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Prevalence of SOS-mediated control of integron integrase expression as an adaptive trait of chromosomal and mobile integrons Cambray, Guillaume Sanchez Alberola, Neus Campoy, Susana Guerin, Emilie Da Re, Sandra González Zorn, Bruno Ploy, Marie-Cécile Barbé, Jordi Mazel, Didier Erill, Ivan Veterinaria 3109 Ciencias Veterinarias 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. Ministerio de Ciencia e Innovación (MICINN) Generalitat de Catalunya Ministère de la Recherche et de l’Enseignement supérieur Conseil Régional du Limousin Fondation pour la Recherche Médicale (FRM) Institut National de la Santé et de la Recherche Médicale (Inserm) Centre National de la Recherche Scientifique (CNRS URA 2171) Unión Europea Centro de Vigilancia Sanitaria Veterinaria (VISAVET) TRUE pub 2023-06-20T04:20:17Z 2023-06-20T04:20:17Z 2011-04-30 journal article https://hdl.handle.net/20.500.14352/45182 1759-8753 10.1186/1759-8753-2-6 eng BFU2008-01078/BMC 2009SGR-1106 (NoE EuroPathoGenomics, LSHB-CT-2005-512061) Atribución 3.0 España https://creativecommons.org/licenses/by/3.0/es/ open access application/pdf BioMedCentral