The IS<i>1</i>elements in<i>Shigella boydii</i>: horizontal transfer, vertical inactivation and target duplication

Hsu, Wen-Bin; Chen, Jiann-Hwa

doi:10.1016/s0378-1097(03)00319-7

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…Notably, GI-DT12 is flanked by typical IS1 elements, which are predominantly found in Escherichia coli (35) and Shigella spp. (23). Although IS1 derivatives are present in plasmid pU302L of S. enterica serovar Typhimurium G8430 (10) and plasmid pAKU_1 of S. enterica serovar Paratyphi A AKU_12601 (22), our study represents the first finding of IS1 derivatives integrated in the chromosome of S. enterica serovar Typhimurium.…”

Section: Discussionmentioning

confidence: 66%

Whole-Genome Analysis of Salmonella enterica Serovar Typhimurium T000240 Reveals the Acquisition of a Genomic Island Involved in Multidrug Resistance via IS 1 Derivatives on the Chromosome

Izumiya

Sekizuka²,

Nakaya

et al. 2011

Antimicrob Agents Chemother

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Salmonella enterica serovar Typhimurium is frequently associated with life-threatening systemic infections, and the recent global emergence of multidrug resistance in S. enterica isolates from agricultural and clinical settings has raised concerns. In this study, we determined the whole-genome sequence of fluoroquinoloneresistant S. enterica serovar Typhimurium T000240 strain (DT12) isolated from human gastroenteritis in 2000. Comparative genome analysis revealed that T000240 displays high sequence similarity to strain LT2, which was originally isolated in 1940, indicating that progeny of LT2 might be reemerging. T000240 possesses a unique 82-kb genomic island, designated as GI-DT12, which is composed of multidrug resistance determinants, including a Tn2670-like composite transposon (class 1 integron [intI1, bla oxa-30 , aadA1, qacE⌬1, and sul1], mercury resistance proteins, and chloramphenicol acetyltransferase), a Tn10-like tetracycline resistance protein (tetA), the aerobactin iron-acquisition siderophore system (lutA and lucABC), and an iron transporter (sitABCD). Since GI-DT12 is flanked by IS1 derivatives, IS1-mediated recombination likely played a role in the acquisition of this genomic island through horizontal gene transfer. The aminoglycoside-(3)-N-acetyltransferase (aac(3)) gene and a class 1 integron harboring the dfrA1 gene cassette responsible for gentamicin and trimethoprim resistance, respectively, were identified on plasmid pSTMDT12_L and appeared to have been acquired through homologous recombination with IS26. This study represents the first characterization of the unique genomic island GI-DT12 that appears to be associated with possible IS1-mediated recombination in S. enterica serovar Typhimurium. It is expected that future whole-genome studies will aid in the characterization of the horizontal gene transfer events for the emerging S. enterica serovar Typhimurium strains.

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Section: Discussionmentioning

confidence: 66%

Whole-Genome Analysis of Salmonella enterica Serovar Typhimurium T000240 Reveals the Acquisition of a Genomic Island Involved in Multidrug Resistance via IS 1 Derivatives on the Chromosome

Izumiya

Sekizuka²,

Nakaya

et al. 2011

Antimicrob Agents Chemother

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The role of horizontal gene transfer in the evolution of selected foodborne bacterial pathogens

Kelly¹,

Vespermann

Bolton

2009

Food and Chemical Toxicology

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Evolutionary Changes of the flhDC Flagellar Master Operon in Shigella Strains

2005

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Shigella strains are nonmotile. The master operon of flagellar synthesis, flhDC, was analyzed for genetic damage in 46 Shigella strains representing all known serotypes. In 11 strains (B1, B3, B6, B8, B10, B18, D5, F1B, D10, F3A, and F3C) the flhDC operon was completely deleted. PCR and sequence analysis of the flhDC region of the remaining 35 strains revealed many insertions or deletions associated with insertion sequences, and the majority of the strains were found to be defective in their flhDC genes. As these genes also play a role in regulation of nonflagellar genes, the loss may have other consequences or be driven by selection pressures other than those against flagellar motility. It has been suggested that Shigella strains fall mostly into three clusters within Escherichia coli, with five outlier strains, four of which are also within E. coli (G. M. Pupo, R. Lan, and P. R. Reeves, Proc. Natl. Acad. Sci. USA 97:10567-10572, 2000). The distribution of genetic changes in the flhDC region correlated very well with the three clusters and outlier strains found using housekeeping gene DNA sequences, enabling us to follow the sequence of mutational change in the flhDC locus. Two cluster 2 strains were found to have unique flhDC sequences, which are most probably due to recombination during the exchange of the adjacent O-antigen gene clusters.Shigella is a pathogen that causes bacillary dysentery or shigellosis in humans. Historically, Shigella was distinguished from Escherichia coli by its biochemical characteristics and nonmotility (6), but in recent years it has been suggested that Shigella strains are so close to E. coli as to be effectively members of the same species. Our recent study (18) suggested that with the exception of Shigella boydii 13, Shigella strains fall into three main clusters and several outliers within E. coli (note that we prefer that Shigella and the four species names not be italicized since we contend that they are in effect forms of E. coli; however, this is not consistent with this journal's policy).E. coli strains are generally motile and produce flagella, with over 50 genes involved. These genes are located in three regions of the chromosome and organized in at least 12 operons. These operons are grouped into three classes, reflecting their transcriptional hierarchy (3). The single class 1 operon, comprising the flhDC genes, is the master operon of the flagellar transcriptional hierarchy (11). Class 2 operons encode proteins for the components and assembly of the hook-basal body and transcriptional regulator, including the flagellum-specific sigma factor gene fliA. FliA is indispensable for the expression of class 3 genes, including the flagellin gene, fliC. Consequently, mutations in the flhDC genes have a decisive effect on expression of other flagellar operons, resulting in the loss of flagella and motility. Although Shigella strains are characteristically nonmotile, they have been shown to have the components for synthesis of flagella. In some strains cryptic flagellin genes hav...

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The IS1elements inShigella boydii: horizontal transfer, vertical inactivation and target duplication

Cited by 4 publications

References 32 publications

Whole-Genome Analysis of Salmonella enterica Serovar Typhimurium T000240 Reveals the Acquisition of a Genomic Island Involved in Multidrug Resistance via IS 1 Derivatives on the Chromosome

Whole-Genome Analysis of Salmonella enterica Serovar Typhimurium T000240 Reveals the Acquisition of a Genomic Island Involved in Multidrug Resistance via IS 1 Derivatives on the Chromosome

The role of horizontal gene transfer in the evolution of selected foodborne bacterial pathogens

Evolutionary Changes of the flhDC Flagellar Master Operon in Shigella Strains

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