title: Polymorphism of gene cassette promoter variants of class 1 integron harbored in S. Choleraesuis and Typhimurium isolated from Taiwan.
abstract: Integrons, mobile genetic units, capture and incorporate antibiotic resistance gene cassette by site-specific recombination. Class 1 integrons are widespread and associated with dispersion of antibiotic resistance among Gram-negative bacteria. The expression of gene cassette in Class 1 can vary, based on the Pc promoter but seldom from another promoter hiding downstream of Pc, called P2. To probe distribution and prevalence of gene cassette promoter variants, we analyzed 169S. Choleraesuis and 191S. Typhimurium isolates from humans and animals, finding 95.27% occurrence of integrin among S. Choleraesuis, 83.25% amongS. Typhimurium. PCR-RFLP analysis identified four promoters (PcS+P2, PcWTGN-10+P2, PcH1+P2, and PcWTGN-10+P2-GGG) in said integron-positive isolates; major types inS. Choleraesuis andS. Typhimurium were PcS+P2and PcWTGN-10+P2, respectively. Likewise, β-galactosidase assay rated promoter strength of variants by transcriptional fusion constructs to show extended -10 promoter (TGn/-10 promoter) in Pc and three-nucleotide insertion (GGG) between -35 and -10 region of P2improving promoter strength of gene cassette.
authors.affiliation: Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan.
authors.forename: Chih-Sian
authors.initials: CS
authors.lastname: Tseng
authors.affiliation: Graduate Institute of Microbiology and Public Health, School of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Yen
authors.affiliation: Graduate Institute of Microbiology and Public Health, School of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Chao-Chin
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan.
authors.forename: Yuan-Man
authors.initials: YM
authors.lastname: Hsu
keywords: Class 1 integrons; Gene cassette; Promoter; Salmonella