Recovery of a Functional Class 2 Integron from an
            <i>Escherichia coli</i>
            Strain Mediating a Urinary Tract Infection

Márquez, Carolina; Labbate, Maurizio; Baccino, Daniel; Chowdhury, Piklu Roy; Ramírez, María Soledad; Centrón, Daniela; Borthagaray, Graciela; Stokes, H. W.

doi:10.1128/aac.00710-08

Cited by 48 publications

(34 citation statements)

References 24 publications

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“…In contrast, the full-length IntI2 from Providencia stuartii and E. coli as well as the IntI2-like sequences described herein share a hydrophilic, neutral Gln residue at the ochre 179 position which is encoded by a CAA or a CAG triplet, indicating that functional IntI2s are more common and widely distributed than previously assessed with culture techniques (6,40). Furthermore, the detection of a potentially functional IntI2-like genotype (AMS25-Int-D03) at the agricultural field AMS25 (Table 1), as well as the prevalence of class 2 elements at this site (ϳ73% of the retrieved sequences), suggested that fecal bacteria serving as IntI2 hosts were persistent under field conditions after 1 month of manure application.…”

Section: Resultsmentioning

confidence: 48%

“…Except for the identical IntI2 elements recently reported in Providencia stuartii and Escherichia coli strains isolated from beef cattle sources and the human urinary tract, respectively, all known integrases encoded by class 2 integrons are considered nonfunctional due to the presence of the ochre 179 codon (6,40,42). Nevertheless, it has been argued that integrons with truncated class 2 integrases might be implicated in the transfer and high prevalence of antibiotic resistance genes among clinical isolates, possibly via the in trans activities of other functional integrases or the suppression of the stop codon (27).…”

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confidence: 99%

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Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact

Rodríguez-Minguela

Apajalahti

Chai

et al. 2009

Appl Environ Microbiol

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An intI-targeted PCR assay was optimized to evaluate the frequency of partial class 2-like integrases relative to putative, environmental IntI elements in clone libraries generated from 17 samples that included various terrestrial, marine, and deep-sea habitats with different exposures to human influence. We identified 169 unique IntI phylotypes (<98% amino acid identity) relative to themselves and with respect to those previously described. Among these, six variants showed an undescribed, extended, IntI-specific additional domain. A connection between human influence and the dominance of IntI-2-like variants was also observed. IntI phylotypes 80 to 99% identical to class 2 integrases comprised ϳ70 to 100% (n ‫؍‬ 65 to 87) of the IntI elements detected in samples with a high input of fecal waste, whereas IntI2-like sequences were undetected in undisturbed settings and poorly represented (1 to 10%; n ‫؍‬ 40 to 79) in environments with moderate or no recent fecal or anthropogenic impact. Eleven partial IntI2-like sequences lacking the signature ochre 179 codon were found among samples of biosolids and agricultural soil supplemented with swine manure, indicating a wider distribution of potentially functional IntI2 variants than previously reported. To evaluate IntI2 distribution patterns beyond the usual hosts, namely, the Enterobacteriaceae, we coupled PCR assays targeted at intI and 16S rRNA loci to G؉C fractionation of total DNA extracted from manured cropland. IntI2-like sequences and 16S rRNA phylotypes related to Firmicutes (Clostridium and Bacillus) and Bacteroidetes (Chitinophaga and Sphingobacterium) dominated a low-G؉C fraction (ϳ40 to 45%), suggesting that these groups could be important IntI2 hosts in manured soil. Moreover, G؉G fractionation uncovered an additional set of 36 novel IntI phylotypes (<98% amino acid identity) undetected in bulk DNA and revealed the prevalence of potentially functional IntI2 variants in the low-G؉C fraction.

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Section: Resultsmentioning

confidence: 48%

mentioning

confidence: 99%

Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact

Rodríguez-Minguela

Apajalahti

Chai

et al. 2009

Appl Environ Microbiol

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“…The activity of this protein is restored when the stop codon at position 179 is replaced by a glutamate codon (11). Recently, two new intI2 genes were identified within integrons found in Providencia stuartii (2) and Escherichia coli (16). The sequences of these genes are not interrupted; position 179 is occupied by a glutamine codon, and the genes apparently code for functional enzymes.…”

mentioning

confidence: 93%

“…The sequences of these genes are not interrupted; position 179 is occupied by a glutamine codon, and the genes apparently code for functional enzymes. These intI2 genes each differ from intI2* of Tn7 at five positions (2,16).…”

mentioning

confidence: 99%

Analysis by Mutagenesis of a Chromosomal Integron Integrase from Shewanella amazonensis SB2BT

Larouche

Roy

2009

J Bacteriol

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Integrons are mobile genetic elements that can integrate and disseminate genes as cassettes by a site-specific recombination mechanism. Integrons contain an integrase gene (intI) that carries out recombination by interacting with two different target sites; the attI site in cis with the integrase and the palindromic attC site of a cassette. The plasmid-specified IntI1 excises a greater variety of cassettes (principally antibiotic resistance genes), and has greater activity, than chromosomal integrases. The aim of this study was to analyze the capacity of the chromosomal integron integrase SamIntIA of the environmental bacterium Shewanella amazonensis SB2BT to excise various cassettes and to compare the properties of the wild type with those of mutants that substitute consensus residues of active integron integrases. We show that the SamIntIA integrase is very weakly active in the excision of various cassettes but that the V206R, V206K, and V206H substitutions increase its efficiency for the excision of cassettes. Our results also suggest that the cysteine residue in the ␤-5 strand is essential to the activity of Shewanella-type integrases, while the cysteine in the ␤-4 strand is less important for the excision activity.

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“…The IntI2 encoded by this gene is capable of recombination reactions, and its cassette array carries a gene for trimethoprim resistance, dfrA14, that is more usually associated with class 1 integrons. In addition, it carries an unusual cassette, potentially encoding a lipoprotein signal peptidase, which may be of relevance for pathogenicity (165). Thus, integrons are still being recruited from the environmental pool of such elements and will continue to accumulate new gene cassettes relevant to resistance, pathogenicity and virulence.…”

Section: Origin Of Class 2 Clinical Integronsmentioning

confidence: 99%

Integrons: Past, Present, and Future

Gillings

2014

Microbiol Mol Biol Rev

570

472

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SUMMARY Integrons are versatile gene acquisition systems commonly found in bacterial genomes. They are ancient elements that are a hot spot for genomic complexity, generating phenotypic diversity and shaping adaptive responses. In recent times, they have had a major role in the acquisition, expression, and dissemination of antibiotic resistance genes. Assessing the ongoing threats posed by integrons requires an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons before the antibiotic era. It shows how antibiotic use selected particular integrons from among the environmental pool of these elements, such that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens. Finally, it examines the potential consequences of widespread pollution with the novel integrons that have been assembled via the agency of human antibiotic use and speculates on the potential uses of integrons as platforms for biotechnology.

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Recovery of a Functional Class 2 Integron from an Escherichia coli Strain Mediating a Urinary Tract Infection

Cited by 48 publications

References 24 publications

Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact

Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact

Analysis by Mutagenesis of a Chromosomal Integron Integrase from Shewanella amazonensis SB2BT

Integrons: Past, Present, and Future

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