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Self‐control in DNA site‐specific recombination mediated by the tyrosine recombinase TnpI
Author(s) -
Vanhooff Virginie,
Galloy Christine,
Agaisse Hervé,
Lereclus Didier,
Révet Bernard,
Hallet Bernard
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05127.x
Subject(s) - biology , recombinase , recombination , dna , flp frt recombination , site specific recombination , genetics , computational biology , genetic recombination , gene
Summary Tn 4430 is a distinctive transposon of the Tn 3 family that encodes a tyrosine recombinase (TnpI) to resolve replicative transposition intermediates. The internal resolution site of Tn 4430 (IRS, 116 bp) contains two inverted repeats (IR1 and IR2) at the crossover core site, and two additional TnpI binding motifs (DR1 and DR2) adjacent to the core. Deletion analysis demonstrated that DR1 and DR2 are not required for recombination in vivo and in vitro . Their function is to provide resolution selectivity to the reaction by stimulating recombination between directly oriented sites on a same DNA molecule. In the absence of DR1 and/or DR2, TnpI‐mediated recombination of supercoiled DNA substrates gives a mixture of topologically variable products, while deletion between two wild‐type IRSs exclusively produces two‐noded catenanes. This demonstrates that TnpI binding to the accessory motifs DR1 and DR2 contributes to the formation of a specific synaptic complex in which catalytically inert recombinase subunits act as architectural elements to control recombination sites pairing and strand exchange. A model for the organization of TnpI/IRS recombination complex is presented.