aadA | GeneID:1238687 | Escherichia coli

AAO38248   ABB89109   ABB89112   ABN54714   ABQ02275   ABQ52460   ABX75135   ABY55288   ACL98087   BAB12604   BAD08525   BAD10982   BAD99261   BAD99265   CAA26848   NP_065311   XUECSA  

1. [ ] Eckert C, et al. (2006) "DNA sequence analysis of the genetic environment of various blaCTX-M genes." J Antimicrob Chemother. 57(1):14-23. PMID:16291869

OBJECTIVES: Over a 3 year period (2000-2003) 21 Escherichia coli, 5 Klebsiella pneumoniae, 1 Serratia marcescens and 1 Proteus mirabilis producing CTX-M-type beta-lactamase were collected from five different hospitals in Paris, France. This study was conducted to analyse the genetic environment of these 28 bla(CTX-M) genes. METHODS: Antimicrobial susceptibility testing was performed by the disc diffusion method and MICs of various beta-lactams were determined by an agar dilution method. PCR was used to detect and sequence alleles encoding CTX-M, TEM, SHV and CMY enzymes. The genetic environment was analysed by amplification and direct sequencing using various set of PCR primers or cloning in pBK-CMV. RESULTS: Sequence analysis revealed that these isolates contained seven different bla(CTX-M) genes: bla(CTX-M-1) (4 strains), bla(CTX-M-2) (2 strains), bla(CTX-M-3) (4 strains), bla(CTX-M-9) (1 strain), bla(CTX-M-14) (5 strains), bla(CTX-M-15) (11 strains), bla(CTX-M-24) (1 strain). TEM-1 was associated with CTX-M-type enzymes in 15 isolates. Two strains produced both CTX-M-15 and SHV-2 or CTX-M-14 and CMY-2. In 25 strains the insertion sequence ISEcp1 was located upstream of the 5' end of the bla(CTX-M) gene. Among these strains, in five isolates, ISEcp1 was disrupted by insertion sequences such as IS26 (in three of them) or IS1 or IS10. Insertion sequence IS903 was found downstream of bla(CTX-M-14) or bla(CTX-M-24). Examination of the other three bla(CTX-M) genes (two bla(CTX-M-2) and one bla(CTX-M-9)) by cloning, sequencing and PCR analysis revealed the presence of complex Class 1 integrons, In35, an integron similar to In60 and a novel integron. CONCLUSIONS: This work further confirmed the predominant role of ISEcp1 in the mobilization of bla(CTX-M) genes of the CTX-M-1 cluster and the presence of In35, of an integron similar to In60 and a novel complex Class 1 integron.

2. [ ] Valverde A, et al. (2006) "In117, an unusual In0-like class 1 integron containing CR1 and bla(CTX-M-2) and associated with a Tn21-like element." Antimicrob Agents Chemother. 50(2):799-802. PMID:16436750

An unusual In0-like class 1 integron containing a common region that includes the putative recombinase gene named orf513 (CR1) and bla(CTX-M-2) was characterized from Escherichia coli. The integron contained an unusual gene cassette array, estX-aadA1, embedded between the 5'-conserved segment (5'-CS) and 3'-CS1 regions and was flanked by mer-Tn21 sequences downstream of the tni truncated module. This element constitutes one of the few examples of CR1-bearing class 1 integrons that has been fully characterized.

3. [ ] Du X, et al. (2005) "Characterization of class 1 integrons-mediated antibiotic resistance among calf pathogenic Escherichia coli." FEMS Microbiol Lett. 245(2):295-298. PMID:15837385

Escherichia coli isolates from calf diarrhea cases (n=22) in the Beijing surrounding region in China were characterized for disease serotype, virulence factors, antimicrobial susceptibility pattern and class 1 integrons. 59% (n=13) of the isolates were positive for the int I1 gene. The presence and genetic content of class 1 integrons in 13 E. coli isolates were examined by PCR and sequencing. Sequencing analysis revealed six gene cassettes, which encoded resistance to trimethoprim (dfrA1, dfrA17), aminoglycosides (aadB, aadA1 and aadA5) and chloramphenicol (cmlA). The gene cassette arrays dfrA1-orf (45%) and aadB-orf-cmlA (32%) were most prevalent among these isolates. These data revealed the high prevalence of class 1 integrons among calf pathogenic E. coli isolates in the Beijing surrounding region in China, which may provide important and useful surveillance information reflecting specific antibiotic selective pressure.

4. [ ] Sunde M, et al. (2005) "Class I integron with a group II intron detected in an Escherichia coli strain from a free-range reindeer." Antimicrob Agents Chemother. 49(6):2512-2514. PMID:15917559

An Escherichia coli strain, isolated from wild reindeer in a remote mountain area, contained a class 1 integron with two unusual features: a group II intron and a cassette with homology to a superintegron cassette. Alignments indicate that attC sites of gene cassettes may be insertion sites for introns.

5. [ ] Tortola MT, et al. (2005) "First detection of a carbapenem-hydrolyzing metalloenzyme in two enterobacteriaceae isolates in Spain." Antimicrob Agents Chemother. 49(8):3492-3494. PMID:16048967

Two strains of Enterobacteriaceae, Escherichia coli and Klebsiella pneumoniae, producing VIM-1 were isolated for the first time in Spain. In both strains, bla(VIM-1) was found to be carried on a gene cassette inserted into a class 1 integron. The bla(VIM-1)-containing integron was located on a transferable plasmid.

6. [ ] Miriagou V, et al. (2004) "CMY-13, a novel inducible cephalosporinase encoded by an Escherichia coli plasmid." Antimicrob Agents Chemother. 48(8):3172-3174. PMID:15273143

An IncN plasmid (p541) from Escherichia coli carried a Citrobacter freundii-derived sequence of 4,252 bp which included an ampC-ampR region and was bound by two directly repeated IS26 elements. ampC encoded a novel cephalosporinase (CMY-13) with activity similar to that of CMY-2. AmpR was likely functional as indicated in induction experiments.

7. [ ] Waturangi DE, et al. (2003) "Identification of class 1 integrons-associated gene cassettes in Escherichia coli isolated from Varanus spp. in Indonesia." J Antimicrob Chemother. 51(1):175-177. PMID:12493806
8. [ ] Dubois V, et al. (2003) "Decreased susceptibility to cefepime in a clinical strain of Escherichia coli related to plasmid- and integron-encoded OXA-30 beta-lactamase." Antimicrob Agents Chemother. 47(7):2380-2381. PMID:12821505
9. [ ] Vourli S, et al. (2003) "Characterization of In111, a class 1 integron that carries the extended-spectrum beta-lactamase gene blaIBC-1." FEMS Microbiol Lett. 225(1):149-153. PMID:12900034

A class 1 integron, In111, carried by a self-transferable plasmid from an Escherichia coli clinical strain was characterized. The variable region of In111 constituted an array of gene cassettes encoding the extended-spectrum beta-lactamase IBC-1, the aminoglycoside-modifying enzymes AAC(6')-Ib and ANT(3")-Ia, dihydrofolate reductase I and a putative polypeptide (SMR-2) sharing similarity with the Qac transporters. Transcription of the gene cassettes was driven by a hybrid-type P1 promoter located in a typical 5' conserved segment (CS). The 3'CS included sulI, qacEDelta1, orf5 and orf6. In111 was bounded on the right by an inversely oriented IRt. The 5'CS was preceded by an intact IS26 element followed by an aphA1 gene.

10. [ ] Biskri L, et al. (2003) "Erythromycin esterase gene ere(A) is located in a functional gene cassette in an unusual class 2 integron." Antimicrob Agents Chemother. 47(10):3326-3331. PMID:14506050

The gene ere(A) of the plasmid pIP1100 is larger than originally reported and is organized as an integron gene cassette. The ere(A) gene cassette carries its own promoter and is propagated by a class 2 integron with an insertion sequence element, IS1, inserted upstream of the intI2 gene. The mobility of the ere(A) cassette has been demonstrated.

11. [ ] Liebert CA, et al. (1999) "Transposon Tn21, flagship of the floating genome." Microbiol Mol Biol Rev. 63(3):507-522. PMID:10477306

The transposon Tn21 and a group of closely related transposons (the Tn21 family) are involved in the global dissemination of antibiotic resistance determinants in gram-negative facultative bacteria. The molecular basis for their involvement is carriage by the Tn21 family of a mobile DNA element (the integron) encoding a site-specific system for the acquisition of multiple antibiotic resistance genes. The paradigm example, Tn21, also carries genes for its own transposition and a mercury resistance (mer) operon. We have compiled the entire 19,671-bp sequence of Tn21 and assessed the possible origins and functions of the genes it contains. Our assessment adds molecular detail to previous models of the evolution of Tn21 and is consistent with the insertion of the integron In2 into an ancestral Tn501-like mer transposon. Codon usage analysis indicates distinct host origins for the ancestral mer operon, the integron, and the gene cassette and two insertion sequences which lie within the integron. The sole gene of unknown function in the integron, orf5, resembles a puromycin-modifying enzyme from an antibiotic producing bacterium. A possible seventh gene in the mer operon (merE), perhaps with a role in Hg(II) transport, lies in the junction between the integron and the mer operon. Analysis of the region interrupted by insertion of the integron suggests that the putative transposition regulator, tnpM, is the C-terminal vestige of a tyrosine kinase sensor present in the ancestral mer transposon. The extensive dissemination of the Tn21 family may have resulted from the fortuitous association of a genetic element for accumulating multiple antibiotic resistances (the integron) with one conferring resistance to a toxic metal at a time when clinical, agricultural, and industrial practices were rapidly increasing the exposure to both types of selective agents. The compendium offered here will provide a reference point for ongoing observations of related elements in multiply resistant strains emerging worldwide.

12. [ ] Collis CM, et al. (1998) "Binding of the purified integron DNA integrase Intl1 to integron- and cassette-associated recombination sites." Mol Microbiol. 29(2):477-490. PMID:9720866

The site-specific recombinase Intl1, encoded by class 1 integrons, catalyses the integration and excision of gene cassettes by recognizing two classes of sites, the integron-associated attl1 site and the 59-base element (59-be) family of sites that are associated with gene cassettes. Intl1 includes the four conserved amino acids that are characteristic of members of the integrase family, and Intl1 proteins with single amino acid substitutions at each of these positions had substantially reduced catalytic activity, consistent with this classification. Intl1 was purified as a fusion protein and shown to bind to isolated attl1 or 59-be recombination sites. Binding to attl1 was considerably stronger than to a 59-be. Binding adjacent to the recombination cross-over point was not detected. A strong Intl1 binding site within attl1 was localized by both deletion and footprinting analysis to a 14 bp region 24-37 bp to the left of the recombination cross-over point, and this region is known to be critical for recombination in vivo (Recchia et al., 1994). An imperfect (13/15) direct repeat of this region, located 41-55 bp to the left of the recombination cross-over point, contains a weaker Intl1 binding site. Mutation of the stronger binding site showed that a single base pair change accounted for the difference in the strength of binding.

13. [ ] Recchia GD, et al. (1995) "Gene cassettes: a new class of mobile element." Microbiology. 141 ( Pt 12)():3015-3027. PMID:8574395
14. [ ] Recchia GD, et al. (1994) "Characterisation of specific and secondary recombination sites recognised by the integron DNA integrase." Nucleic Acids Res. 22(11):2071-2078. PMID:8029014

Integrons determine a site-specific recombination system which is responsible for the acquisition of genes, particularly antibiotic resistance genes. The integrase encoded by integrons recognises two distinct classes of recombination sites. The first is the family of imperfect inverted repeats, known as 59-base elements, which are associated with the mobile gene cassettes. The second consists of a single site into which the cassettes are inserted. This site, here designated attI, is located adjacent to the int gene in the recipient integron structure. The attI site has none of the recognisable features of members of the 59-base element family except for a seven-base core site, GTTRRRY, at the recombination crossover point. Using a conduction assay to quantitate site activity, the sequence required for maximal attI site activity was confined to a region of > 39 and < or = 70 bases. Both integrative and excisive site-specific recombination events involving attI and a 59-base element site were demonstrated, but no evidence for events involving two attI sites was obtained. Integrase-mediated recombination between a 59-base element and several secondary sites in pACYC184 with the consensus GNT occurred at low frequency, and such events could potentially lead to insertion of gene cassettes at many non-specific sites.

15. [ ] Kim SR, et al. (1992) "Nucleotide sequence of the R721 shufflon." J Bacteriol. 174(21):7053-7058. PMID:1400257

The shufflon is a DNA region that undergoes complex rearrangement mediated by the product of a putative site-specific recombinase gene, rci. The DNA sequences of the shufflon region and the rci gene of IncI2 plasmid R721 were determined. The R721 shufflon consists of three invertible DNA segments that are homologous to the shufflon segments found in IncI1 plasmid R64. Structural analysis of open reading frames indicated that the R721 shufflon possibly functions as a biological switch for selecting one of the six pilV genes in which the N-terminal region is constant and the C-terminal region is variable. The R721 rci gene was shown to encode a basic protein of 374 amino acid residues.

16. [ ] Mercier J, et al. (1990) "Structural and functional characterization of tnpI, a recombinase locus in Tn21 and related beta-lactamase transposons." J Bacteriol. 172(7):3745-3757. PMID:2163386

A novel discrete mobile DNA element from Tn21 from the plasmid R100.1 is described, and its mobilization function was confirmed experimentally. In addition, the element behaves as a recombinase-active locus (tnpI) which facilitates insertions of antibiotic resistance genes as modules or cassettes at defined hot spots or integration sites. A similar tnpI sequence was detected by DNA hybridization in a series of beta-lactamase transposons and plasmids and localized on their physical maps. The genetic function of the locus cloned from Tn21 into pACYC184 was tested for conduction and integration into the plasmids R388 and pOX38Km, and the results suggested recombinase-integrase activity and recA independence. DNA sequence analysis of the tnpI locus revealed no inverted or direct terminal repeats or transposition features of class I and class II transposons. The coding capacity revealed three putative open reading frames encoding 131, 134, and 337 amino acids. Orf3 encoded a putative polypeptide product of 337 amino acids that shared highly significant identity with the carboxyl region of integrase proteins. A comparison and an alignment of the tnpI locus from Tn21 and its flanking sequences identified similar sequences in plasmids and in transposons. The alignment revealed discrete nucleotide changes in these tnpI-like loci and a conserved 3' and 5' GTTA/G hot spot as a duplicated target site. Our data confirm the remarkable ubiquity of tnpI associated with antibiotic resistance genes. We present a model of transposon modular evolution into more complex multiresistant units via tnpI and site-specific insertions, deletions, and DNA rearrangements at this locus.

17. [ ] Sundstrom L, et al. (1990) "The dhfrI trimethoprim resistance gene of Tn7 can be found at specific sites in other genetic surroundings." Antimicrob Agents Chemother. 34(4):642-650. PMID:2188588

The dhfrI gene, mediating high-level trimethoprim resistance, was earlier found only on Tn7. Evidence is given here for an alternative location of this gene at a site identical to sites observed earlier for dhfrII on plasmid R388, dhfrV on pLMO20, and aadA on Tn21. All these genes and dhfrI are precisely inserted as discrete GTTA-flanked elements at distinct loci in very conserved surrounding sequences. One of these dhfrI insertions was observed to occur in association with a similarly inserted aadA nucleotidyltransferase gene, which mediates streptomycin and spectinomycin resistance. Close to the insertion site, there is an open reading frame translating into a 337-amino-acid peptide which shows striking similarities to recombinases of the integrase family, sulI, the sulfonamide resistance gene, is very often found close to the insertion point forming a genetic surrounding, originally observed as a part of Tn21-like transposons. The alleged integration mechanism thus provides a recombination pathway for the genetic linkage of sulfonamide and other antibiotic resistance genes, including the most frequently encountered gene for trimethoprim resistance, dhfrI. Furthermore, the newly observed location of dhfrI could shed light on the evolution of the antibiotic resistance region of Tn7, which could be able to take up genes by the same mechanism as that of Tn21-like transposons.

18. [ ] Sundstrom L, et al. (1988) "Site-specific recombination promotes linkage between trimethoprim- and sulfonamide resistance genes. Sequence characterization of dhfrV and sulI and a recombination active locus of Tn21." Mol Gen Genet. 213(2-3):191-201. PMID:3054482

A new gene for trimethoprim resistance, dhfrV, found in several plasmid isolates with different characteristics, was sequenced and found to correspond to a peptide of 157 amino acids showing 75% similarity with the previously characterized, drug resistant dihydrofolate reductase of type I. The sequenced surroundings of dhfrV in plasmid pLMO20, were found to be almost identical with genetic areas surrounding resistance genes in transposon Tn21 and in R plasmid R388. The trimethoprim resistance genes of pLMO20 and R388 and the spectinomycin resistance gene of Tn21 could be regarded as having been inserted, by recombination, into an evolutionary older structure containing the sulfonamide resistance gene, sulI. The latter gene was sequenced and found to correspond to a peptide of 279 amino acids and with a molecular weight of 30,126 daltons. The inserted genes were found to be governed by a promoter situated in the highly conserved structure and also controlling expression of sulI. The insertion points of the different resistance genes were precisely defined, and at the 3' ends of the inserted genes inverted repeats allowing the formation of stem and loop structures were found. Similar structures were found at the 3' ends of the antibiotic resistance genes in Tn7, which could indicate similar recombination mechanisms to be effective in the evolutionary construction of all these different resistance elements.

19. [ ] Ouellette M, et al. (1987) "Precise insertion of antibiotic resistance determinants into Tn21-like transposons: nucleotide sequence of the OXA-1 beta-lactamase gene." Proc Natl Acad Sci U S A. 84(21):7378-7382. PMID:2823258

Several plasmid-encoded beta-lactamases are on multiresistance transposable elements. The OXA-1 beta-lactamase gene is part of Tn2603, which is borne on the R plasmid RGN238. We report here the complete nucleotide sequence of the OXA-1 beta-lactamase gene and flanking sequences. The OXA-1 gene shows a greater than 50% sequence divergence from the OXA-2 gene, yet there is significant functional similarity at the peptide level. Analysis of 5' and 3' flanking sequences shows that Tn2603 differs from its probable precursor, Tn21, by a precise 1004-base-pair insertion, containing the OXA-1 structural gene, at the target sequence AAAGTT, which is located between the Tn21 streptomycin/spectinomycin (aadA) promoter and its structural gene. A 5- for 6-base repeat of the target sequence is found at the end of the insertion. The same precise insertion and repeat of the target sequence are found for the OXA-2 gene from R46. The 5' flanking regions of two other genes, the trimethoprim-resistance gene from R388 and the gentamicin resistance (aadB) gene from pDGO100, are greater than 98% homologous to the 5' flanking sequences of the OXA-1, OXA-2, and aadA genes until they diverge at the target sequence. From the available sequence data a recombinational hot spot is defined at the nucleotide level 5' of the aadA gene of Tn21, and a second potential hot spot is proposed 3' of this gene.

20. [ ] Hollingshead S, et al. (1985) "Nucleotide sequence analysis of a gene encoding a streptomycin/spectinomycin adenylyltransferase." Plasmid. 13(1):17-30. PMID:2986186

The nucleotide sequence of 1400 bp from R-plasmid R538-1 containing the streptomycin/spectinomycin adenyltransferase gene (aadA) was determined, and the location of the aadA gene was identified by a combination of insertion and deletion mutants. Its gene product, aminoglycoside 3"-adenylyltransferase (AAD(3")(9), has a Mr of 31,600.

21. [ ] Fling ME, et al. (1985) "Nucleotide sequence of the transposon Tn7 gene encoding an aminoglycoside-modifying enzyme, 3"(9)-O-nucleotidyltransferase." Nucleic Acids Res. 13(19):7095-7106. PMID:2997737

The nucleotide sequence of a transposon Tn7 DNA fragment encoding a 3"(9)-O-nucleotidyltransferase, an aminoglycoside-modifying enzyme, which mediates bacterial resistance to spectinomycin and streptomycin, was determined. The aadA structural gene was 786 bases long and predicted a polypeptide of 262 amino acids with a calculated molecular weight of 29,207. Comparison of the DNA sequences of Tn7 and plasmid R538-1 indicated that their aadA genes were nearly identical. Comparison of the polypeptides predicted by the aadA genes of Tn7 and Tn554 indicated that the genes were related.

22. [ ] Ounissi H, et al. (1985) "Nucleotide sequence of the gene ereA encoding the erythromycin esterase in Escherichia coli." Gene. 35(3):271-278. PMID:3899861

We have cloned and determined the nucleotide sequence of the gene ereA of plasmid pIP1100 which confers high-level resistance to erythromycin (Em) in Escherichia coli. The gene was defined by initiation and termination codons and by in vitro insertion-inactivation into an open reading frame (ORF) of 1032 bp corresponding to a product with an Mr of 37 765. However, the enzyme, an Em esterase, displayed an apparent Mr of 43 000 upon electrophoresis of a minicell extract on the SDS-polyacrylamide gels. The G + C content (50.5%) of the gene ereA and the preferential codon usage in its ORF suggest that this resistance determinant should be indigenous to E. coli.