loop occupying the minor groove. It is followed by a single-stranded DNA segment that enters the active site, after a sharp U-turn forming a hydrophobic cage that traps the N-terminal methionine. Structural analysis combined with site-directed mutagenesis defines the architecture of the active site.
authors: Institut de Biologia Molecular de Barcelona, CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain.
authors: Alicia
authors: A
authors: Guasch
authors: María
authors: M
authors: Lucas
authors: Gabriel
authors: G
authors: Moncalián
authors: Matilde
authors: M
authors: Cabezas
authors: Rosa
authors: R
authors: Pérez-Luque
authors: F Xavier
authors: FX
authors: Gomis-Rüth
authors: Fernando
authors: F
authors: de la Cruz
authors: Miquel
authors: M
authors: Coll
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004254:DNA Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011487:Protein Conformation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D004247:DNA; D004254:DNA Nucleotidyltransferases; C110340:DNA relaxase; D004706:Endodeoxyribonucleases