Conjugative Plasmids of Streptomyces

1993 ◽  
pp. 293-311 ◽  
Author(s):  
David A. Hopwood ◽  
Tobias Kieser
Keyword(s):  
Conjugative Plasmids

scholarly journals Conjugative plasmids: vessels of the communal gene pool

2009 ◽  
Vol 364 (1527) ◽  
pp. 2275-2289 ◽  
Author(s):  
Anders Norman ◽  
Lars H. Hansen ◽  
Søren J. Sørensen
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Significant Contribution ◽  
Prokaryotic Genome ◽  
Whole Genome ◽  
Adaptive Traits ◽  
Conjugative Plasmids ◽  
Environmental Setting ◽  
Genome Analyses ◽  
Insight Into

Comparative whole-genome analyses have demonstrated that horizontal gene transfer (HGT) provides a significant contribution to prokaryotic genome innovation. The evolution of specific prokaryotes is therefore tightly linked to the environment in which they live and the communal pool of genes available within that environment. Here we use the term supergenome to describe the set of all genes that a prokaryotic ‘individual’ can draw on within a particular environmental setting. Conjugative plasmids can be considered particularly successful entities within the communal pool, which have enabled HGT over large taxonomic distances. These plasmids are collections of discrete regions of genes that function as ‘backbone modules’ to undertake different aspects of overall plasmid maintenance and propagation. Conjugative plasmids often carry suites of ‘accessory elements’ that contribute adaptive traits to the hosts and, potentially, other resident prokaryotes within specific environmental niches. Insight into the evolution of plasmid modules therefore contributes to our knowledge of gene dissemination and evolution within prokaryotic communities. This communal pool provides the prokaryotes with an important mechanistic framework for obtaining adaptability and functional diversity that alleviates the need for large genomes of specialized ‘private genes’.

scholarly journals Novel Conjugative Plasmid from Escherichia coli of Swine Origin That Coharbors the Multiresistance Genecfrand the Extended-Spectrum-β-Lactamase GeneblaCTX-M-14b

2014 ◽  
Vol 59 (2) ◽  
pp. 1337-1340 ◽  
Author(s):  
Wan-Jiang Zhang ◽  
Xiu-Mei Wang ◽  
Lei Dai ◽  
Xin Hua ◽  
Zhimin Dong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Conjugative Plasmid ◽  
Content Type ◽  
Conjugative Plasmids ◽  
Extended Spectrum ◽  
Lactamase Gene

ABSTRACTTwo porcineEscherichia coliisolates harbored thecfrgene on conjugative plasmids of 38,405 bp (pGXEC6) and 41,646 bp (pGXEC3). In these two plasmids, thecfrgene was located within a 4,612-bp region containing atnpA-IS26-cfr-IS26-Δhypelement. Plasmid pGXEC3 was almost identical to pGXEC6 except for a 3,235-bp ISEcp1-blaCTX-M-14binsertion. The colocation of the multiresistancecfrgene with an extended-spectrum-β-lactamase gene on a conjugative plasmid may support the dissemination of these genes by coselection.

scholarly journals Prevalence and Molecular Characterization of mcr-1-Positive Salmonella Strains Recovered from Clinical Specimens in China

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Mingquan Cui ◽  
Jinfei Zhang ◽  
Zhen Gu ◽  
Ruichao Li ◽  
Edward Wai-chi Chan ◽  
...  
Keyword(s):  
Pulsed Field Gel Electrophoresis ◽  
Clinical Settings ◽  
Colistin Resistance ◽  
Content Type ◽  
Transmission Potential ◽  
Conjugative Plasmids ◽  
Plasmid Analysis ◽  
Antimicrobial Resistance Genes ◽  
Pfge Profiles

ABSTRACT The recently discovered colistin resistance element, mcr-1, adds to the list of antimicrobial resistance genes that rapidly erode the antimicrobial efficacy of not only the commonly used antibiotics but also the last-line agents of carbapenems and colistin. This study investigated the prevalence of the mobile colistin resistance determinant mcr-1 in Salmonella strains recovered from clinical settings in China and the transmission potential of mcr-1-bearing mobile elements harbored by such isolates. The mcr-1 gene was recoverable in 1.4% of clinical isolates tested, with the majority of them belonging to Salmonella enterica serotype Typhimurium. These isolates exhibited diverse pulsed-field gel electrophoresis (PFGE) profiles and high resistance to antibiotics other than colistin and particularly to cephalosporins. Plasmid analysis showed that mcr-1 was carried on a variety of plasmids with sizes ranging from ∼30 to ∼250 kb, among which there were conjugative plasmids of ∼30 kb, ∼60 kb, and ∼250 kb and nonconjugative plasmids of ∼140 kb, ∼180 kb, and ∼240 kb. Sequencing of representative mcr-1-carrying plasmids revealed that all conjugative plasmids belonged to the IncX4, IncI2, and IncHI2 types and were highly similar to the corresponding types of plasmids reported previously. Nonconjugative plasmids all belonged to the IncHI2 type, and the nontransferability of these plasmids was attributed to the loss of a region carrying partial or complete tra genes. Our data revealed that, similar to the situation in Escherichia coli, mcr-1 transmission in Salmonella was accelerated by various plasmids, suggesting that transmission of mcr-1-carrying plasmids between different species of Enterobacteriaceae may be a common event.

Molecular analyses of conjugative, gentamicin-resistance plasmids from staphylococcal clinical isolates

1988 ◽  
Vol 34 (9) ◽  
pp. 1050-1057 ◽  
Author(s):  
Ioannis Zorbas ◽  
Robert T. Hall ◽  
Sue L. Hall ◽  
William G. Barnes ◽  
Marvin Rogolsky
Keyword(s):  
Restriction Endonuclease ◽  
Clinical Isolates ◽  
Genetic Determinants ◽  
Conjugative Plasmids ◽  
Molecular Weights ◽  
Geographical Regions ◽  
Gentamicin Resistance ◽  
Ecori Restriction ◽  
High Degree ◽  
Endonuclease Digestion

Gentamicin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains which were isolated from infants with staphylococcal bacteremia were analyzed for the presence of self-transmissible gentamicin-resistance (Gmr) plasmids. Conjugative GMr plasmids of approximately 43.8–63 kilobases (kb) were found in all S. aureus strains. Inter- and intra-species transfer of Gmr plasmids by conjugation was observed from S. aureus to S. aureus and to S. epidermidis recipient strains. However, neither inter- nor intra-species transfer of gentamicin resistance by conjugation was observed with nine out of nine S. epidermidis donor strains which were mated with either S. epidermidis or S. aureus recipient strains. These conjugative Gmr plasmids were unable to comobilize a smaller (15-kb) plasmid present in all but two S. aureus clinical isolates. Many of the conjugative Gmr plasmids also carried genetic determinants for kanamycin, tobramycin, neomycin, and ethidium bromide resistance, and for β-lactamase synthesis. EcoRI restriction endonuclease digests of the S. aureus Gmr conjugative plasmids revealed three different digestion patterns. Four EcoRI restriction endonuclease digestion fragments of 15, 11.4, 6.3, and 4.6 kb in size were common to all plasmids. These plasmids and conjugative Gmr staphylococcal plasmids from other geographical regions shared restriction digestion fragments of similar molecular weights. DNA hybridization with biotinylated S. aureus plasmid pIZ7814 DNA revealed a high degree of homology among these plasmids. A 50.9-kb plasmid from one of the nonconjugative S. epidermidis clinical isolates showed homology with the probe DNA but lacked a portion of a 6.3-kb fragment which was present in all conjugative plasmids and believed to carry much genetic information for conjugation.

scholarly journals Plasmid-encoded H-NS controls extracellular matrix composition in a modern Acinetobacter baumannii urinary isolate

2021 ◽  
Author(s):  
Saida Benomar ◽  
Gisela Di Venanzio ◽  
Mario F. Feldman
Keyword(s):  
Extracellular Matrix ◽  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Gene Cluster ◽  
Biofilm Formation ◽  
Therapeutic Potential ◽  
Matrix Composition ◽  
Type Vi Secretion System ◽  
Gram Negative ◽  
Conjugative Plasmids

Acinetobacter baumannii is emerging as a multidrug-resistant (MDR) nosocomial pathogen of increasing threat to human health worldwide. The recent MDR urinary isolate UPAB1 carries the plasmid pAB5, a member of a family of large conjugative plasmids (LCP). LCP encode several antibiotic resistance genes and repress the type VI secretion system (T6SS) to enable their dissemination, employing two TetR transcriptional regulators. Furthermore, pAB5 controls the expression of additional chromosomally encoded genes, impacting UPAB1 virulence. Here we show that a pAB5-encoded H-NS transcriptional regulator represses the synthesis of the exopolysaccharide PNAG and the expression of a previously uncharacterized three-gene cluster that encodes a protein belonging to the CsgG/HfaB family. Members of this protein family are involved in amyloid or polysaccharide formation in other species. Deletion of the CsgG homolog abrogated PNAG production and CUP pili formation, resulting in a subsequent reduction in biofilm formation. Although this gene cluster is widely distributed in Gram-negative bacteria, it remains largely uninvestigated. Our results illustrate the complex cross-talks that take place between plasmids and the chromosomes of their bacterial host, which in this case can contribute to the pathogenesis of Acinetobacter . IMPORTANCE The opportunistic human pathogen Acinetobacter baumannii displays the highest reported rates of multidrug resistance among Gram-negative pathogens. Many A. baumannii strains carry large conjugative plasmids like pAB5. In recent years, we have witnessed an increase in knowledge about the regulatory cross-talks between plasmids and bacterial chromosomes. Here we show that pAB5 controls the composition of the bacterial extracellular matrix, resulting in a drastic reduction in biofilm formation. The association between biofilm formation, virulence, and antibiotic resistance is well-documented. Therefore, understanding the factors involved in the regulation of biofilm formation in Acinetobacter has remarkable therapeutic potential.

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