title: Translation regulation of integrons gene cassette expression by the attC sites.
abstract: Integron are genetic elements able to carry, capture and shuffle the genes embedded in gene cassettes. The attC recombination sites adopt a stable secondary structure when single-stranded that is necessary for their recombination. In this study, we evaluated the impact of the structure of the attC site on expression of the 3' gene in class 1 integrons. This was analysed by substituting the attC of the bla(IMP-8) gene cassette with various mutated attC sites spanning a wide range of sizes and secondary structures, and measuring the integron-dependent translation of the 3'aac(6')-Ib7 gene. In the resulting constructs, the 5'-attC site differentially affected the expression of the aac(6')-Ib7 gene. Contrary to what was expected from their proposed role as Rho-independent transcription terminators, the transcription of the aac(6')-Ib7 gene was not affected by the various attC sites. Mutations of natural sites revealed that destabilization of the potential stem-loop structure of the attC site in the transcript could enhance the expression of the 3' gene. In particular, the presence of a translated open reading frame was shown to increase translation of the 3' gene. These findings might be explained by the capacity of the stem-loop structures to impede ribosome progression.
authors.affiliation: Assistance Publique Hôpitaux de Paris, Hôpital Lariboisière, Service de Bactériologie-Virologie, Université Paris VII, 2 rue Ambroise Paré, 75010 Paris, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Jacquier
authors.forename: Caroline
authors.initials: C
authors.lastname: Zaoui
authors.forename: Marie-Jose
authors.initials: MJ
authors.lastname: Sanson-le Pors
authors.forename: Didier
authors.initials: D
authors.lastname: Mazel
authors.forename: Béatrice
authors.initials: B
authors.lastname: Berçot
mesh_terms: D001287:Attachment Sites, Microbiological; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005822:Genetic Vectors; D032023:Integrons; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger