scholarly journals What makes a megaplasmid?

2021 ◽  
Vol 377 (1842) ◽  
Author(s):  
James P. J. Hall ◽  
João Botelho ◽  
Adrian Cazares ◽  
David A. Baltrus
Keyword(s):  
Mobile Genetic Elements ◽  
Gene Content ◽  
Large Plasmid ◽  
Theme Issue ◽  
Genetic Elements ◽  
Naturally Occurring ◽  
Long Read ◽  
Large Plasmids ◽  
Plasmid Size ◽  
Genome Assemblies

Naturally occurring plasmids come in different sizes. The smallest are less than a kilobase of DNA, while the largest can be over three orders of magnitude larger. Historically, research has tended to focus on smaller plasmids that are usually easier to isolate, manipulate and sequence, but with improved genome assemblies made possible by long-read sequencing, there is increased appreciation that very large plasmids—known as megaplasmids—are widespread, diverse, complex, and often encode key traits in the biology of their host microorganisms. Why are megaplasmids so big? What other features come with large plasmid size that could affect bacterial ecology and evolution? Are megaplasmids 'just' big plasmids, or do they have distinct characteristics? In this perspective, we reflect on the distribution, diversity, biology, and gene content of megaplasmids, providing an overview to these large, yet often overlooked, mobile genetic elements. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

scholarly journals Mobile Genetic Elements Related to the Diffusion of Plasmid-Mediated AmpC β-Lactamases or Carbapenemases from Enterobacteriaceae: Findings from a Multicenter Study in Spain

2015 ◽  
Vol 59 (9) ◽  
pp. 5260-5266 ◽  
Author(s):  
L. Zamorano ◽  
E. Miró ◽  
C. Juan ◽  
L. Gómez ◽  
G. Bou ◽  
...  
Keyword(s):  
Southern Hybridization ◽  
Mobile Genetic Elements ◽  
Pulsed Field Gel Electrophoresis ◽  
Content Type ◽  
Genetic Elements ◽  
Chromosomal Origin ◽  
Class 1 ◽  
Rapid Dissemination ◽  
Large Plasmids ◽  
Genetic Context

ABSTRACTWe examined the genetic context of 74 acquiredampCgenes and 17 carbapenemase genes from 85 of 640Enterobacteriaceaeisolates collected in 2009. Using S1 pulsed-field gel electrophoresis and Southern hybridization, 37 of 74blaAmpCgenes were located on large plasmids of different sizes belonging to six incompatibility groups. We used sequencing and PCR mapping to investigate the regions flanking the acquiredampCgenes. TheblaCMY-2-like genes were associated with ISEcp1; the surroundingblaDHAgenes were similar toKlebsiella pneumoniaeplasmid pTN60013 associated with IS26and thepspandsapoperons; and theblaACC-1genes were associated with IS26elements inserted into ISEcp1. All of the carbapenemase genes (blaVIM-1,blaIMP-22, andblaIMP-28) were located in class 1 integrons. Therefore, although plasmids are the main cause of the rapid dissemination ofampCgenes amongEnterobacteriaceae, we need to be aware that other mobile genetic elements, such as insertion sequences, transposons, or integrons, can be involved in the mobilization of these genes of chromosomal origin. Additionally, three new integrons (In846 to In848) are described in this study.

scholarly journals To catch a hijacker: abundance, evolution and genetic diversity of P4-like bacteriophage satellites

2021 ◽  
Vol 377 (1842) ◽  
Author(s):  
Jorge A. Moura de Sousa ◽  
Eduardo P. C. Rocha
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Core Genome ◽  
Mobile Genetic Elements ◽  
Abundance Distribution ◽  
Theme Issue ◽  
Genetic Elements ◽  
The Core ◽  
Antagonistic Interactions ◽  
Variable Genes

Bacteriophages (phages) are bacterial parasites that can themselves be parasitized by phage satellites. The molecular mechanisms used by satellites to hijack phages are sometimes understood in great detail, but the origins, abundance, distribution and composition of these elements are poorly known. Here, we show that P4-like elements are present in more than 30% of the genomes of Enterobacterales, and in almost half of those of Escherichia coli , sometimes in multiple distinct copies. We identified over 1000 P4-like elements with very conserved genetic organization of the core genome and a few hotspots with highly variable genes. These elements are never found in plasmids and have very little homology to known phages, suggesting an independent evolutionary origin. Instead, they are scattered across chromosomes, possibly because their integrases are often exchanged with other elements. The rooted phylogenies of hijacking functions are correlated and suggest longstanding coevolution. They also reveal broad host ranges in P4-like elements, as almost identical elements can be found in distinct bacterial genera. Our results show that P4-like phage satellites constitute a very distinct, widespread and ancient family of mobile genetic elements. They pave the way for studying the molecular evolution of antagonistic interactions between phages and their satellites. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

scholarly journals Evidence of an epidemic spread of KPC-producing Enterobacterales in Czech hospitals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lucie Kraftova ◽  
Marc Finianos ◽  
Vendula Studentova ◽  
Katerina Chudejova ◽  
Vladislav Jakubu ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Infection Control ◽  
Mobile Genetic Elements ◽  
Epidemic Spread ◽  
Sequencing Data ◽  
Genetic Elements ◽  
Long Read ◽  
Genetic Rearrangements

AbstractThe aim of the present study is to describe the ongoing spread of the KPC-producing strains, which is evolving to an epidemic in Czech hospitals. During the period of 2018–2019, a total of 108 KPC-producing Enterobacterales were recovered from 20 hospitals. Analysis of long-read sequencing data revealed the presence of several types of blaKPC-carrying plasmids; 19 out of 25 blaKPC-carrying plasmids could be assigned to R (n = 12), N (n = 5), C (n = 1) and P6 (n = 1) incompatibility (Inc) groups. Five of the remaining blaKPC-carrying plasmids were multireplicon, while one plasmid couldn’t be typed. Additionally, phylogenetic analysis confirmed the spread of blaKPC-carrying plasmids among different clones of diverse Enterobacterales species. Our findings demonstrated that the increased prevalence of KPC-producing isolates was due to plasmids spreading among different species. In some districts, the local dissemination of IncR and IncN plasmids was observed. Additionally, the ongoing evolution of blaKPC-carrying plasmids, through genetic rearrangements, favours the preservation and further dissemination of these mobile genetic elements. Therefore, the situation should be monitored, and immediate infection control should be implemented in hospitals reporting KPC-producing strains.

Diversification of plasmids in a genus of pathogenic and nitrogen-fixing bacteria

2021 ◽  
Vol 377 (1842) ◽  
Author(s):  
Alexandra J. Weisberg ◽  
Marilyn Miller ◽  
Walt Ream ◽  
Niklaus J. Grünwald ◽  
Jeff H. Chang
Keyword(s):  
Mobile Genetic Elements ◽  
Nitrogen Fixing ◽  
Genome Sequences ◽  
Theme Issue ◽  
Nitrogen Fixing Bacteria ◽  
Disease Symptoms ◽  
Genetic Elements ◽  
Virulence Plasmids ◽  
Evolution Of Genomes

Members of the agrobacteria–rhizobia complex (ARC) have multiple and diverse plasmids. The extent to which these plasmids are shared and the consequences of their interactions are not well understood. We extracted over 4000 plasmid sequences from 1251 genome sequences and constructed a network to reveal interactions that have shaped the evolutionary histories of oncogenic virulence plasmids. One newly discovered type of oncogenic plasmid is a mosaic with three incomplete, but complementary and partially redundant virulence loci. Some types of oncogenic plasmids recombined with accessory plasmids or acquired large regions not known to be associated with pathogenicity. We also identified two classes of partial virulence plasmids. One class is potentially capable of transforming plants, but not inciting disease symptoms. Another class is inferred to be incomplete and non-functional but can be found as coresidents of the same strain and together are predicted to confer pathogenicity. The modularity and capacity for some plasmids to be transmitted broadly allow them to diversify, convergently evolve adaptive plasmids and shape the evolution of genomes across much of the ARC. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

scholarly journals Bacillus cytotoxicus Genomics: Chromosomal Diversity and Plasmidome Versatility

2021 ◽  
Vol 12 ◽  
Author(s):  
Nancy Fayad ◽  
Klèma Marcel Koné ◽  
Annika Gillis ◽  
Jacques Mahillon
Keyword(s):  
Bacillus Cereus ◽  
Potential Role ◽  
Random Amplified Polymorphic Dna ◽  
Mobile Genetic Elements ◽  
Genomic Diversity ◽  
Genome Plasticity ◽  
Genetic Elements ◽  
Gene Coding ◽  
Group Members ◽  
Large Plasmids

Bacillus cytotoxicus is the thermotolerant representative of the Bacillus cereus group. This group, also known as B. cereus sensu lato, comprises both beneficial and pathogenic members and includes psychrotolerant and thermotolerant species. Bacillus cytotoxicus was originally recovered from a fatal outbreak in France in 1998. This species forms a remote cluster from the B. cereus group members and reliably contains the cytk-1 gene, coding for a cytotoxic variant of cytotoxin K. Although this species was originally thought to be homogenous, intra-species diversity has been recently described with four clades, six random amplified polymorphic DNA (RAPD) patterns, and 11 plasmids profiles. This study aimed to get new insights into the genomic diversity of B. cytotoxicus and to decipher the underlying chromosomal and plasmidial variations among six representative isolates through whole genome sequencing (WGS). Among the six sequenced strains, four fitted the previously described genomic clades A and D, while the remaining two constituted new distinct branches. As for the plasmid content of these strains, three large plasmids were putatively conjugative and three small ones potentially mobilizable, harboring coding genes for putative leaderless bacteriocins. Mobile genetic elements, such as prophages, Insertion Sequences (IS), and Bacillus cereus repeats (bcr) greatly contributed to the B. cytotoxicus diversity. As for IS elements and bcr, IS3 and bcr1 were the most abundant elements and, along with the group II intron B.c.I8, were found in all analyzed B. cytotoxicus strains. When compared to other B. cytotoxicus strains, the type-strain NVH 391-98 displayed a relatively low number of IS. Our results shed new light on the contribution of mobile genetic elements to the genome plasticity of B. cytotoxicus and their potential role in horizontal gene transfer.

scholarly journals Novel canine high-quality metagenome-assembled genomes, prophages, and host-associated plasmids by long-read metagenomics together with Hi-C proximity ligation

2021 ◽  
Author(s):  
Anna Cusco ◽  
Daniel Perez ◽  
Joaquim Vines ◽  
Norma Fabregas ◽  
Olga Francino
Keyword(s):  
Mobile Genetic Elements ◽  
Bacterial Host ◽  
High Quality ◽  
Short Read ◽  
Genetic Elements ◽  
Proximity Ligation ◽  
Long Read ◽  
Ribosomal Operons ◽  
Species Specific ◽  
Public Datasets

Long-read metagenomics facilitates the assembly of high-quality metagenome-assembled genomes (HQ MAGs) out of complex microbiomes. It provides highly contiguous assemblies by spanning repetitive regions, complete ribosomal genes, and mobile genetic elements. Hi-C proximity ligation data bins the long contigs and their associated extra-chromosomal elements to their bacterial host. Here, we characterized a canine fecal sample combining a long-read metagenomics assembly with Hi-C data, and further correcting frameshift errors. We retrieved 27 HQ MAGs and seven medium-quality (MQ) MAGs considering MIMAG criteria. All the long-read canine MAGs improved previous short-read MAGs from public datasets regarding contiguity of the assembly, presence, and completeness of the ribosomal operons, and presence of canonical tRNAs. This trend was also observed when comparing to representative genomes from a pure culture (short-read assemblies). Moreover, Hi-C data linked six potential plasmids to their bacterial hosts. Finally, we identified 51 bacteriophages integrated into their bacterial host, providing novel host information for eight viral clusters that included Gut Phage Database viral genomes. Even though three viral clusters were species-specific, most of them presented a broader host range. In conclusion, long-read metagenomics retrieved long contigs harboring complete assembled ribosomal operons, prophages, and other mobile genetic elements. Hi-C binned together the long contigs into HQ and MQ MAGs, some of them representing closely related species. Long-read metagenomics and Hi-C proximity ligation are likely to become a comprehensive approach to HQ MAGs discovery and assignment of extra-chromosomal elements to their bacterial host.

scholarly journals Characterization of Mobile Genetic Elements Using Long-Read Sequencing for Tracking Listeria monocytogenes from Food Processing Environments

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 822
Author(s):  
Hee Jin Kwon ◽  
Zhao Chen ◽  
Peter Evans ◽  
Jianghong Meng ◽  
Yi Chen
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Genetic Relatedness ◽  
Mobile Genetic Elements ◽  
Recent Common Ancestor ◽  
Nucleotide Substitution Rate ◽  
Genetic Elements ◽  
Most Recent Common Ancestor ◽  
Long Read ◽  
The U.S

Recently developed nanopore sequencing technologies offer a unique opportunity to rapidly close the genome and to identify complete sequences of mobile genetic elements (MGEs). In this study, 17 isolates of Listeria monocytogenes (Lm) epidemic clone II (ECII) from seven ready-to-eat meat or poultry processing facilities, not known to be associated with outbreaks, were shotgun sequenced, and among them, five isolates were further subjected to long-read sequencing. Additionally, 26 genomes of Lm ECII isolates associated with three listeriosis outbreaks in the U.S. and South Africa were obtained from the National Center for Biotechnology Information (NCBI) database and analyzed to evaluate if MGEs may be used as a high-resolution genetic marker for identifying and sourcing the origin of Lm. The analyses identified four comK prophages in 11 non-outbreak isolates from four facilities and three comK prophages in 20 isolates associated with two outbreaks that occurred in the U.S. In addition, three different plasmids were identified among 10 non-outbreak isolates and 14 outbreak isolates. Each comK prophage and plasmid was conserved among the isolates sharing it. Different prophages from different facilities or outbreaks had significant genetic variations, possibly due to horizontal gene transfer. Phylogenetic analysis showed that isolates from the same facility or the same outbreak always closely clustered. The time of most recent common ancestor of the Lm ECII isolates was estimated to be in March 1816 with the average nucleotide substitution rate of 3.1 × 10−7 substitutions per site per year. This study showed that complete MGE sequences provide a good signal to determine the genetic relatedness of Lm isolates, to identify persistence or repeated contamination that occurred within food processing environment, and to study the evolutionary history among closely related isolates.

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