scholarly journals Toxin-Antitoxin Gene Pairs Found in Tn3 Family Transposons Appear To Be an Integral Part of the Transposition Module

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Gipsi Lima-Mendez ◽  
Danillo Oliveira Alvarenga ◽  
Karen Ross ◽  
Bernard Hallet ◽  
Laurence Van Melderen ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Bacterial Population ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Plasmid Maintenance ◽  
Gene Pairs ◽  
Prokaryotic Genomes ◽  
Replicative Transposition ◽  
Genetic Context

ABSTRACT Much of the diversity of prokaryotic genomes is contributed by the tightly controlled recombination activity of transposons (Tns). The Tn3 family is arguably one of the most widespread transposon families. Members carry a large range of passenger genes incorporated into their structures. Family members undergo replicative transposition using a DDE transposase to generate a cointegrate structure which is then resolved by site-specific recombination between specific DNA sequences (res) on each of the two Tn copies in the cointegrate. These sites also carry promoters controlling expression of the recombinase and transposase. We report here that a number of Tn3 members encode a type II toxin-antitoxin (TA) system, typically composed of a stable toxin and a labile antitoxin that binds the toxin and inhibits its lethal activity. This system serves to improve plasmid maintenance in a bacterial population and, until recently, was believed to be associated with bacterial persistence. At least six different TA gene pairs are associated with various Tn3 members. Our data suggest that several independent acquisition events have occurred. In contrast to most Tn3 family passenger genes, which are generally located away from the transposition module, the TA gene pairs abut the res site upstream of the resolvase genes. Although their role when part of Tn3 family transposons is unclear, this finding suggests a potential role for the embedded TA in stabilizing the associated transposon with the possibility that TA expression is coupled to expression of transposase and resolvase during the transposition process itself. IMPORTANCE Transposable elements (TEs) are important in genetic diversification due to their recombination properties and their ability to promote horizontal gene transfer. Over the last decades, much effort has been made to understand TE transposition mechanisms and their impact on prokaryotic genomes. For example, the Tn3 family is ubiquitous in bacteria, molding their host genomes by the paste-and-copy mechanism. In addition to the transposition module, Tn3 members often carry additional passenger genes (e.g., conferring antibiotic or heavy metal resistance and virulence), and three were previously known to carry a toxin-antitoxin (TA) system often associated with plasmid maintenance; however, the role of TA systems within the Tn3 family is unknown. The genetic context of TA systems in Tn3 members suggests that they may play a regulatory role in ensuring stable invasion of these Tns during transposition.

scholarly journals Toxin-antitoxin gene pairs found in Tn3 family transposons appear to be an integral part of the transposition module

2019 ◽  
Author(s):  
Gipsi Lima-Mendez ◽  
Danillo Oliveira Alvarenga ◽  
Karen Ross ◽  
Bernard Hallet ◽  
Laurence Van Melderen ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Bacterial Population ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Plasmid Maintenance ◽  
Gene Pairs ◽  
Prokaryotic Genomes ◽  
Replicative Transposition ◽  
Genetic Context

AbstractMuch of the diversity of prokaryotic genomes is contributed by the tightly controlled recombination activity of transposons (Tn). The Tn3 family is arguably one of the most widespread transposon families. Members carry a large range of passenger genes incorporated into their structures. Family members undergo replicative transposition using a DDE transposase to generate a cointegrate structure which is then resolved by site-specific recombination between specific DNA sequences (res) on each of the two Tn copies in the cointegrate. These sites also carry promoters controlling expression of the recombinase and transposase. We report here that a number of Tn3 members encode a type II toxin-antitoxin (TA) system, typically composed of a stable toxin and a labile antitoxin that binds the toxin and inhibits its lethal activity. This system serves to improve plasmid maintenance in a bacterial population and, until recently, was believed to be associated with bacterial persistence. At least six different TA gene pairs are associated with various Tn3 members. Our data suggest that several independent acquisition events have occurred. In contrast to most Tn3 family passenger genes which are generally located away from the transposition module, the TA gene pairs abut the res site upstream of the resolvase genes. Although their role when part of Tn3 family transposons is unclear, this finding suggests a potential role for the embedded TA in stabilizing the associated transposon with the possibility that TA expression is coupled to expression of transposase and resolvase during the transposition process itself.ImportanceTransposable Elements (TEs) are important in genetic diversification due to their recombination properties and their ability to promote horizontal gene transfer. Over the last decades, much effort has been made to understand TE transposition mechanisms and their impact on prokaryotic genomes. For example, the Tn3 family is ubiquitous in bacteria, moulding their host genomes by the paste-and-copy mechanism. In addition to the transposition module, Tn3 members often carry additional passenger genes (e.g., conferring antibiotic or heavy metal resistance and virulence) and three were previously known to carry a toxin-antitoxin (TA) system often associated with plasmid maintenance; however, the role of TA systems within the Tn3 family is unknown. The genetic context of TA systems in Tn3 members suggests that they may play a regulatory role in ensuring stable invasion of these Tn during transposition.

scholarly journals Tensor Rules in the Stochastic Organization of Genomes and Genetic Stochastic Resonance in Algebraic Biology

2021 ◽  
Author(s):  
Sergey V. Petoukhov
Keyword(s):  
Quantum Mechanics ◽  
Dna Sequences ◽  
Genomic Dna ◽  
Analytical Tool ◽  
Prokaryotic Genomes ◽  
Algebraic Biology ◽  
Dna Nucleotide Sequence ◽  
A Chain ◽  
Product Of Matrices

The article is devoted to the new results of the author, which add his previously published ones, of studying hidden rules and symmetries in structures of long single-stranded DNA sequences in eukaryotic and prokaryotic genomes. The author uses the existence of different alphabets of n-plets in DNA: the alphabet of 4 nucleotides, the alphabet of 16 douplets, the alphabet of 64 triplets, etc. Each of such DNA alphabets of n-plets can serve for constructing a text as a chain of these n-plets. Using this possibility, the author represents any long DNA nucleotide sequence as a bunch of many so-called n-texts, each of which is written on the basis of one of these alphabets of n-plets. Each of such n-texts has its individual percents of different n-plets in its genomic DNA. But it turns out that in such multi-alphabetical or multilayer presentation of each of many genomic DNA, analyzed by the author, universal rules of probabilities and symmetry exist in interrelations of its different n-texts regarding their percents of n-plets. In this study, the tensor product of matrices and vectors is used as an effective analytical tool borrowed from the arsenal of quantum mechanics. Some additions to the topic of algebra-holographic principles in genetics are also presented. Taking into account the described genomic rules of probability, the author puts also forward a concept of the important role of stochastic resonances in genetic informatics.

scholarly journals Hyperbolic Rules of the Oligomer Cooperative Organization of Eukaryotic and Prokaryotic Genomes

2020 ◽  
Author(s):  
Sergey Petoukhov
Keyword(s):  
Quantum Information ◽  
Dna Sequences ◽  
Coding System ◽  
Harmonic Progression ◽  
General Rules ◽  
Prokaryotic Genomes ◽  
Algebraic Invariants ◽  
Cooperative Organization ◽  
Long Genes

The author's method of oligomer sums for analysis of oligomer compositions of eukaryotic and prokaryotic genomes is described. The use of this method revealed the existence of general rules for cooperative oligomeric organization of a wide list of genomes. These rules are called hyperbolic because they are associated with hyperbolic sequences including the harmonic progression 1, 1/2, 1/3, .., 1/n. These rules are demonstrated by examples of quantitative analysis of many genomes from the human genome to the genomes of archaea and bacteria. The hyperbolic (harmonic) rules, speaking about the existence of algebraic invariants in full genomic sequences, are considered as candidates for the role of universal rules for cooperative organization of genomes. The described phenomenological results were obtained as consequences of the previously published author's quantum-information model of long DNA sequences. The oligomer sums method was also applied to the analysis of long genes and viruses including the COVID-19 virus; this revealed, in characteristics of many of them, the phenomenon of rhythmically repeating deviations from model hyperbolic sequences; these deviations are associated with DNA triplets and should be systematically analyzed for a deeper understanding the genetic coding system. The topics of the algebraic harmony in living bodies and of the quantum-information approach in biology are discussed.

scholarly journals Transposable elements in natural populations of Drosophila melanogaster

2010 ◽  
Vol 365 (1544) ◽  
pp. 1219-1228 ◽  
Author(s):  
Yuh Chwen G. Lee ◽  
Charles H. Langley
Keyword(s):  
Transposable Elements ◽  
Dna Sequences ◽  
Copy Number ◽  
Population Genomics ◽  
Natural Populations ◽  
Crossing Over ◽  
Large Role ◽  
Essential Components ◽  
Replicative Transposition

Transposable elements (TEs) are families of small DNA sequences found in the genomes of virtually all organisms. The sequences typically encode essential components for the replicative transposition sequences of that TE family. Thus, TEs are simply genomic parasites that inflict detrimental mutations on the fitness of their hosts. Several models have been proposed for the containment of TE copy number in outbreeding host populations such as Drosophila . Surveys of the TEs in genomes from natural populations of Drosophila have played a central role in the investigation of TE dynamics. The early surveys indicated that a typical TE insertion is rare in a population, which has been interpreted as evidence that each TE is selected against. The proposed mechanisms of this natural selection are reviewed here. Subsequent and more targeted surveys identify heterogeneity among types of TEs and also highlight the large role of homologous and possibly ectopic crossing over in the dynamics of the Drosophila TEs. The recent discovery of germline-specific RNA interference via the piwi-interacting RNA pathway opens yet another interesting mechanism that may be critical in containing the copy number of TEs in natural populations of Drosophila . The expected flood of Drosophila population genomics is expected to rapidly advance understanding of the dynamics of TEs.

Role of arsenic and its resistance in nature

2011 ◽  
Vol 57 (10) ◽  
pp. 769-774 ◽  
Author(s):  
Sukhvinder Kaur ◽  
Majid Rasool Kamli ◽  
Arif Ali
Keyword(s):  
Heavy Metals ◽  
Arsenic Exposure ◽  
Environmental Pollutants ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Microbial Interactions ◽  
Transcriptional Unit ◽  
Toxic Heavy Metals ◽  
Toxic Metalloid

Contamination of the environment with heavy metals has increased drastically over the last few decades. The heavy metals that are toxic include mercury, cadmium, arsenic, and selenium. Of these heavy metals, arsenic is one of the most important global environmental pollutants and is a persistent bioaccumulative carcinogen. It is a toxic metalloid that exists in two major inorganic forms: arsenate and arsenite. Arsenite disrupts enzymatic functions in cells, while arsenate behaves as a phosphate analog and interferes with phosphate uptake and utilization. Despite its toxicity, arsenic may be actively sequestered in plant and animal tissues. Various microbes interact with this metal and have shown resistance to arsenic exposure, and they appear to possess the ars operon for arsenic resistance consisting of three to five genes, i.e., arsRBC or arsRDABC, organized into a single transcriptional unit; some microbes even use it for respiration. Microbial interactions with metals may have several implications for the environment. Microbes may play a role in cycling of toxic heavy metals and in remediation of metal-contaminated sites. There is a correlation between tolerance to heavy metals and antibiotic resistance, a global problem currently threatening the treatment of infections in plants, animals, and humans. The purpose of this review is to highlight the nature and role of toxic arsenic in bacterial systems and to discuss the various genes responsible for this heavy-metal resistance in nature and the mechanisms to detoxify this element.

scholarly journals Sequencing and Characterization of pBM400 from Bacillus megaterium QM B1551

2003 ◽  
Vol 69 (11) ◽  
pp. 6888-6898 ◽  
Author(s):  
Michael D. Scholle ◽  
Christen A. White ◽  
Muthusamy Kunnimalaiyaan ◽  
Patricia S. Vary
Keyword(s):  
Bacillus Megaterium ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Open Reading Frames ◽  
Virulence Plasmid ◽  
Insertion Element ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Rna Interaction

ABSTRACT Bacillus megaterium QM B1551 plasmid pBM400, one of seven indigenous plasmids, has been labeled with a selectable marker, isolated, completely sequenced, and partially characterized. A sequence of 53,903 bp was generated, revealing a total of 50 predicted open reading frames (ORFs); 33 were carried on one strand and 17 were carried on the other. These ORFs comprised 57% of the pBM400 sequence. Besides the replicon region and a complete rRNA operon that have previously been described, several interesting genes were found, including genes for predicted proteins for cell division (FtsZ and FtsK), DNA-RNA interaction (FtsK, Int/Rec, and reverse transcriptase), germination (CwlJ), styrene degradation (StyA), and heavy metal resistance (Cu-Cd export and ATPase). Three of the ORF products had high similarities to proteins from the Bacillus anthracis virulence plasmid pXO1. An insertion element with similarity to the IS256 family and several hypothetical proteins similar to those from the chromosomes of other Bacillus and Lactococcus species were present. This study provides a basis for isolation and sequencing of other high-molecular-weight plasmids from QM B1551 and for understanding the role of megaplasmids in gram-positive bacteria. The genes carried by pBM400 suggest a possible role of this plasmid in the survival of B. megaterium in hostile environments with heavy metals or styrene and also suggest that there has been an exchange of genes within the gram-positive bacteria, including pathogens.

scholarly journals Algebraic Rules for the Percentage Composition of Oligomers in Genomes

2021 ◽  
Author(s):  
Sergey Petoukhov
Keyword(s):  
Dna Sequences ◽  
Genomic Dna ◽  
Gestalt Psychology ◽  
Matrix Representations ◽  
Quantum Biology ◽  
Percentage Composition ◽  
Discrete Signals ◽  
Algebraic Properties ◽  
Prokaryotic Genomes

The article presents the author's results of studying hidden rules of structural organizations of long DNA sequences in eukaryotic and prokaryotic genomes. The results concern some rules of percentages (or probabilities) of n-plets in genomes. To reveal such rules, the author considers genomic DNA nucleotide sequences as multilayers sequences of n-plets and studies the percentage contents of n-plets in different layers. Unexpected rules of invariance of total sums of percentages in certain tetra-groupings of n-plets in different layers of genomic DNA sequences are revealed. These discovered rules are candidates for the role of universal genomic rules. A tensor family of matrix representations of interrelated DNA-alphabets of 4 nucleotides, 16 doublets, 64 triplets, and 256 tetraplets is used in the study. This matrix approach allows revealing algebraic properties of the mentioned genetic rules of probabilities, which are useful for developing algebraic and quantum biology. Some analogies of the discovered genetic phenomena with phenomena of Gestalt psychology are noted and discussed. The author connects the received results about the genomic percentages rules with a supposition of P. Jordan, who is one of the creators of quantum mechanics and quantum biology, that life's missing laws are the rules of chance and probability of the quantum world. Additional attention is paid to the algebraic features of the system of structured DNA alphabets and their relationship with the methods of algebraic holography, known in the technique of processing discrete signals. The concept of algebraic-holographic genetics is being developed for the understanding of inherited holographic properties of organisms.

Emergence of plasmid-mediated oxazolidinone resistance gene poxtA from CC17 Enterococcus faecium of pig origin

2019 ◽  
Vol 74 (9) ◽  
pp. 2524-2530 ◽  
Author(s):  
Jinhu Huang ◽  
Mengli Wang ◽  
Yi Gao ◽  
Li Chen ◽  
Liping Wang
Keyword(s):  
Host Range ◽  
Resistance Gene ◽  
Enterococcus Faecium ◽  
Susceptibility Testing ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Broad Host Range ◽  
Broad Host Range Plasmids ◽  
Genetic Context ◽  
Selection Of

AbstractObjectivesTo characterize the oxazolidinone resistance gene poxtA on broad-host-range Inc18 plasmids from CC17 Enterococcus faecium of pig origin.MethodsOxazolidinone-resistant E. faecium isolates were screened for the presence of poxtA. The poxtA-carrying isolates were characterized by antimicrobial susceptibility testing, conjugation, S1-PFGE and hybridization. The poxtA-carrying plasmids were completely sequenced and their instability was verified.ResultsTwo individual CC17 E. faecium strains were positive for poxtA. S1-PFGE and hybridization revealed the presence of a poxtA-carrying plasmid of ∼62 kb in both WZ27-2 and the transconjugant, while poxtA-carrying plasmids of different sizes were observed in QF25-1 and the transconjugant. The two poxtA-carrying plasmids, pC25-1 and pC27-2, belonged to the broad-host-range plasmids of the Inc18 family and carried dfrG, aadE, Δsat4, aph(3′)-III, erm(B), tet(M), tet(L) and fexB. Plasmid pC27-2 was virtually identical to pC25-1, with minor differences. The calculated transfer frequency was ∼0.87 × 10−8 and ∼1.03 × 10−7 per recipient to plasmids pC25-1 and pC27-2, respectively. Instability assays of the region with four adjacent IS1216Es, which forms three IS1216E translocatable units, revealed the formation of a series of mosaic circular intermediates.ConclusionsWe report the emergence of the plasmid-mediated oxazolidinone resistance gene poxtA in E. faecium from different farms in China. Comparison of the poxtA genetic context suggests that IS1216E elements play an important role in the dissemination of poxtA. The co-occurrence of poxtA with other antimicrobial and heavy metal resistance genes on the broad-host-range plasmids of the Inc18 family may lead to the co-selection of poxtA, contributing to its persistence and accelerating its dissemination.

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