Gradman Richard J.

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Gradman
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Richard J.
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  • Article
    Tn5 synaptic complex formation : role of transposase residue W450
    (American Society for Microbiology, 2007-12-14) Gradman, Richard J. ; Reznikoff, William S.
    A series of Tn5 transposases (Tnp's) with mutations at the conserved amino acid position W450, which was structurally predicted to be important for synapsis, have been generated and characterized. This study demonstrates that W450 is involved in hydrophobic (and possibly aromatic) contacts within the Tnp monomer that negatively regulate synaptic complex formation.
  • Article
    A bifunctional DNA binding region in Tn5 transposase
    (Blackwell, 2007-12-16) Gradman, Richard J. ; Ptacin, Jerod L. ; Bhasin, Archna ; Reznikoff, William S. ; Goryshin, Igor Y.
    Tn5 transposition is a complicated process that requires the formation of a highly ordered protein–DNA structure, a synaptic complex, to catalyse the movement of a sequence of DNA (transposon) into a target DNA. Much is known about the structure of the synaptic complex and the positioning of protein–DNA contacts, although many protein–DNA contacts remain largely unstudied. In particular, there is little evidence for the positioning of donor DNA and target DNA. In this communication, we describe the isolation and analysis of mutant transposases that have, for the first time, provided genetic and biochemical evidence for the stage-specific positioning of both donor and target DNAs within the synaptic complex. Furthermore, we have provided evidence that some of the amino acids that contact donor DNA also contact target DNA, and therefore suggest that these amino acids help define a bifunctional DNA binding region responsible for these two transposase–DNA binding events.