Synapsis and catalysis by activated Tn3 resolvase mutants

Olorunniji, F.J., He, J., Wenwieser, S.V.C.T., Boocock, M.R. and Stark, W.M. (2008) Synapsis and catalysis by activated Tn3 resolvase mutants. Nucleic Acids Research, 36(22), pp. 7181-7191. (doi: 10.1093/nar/gkn885)

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The serine recombinase Tn3 resolvase catalyses recombination between two 114 bp res sites, each of which contains binding sites for three resolvase dimers. We have analysed the in vitro properties of resolvase variants with ‘activating’ mutations, which can catalyse recombination at binding site I of res when the rest of res is absent. Site I × site I recombination promoted by these variants can be as fast as res × res recombination promoted by wild-type resolvase. Activated variants have reduced topological selectivity and no longer require the 2–3′ interface between subunits that is essential for wild-type resolvase-mediated recombination. They also promote formation of a stable synapse comprising a resolvase tetramer and two copies of site I. Cleavage of the DNA strands by the activated mutants is slow relative to the rate of synapsis. Stable resolvase tetramers were not detected in the absence of DNA or bound to a single site I. Our results lead us to conclude that the synapse is assembled by sequential binding of resolvase monomers to site I followed by interaction of two site I-dimer complexes. We discuss the implications of our results for the mechanisms of synapsis and regulation in recombination by wild-type resolvase.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Boocock, Dr Martin and Stark, Professor Marshall and Olorunniji, Dr Femi
Authors: Olorunniji, F.J., He, J., Wenwieser, S.V.C.T., Boocock, M.R., and Stark, W.M.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Nucleic Acids Research
Publisher:Oxford University Press
ISSN (Online):1362-4962
Published Online:10 November 2008

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