Synapsis of Tn3 recombination sites: unpaired sites destabilize synapses by a partner exchange mechanism

Catalysis of site-specific recombination is preceded by the formation of a synapse comprising two DNA sites and multiple subunits of the recombinase, together with other "accessory" proteins in some cases. We investigated the stability of synapses of Tn3 resolvase-bound res recombination s...

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Bibliographic Details
Published in:Journal of molecular biology 2002-05, Vol.319 (2), p.385-393
Main Authors: He, Jiuya, McIlwraith, Michael J, Burke, Mary E, Boocock, Martin R, Stark, W Marshall
Format: Article
Language:English
Subjects:
Base Sequence
Binding Sites
Crossing Over, Genetic - genetics
DNA Transposable Elements - genetics
DNA-Binding Proteins - metabolism
Nucleic Acid Conformation
Plasmids - chemistry
Plasmids - genetics
Plasmids - metabolism
Recombinases
Recombination, Genetic - genetics
Repetitive Sequences, Nucleic Acid - genetics
Substrate Specificity
Templates, Genetic
Transposases - metabolism
Transposon Resolvases
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Summary:Catalysis of site-specific recombination is preceded by the formation of a synapse comprising two DNA sites and multiple subunits of the recombinase, together with other "accessory" proteins in some cases. We investigated the stability of synapses of Tn3 resolvase-bound res recombination sites, in plasmids containing either two or three res sites. Although synapses are long-lived in plasmids with just two res sites, persisting for tens of minutes, a synapse of any two sites is relatively short-lived in plasmids with three res sites. The three alternative pairwise synapses that can be formed in three-res plasmids re-assort rapidly relative to the rate of recombination. We propose a "partner exchange" mechanism for this re-assortment, involving direct attack on a synapse by an unpaired res site. This mechanism reconciles studies on selective synapsis in multi-res substrates, which imply rapid interchange of synaptic pairings, with studies indicating that synapses of two Tn3res sites are stable.
ISSN:0022-2836
DOI:10.1016/S0022-2836(02)00310-8