Prevalence of SOS-mediated control of integron integrase expression as an adaptive trait of chromosomal and mobile integrons
Cambray, Guillaume (Institut Pasteur (París, França))
Sánchez Alberola, Neus (Universitat Autònoma de Barcelona. Departament de Genètica i de Microbiologia)
Campoy Sánchez, Susana (Universitat Autònoma de Barcelona. Departament de Genètica i de Microbiologia)
Guerin, Émilie (Université de Limoges. Faculté de Médecine (Limoges, França))
Da Re, Sandra (Université de Limoges. Faculté de Médecine (Limoges, França))
González Zorn, Bruno (Universidad Complutense de Madrid. Departamento de Sanidad Animal)
Ploy, Marie-Cécile (Université de Limoges. Faculté de Médecine (Limoges, França))
Barbé García, Jordi (University of Maryland. Department of Biological Sciences)
Mazel, Didier (Institut Pasteur (París, França))
Erill, Ivan (University of Maryland. Department of Biological Sciences)

Data:	2011
Resum:	Background: Integrons are found in hundreds of environmental bacterial species, but are mainly known as the agents responsible for the capture and spread of antibiotic-resistance determinants between Gram-negative pathogens. The SOS response is a regulatory network under control of the repressor protein LexA targeted at addressing DNA damage, thus promoting genetic variation in times of stress. We recently reported a direct link between the SOS response and the expression of integron integrases in Vibrio cholerae and a plasmid-borne class 1 mobile integron. SOS regulation enhances cassette swapping and capture in stressful conditions, while freezing the integron in steady environments. We conducted a systematic study of available integron integrase promoter sequences to analyze the extent of this relationship across the Bacteria domain. Results: Our results showed that LexA controls the expression of a large fraction of integron integrases by binding to Escherichia coli-like LexA binding sites. In addition, the results provide experimental validation of LexA control of the integrase gene for another Vibrio chromosomal integron and for a multiresistance plasmid harboring two integrons. There was a significant correlation between lack of LexA control and predicted inactivation of integrase genes, even though experimental evidence also indicates that LexA regulation may be lost to enhance expression of integron cassettes. Conclusions: Ancestral-state reconstruction on an integron integrase phylogeny led us to conclude that the ancestral integron was already regulated by LexA. The data also indicated that SOS regulation has been actively preserved in mobile integrons and large chromosomal integrons, suggesting that unregulated integrase activity is selected against. Nonetheless, additional adaptations have probably arisen to cope with unregulated integrase activity. Identifying them may be fundamental in deciphering the uneven distribution of integrons in the Bacteria domain.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; Versió publicada
Publicat a:	Mobile DNA, Vol. 2, N. 6 (April 2011) , p. 1-15, ISSN 1759-8753

DOI: 10.1186/1759-8753-2-6
PMID: 21529368

15 p, 4.9 MB	Additional file 3 6113x4745, 950.7 KB	Additional file 6 1 p, 345.6 KB	Additional file 7 1 p, 160.8 KB	Additional file 12 2 p, 45.0 KB	Additional file 13 1 p, 51.8 KB

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