Nucleic Acids Research Advance Access originally published online on September 20, 2007
Nucleic Acids Research 2007 35(19):6475-6489; doi:10.1093/nar/gkm709
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Nucleic Acids Research, 2007, Vol. 35, No. 19 6475-6489
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Identification of key structural determinants of the IntI1 integron integrase that influence attC x attI1 recombination efficiency
1Unité Plasticité du Génome Bactérien, CNRS URA 2171 and 2Laboratoire de Biochimie et Biophysique des Macromolécules, CNRS URA 2185, Institut Pasteur, 25 rue du Dr Roux, 75724, Paris 75724, France
*To whom correspondence should be addressed. Tel: +33 1 40 61 32 84; Fax: +33 1 45 68 88 34; Email: mazel{at}pasteur.fr
Received May 25, 2007. Revised August 27, 2007. Accepted August 27, 2007.
The integron platform codes for an integrase (IntI) from the tyrosine family of recombinases that mediates recombination between a proximal double-strand recombination site, attI and a single-strand target recombination site, attC. The attI site is only recognized by its cognate integrase, while the various tested attCs sites are recombined by several different IntI integrases. We have developed a genetic system to enrich and select mutants of IntI1 that provide a higher yield of recombination in order to identify key protein structural elements important for attC x attI1 recombination. We isolated mutants with higher activity on wild type and mutant attC sites. Interestingly, three out of four characterized IntI1 mutants selected on different substrates are mutants of the conserved aspartic acid in position 161. The IntI1 model we made based on the VchIntIA 3D structure suggests that substitution at this position, which plays a central role in multimer assembly, can increase or decrease the stability of the complex and accordingly influence the rate of attI x attC recombination versus attC x attC. These results suggest that there is a balance between the specificity of the protein and the protein/protein interactions in the recombination synapse.
Present address: Gaëlle Demarre, Laboratory of Biochemistry and Molecular Biology, NCI, 37/6044, NIH, Bethesda, MD 20892-4260, USA