# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 3015 | 0 | 0.9916 | Genetic structure and biological properties of the first ancient multiresistance plasmid pKLH80 isolated from a permafrost bacterium. A novel multidrug-resistance plasmid, pKLH80, previously isolated from Psychrobacter maritimus MR29-12 found in ancient permafrost, was completely sequenced and analysed. In our previous studies, we focused on the pKLH80 plasmid region containing streptomycin and tetracycline resistance genes, and their mobilization with an upstream-located ISPpy1 insertion sequence (IS) element. Here, we present the complete sequence of pKLH80 and analysis of its backbone genetic structure, including previously unknown features of the plasmid's accessory region, notably a novel variant of the β-lactamase gene blaRTG-6. Plasmid pKLH80 was found to be a circular 14 835 bp molecule that has an overall G+C content of 40.3 mol% and encodes 20 putative ORFs. There are two distinctive functional modules within the plasmid backbone sequence: (i) the replication module consisting of repB and the oriV region; and (ii) the mobilization module consisting of mobA, mobC and oriT. All of the aforementioned genes share sequence identities with corresponding genes of different species of Psychrobacter. The plasmid accessory region contains antibiotic resistance genes and IS elements (ISPsma1 of the IS982 family, and ISPpy1 and ISAba14 of the IS3 family) found in environmental and clinical bacterial strains of different taxa. We revealed that the sequences flanking blaRTG-6 and closely related genes from clinical bacteria are nearly identical. This fact suggests that blaRTG-6 from the environmental strain of Psychrobacter is a progenitor of blaRTG genes of clinical bacteria. We also showed that pKLH80 can replicate in different strains of Acinetobacter and Psychrobacter genera. The roles of IS elements in the horizontal transfer of antibiotic resistance genes are examined and discussed. | 2014 | 25063046 |
| 3028 | 1 | 0.9913 | Novel macrolide resistance module carried by the IncP-1beta resistance plasmid pRSB111, isolated from a wastewater treatment plant. The macrolide resistance plasmid pRSB111 was isolated from bacteria residing in the final effluents of a wastewater treatment plant. The 47-kb plasmid confers resistance to azithromycin, clarithromycin, erythromycin, roxithromycin, and tylosin when it is carried by Pseudomonas sp. strain B13 and is very similar to prototype IncP-1beta plasmid pB3, which was previously isolated from an activated-sludge bacterial community of a wastewater treatment plant. The two plasmids differ in their accessory regions, located downstream of the conjugative transfer module gene traC. Nucleotide sequence analysis of the pRSB111 accessory region revealed that it contains a new macrolide resistance module composed of the genes mphR(E), mph(E), and mrx(E), which putatively encode a transcriptional regulator, a macrolide phosphotransferase, and a transmembrane transport protein, respectively. Analysis of the contributions of the individual genes of the macrolide resistance module revealed that mph(E) and mrx(E) are required for high-level macrolide resistance. The resistance genes are flanked by two insertion sequences, namely, ISPa15 and ISRSB111. Two truncated transposable elements, IS6100 and remnants of a Tn3-like transposon, were identified in the vicinity of ISRSB111. The accessory element of pRSB111 apparently replaced the Tn402-like element present on the sister plasmid, pB3, as suggested by the conservation of Tn402-specific terminal inverted repeats on pRSB111. | 2007 | 17101677 |
| 3027 | 2 | 0.9912 | Tn5045, a novel integron-containing antibiotic and chromate resistance transposon isolated from a permafrost bacterium. A novel antibiotic and chromate resistance transposon, Tn5045, was isolated from a permafrost strain of Pseudomonas sp. Tn5045 is a compound transposon composed of three distinct genetic elements. The backbone element is a Tn1013-like Tn3 family transposon, termed Tn1013∗, that contains the tnpA and the tnpR genes, encoding the transposase and resolvase, respectively, the res-site and four genes (orfA, B, C, D) related to different house-keeping genes. The second element is class 1 integron, termed InC∗, which is inserted into the Tn1013∗ res-region and contains 5'-CS-located integrase, 3'-CS-located qacE∆1 and sulfonamide resistance sulI genes, and a single cassette encoding the streptomycin resistance aadA2-gene. The third element is a TnOtChr-like Tn3 family transposon termed TnOtChr∗, which is inserted into the transposition module of the integron and contains genes of chromate resistance (chrB, A, C, F). Tn5045 is the first example of an ancient integron-containing mobile element and also the first characterized compound transposon coding for both antibiotic and chromate, resistance. Our data demonstrate that antibiotic and chromate resistance genes were distributed in environmental bacteria independently of human activities and provide important insights into the origin and evolution of antibiotic resistance integrons. | 2011 | 21262357 |
| 3021 | 3 | 0.9909 | Sequencing and comparative analysis of IncP-1α antibiotic resistance plasmids reveal a highly conserved backbone and differences within accessory regions. Although IncP-1 plasmids are important for horizontal gene transfer among bacteria, in particular antibiotic resistance spread, so far only three plasmids from the subgroup IncP-1α have been completely sequenced. In this study we doubled this number. The three IncP-1α plasmids pB5, pB11 and pSP21 were isolated from bacteria of two different sewage treatment plants and sequenced by a combination of next-generation and capillary sequencing technologies. A comparative analysis including the previously analysed IncP-1α plasmids RK2, pTB11 and pBS228 revealed a highly conserved plasmid backbone (at least 99.9% DNA sequence identity) comprising 54 core genes. The accessory elements of the plasmid pB5 constitute a class 1 integron interrupting the parC gene and an IS6100 copy inserted into the integron. In addition, the tetracycline resistance genes tetAR and the ISTB11-like element are located between the klc operon and the trfA-ssb operon. Plasmid pB11 is loaded with a Tn5053-like mercury resistance transposon between the parCBA and parDE operons and contains tetAR that are identical to those identified in plasmid pB5 and the insertion sequence ISSP21. Plasmid pSP21 harbours an ISPa7 element in a Tn402 transposon including a class 1 integron between the partitioning genes parCBA and parDE. The IS-element ISSP21 (99.89% DNA sequence identity to ISSP21 from pB11), inserted downstream of the tetR gene and a copy of ISTB11 (identical to ISTB11 on pTB11) inserted between the genes pncA and pinR. On all three plasmids the accessory genes are almost always located between the backbone modules confirming the importance of the backbone functions for plasmid maintenance. The striking backbone conservation among the six completely sequenced IncP-1α plasmids is in contrast to the much higher diversity within the IncP-1β subgroup. | 2011 | 21115076 |
| 3019 | 4 | 0.9907 | Identification and Characterization of New Resistance-Conferring SGI1s (Salmonella Genomic Island 1) in Proteus mirabilis. Salmonella genomic island 1 (SGI1) is a resistance-conferring chromosomal genomic island that contains an antibiotic resistance gene cluster. The international spread of SGI1-containing strains drew attention to the role of genomic islands in the dissemination of antibiotic resistance genes in Salmonella and other Gram-negative bacteria. In this study, five SGI1 variants conferring multidrug and heavy metal resistance were identified and characterized in Proteus mirabilis strains: SGI1-PmCAU, SGI1-PmABB, SGI1-PmJN16, SGI1-PmJN40, and SGI1-PmJN48. The genetic structures of SGI1-PmCAU and SGI1-PmABB were identical to previously reported SGI1s, while structural analysis showed that SGI1-PmJN16, SGI1-PmJN40, and SGI1-PmJN48 are new SGI1 variants. SGI1-PmJN16 is derived from SGI1-Z with the MDR region containing a new gene cassette array dfrA12-orfF-aadA2-qacEΔ1-sul1-chrA-orf1. SGI1-PmJN40 has an unprecedented structure that contains two right direct repeat sequences separated by a transcriptional regulator-rich DNA fragment, and is predicted to form two different extrachromosomal mobilizable DNA circles for dissemination. SGI1-PmJN48 lacks a common ORF S044, and its right junction region exhibits a unique genetic organization due to the reverse integration of a P. mirabilis chromosomal gene cluster and the insertion of part of a P. mirabilis plasmid, making it the largest known SGI1 to date (189.1 kb). Further mobility functional analysis suggested that these SGIs can be excised from the chromosome for transfer between bacteria, which promotes the horizontal transfer of antibiotic and heavy metal resistance genes. The identification and characterization of the new SGI1 variants in this work suggested the diversity of SGI1 structures and their significant roles in the evolution of bacteria. | 2018 | 30619228 |
| 3029 | 5 | 0.9906 | Antibiotic multiresistance plasmid pRSB101 isolated from a wastewater treatment plant is related to plasmids residing in phytopathogenic bacteria and carries eight different resistance determinants including a multidrug transport system. Ten different antibiotic resistance plasmids conferring high-level erythromycin resistance were isolated from an activated sludge bacterial community of a wastewater treatment plant by applying a transformation-based approach. One of these plasmids, designated pRSB101, mediates resistance to tetracycline, erythromycin, roxythromycin, sulfonamides, cephalosporins, spectinomycin, streptomycin, trimethoprim, nalidixic acid and low concentrations of norfloxacin. Plasmid pRSB101 was completely sequenced and annotated. Its size is 47 829 bp. Conserved synteny exists between the pRSB101 replication/partition (rep/par) module and the pXAC33-replicon from the phytopathogen Xanthomonas axonopodis pv. citri. The second pRSB101 backbone module encodes a three-Mob-protein type mobilization (mob) system with homology to that of IncQ-like plasmids. Plasmid pRSB101 is mobilizable with the help of the IncP-1alpha plasmid RP4 providing transfer functions in trans. A 20 kb resistance region on pRSB101 is located within an integron-containing Tn402-like transposon. The variable region of the class 1 integron carries the genes dhfr1 for a dihydrofolate reductase, aadA2 for a spectinomycin/streptomycin adenylyltransferase and bla(TLA-2) for a so far unknown Ambler class A extended spectrum beta-lactamase. The integron-specific 3'-segment (qacEDelta1-sul1-orf5Delta) is connected to a macrolide resistance operon consisting of the genes mph(A) (macrolide 2'-phosphotransferase I), mrx (hydrophobic protein of unknown function) and mphR(A) (regulatory protein). Finally, a putative mobile element with the tetracycline resistance genes tetA (tetracycline efflux pump) and tetR was identified upstream of the Tn402-specific transposase gene tniA. The second 'genetic load' region on pRSB101 harbours four distinct mobile genetic elements, another integron belonging to a new class and footprints of two more transposable elements. A tripartite multidrug (MDR) transporter consisting of an ATP-binding-cassette (ABC)-type ATPase and permease, and an efflux membrane fusion protein (MFP) of the RND-family is encoded between the replication/partition and the mobilization module. Homologues of the macrolide resistance genes mph(A), mrx and mphR(A) were detected on eight other erythromycin resistance-plasmids isolated from activated sludge bacteria. Plasmid pRSB101-like repA amplicons were also obtained from plasmid-DNA preparations of the final effluents of the wastewater treatment plant indicating that pRSB101-like plasmids are released with the final effluents into the environment. | 2004 | 15528650 |
| 3007 | 6 | 0.9905 | Analysis of the complete nucleotide sequence of an Actinobacillus pleuropneumoniae streptomycin-sulfonamide resistance plasmid, pMS260. pMS260 is an 8.1-kb non-conjugative but mobilizable plasmid that was isolated from Actinobacillus pleuropneumoniae and encodes streptomycin (SM) and sulfonamide (SA) resistances. The analysis of the complete nucleotide sequence of the plasmid revealed a high degree of similarity between pMS260 and the broad-host-range IncQ family plasmids. pMS260 had a single copy of an origin of vegetative replication (oriV). This sequence was identical to a functional oriV of the IncQ-like plasmid pIE1130 that had been exogenously isolated from piggery manure. However, pMS260 did not carry the second IncQ plasmid RSF1010-like oriV region present in pIE1130. A pIE1130-identical transfer origin was also found in pMS260. In addition, the deduced amino acid sequences from 10 open reading frames identified in pMS260 were entirely or nearly identical to those from genes for the replication, mobilization, and SM-SA resistance of pIE1130, indicating that pMS260 belongs to the IncQ-1 gamma subgroup. pMS260 is physically indistinguishable from pIE1130 apart from two DNA regions that contain the chloramphenicol and kanamycin resistance genes (catIII and aphI, respectively) and the second oriV-like region of pIE1130. The codon bias analysis of each gene of pIE1130 and the presence of potential recombination sites in the sulII-strA intergenic regions suggest that pIE1130 seems to have acquired the catIII and aphI genes more recently than the other genes of pIE1130. Therefore, pMS260 may be the ancestor of pIE1130. Information regarding the broad-host-range replicon of pMS260 will be useful in the development of genetic systems for a wide range of bacteria including A. pleuropneumoniae. | 2004 | 14711528 |
| 815 | 7 | 0.9902 | The sequence of the mer operon of pMER327/419 and transposon ends of pMER327/419, 330 and 05. Three different, independently isolated mercury-resistance-conferring plasmids, pMER327/419, pMER330 and pMER05, from cultures originating from the river Mersey (UK), contain identical regulatory merR genes and transposon ends. The mer determinant from pMER327/419 contains an additional potential ORF (ORF F) located between merP and merA when compared with the archetypal Tn501. Although these plasmids confer narrow-spectrum resistance (resistance to Hg2+, but not organomercurials) their merR genes encode a potential organomercurial-sensing protein. Transposition of the mer of pMER05 into plasmid RP4 was demonstrated and, as with Tn502 and Tn5053, insertion occurred at a specific region. The sequence of pMER05 is identical at the 'left' and 'right' termini and across merR to Tn5053, which was independently isolated from the chromosome of a Xanthomonas sp. bacteria from the Khaidarkan mercury mine in Kirgizia, former Soviet Union [Kholodii et al., J. Mol. Biol. 230 (1993a) 1103-1107]. The transpositional unit of pMER05 is, like that of Tn5053, bounded by DNA homologous to the imperfect 25-bp inverted repeats (IR) of the In2 integron, which brackets antibiotic-resistance cassettes in Tn21 subgroup transposons. At one end of the transposable element, and internal to the In2-like IR, is a 38-bp IR which closely resembles the IR that bounds Tn21. | 1994 | 8063107 |
| 3016 | 8 | 0.9902 | Complete nucleotide sequence of the conjugative tetracycline resistance plasmid pFBAOT6, a member of a group of IncU plasmids with global ubiquity. This study presents the first complete sequence of an IncU plasmid, pFBAOT6. This plasmid was originally isolated from a strain of Aeromonas caviae from hospital effluent (Westmorland General Hospital, Kendal, United Kingdom) in September 1997 (G. Rhodes, G. Huys, J. Swings, P. McGann, M. Hiney, P. Smith, and R. W. Pickup, Appl. Environ. Microbiol. 66:3883-3890, 2000) and belongs to a group of related plasmids with global ubiquity. pFBAOT6 is 84,748 bp long and has 94 predicted coding sequences, only 12 of which do not have a possible function that has been attributed. Putative replication, maintenance, and transfer functions have been identified and are located in a region in the first 31 kb of the plasmid. The replication region is poorly understood but exhibits some identity at the protein level with replication proteins from the gram-positive bacteria Bacillus and Clostridium. The mating pair formation system is a virB homologue, type IV secretory pathway that is similar in its structural organization to the mating pair formation systems of the related broad-host-range (BHR) environmental plasmids pIPO2, pXF51, and pSB102 from plant-associated bacteria. Partitioning and maintenance genes are homologues of genes in IncP plasmids. The DNA transfer genes and the putative oriT site also exhibit high levels of similarity with those of plasmids pIPO2, pXF51, and pSB102. The genetic load region encompasses 54 kb, comprises the resistance genes, and includes a class I integron, an IS630 relative, and other transposable elements in a 43-kb region that may be a novel Tn1721-flanked composite transposon. This region also contains 24 genes that exhibit the highest levels of identity to chromosomal genes of several plant-associated bacteria. The features of the backbone of pFBAOT6 that are shared with this newly defined group of environmental BHR plasmids suggest that pFBAOT6 may be a relative of this group, but a relative that was isolated from a clinical bacterial environment rather than a plant-associated bacterial environment. | 2004 | 15574953 |
| 3060 | 9 | 0.9901 | Integron mobilization unit as a source of mobility of antibiotic resistance genes. Antibiotic resistance genes are spread mostly through plasmids, integrons (as a form of gene cassettes), and transposons in gram-negative bacteria. We describe here a novel genetic structure, named the integron mobilization unit (IMU), that has characteristics similar to those of miniature inverted transposable elements (MITEs). Two IMUs (288 bp each) were identified from a carbapenem-resistant Enterobacter cloacae isolate that formed a composite structure encompassing a defective class 1 integron containing the carbapenem resistance gene bla(GES-5). This beta-lactamase gene was located on a 7-kb IncQ-type plasmid named pCHE-A, which was sequenced completely. The plasmid pCHE-A was not self conjugative but was mobilizable, and it was successfully transferred from E. cloacae to Pseudomonas aeruginosa. The in silico analysis of the extremities of the IMU elements identified similarities with those of insertion sequence ISSod9 from Shewanella oneidensis MR-1. The mobilization of the IMU composite structure was accomplished by using the transposase activity of ISSod9 that was provided in trans. This is the first identification of MITE-type structures as a source of gene mobilization, implicating here a clinically relevant antibiotic resistance gene. | 2009 | 19332679 |
| 3020 | 10 | 0.9901 | Combining sequencing approaches to fully resolve a carbapenemase-encoding megaplasmid in a Pseudomonas shirazica clinical strain. Horizontal transfer of plasmids plays a pivotal role in dissemination of antibiotic resistance genes and emergence of multidrug-resistant bacteria. Plasmid sequencing is thus paramount for accurate epidemiological tracking in hospitals and routine surveillance. Combining Nanopore and Illumina sequencing allowed full assembly of a carbapenemase-encoding megaplasmid carried by multidrug-resistant clinical isolate FFUP_PS_41. Average nucleotide identity analyses revealed that FFUP_PS_41 belongs to the recently proposed new species Pseudomonas shirazica, related to the P. putida phylogenetic group. FFUP_PS_41 harbours a 498,516-bp megaplasmid (pJBCL41) with limited similarity to publicly-available plasmids. pJBCL41 contains genes predicted to encode replication, conjugation, partitioning and maintenance functions and heavy metal resistance. The |aacA7|blaVIM-2|aacA4| cassette array (resistance to carbapenems and aminoglycosides) is located within a class 1 integron that is a defective Tn402 derivative. This transposon lies within a 50,273-bp region bound by Tn3-family 38-bp inverted repeats and flanked by 5-bp direct repeats (DR) that composes additional transposon fragments, five insertion sequences and a Tn3-Derived Inverted-Repeat Miniature Element. The hybrid Nanopore/Illumina approach allowed full resolution of a carbapenemase-encoding megaplasmid from P. shirazica. Identification of novel megaplasmids sheds new light on the evolutionary effects of gene transfer and the selective forces driving antibiotic resistance. | 2019 | 31381486 |
| 9874 | 11 | 0.9899 | Genomic islands related to Salmonella genomic island 1; integrative mobilisable elements in trmE mobilised in trans by A/C plasmids. Salmonella genomic island 1 (SGI1), an integrative mobilisable element (IME), was first reported 20 years ago, in the multidrug resistant Salmonella Typhimurium DT104 clone. Since this first report, many variants and relatives have been found in Salmonella enterica and Proteus mirabilis. Thanks to whole genome sequencing, more and more complete sequences of SGI1-related elements (SGI1-REs) have been reported in these last few years among Gammaproteobacteria. Here, the genetic organisation and main features common to SGI1-REs are summarised to help to classify them. Their integrases belong to the tyrosine-recombinase family and target the 3'-end of the trmE gene. They share the same genetic organisation (integrase and excisionase genes, replicase module, SgaCD-like transcriptional activator genes, traN, traG, mpsB/mpsA genes) and they harbour AcaCD binding sites promoting their excision, replication and mobilisation in presence of A/C plasmid. SGI1-REs are mosaic structures suggesting that recombination events occurred between them. Most of them harbour a multiple antibiotic resistance (MAR) region and the plasticity of their MAR region show that SGI1-REs play a key role in antibiotic resistance and might help multiple antibiotic resistant bacteria to adapt to their environment. This might explain the emergence of clones with SGI1-REs. | 2021 | 33582118 |
| 820 | 12 | 0.9899 | Nucleotide sequence analysis of a transposon (Tn5393) carrying streptomycin resistance genes in Erwinia amylovora and other gram-negative bacteria. A class II Tn3-type transposable element, designated Tn5393 and located on plasmid pEa34 from streptomycin-resistant strain CA11 of Erwinia amylovora, was identified by its ability to move from pEa34 to different sites in plasmids pGEM3Zf(+) and pUCD800. Nucleotide sequence analysis reveals that Tn5393 consists of 6,705 bp with 81-bp terminal inverted repeats and generates 5-bp duplications of the target DNA following insertion. Tn5393 contains open reading frames that encode a putative transposase (tnpA) and resolvase (tnpR) of 961 and 181 amino acids, respectively. The two open reading frames are separated by a putative recombination site (res) consisting of 194 bp. Two streptomycin resistance genes, strA and strB, were identified on the basis of their DNA sequence homology to streptomycin resistance genes in plasmid RSF1010. StrA is separated from tnpR by a 1.2-kb insertion element designated IS1133. The tnpA-res-tnpR region of Tn5393 was detected in Pseudomonas syringae pv. papulans Psp36 and in many other gram-negative bacteria harboring strA and strB. Except for some strains of Erwinia herbicola, these other gram-negative bacteria lacked insertion sequence IS1133. The prevalence of strA and strB could be accounted for by transposition of Tn5393 to conjugative plasmids that are then disseminated widely among gram-negative bacteria. | 1993 | 8380801 |
| 3023 | 13 | 0.9896 | ICEAplChn1, a novel SXT/R391 integrative conjugative element (ICE), carrying multiple antibiotic resistance genes in Actinobacillus pleuropneumoniae. SXT/R391 integrative conjugative elements (ICEs) are capable of self-transfer by conjugation and highly prevalent in various aquatic bacteria and Proteus species. In the present study, a novel SXT/R391 ICE, named ICEAplChn1, was identified in the multidrug resistant (MDR) Actinobacillus pleuropneumoniae strain app6. ICEAplChn1 was composed of the typical SXT/R391 backbone and insertion DNA at eight hotspots, including HS1, HS2, HS3, HS4, HS5, VRII, VRIII and a new variation region VRVI. Many of the insertion contents were not present in other reported SXT/R391 family members, including ICEApl2, a recently identified SXT/R391 ICE from a clinical isolate of A. pleuropneumoniae. Remarkably, the VRIII region had accumulated seven resistance genes tet(A), erm(42), floR, aphA6, strB (two copies), strA and sul2. Of them, erm(42) and aphA6 emerged for the first time not only in the SXT/R391 elements but also in A. pleuropneumoniae. Phylogenetic analysis showed considerable variation of the backbone sequence of ICEAplChn1, as compared to those of other SXT/R391 ICEs. A circular intermediate form of ICEAplChn1 was detected by nested PCR. However, the conjugation experiments using different bacteria as recipients failed. These findings demonstrated that SXT/R391 ICEs are able to adapt to a broader range of host bacterial species. The presence of the MDR gene cluster in ICEAplChn1 underlines that SXT/R391 ICE could serve as an important vector for the accumulation of antibiotic resistance genes. | 2018 | 29885796 |
| 3008 | 14 | 0.9894 | Sequence of conjugative plasmid pIP1206 mediating resistance to aminoglycosides by 16S rRNA methylation and to hydrophilic fluoroquinolones by efflux. Self-transferable IncFI plasmid pIP1206, isolated from an Escherichia coli clinical isolate, carries two new resistance determinants: qepA, which confers resistance to hydrophylic fluoroquinolones by efflux, and rmtB, which specifies a 16S rRNA methylase conferring high-level aminoglycoside resistance. Analysis of the 168,113-bp sequence (51% G+C) revealed that pIP1206 was composed of several subregions separated by copies of insertion sequences. Of 151 open reading frames, 56 (37%) were also present in pRSB107, isolated from a bacterium in a sewage treatment plant. pIP1206 contained four replication regions (RepFIA, RepFIB, and two partial RepFII regions) and a transfer region 91% identical with that of pAPEC-O1-ColBM, a plasmid isolated from an avian pathogenic E. coli. A putative oriT region was found upstream from the transfer region. The antibiotic resistance genes tet(A), catA1, bla(TEM-1), rmtB, and qepA were clustered in a 33.5-kb fragment delineated by two IS26 elements that also carried a class 1 integron, including the sulI, qacEDelta1, aad4, and dfrA17 genes and Tn10, Tn21, and Tn3-like transposons. The plasmid also possessed a raffinose operon, an arginine deiminase pathway, a putative iron acquisition gene cluster, an S-methylmethionine metabolism operon, two virulence-associated genes, and a type I DNA restriction-modification (R-M) system. Three toxin/antitoxin systems and the R-M system ensured stabilization of the plasmid in the host bacteria. These data suggest that the mosaic structure of pIP1206 could have resulted from recombination between pRSB107 and a pAPEC-O1-ColBM-like plasmid, combined with structural rearrangements associated with acquisition of additional DNA by recombination and of mobile genetic elements by transposition. | 2008 | 18458128 |
| 348 | 15 | 0.9894 | Conjugative DNA transfer in Streptomyces by TraB: is one protein enough? Antibiotic-producing soil bacteria of the genus Streptomyces form a huge natural reservoir of antibiotic resistance genes for the dissemination within the soil community. Streptomyces plasmids encode a unique conjugative DNA transfer system clearly distinguished from classical conjugation involving a single-stranded DNA molecule and a type IV protein secretion system. Only a single plasmid-encoded protein, TraB, is sufficient to translocate a double-stranded DNA molecule into the recipient in Streptomyces matings. TraB is a hexameric pore-forming ATPase that resembles the chromosome segregator protein FtsK and translocates DNA by recognizing specific 8-bp repeats present in the plasmid clt locus. Mobilization of chromosomal genes does not require integration of the plasmid, because TraB also recognizes clt-like sequences distributed all over the chromosome. | 2012 | 23082971 |
| 3000 | 16 | 0.9893 | A large conjugative Acinetobacter baumannii plasmid carrying the sul2 sulphonamide and strAB streptomycin resistance genes. Acinetobacter baumannii is an important nosocomial pathogen that often complicates treatment because of its high level of resistance to antibiotics. Though plasmids can potentially introduce various genes into bacterial strains, compared to other Gram-negative bacteria, information about the unique A. baumannii plasmid repertoire is limited. Here, whole genome sequence data was used to determine the plasmid content of strain A297 (RUH875), the reference strain for the globally disseminated multiply resistant A. baumannii clone, global clone 1(GC1). A297 contains three plasmids. Two known plasmids were present; one, pA297-1 (pRAY*), carries the aadB gentamicin, kanamycin and tobramycin resistance gene and another is an 8.7kb cryptic plasmid often found in GC1 isolates. The third plasmid, pA297-3, is 200kb and carries the sul2 sulphonamide resistance gene and strAB streptomycin resistance gene within Tn6172 and a mer mercuric ion resistance module elsewhere. pA297-3 transferred sulphonamide, streptomycin and mercuric ion resistance at high frequency to a susceptible A. baumannii recipient, and contains several genes potentially involved in conjugative transfer. However, a relaxase gene was not found. It also includes several genes encoding proteins involved in DNA metabolism such as partitioning. However, a gene encoding a replication initiation protein could not be found. pA297-3 includes two copies of a Miniature Inverted-Repeat Transposable Element (MITE), named MITE-297, bracketing a 77.5kb fragment, which contains several IS and the mer module. Several plasmids related to but smaller than pA297-3 were found in the GenBank nucleotide database. They were found in different A. baumannii clones and are wide spread. They all contain either Tn6172 or a variant in the same position in the backbone as Tn6172 in pA297-3. Some related plasmids have lost the segment between the MITE-297 copies and retain only one MITE-297. Others have segments of various lengths between two MITE-297 copies, and these can be derived from the region in pA297-3 via a deletion adjacent to IS related to IS26 such as IS1007 or IS1007-like. pA297-3 and its relatives represent a third type of conjugative Acinetobacter plasmid that contributes to the dissemination of antibiotic resistance in this species. | 2016 | 27601280 |
| 493 | 17 | 0.9893 | Mercury resistance transposons of gram-negative environmental bacteria and their classification. A total of 29 mercury resistance transposons were isolated from mercury-resistant environmental strains of proteobacteria collected in different parts of Eurasia and the USA and tested for hybridization with probes specific for transposase genes of known mercury resistance transposons. 9 were related to Tn21 in this test, 12 were related to Tn5053, 4 to Tn5041 and 1 to Tn5044; three transposons were negative in this test. Restriction mapping and DNA sequencing revealed that 12 transposons were identical or nearly identical to their corresponding relatives while the rest showed varying divergence from their closest relatives. Most of these previously unknown transposons apparently arose as a result of homologous or site-specific recombination. One of these, Tn5046, was completely sequenced, and shown to be a chimera with the mer operon and the transposition module derived from the transposons related to Tn5041 and to Tn5044, respectively. Transposon Tn5070, showing no hybridization with the specific probes used in this study, was also completely sequenced. The transposition module of Tn5070 was most closely related to that of Tn3 while the mer operon was most closely related to that of plasmid pMERPH. The merR of Tn5070 is transcribed in the same direction as the mer structural genes, which is typical for mer operons of gram-positive bacteria. Our data suggest that environmental bacteria may harbor many not yet recognized mercury resistance transposons and warrant their further inventory. | 2001 | 11763242 |
| 3036 | 18 | 0.9893 | Complete nucleotide sequences of 84.5- and 3.2-kb plasmids in the multi-antibiotic resistant Salmonella enterica serovar Typhimurium U302 strain G8430. The multi-antibiotic resistant (MR) Salmonella enterica serovar Typhimurium phage type U302 strain G8430 exhibits the penta-resistant ACSSuT-phenotype (ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracycline), and is also resistant to carbenicillin, erythromycin, kanamycin, and gentamicin. Two plasmids, 3.2- and 84.5-kb in size, carrying antibiotic resistance genes were isolated from this strain, and the nucleotide sequences were determined and analyzed. The 3.2-kb plasmid, pU302S, belongs to the ColE1 family and carries the aph(3')-I gene (Kan(R)). The 84.5-kb plasmid, pU302L, is an F-like plasmid and contains 14 complete IS elements and multiple resistance genes including aac3, aph(3')-I, sulII, tetA/R, strA/B, bla(TEM-1), mph, and the mer operon. Sequence analyses of pU302L revealed extensive homology to various plasmids or transposons, including F, R100, pHCM1, pO157, and pCTX-M3 plasmids and TnSF1 transposon, in regions involved in plasmid replication/maintenance functions and/or in antibiotic resistance gene clusters. Though similar to the conjugative plasmids F and R100 in the plasmid replication regions, pU302L does not contain oriT and the tra genes necessary for conjugal transfer. This mosaic pattern of sequence similarities suggests that pU302L acquired the resistance genes from a variety of enteric bacteria and underscores the importance of a further understanding of horizontal gene transfer among the enteric bacteria. | 2007 | 16828159 |
| 1763 | 19 | 0.9892 | Multidrug Resistance Genes Carried by a Novel Transposon Tn7376 and a Genomic Island Named MMGI-4 in a Pathogenic Morganella morganii Isolate. Antimicrobial resistance in Morganella morganii is increasing in recent years, which is mainly introduced via extra genetic and mobile elements. The aim of our study is to analyze the multidrug resistance (MDR) and characterize the mobile genetic elements (MGEs) in M. morganii isolates. Here, we report the characteristic of a pathogenic M. morganii isolate containing multidrug resistance genes that are mainly carried by a novel transposon Tn7376 and a genomic island. Sequence analysis suggested that the Tn7376 could be generated through homologous recombination between two different IS26-bounded translocatable units (TUs), namely, module A (IS26-Hp-IS26-mph(A)-mrx(A)-mphR-IS6100-chrA-sul1-qacEΔ1) and module B (ISCR1-sul1-qacEΔ1-cmlA1-aadA1-aadB-intI1-IS26), and the genomic island named MMGI-4 might derive from a partial structure of different original genomic islands that also carried IS26-mediated TUs. Notably, a 2,518-bp sequence linked to the module A and B contains a 570-bp dfrA24 gene. To the best of our knowledge, this is the first report of the novel Tn7376 possessing a complex class 1 integron that carried an infrequent gene dfrA24 in M. morganii. IMPORTANCE Mobile genetic elements (MGEs), especially for IS26-bounded translocatable units, may act as a reservoir for a variety of antimicrobial resistance genes in clinically important pathogenic bacteria. We expounded this significant genetic characteristic by investigating a representative M. morganii isolate containing multidrug resistance genes, including the infrequent dfrA24. Our study suggested that these acquired resistance genes were mainly driven by IS26-flanked important MGEs, such as the novel Tn7376 and the MMGI-4. We demonstrated that IS26-related MGEs contributed to the emergence of the extra gene dfrA24 in M. morganii through some potential genetic events like recombination, transposition, and integration. Therefore, it is of importance to investigate persistently the prevalence these MEGs in the clinical pathogens to provide risk assessment of emergence and development of novel resistance genes. | 2022 | 35510850 |