The linkage change of a knotting reaction catalysed by Tn3 resolvase.
Tn3 resolvase catalyses recombination between a pair of identical res sites, directly repeated on a supercoiled plasmid molecule. The normal in vitro product is a two-noded catenane. A plasmid with a single base substitution at one res site is converted to non-recombinant knots by resolvase; the first major product is a four-noded knot. The linkage change, delta Lk, on formation of the four-noded knot is +4. The formation of the observed knots from the mutant substrate, and this value of delta Lk were predicted by and in agreement with a "simple rotation" model for catalysis of strand exchange by resolvase. A number of alternative mechanisms for knotting by resolvase are inconsistent with the observed topological changes.
Stark
W M
WM
Department of Genetics, University of Glasgow, Scotland, U.K.
Boocock
M R
MR
D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D009713:Nucleotidyltransferases / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D019895:Transposases
D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D009713:Nucleotidyltransferases; D019895:Transposases