title: 3D reconstruction of the Mu transposase and the Type 1 transpososome: a structural framework for Mu DNA transposition.
abstract: Mu DNA transposition proceeds through a series of higher-order nucleoprotein complexes called transpososomes. The structural core of the transpososome is a tetramer of the transposase, Mu A, bound to the two transposon ends. High-resolution structural analysis of the intact transposase and the transpososome has not been successful to date. Here we report the structure of Mu A at 16-angstroms and the Type 1 transpososome at 34-angstroms resolution, by 3D reconstruction of images obtained by scanning transmission electron microscopy (STEM) at cryo-temperatures. Electron spectroscopic imaging (ESI) of the DNA-phosphorus was performed in conjunction with the structural investigation to derive the path of the DNA through the transpososome and to define the DNA-binding surface in the transposase. Our model of the transpososome fits well with the accumulated biochemical literature for this intricate transposition system, and lays a structural foundation for biochemical function, including catalysis in trans and the complex circuit of macromolecular interactions underlying Mu DNA transposition.
authors.affiliation: Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Joy F
authors.initials: JF
authors.lastname: Yuan
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Beniac
authors.forename: George
authors.initials: G
authors.lastname: Chaconas
authors.forename: F Peter
authors.initials: FP
authors.lastname: Ottensmeyer
mesh_terms: D010583:Bacteriophage mu / Q000737:chemistry* / Q000201:enzymology; D004251:DNA Transposable Elements; D017348:Microscopy, Electron, Scanning Transmission; D046032:Microscopy, Energy-Filtering Transmission Electron; D017434:Protein Structure, Tertiary; D019895:Transposases / Q000737:chemistry*
chemical_list: D004251:DNA Transposable Elements; C114697:mu transposase; D019895:Transposases