fpr
 , a Deficient Xer Recombination Site from a
 Salmonella
 Plasmid, Fails To Confer Stability by Dimer Resolution: Comparative Studies with the pJHCMW1
 mwr
 Site

Tran, Tung; Sherratt, David J.; Tolmasky, Marcelo E.

doi:10.1128/jb.01082-09

Cited by 10 publications

(15 citation statements)

References 25 publications

(22 reference statements)

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“…Figure 3C shows that the level of resolution of dimers containing pbr1 or pbr2 is considerably lower than those of the controls containing cer or mwr. We have shown before that levels of resolution as low as that one exhibited by mwr-harboring dimers in cells grown in L broth containing 0.5% NaCl are not enough to confer stability by multimer resolution (34,35). As shown in Fig.…”

Section: Resultsmentioning

confidence: 94%

Small Plasmids Harboring qnrB19 : a Model for Plasmid Evolution Mediated by Site-Specific Recombination at oriT and Xer Sites

Tran

Andres

Petroni

et al. 2012

Antimicrob Agents Chemother

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Plasmids pPAB19-1, pPAB19-2, pPAB19-3, and pPAB19-4, isolated from Salmonella and Escherichia coli clinical strains from hospitals in Argentina, were completely sequenced. These plasmids include the qnrB19 gene and are 2,699, 3,082, 2,989, and 2,702 nucleotides long, respectively, and they share extensive homology among themselves and with other previously described small qnrB19-harboring plasmids. The genetic environment of qnrB19 in all four plasmids is identical to that in these other plasmids and in transposons such as Tn2012, Tn5387, and Tn5387-like. Nucleotide sequence comparisons among these and previously described plasmids showed a variable region characterized by being flanked by an oriT locus and a Xer recombination site. We propose that this arrangement could play a role in the evolution of plasmids and present a model for DNA swapping between plasmid molecules mediated by site-specific recombination events at oriT and a Xer target site. Qnrs are pentapeptide repeat proteins that mediate resistance to quinolones by protecting type II DNA topoisomerases (14, 28). They are known since 1998 when the first qnr gene was found in the multiresistance plasmid pMG252 harbored by a Klebsiella pneumoniae strain isolated from the urine of a patient at the University of Alabama (20). Since then five qnr families (qnrA, qnrB, qnrC, qnrD, and qnrS) have been found, usually hosted in large plasmids (31). The first qnrB gene (qnrB1) was identified in a plasmid from a K. pneumoniae strain isolated in South India (16), and 38 members of the family quickly followed (http://www.lahey .org/qnrStudies/) (13). The qnrB19 gene has been found in several genera of Enterobacteriaceae isolated from humans (healthy people and clinical isolates), animals, and food of animal origin in numerous geographical regions (6,9,12,17,21,22,27). An interesting characteristic of the qnrB19 allele is that it has been found within large plasmids, associated to ISEcp1C-based transposons (6,9,27), and in small plasmids (ϳ3 kbp) lacking ISEcp1C or any other insertion sequence (12,17,22) (Table 1). However, in spite of being located in such dissimilar elements, the qnrB19 genes share a conserved genetic environment (22).We have recently analyzed a collection of clinical enterobacterial isolates with decreased quinolone susceptibility, and we found four small plasmids harboring qnrB19 (2). We describe here their molecular features and characterize their relationships with other qnrB19-harboring genetic platforms. Furthermore, we propose possible pathways of evolution of the qnrB19 environment as well as a site-specific recombination-based model for DNA modifications at a variable region found in these plasmids. MATERIALS AND METHODSBacterial strains and plasmids. The plasmids pPAB19-1, pPAB19-2, pPAB19-3, and pPAB19-4 analyzed in the present study were isolated from Salmonella enterica serovar Infantis M7849, Escherichia coli M9996, E. coli M9888, and Salmonella sp. strain M9397, respectively (Table 1). Salmonella Infantis M7849 was isolated at the ...

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Section: Resultsmentioning

confidence: 94%

Small Plasmids Harboring qnrB19 : a Model for Plasmid Evolution Mediated by Site-Specific Recombination at oriT and Xer Sites

Tran

Andres

Petroni

et al. 2012

Antimicrob Agents Chemother

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“…These sites have been detected so far only on two natural plasmids, pJHCMW1 (22) and pFPTB1 (29), in a Salmonella enterica serovar Typhimurium isolate and in a K. pneumoniae isolate, respectively (22,29), each carrying a transposon inserted about 20 bp downstream of Xer. It has been postulated that multimer resolution of these plasmids is provided by the transposon resolvase besides the Xer system, suggesting that they form a group of plasmids whose stability is significantly enhanced by transposon acquisition (28). pKBuS13 is, to our knowledge, the third natural plasmid belonging to this group.…”

Section: Resultsmentioning

confidence: 99%

“…pKBuS13 is, to our knowledge, the third natural plasmid belonging to this group. However, its Xer recombination system is probably ineffective because the fpr site is the less efficient among those detected in the core region (28), and, most importantly, its accessory region is broken by Tn4401b insertion. Xer system inactivity is supported by two observations: (i) under nonselective conditions, both K. pneumoniae KBu-1 and E. coli JM101 lost pKBuS13 at approximately the same rate of pUC19, which lacks an Xer recombination site and is randomly partitioned during cell division (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This locus, involved in the resolution of plasmid multimers (26), usually consists of a core region containing the binding sites for two recombinases (XerC and XerD) and an accessory region, which provides the binding sites for the specific accessory proteins needed for the regulation of the entire process. Different core recombination sites have been described (mwr, psi, cer, dif, dxs, and fpr), which work with different efficiency and are regulated by different accessory proteins (27,28). Two of them, mwr and fpr, are osmoregulated: that is, at high salt concentrations their recombination efficiency is lower than that required for multimers resolution.…”

Section: Resultsmentioning

confidence: 99%

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pKBuS13, a KPC-2-Encoding Plasmid from Klebsiella pneumoniae Sequence Type 833, Carrying Tn 4401b Inserted into an Xer Site-Specific Recombination Locus

Garbari

Busetti

Dolzani

et al. 2015

Antimicrob Agents Chemother

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Here, we report the first detection of a Klebsiella pneumoniae carbapenemase 2 (KPC-2)-producing Klebsiella pneumoniae strain belonging to sequence type 833 (ST833), collected in an Italian hospital from a patient coming from South America. Its bla KPC determinant was carried by a ColE1 plasmid, pKBuS13, that showed the Tn4401b::bla KPC-2 transposon inserted into the regulatory region of an Xer site-specific recombination locus. This interfered with the correct resolution of plasmid multimers into monomers, lowering plasmid stability and leading to overestimation of the number of plasmids harbored by a single host cell. Sequencing of the fragments adjacent to Tn4401b detected a region that did not have significant matches in databases other than the genome of a carbapenem-resistant Escherichia coli strain collected during the same year at a hospital in Boston. This is interesting in an epidemiologic context, as it suggests that despite the absence of tra genes and the instability under nonselective conditions, the circulation of pKBuS13 or of analogous plasmids might be wider than reported. During the last decade, Klebsiella pneumoniae strains producing K. pneumoniae carbapenemase (KPC) enzymes have become a matter of great concern, as they are often susceptible to only a few antibiotics, cause high mortality among patients with bloodstream infections, and are increasingly being reported worldwide (1).KPC-type beta-lactamases include 22 variants (http://www .lahey.org/Studies/other.asp) that have been detected in a large number of K. pneumoniae lineages. Among them, KPC-2 and KPC-3 are predominant and largely disseminated worldwide by strains belonging to the clonal complex 258 (CC258), including the sequence type 258 (ST258) lineage defined by multilocus sequence typing (MLST) and its single-locus variants (e.g., ST11, ST437, and ST512) (2-6). Dissemination of bla KPC genes is fueled by their association with Tn4401, a 10-kb Tn3-like element that has been detected on plasmids belonging to different incompatibility groups (FII, N, L/M) and of different sizes (10 to 170 kb) (7).In Italy, KPC-producing K. pneumoniae (KPC-K. pneumoniae) strains have increasingly been reported since 2009 (8). Most of them belong to the globally spread ST258 and ST512 clones, but some isolates of different STs (ST101 and ST307) have been detected too (9).In the present work, we report the isolation in the Trieste area (northeast Italy) of a KPC-K. pneumoniae strain belonging to ST833 from the blood culture of a patient coming from a Venezuelan hospital. ST833 is a single locus variant of ST11, which has recently been described as one of the lineages responsible for dissemination of bla KPC determinants carried on different plasmids in Latin America (2, 10, 11). To our knowledge, this is the first finding of a KPC-K. pneumoniae strain belonging to ST833. In addition we describe its bla KPC-2 -carrying plasmid, which shows interesting features in an epidemiologic context. MATERIALS AND METHODSBacterial strains and growth conditions. Th...

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“…3) (78). It is of interest that numerous Xer site-specific recombination sites with identical deficiency in the ARG box have been detected and in some cases experiments demonstrated that they mediate dimer resolution at low efficiency (81). This fact, taken together with other findings like the presence of Xer site-specific recombination sites flanking blaOXA genes in Acinetobacter plasmids (90, 93-96) or the presence of different DNA fragments flanked by a Xer recombination site and an oriT in otherwise identical plasmids (54, 88) leads to the idea that not all Xer recombination sites stabilize plasmids by multimer resolution but may play other, or additional, roles related to plasmid evolution.…”

Section: Small Plasmidsmentioning

confidence: 99%

Plasmid-Mediated Antibiotic Resistance and Virulence in Gram-Negatives: the Klebsiella pneumoniae Paradigm

et al. 2014

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Summary Plasmids harbor genes coding for specific functions including virulence factors and antibiotic resistance that permit bacteria to survive the hostile environment found in the host and resist treatment. Together with other genetic elements such as integrons and transposons, and using a variety of mechanisms, plasmids participate in the dissemination of these traits resulting in the virtual elimination of barriers among different kinds of bacteria. In this article we review the current information about physiology and role in virulence and antibiotic resistance of plasmids from the gram-negative opportunistic pathogen Klebsiella pneumoniae. This bacterium has acquired multidrug resistance and is the causative agent of serious communityand hospital-acquired infections. It is also included in the recently defined ESKAPE group of bacteria that cause most of US hospital infections.

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fpr , a Deficient Xer Recombination Site from a Salmonella Plasmid, Fails To Confer Stability by Dimer Resolution: Comparative Studies with the pJHCMW1 mwr Site

Cited by 10 publications

References 25 publications

Small Plasmids Harboring qnrB19 : a Model for Plasmid Evolution Mediated by Site-Specific Recombination at oriT and Xer Sites

Small Plasmids Harboring qnrB19 : a Model for Plasmid Evolution Mediated by Site-Specific Recombination at oriT and Xer Sites

pKBuS13, a KPC-2-Encoding Plasmid from Klebsiella pneumoniae Sequence Type 833, Carrying Tn 4401b Inserted into an Xer Site-Specific Recombination Locus

Plasmid-Mediated Antibiotic Resistance and Virulence in Gram-Negatives: the Klebsiella pneumoniae Paradigm

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