scholarly journals Persistent, Toxin-Antitoxin System-Independent, Tetracycline Resistance-Encoding Plasmid from a Dairy Enterococcus faecium Isolate

2011 ◽  
Vol 77 (20) ◽  
pp. 7096-7103 ◽  
Author(s):  
Xinhui Li ◽  
Valente Alvarez ◽  
Willis James Harper ◽  
Hua H. Wang
Keyword(s):  
Gene Cluster ◽  
Enterococcus Faecium ◽  
Retention Rate ◽  
Acquired Resistance ◽  
Tetracycline Resistance ◽  
Open Reading Frames ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Plasmid Stabilization ◽  
Encoding Genes

ABSTRACTA tetracycline-resistant (Tetr) dairyEnterococcus faeciumisolate designated M7M2 was found to carry bothtet(M) andtet(L) genes on a 19.6-kb plasmid. After consecutive transfer in the absence of tetracycline, the resistance-encoding plasmid persisted in 99% of the progenies. DNA sequence analysis revealed that the 19.6-kb plasmid contained 28 open reading frames (ORFs), including atet(M)-tet(L)-mobgene cluster, as well as a 10.6-kb backbone highly homologous (99.9%) to the reported plasmid pRE25, but without an identified toxin-antitoxin (TA) plasmid stabilization system. The derived backbone plasmid without the Tetrdeterminants exhibited a 100% retention rate in the presence of acridine orange, suggesting the presence of a TA-independent plasmid stabilization mechanism, with its impact on the persistence of a broad spectrum of resistance-encoding traits still to be elucidated. Thetet(M)-tet(L) gene cluster from M7M2 was functional and transmissible and led to acquired resistance inEnterococcus faecalisOG1RF by electroporation and inStreptococcus mutansUA159 by natural transformation. Southern hybridization showed that both thetet(M) andtet(L) genes were integrated into the chromosome ofS. mutansUA159, while the whole plasmid was transferred to and retained inE. faecalisOG1RF. Quantitative real-time reverse transcription-PCR (RT-PCR) indicated tetracycline-induced transcription of both thetet(M) andtet(L) genes of pM7M2. The results indicated that multiple mechanisms might have contributed to the persistence of antibiotic resistance-encoding genes and that the plasmids pM7M2, pIP816, and pRE25 are likely correlated evolutionarily.

scholarly journals Establishment of anIn Vitrod-Cycloserine-Synthesizing System by UsingO-Ureido-l-Serine Synthase and d-Cycloserine Synthetase Found in the Biosynthetic Pathway

2013 ◽  
Vol 57 (6) ◽  
pp. 2603-2612 ◽  
Author(s):  
Narutoshi Uda ◽  
Yasuyuki Matoba ◽  
Takanori Kumagai ◽  
Kosuke Oda ◽  
Masafumi Noda ◽  
...  
Keyword(s):  
Gene Cluster ◽  
High Performance ◽  
Sequence Similarity ◽  
Open Reading Frames ◽  
Homocysteine Thiolactone ◽  
Putative Gene ◽  
Content Type ◽  
Dna Fragment ◽  
Layer Chromatography

ABSTRACTWe have recently cloned a DNA fragment containing a gene cluster that is responsible for the biosynthesis of an antituberculosis antibiotic,d-cycloserine. The gene cluster is composed of 10 open reading frames, designateddcsAtodcsJ. Judging from the sequence similarity between each putative gene product and known proteins, DcsC, which displays high homology to diaminopimelate epimerase, may catalyze the racemization ofO-ureidoserine. DcsD is similar toO-acetylserine sulfhydrylase, which generatesl-cysteine usingO-acetyl-l-serine with sulfide, and therefore, DcsD may be a synthase to generateO-ureido-l-serine usingO-acetyl-l-serine and hydroxyurea. DcsG, which exhibits similarity to a family of enzymes with an ATP-grasp fold, may be an ATP-dependent synthetase convertingO-ureido-d-serine intod-cycloserine. In the present study, to characterize the enzymatic functions of DcsC, DcsD, and DcsG, each protein was overexpressed inEscherichia coliand purified to near homogeneity. The biochemical function of each of the reactions catalyzed by these three proteins was verified by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and, in some cases, mass spectrometry. The results from this study demonstrate that by using a mixture of the three purified enzymes and the two commercially available substratesO-acetyl-l-serine and hydroxyurea, synthesis ofd-cycloserine was successfully attained. Thesein vitrostudies yield the conclusion that DcsD and DcsG are necessary for the syntheses ofO-ureido-l-serine andd-cycloserine, respectively. DcsD was also able to catalyze the synthesis ofl-cysteine when sulfide was added instead of hydroxyurea. Furthermore, the present study shows that DcsG can also form other cyclicd-amino acid analogs, such asd-homocysteine thiolactone.

scholarly journals Novel Plasmid-Borne Multidrug Resistance Gene Cluster Includinglsa(E) from a Linezolid-Resistant Enterococcus faecium Isolate of Swine Origin

2015 ◽  
Vol 59 (11) ◽  
pp. 7113-7116 ◽  
Author(s):  
Hongbin Si ◽  
Wan-Jiang Zhang ◽  
Shengbo Chu ◽  
Xiu-Mei Wang ◽  
Lei Dai ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Gene Cluster ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Insertion Element ◽  
Multidrug Resistance Gene ◽  
Content Type ◽  
Recombination Processes ◽  
Faecium Isolate

ABSTRACTA novel nonconjugative plasmid of 28,489 bp from a porcine linezolid-resistantEnterococcus faeciumisolate was completely sequenced. This plasmid harbored a novel type of multiresistance gene cluster that comprised the resistance geneslnu(B),lsa(E),spw,aadE,aphA3, and two copies oferm(B), which account for resistance to macrolides, lincosamides, streptogramins, pleuromutilins, streptomycin, spectinomycin, and kanamycin/neomycin. Structural comparisons suggested that this plasmid might have developed from other enterococcal plasmids by insertion element (IS)-mediated interplasmid recombination processes.

Functional characterization of a gene cluster responsible for inositol catabolism associated with hospital-adapted isolates of Enterococcus faecium

Microbiology ◽  
2021 ◽  
Vol 167 (9) ◽  
Author(s):  
Janetta Top ◽  
Jery Baan ◽  
Adinda Bisschop ◽  
Sergio Arredondo-Alonso ◽  
Willem van Schaik ◽  
...  
Keyword(s):  
Mouse Model ◽  
Gene Cluster ◽  
Enterococcus Faecium ◽  
Type Species ◽  
Integration Site ◽  
Functional Characterization ◽  
Donor Strain ◽  
Integrase Gene ◽  
Content Type ◽  
Link Type

Enterococcus faecium is a nosocomial, multidrug-resistant pathogen. Whole genome sequence studies revealed that hospital-associated E. faecium isolates are clustered in a separate clade A1. Here, we investigated the distribution, integration site and function of a putative iol gene cluster that encodes for myo-inositol (MI) catabolism. This iol gene cluster was found as part of an ~20 kbp genetic element (iol element), integrated in ICEEfm1 close to its integrase gene in E. faecium isolate E1679. Among 1644 E. faecium isolates, ICEEfm1 was found in 789/1227 (64.3 %) clade A1 and 3/417 (0.7 %) non-clade A1 isolates. The iol element was present at a similar integration site in 180/792 (22.7 %) ICEEfm1-containing isolates. Examination of the phylogenetic tree revealed genetically closely related isolates that differed in presence/absence of ICEEfm1 and/or iol element, suggesting either independent acquisition or loss of both elements. E. faecium iol gene cluster containing isolates E1679 and E1504 were able to grow in minimal medium with only myo-inositol as carbon source, while the iolD-deficient mutant in E1504 (E1504∆iolD) lost this ability and an iol gene cluster negative recipient strain gained this ability after acquisition of ICEEfm1 by conjugation from donor strain E1679. Gene expression profiling revealed that the iol gene cluster is only expressed in the absence of other carbon sources. In an intestinal colonization mouse model the colonization ability of E1504∆iolD mutant was not affected relative to the wild-type E1504 strain. In conclusion, we describe and functionally characterise a gene cluster involved in MI catabolism that is associated with the ICEEfm1 island in hospital-associated E. faecium isolates. We were unable to show that this gene cluster provides a competitive advantage during gut colonisation in a mouse model. Therefore, to what extent this gene cluster contributes to the spread and ecological specialisation of ICEEfm1-carrying hospital-associated isolates remains to be investigated.

scholarly journals The Gene Cluster forpara-Nitrophenol Catabolism Is Responsible for 2-Chloro-4-Nitrophenol Degradation in Burkholderia sp. Strain SJ98

2014 ◽  
Vol 80 (19) ◽  
pp. 6212-6222 ◽  
Author(s):  
Jun Min ◽  
Jun-Jie Zhang ◽  
Ning-Yi Zhou
Keyword(s):  
Gene Cluster ◽  
Gene Knockout ◽  
Gene Clusters ◽  
Sole Source ◽  
Pcr Analysis ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Biochemical Analyses ◽  
Nitrophenol Degradation

ABSTRACTBurkholderiasp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) orpara-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of thepnpgenes in thepnpABA1CDEFcluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activityin vitroin the conversion of 2C4NP to CBQ. Genetic analyses indicated thatpnpAplays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.

scholarly journals Genetic Characterization of Plasmid-Borne blaOXA-58 in Distinct Acinetobacter Species

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Adriana P. Matos ◽  
Rodrigo Cayô ◽  
Luiz G. P. Almeida ◽  
Ana Paula Streling ◽  
Carolina S. Nodari ◽  
...  
Keyword(s):  
Open Reading Frames ◽  
South American ◽  
Acinetobacter Species ◽  
Content Type ◽  
Clinical Strains ◽  
Carbapenem Resistant ◽  
Encoding Genes ◽  
Reading Frames ◽  
Over Time

ABSTRACT We characterize by whole-plasmid-sequence (WPS) two-plasmid-borne blaOXA-58 obtained from Acinetobacter seifertii (Asp-1069) and A. baumannii (Acb-45063) clinical strains recovered 17 years apart from distinct Brazilian regions. Multilocus sequence type (MLST) analysis showed that the Asp-1069 and Acb-45063 strains belong to ST551 and ST15/CC15, respectively. WPS analysis demonstrated that blaOXA-58 was located in two distinct plasmids named pAs1069_a (24,672 bp/44 open reading frames [ORFs]) and pAb45063_b (19,808 bp/24 ORFs), which belong to the GR8/GR23 (repAci23) and GR4 (repAci4) incompatibility groups, respectively. The genetic environments surrounding blaOXA-58 revealed that it was flanked by two intact ISAba3 copies on pAb45063_b, which differed from pAs1069_a. In the latter, the upstream ISAba3 copy was truncated by insertion of ISAba825 element. Although Re27-specific recombination sites were found adjacent to ISAba3-blaOXA-58-ISAba3 arrangement on pAb45063_b, such structures were absent on pAs1069_a. The conserved ISAba125-araC1-lysE arrangement was disrupted by TnaphA6 harboring the aminoglycosides resistance gene aphA6 on pAs1069_a, while an IS26-blaTEM-1-aac(3)-IIa-IS26 genetic structure was found upstream from ISAba3-blaOXA-58-ISAba3 on pAb45063_b. Other two plasmids, pAb45063_a (183,767 bp/209 ORFs) and pAs1069_b (13,129 bp/14 ORFs), were also found in the OXA-58-producing Acinetobacter species strains, harboring the strA and strB genes and the sul2 gene, which confer resistance to streptomycin and sulfonamides, respectively. The plasmid-mediated virulence factors corresponding to genes tonB, spl, glmM, ppa, sulP, and map were found in both strains, as well distinct toxin-antitoxin system-encoding genes stbD and relE (pAs1069_a), brnT and brnA (pAb45063_b), and xreE (pAb45063_a). Although infrequently reported in Brazil, plasmid-borne blaOXA-58 showed a complex and diverse genetic backbone that confers stability in different Acinetobacter species that have been isolated from nosocomial settings over time. IMPORTANCE Although the blaOXA-58 gene has been infrequently described in Brazil, contrasting with other bordering South American countries, we verified the maintenance of this resistance determinant over time among carbapenem-resistant Acinetobacter species isolates, not only in nosocomial settings but also in the environment. In addition, to the best of our knowledge, this is the first study to have used WPS analysis to evaluate the genetic surroundings of blaOXA-58 in Brazil. Moreover, the A. seifertii and A. baumannii clinical strains evaluated in this study were recovered 17 years apart in hospitals located in distinct Brazilian geographic regions.

scholarly journals Characterization of Maltocin P28, a Novel Phage Tail-Like Bacteriocin from Stenotrophomonas maltophilia

2013 ◽  
Vol 79 (18) ◽  
pp. 5593-5600 ◽  
Author(s):  
Jian Liu ◽  
Peng Chen ◽  
Congyi Zheng ◽  
Yu-Ping Huang
Keyword(s):  
Gene Cluster ◽  
Stenotrophomonas Maltophilia ◽  
Opportunistic Pathogen ◽  
Multidrug Resistant ◽  
Gene Organization ◽  
Open Reading Frames ◽  
Proteinase K ◽  
Major Protein ◽  
Content Type ◽  
Phage Tail

ABSTRACTStenotrophomonas maltophiliais an important global opportunistic pathogen for which limited therapeutics are available because of the emergence of multidrug-resistant strains. A novel bacteriocin, maltocin P28, which is produced byS. maltophiliastrain P28, may be the first identified phage tail-like bacteriocin fromS. maltophilia. Maltocin P28 resembles a contractile but nonflexible phage tail structure based on electron microscopy, and it is sensitive to trypsin, proteinase K, and heat. SDS-PAGE analysis of maltocin P28 revealed two major protein bands of approximately 43 and 20 kDa. The N-terminal amino acid residues of these two major subunits were sequenced, and the maltocin P28 gene cluster was located on theS. maltophiliaP28 chromosome. Our sequence analysis results indicate that this maltocin gene cluster consists of 23 open reading frames (ORFs), and that its gene organization is similar to that of the P2 phage genome and R2 pyocin gene cluster. ORF17 and ORF18 encode the two major structural proteins, which correspond to gpFI (tail sheath) and gpFII (tail tube) of P2 phage, respectively. We found that maltocin P28 had bactericidal activity against 38 of 81 testedS. maltophiliastrains. Therefore, maltocin P28 is a promising therapeutic substitute for antibiotics forS. maltophiliainfections.

scholarly journals Genomic Analysis of Reduced Susceptibility to Tigecycline in Enterococcus faecium

2014 ◽  
Vol 59 (1) ◽  
pp. 239-244 ◽  
Author(s):  
Vincent Cattoir ◽  
Christophe Isnard ◽  
Thibaud Cosquer ◽  
Arlène Odhiambo ◽  
Fiona Bucquet ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Enterococcus Faecium ◽  
Efflux Pump ◽  
Acquired Resistance ◽  
Ribosomal Subunit ◽  
Genomic Analysis ◽  
Lactate Oxidase ◽  
Content Type

ABSTRACTTigecycline (TIG) is approved for use for the treatment of complicated intra-abdominal infections, skin and skin structure infections, as well as pneumonia. Acquired resistance or reduced susceptibility to TIG has been observed in Gram-negative rods, has seldom been reported in Gram-positive organisms, and has not yet been reported inEnterococcus faecium. Using the serial passage method,in vitromutant AusTig andin vitromutants HMtig1 and HMtig2 with decreased TIG susceptibility (MICs, 0.25 μg/ml) were obtained from strainsE. faeciumAus0004 and HM1070 (MICs, 0.03 μg/ml), respectively. In addition, two vancomycin-resistantE. faeciumclinical isolates (EF16 and EF22) with reduced susceptibility to TIG (MICs, 0.5 and 0.25 μg/ml, respectively) were studied. Compared to the wild-type strains, thein vitromutants also showed an increase in the MICs of other tetracyclines. An efflux mechanism did not seem to be involved in the reduced TIG susceptibility, since the presence of efflux pump inhibitors (reserpine or pantoprazole) did not affect the MICs of TIG. Whole-genome sequencing of AusTig was carried out, and genomic comparison with the Aus0004 genome was performed. Four modifications leading to an amino acid substitution were found. These mutations affected therpsJgene (efau004_00094, coding for the S10 protein of the 30S ribosomal subunit),efau004_01228(encoding a cation transporter),efau004_01636(coding for a hypothetical protein), andefau004_02455(encoding thel-lactate oxidase). The four other strains exhibiting reduced TIG susceptibility were screened for the candidate mutations. This analysis revealed that three of them showed an amino acid substitution in the same region of the RpsJ protein. In this study, we characterized for the first time genetic determinants linked to reduced TIG susceptibility in enterococci.

scholarly journals The tet39 Determinant and the msrE-mphE Genes in Acinetobacter Plasmids Are Each Part of Discrete Modules Flanked by Inversely Oriented pdif (XerC-XerD) Sites

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Grace A. Blackwell ◽  
Ruth M. Hall
Keyword(s):  
Insertion Sequence ◽  
Insertion Site ◽  
Tetracycline Resistance ◽  
Open Reading Frames ◽  
Gene Encoding ◽  
Content Type ◽  
System A ◽  
Genes Encoding ◽  
Putative Toxin ◽  
Reading Frames

ABSTRACT The tet39 tetracycline resistance determinant and the macrolide resistance genes msrE and mphE were found in an 18.2-kb plasmid, pS30-1, recovered from a global clone 2 (GC2) Acinetobacter baumannii isolate from Singapore, that conferred resistance to tetracycline and erythromycin. pS30-1 also contains mobA and mobC genes encoding MOBQ family proteins, but attempts to mobilize pS30-1 utilizing a coresident conjugative repAci6 plasmid were unsuccessful. Eight pdif sites, consisting of inversely oriented binding sites for the XerC and XerD recombinases separated by 6 bp, were detected in pS30-1. The tet39 determinant and the msrE-mphE gene pair are each surrounded by two pdif sites in inverse orientation. Identical regions in different contexts and many previously unnoticed pdif sites were found in a number of different plasmids in GenBank, showing that the tet39 and msrE-mphE dif modules are mobile. A putative toxin/antitoxin system, a gene encoding a serine recombinase, and open reading frames of unknown function were also part of dif modules in pS30-1. In general, modules with internal XerC or XerD sites alternate. Two copies of ISAjo2-1 (94% identical to ISAjo2) in pS30-1 were inserted 5 bp from a XerC site, and this appears to be the preferred insertion site for this insertion sequence (IS) group. Apparently, Acinetobacter plasmids exploit the Acinetobacter XerC-XerD recombinases to mobilize DNA units containing resistance and other genes, via an uncharacterized mechanism. The tet39 and msrE-mphE dif modules add to the oxa24 module and the oxa58 module redefined here, bringing the total of resistance gene-containing dif modules in Acinetobacter plasmids to four.

scholarly journals Identification and Molecular Characterization of the Chromosomal Exopolysaccharide Biosynthesis Gene Cluster from Lactococcus lactis subsp. cremoris SMQ-461

2005 ◽  
Vol 71 (11) ◽  
pp. 7414-7425 ◽  
Author(s):  
N. Dabour ◽  
G. LaPointe
Keyword(s):  
Gene Cluster ◽  
Lactococcus Lactis ◽  
Repeat Unit ◽  
Raw Milk ◽  
Open Reading Frames ◽  
Pcr Analysis ◽  
Biosynthesis Gene Cluster ◽  
Glycosyltransferase Gene ◽  
Reverse Transcription Pcr ◽  
Exopolysaccharide Biosynthesis

ABSTRACT The exopolysaccharide (EPS) capsule-forming strain SMQ-461 of Lactococcus lactis subsp. cremoris, isolated from raw milk, produces EPS with an apparent molecular mass of >1.6 × 106 Da. The EPS biosynthetic genes are located on the chromosome in a 13.2-kb region consisting of 15 open reading frames. This region is flanked by three IS1077-related tnp genes (L. lactis) at the 5′ end and orfY, along with an IS981-related tnp gene, at the 3′ end. The eps genes are organized in specific regions involved in regulation, chain length determination, biosynthesis of the repeat unit, polymerization, and export. Three (epsGIK) of the six predicted glycosyltransferase gene products showed low amino acid similarity with known glycosyltransferases. The structure of the repeat unit could thus be different from those known to date for Lactococcus. Reverse transcription-PCR analysis revealed that the eps locus is transcribed as a single mRNA. The function of the eps gene cluster was confirmed by disrupting the priming glycosyltransferase gene (epsD) in Lactococcus cremoris SMQ-461, generating non-EPS-producing reversible mutants. This is the first report of a chromosomal location for EPS genetic elements in Lactococcus cremoris, with novel glycosyltransferases not encountered before in lactic acid bacteria.

scholarly journals Genotypic and Phenotypic Evaluation of the Evolution of High-Level Daptomycin Nonsusceptibility in Vancomycin-Resistant Enterococcus faecium

2012 ◽  
Vol 56 (11) ◽  
pp. 6051-6053 ◽  
Author(s):  
Romney M. Humphries ◽  
Theodoros Kelesidis ◽  
Ryan Tewhey ◽  
Warren E. Rose ◽  
Nicholas Schork ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Open Reading Frames ◽  
Vancomycin Resistant Enterococcus ◽  
Single Nucleotide Variants ◽  
Phosphotransferase System ◽  
Single Nucleotide ◽  
Content Type ◽  
Vancomycin Resistant ◽  
High Level ◽  
Reading Frames

ABSTRACTWhole-genome sequencing and cell membrane studies of three clonalEnterococcus faeciumstrains with daptomycin MICs of 4, 32, and 192 μg/ml were performed, revealing nonsynonymous single nucleotide variants in eight open reading frames, including those predicted to encode a phosphoenolpyruvate-dependent, mannose-specific phosphotransferase system, cardiolipin synthetase, and EzrA. Membrane studies revealed a higher net surface charge among the daptomycin-nonsusceptible isolates and increased septum formation in the isolate with a daptomycin MIC of 192 μg/ml.

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