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34800.9951Conjugative 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.201223082971
989010.9951The origin and evolution of IncF33 plasmids based on large-scale data sets. Plasmids that capture multiple antibiotic resistance genes are spreading widely, leading to the emergence and prevalence of multidrug-resistant bacteria. IncF33 plasmids are a newly emerged plasmid type highly prevalent in animal-source Enterobacterales in China, and they are important vectors for transmitting several clinically important antibiotic resistance genes. The study revealed that the IncF33 plasmid is mainly prevalent in China animal-derived Escherichia coli and has the potential for cointegration and intercontinental dissemination. Therefore, it is crucial to enhance surveillance and control measures to limit the spread of IncF33 plasmids and their associated antibiotic resistance genes.202337750716
983420.9949Exploring the role of phage plasmids in gene transfers. Bacteriophages and plasmids drive horizontal gene transfer (HGT) in bacteria. Phage-plasmids (P-Ps) are hybrids of plasmid and phages. Pfeifer and Rocha recently demonstrated that P-Ps can serve as intermediates in gene exchanges between these two types of elements, identified categories of preferentially transferred genes, and reconstructed gene flows involving phage P1-like P-Ps.202438688811
36030.9949Broad host range cloning vectors for gram-negative bacteria. A series of cloning vectors has been constructed based on the broad-host-range plasmid R300B. One of these vectors, pGSS33, has a size of 13.4 kb and carries four antibiotic resistance genes [ampicillin (Apr), chloramphenicol (Cmr), streptomycin (Smr) and tetracycline (Tcr)], all of which have restriction sites for insertional inactivation. The derivation, structure and uses of the plasmids are described.19846092235
981740.9949Common regions e.g. orf513 and antibiotic resistance: IS91-like elements evolving complex class 1 integrons. The ability of bacteria to procure, sometimes rearrange, and evince acquired DNA continues to impress us-even more so if this genetic plasticity involves the sequestering of antibiotic resistance genes. The acquisition of genes in bacteria is often facilitated by transposons, integrons and archetype insertion elements. Recently however, a new element, 'orf513', has been increasingly associated with class 1 integrons. Moreover, these 'complex' class 1 integrons can potentially mediate resistance to chloramphenicol, trimethoprim, aminoglycosides and tetracycline and may carry a range of beta-lactamase genes as well as the qnrA gene. Elements such as 'orf513' demonstrate IS91-like characteristics and will mobilize adjacent DNA via a process called rolling circle replication, and thus we have renamed them 'insertion sequence CRs' (ISCRs) to appropriately reflect their structure-function properties. In this article, we provide a brief description of these new and clinically important mobile elements, and how they are able to mobilize antibiotic resistance genes.200616751201
984350.9948Conjugative transposons: an unusual and diverse set of integrated gene transfer elements. Conjugative transposons are integrated DNA elements that excise themselves to form a covalently closed circular intermediate. This circular intermediate can either reintegrate in the same cell (intracellular transposition) or transfer by conjugation to a recipient and integrate into the recipient's genome (intercellular transposition). Conjugative transposons were first found in gram-positive cocci but are now known to be present in a variety of gram-positive and gram-negative bacteria also. Conjugative transposons have a surprisingly broad host range, and they probably contribute as much as plasmids to the spread of antibiotic resistance genes in some genera of disease-causing bacteria. Resistance genes need not be carried on the conjugative transposon to be transferred. Many conjugative transposons can mobilize coresident plasmids, and the Bacteroides conjugative transposons can even excise and mobilize unlinked integrated elements. The Bacteroides conjugative transposons are also unusual in that their transfer activities are regulated by tetracycline via a complex regulatory network.19958531886
987160.9948An Integrative and Conjugative Element (ICE) Found in Shewanella halifaxensis Isolated from Marine Fish Intestine May Connect Genetic Materials between Human and Marine Environments. Integrative and conjugative elements (ICEs) play a role in the horizontal transfer of antibiotic resistance genes (ARGs). We herein report an ICE from Shewanella halifaxensis isolated from fish intestine with a similar structure to both a clinical bacterial ICE and marine bacterial plasmid. The ICE was designated ICEShaJpn1, a member of the SXT/R391 family of ICEs (SRIs). ICEShaJpn1 has a common core structure with SRIs of clinical and fish origins and an ARG cassette with the pAQU1 plasmid of Photobacterium damselae subsp. damselae, suggesting that the common core of SRIs is widely distributed and ARG cassettes are collected from regional bacteria.202236058879
996070.9947Integrons, transposons and IS elements promote diversification of multidrug resistance plasmids and adaptation of their hosts to antibiotic pollutants from pharmaceutical companies. Plasmids are important vehicles for the dissemination of antibiotic resistance genes (ARGs) among bacteria by conjugation. Here, we determined the complete nucleotide sequences of nine different plasmids previously obtained by exogenous plasmid isolation from river and creek sediments and wastewater from a pharmaceutical company. We identified six IncP/P-1ε plasmids and single members of IncL, IncN and IncFII-like plasmids. Genetic structures of the accessory regions of the IncP/P-1ε plasmids obtained implied that multiple insertions and deletions had occurred, mediated by different transposons and Class 1 integrons with various ARGs. Our study provides compelling evidence that Class 1 integrons, Tn402-like transposons, Tn3-like transposons and/or IS26 played important roles in the acquisition of ARGs across all investigated plasmids. Our plasmid sequencing data provide new insights into how these mobile genetic elements could mediate the acquisition and spread of ARGs in environmental bacteria.202337655671
35480.9947New cloning vectors to facilitate quick allelic exchange in gram-negative bacteria. New cloning vectors have been developed with features to enhance quick allelic exchange in gram-negative bacteria. The conditionally replicative R6K and transfer origins facilitate conjugation and chromosomal integration into a variety of bacterial species, whereas the sacB gene provides counterselection for allelic exchange. The vectors have incorporated the lacZ alpha fragment with an enhanced multicloning site for easy blue/white screening and priming sites identified for efficient in vivo assembly or other DNA assembly cloning techniques. Different antibiotic resistance markers allow versatility for use with different bacteria, and transformation into an Escherichia coli strain capable of conjugation enables a quick method for allelic exchange. As a proof of principle, the authors used these vectors to inactivate genes in Vibrio cholerae and Salmonella typhimurium.202133492170
984490.9947The role of Bacteroides conjugative transposons in the dissemination of antibiotic resistance genes. Investigations into the mechanisms of antibiotic resistance gene transfer utilized by Bacteroides species have led to a greater understanding of how bacteria transfer antibiotic resistance genes, and what environmental stimuli promote such horizontal transfer events. Although Bacteroides spp. harbor a variety of transmissible elements that are involved in the dissemination of antibiotic resistance genes, it is one particular class of elements, the conjugative transposons, that are responsible for most of the resistance gene transfer in Bacteroides. The potential for Bacteroides conjugative transposons to transfer antibiotic resistance genes extends beyond those genes carried by the conjugative transposon itself, because Bacteroides conjugative transposons are able to mobilize coresident plasmids in trans and in cis, and also stimulate the excision and transfer of unlinked integrated elements called mobilizable transposons. These characteristics of conjugative transposons alone have significant implications for the ecology and spread of antibiotic resistance genes, and in terms of biotechnology. A novel feature of the most widespread family of Bacteroides conjugative transposons, the CTnDOT/ERL family, is that their transfer is stimulated 100- to 1000-fold by low concentrations of tetracycline. This is significant because the use of antibiotics not only selects for resistant Bacteroides strains, but also stimulates their transfer. Other Bacteroides conjugative transposons do not require any induction to stimulate transfer, and hence appear to transfer constitutively. The constitutively transferring elements characterized so far appear to have a broader host range than the CTnDOT/ERL family of conjugative transposons, and the prevalence of these elements is on the increase. Since these constitutively transferring elements do not require induction by antibiotics to stimulate transfer, they have the potential to become as pervasive as the CTnDOT/ERL family of conjugative transposons.200212568330
4161100.9947Integron and its role in antimicrobial resistance: A literature review on some bacterial pathogens. In recent years, different acquired resistance mechanisms, including transposons, bacteriophages, plasmids, and integrons have been identified as involved in the spread of resistance genes in bacteria. The role of integrons as mobile genetic elements playing a central role in antibiotic resistance has been well studied and documented. Integrons are the ancient structures that mediate the evolution of bacteria by acquiring, storing, disposing, and resorting to the reading frameworks in gene cassettes. The term integron describes a large family of genetic elements, all of which are able to capture gene cassettes. Integrons were classified into three important classes based on integrase intI gene sequence. Integrons can carry and spread the antibiotic resistance genes among bacteria and are among the most significant routes of distribution of resistance genes via horizontal transfer. All integrons have three essential core features. The first feature is intI, the second one is an integron-associated recombination site, attI, and an integron-associated promoter, Pc, is the last feature. Among them, the class 1 integron is a major player in the dissemination of antibiotic resistance genes across pathogens and commensals. Various classes of integrons possessing a wide variety of gene cassettes are distributed in bacteria throughout the world. This review thus focuses on the distribution of integrons among important bacteria.202133953851
359110.9947Construction of shuttle cloning vectors for Bacteroides fragilis and use in assaying foreign tetracycline resistance gene expression. Shuttle vectors capable of replication in both Escherichia coli and Bacteroides fragilis have been developed. Conjugal transfer of these plasmids from E. coli to B. fragilis is facilitated by inclusion of the origin of transfer of the IncP plasmid RK2. The vectors pDK1 and pDK2 provide unique sites for cloning selectable markers in Bacteroides. pOA10 is a cosmid vector containing the replication region of pCP1 necessary for maintenance in Bacteroides. pDK3, pDK4.1, and pDK4.2 contain the Bacteroides clindamycin resistance gene allowing selection and maintenance in B. fragilis of plasmids containing inserted DNA fragments. pDK3 was used to test the expression in B. fragilis of five foreign tetracycline resistance (TcR) genes. The tetA, -B, and -C markers from facultative gram-negative bacteria, as well as a TcR determinant from Clostridium perfringens, did not express TcR in B. fragilis. The tetM gene, originally described in streptococci, encoded a small but reproducible increase of TcR in Bacteroides. These studies demonstrate the utility of shuttle vectors for introducing cloned genes into Bacteroides and underscore the differences in gene expression in these anaerobes.19883071818
4160120.9946The association between the genetic structures of commonly incompatible plasmids in Gram-negative bacteria, their distribution and the resistance genes. Incompatible plasmids play a crucial role in the horizontal transfer of antibiotic resistance in bacteria, particularly in Gram-negative bacteria, and have thus attracted considerable attention in the field of microbiological research. In the 1970s, these plasmids, housing an array of resistance genes and genetic elements, were predominantly discovered. They exhibit a broad presence in diverse host bacteria, showcasing diversity in geographic distribution and the spectrum of antibiotic resistance genes. The complex genetic structure of plasmids further accelerates the accumulation of resistance genes in Gram-negative bacteria. This article offers a comprehensive review encompassing the discovery process, host distribution, geographic prevalence, carried resistance genes, and the genetic structure of different types incompatible plasmids, including IncA, IncC, IncF, IncL, IncM, IncH, and IncP. It serves as a valuable reference for enhancing our understanding of the role of these different types of plasmids in bacterial evolution and the dissemination of antibiotic resistance.202439660283
4138130.9946The shared antibiotic resistome of soil bacteria and human pathogens. Soil microbiota represent one of the ancient evolutionary origins of antibiotic resistance and have been proposed as a reservoir of resistance genes available for exchange with clinical pathogens. Using a high-throughput functional metagenomic approach in conjunction with a pipeline for the de novo assembly of short-read sequence data from functional selections (termed PARFuMS), we provide evidence for recent exchange of antibiotic resistance genes between environmental bacteria and clinical pathogens. We describe multidrug-resistant soil bacteria containing resistance cassettes against five classes of antibiotics (β-lactams, aminoglycosides, amphenicols, sulfonamides, and tetracyclines) that have perfect nucleotide identity to genes from diverse human pathogens. This identity encompasses noncoding regions as well as multiple mobilization sequences, offering not only evidence of lateral exchange but also a mechanism by which antibiotic resistance disseminates.201222936781
9881140.9946Plasmids and the spread of resistance. Plasmids represent one of the most difficult challenge for counteracting the dissemination of antimicrobial resistance. They contribute to the spread of relevant resistance determinants, promoting horizontal gene transfer among unrelated bacteria. Undistinguishable plasmids were identified in unrelated bacterial strains isolated at huge geographically distant area, with no apparent epidemiological links. These plasmids belong to families that are largely prevalent in naturally occurring bacteria, usually carry multiple physically linked genetic determinants, conferring resistance to different classes of antibiotics simultaneously. Plasmids also harbour virulence factors and addiction systems, promoting their stability and maintenance in the bacterial host, in different environmental conditions. The characteristics of the most successful plasmids that were at the origin of the spread of carbapenemase, expanded-spectrum β-lactamase, and plasmid-mediated quinolone resistance genes are discussed in this review.201323499304
9970150.9946Genome Sequence of Listeria monocytogenes Plasmid pLM-C-273 Carrying Genes Related to Stress Resistance. Mobile genetic elements in bacteria, such as plasmids, act as important vectors for the transfer of antibiotic resistance, virulence, and metal resistance genes. Here, we report the genome sequence of a new plasmid pLM-C-273, identified in a Listeria monocytogenes strain isolated from a clinical sample in Ontario, Canada.201627738039
9837160.9946Mobilizable genomic islands, different strategies for the dissemination of multidrug resistance and other adaptive traits. Mobile genetic elements are near ubiquitous DNA segments that revealed a surprising variety of strategies for their propagation among prokaryotes and between eukaryotes. In bacteria, conjugative elements were shown to be key drivers of evolution and adaptation by efficiently disseminating genes involved in pathogenicity, symbiosis, metabolic pathways, and antibiotic resistance. Conjugative plasmids of the incompatibility groups A and C (A/C) are important vehicles for the dissemination of antibiotic resistance and the consequent global emergence and spread of multi-resistant pathogenic bacteria. Beyond their own mobility, A/C plasmids were also shown to drive the mobility of unrelated non-autonomous mobilizable genomic islands, which may also confer further advantageous traits. In this commentary, we summarize the current knowledge on different classes of A/C-dependent mobilizable genomic islands and we discuss other DNA hitchhikers and their implication in bacterial evolution. Furthermore, we glimpse at the complex genetic network linking autonomous and non-autonomous mobile genetic elements, and at the associated flow of genetic information between bacteria.201728439449
9711170.9946Horizontal DNA transfer between bacteria in the environment. In the environment horizontal DNA transfer between various bacterial species and genera takes place by transformation, transduction, but mainly by conjugation. Conjugation is responsible for the spread of genes coding for antibiotic resistance and xenobiotic degradation. Transfer events are reported in animal, rhizosphere and phylloplane ecosystems and in non polluted and polluted water and soil. Genetic exchange between Bacteria and Archaea is also observed. Evaluation of the extent of interspecies gene transfer is crucial in view of the deliberate release of a variety of unmodified and genetically modified microorganisms into the natural environments.200314743976
272180.9946Chromatic Bacteria - A Broad Host-Range Plasmid and Chromosomal Insertion Toolbox for Fluorescent Protein Expression in Bacteria. Differential fluorescent labeling of bacteria has become instrumental for many aspects of microbiological research, such as the study of biofilm formation, bacterial individuality, evolution, and bacterial behavior in complex environments. We designed a variety of plasmids, each bearing one of eight unique, constitutively expressed fluorescent protein genes in conjunction with one of four different antibiotic resistance combinations. The fluorophores mTagBFP2, mTurquoise2, sGFP2, mClover3, sYFP2, mOrange2, mScarlet-I, and mCardinal, encoding for blue, cyan, green, green-yellow, yellow, orange, red, and far-red fluorescent proteins, respectively, were combined with selectable markers conferring tetracycline, gentamicin, kanamycin, and/or chloramphenicol resistance. These constructs were cloned into three different plasmid backbones: a broad host-range plasmid, a Tn5 transposon delivery plasmid, and a Tn7 transposon delivery plasmid. The utility of the plasmids and transposons was tested in bacteria from the phyla Actinobacteria, Proteobacteria, and Bacteroidetes. We were able to tag representatives from the phylum Proteobacteria at least via our Tn5 transposon delivery system. The present study enables labeling bacteria with a set of plasmids available to the community. One potential application of fluorescently-tagged bacterial species is the study of bacteria-bacteria, bacteria-host, and bacteria-environment interactions.201830631309
3769190.9946Clostridioides difficile as a Dynamic Vehicle for the Dissemination of Antimicrobial-Resistance Determinants: Review and In Silico Analysis. The present paper is divided into two parts. The first part focuses on the role of Clostridioides difficile in the accumulation of genes associated with antimicrobial resistance and then the transmission of them to other pathogenic bacteria occupying the same human intestinal niche. The second part describes an in silico analysis of the genomes of C. difficile available in GenBank, with regard to the presence of mobile genetic elements and antimicrobial resistance genes. The diversity of the C. difficile genome is discussed, and the current status of resistance of the organisms to various antimicrobial agents is reviewed. The role of transposons associated with antimicrobial resistance is appraised; the importance of plasmids associated with antimicrobial resistance is discussed, and the significance of bacteriophages as a potential shuttle for antimicrobial resistance genes is presented. In the in silico study, 1101 C. difficile genomes were found to harbor mobile genetic elements; Tn6009, Tn6105, CTn7 and Tn6192, Tn6194 and IS256 were the ones more frequently identified. The genes most commonly harbored therein were: ermB, blaCDD, vanT, vanR, vanG and vanS. Tn6194 was likely associated with resistance to erythromycin, Tn6192 and CTn7 with resistance to the β-lactams and vancomycin, IS256 with resistance to aminoglycoside and Tn6105 to vancomycin.202134202117