Editing Integron (section)

== Integron function ==
Cassette maintenance requires that they be integrated within a replicative element (chromosome, plasmids). The integrase encoded by the integron preferentially catalyses two types of recombination reaction: 1) attC x attC, which results in cassette excision, 2) attI x attC, which allows integration of the cassette at the attI site of the integron. Once inserted, the cassette is maintained during cell division.<ref name=":0">{{Cite journal |last1=Hall |first1=Ruth M. |last2=Collis |first2=Christina M. |date=2006-10-27 |title=Mobile gene cassettes and integrons: capture and spread of genes by site-specific recombination |journal=Molecular Microbiology |volume=15 |issue=4 |pages=593–600 |doi=10.1111/j.1365-2958.1995.tb02368.x |pmid=7783631 |s2cid=16476838 |issn=0950-382X|doi-access=free }}</ref> Successive integrations of gene cassettes result in the formation of a series of cassettes. The cassette integrated last is then the one closest to the Pc promoter at the attI site. The IntI-catalysed mode of recombination involves structured single-stranded DNA and gives the attC site recognition mode unique characteristics.<ref>{{Cite journal |last1=MacDonald |first1=Douglas |last2=Demarre |first2=Gaëlle |last3=Bouvier |first3=Marie |last4=Mazel |first4=Didier |last5=Gopaul |first5=Deshmukh N. |date=2006 |title=Structural basis for broad DNA-specificity in integron recombination |url=http://dx.doi.org/10.1038/nature04643 |journal=Nature |volume=440 |issue=7088 |pages=1157–1162 |doi=10.1038/nature04643 |pmid=16641988 |s2cid=4403903 |issn=0028-0836}}</ref> The integration of gene cassettes within an integron also provides a Pc promoter that allows expression of all cassettes in the array, much like an operon.<ref name=":0" /> The level of gene expression of a cassette is then a function of the number and nature of the cassettes that precede it. In 2009, [[:fr:Didier_Mazel|Didier Mazel]] and his team showed that the expression of the IntI integrase was controlled by the bacterial SOS response, thus coupling this adaptive apparatus to the stress response in bacteria.<ref>{{Cite journal |last1=Guerin |first1=Émilie |last2=Cambray |first2=Guillaume |last3=Sanchez-Alberola |first3=Neus |last4=Campoy |first4=Susana |last5=Erill |first5=Ivan |last6=Da Re |first6=Sandra |last7=Gonzalez-Zorn |first7=Bruno |last8=Barbé |first8=Jordi |last9=Ploy |first9=Marie-Cécile |last10=Mazel |first10=Didier |date=2009-05-22 |title=The SOS Response Controls Integron Recombination |url=https://www.science.org/doi/10.1126/science.1172914 |journal=Science |language=en |volume=324 |issue=5930 |pages=1034 |doi=10.1126/science.1172914 |pmid=19460999 |s2cid=42334786 |issn=0036-8075}}</ref>