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Barth ZK, Hicklin I, Thézé J, Takatsuka J, Nakai M, Herniou EA, Brown AM, Aylward FO. Genomic analysis of hyperparasitic viruses associated with entomopoxviruses. Virus Evol 2024; 10:veae051. [PMID: 39100687 PMCID: PMC11296320 DOI: 10.1093/ve/veae051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 05/17/2024] [Accepted: 07/11/2024] [Indexed: 08/06/2024] Open
Abstract
Polinton-like viruses (PLVs) are a diverse group of small integrative dsDNA viruses that infect diverse eukaryotic hosts. Many PLVs are hypothesized to parasitize viruses in the phylum Nucleocytoviricota for their own propagation and spread. Here, we analyze the genomes of novel PLVs associated with the occlusion bodies of entomopoxvirus (EPV) infections of two separate lepidopteran hosts. The presence of these elements within EPV occlusion bodies suggests that they are the first known hyperparasites of poxviruses. We find that these PLVs belong to two distinct lineages that are highly diverged from known PLVs. These PLVs possess mosaic genomes, and some essential genes share homology with mobile genes within EPVs. Based on this homology and observed PLV mosaicism, we propose a mechanism to explain the turnover of PLV replication and integration genes.
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Affiliation(s)
- Zachary K Barth
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, USA
| | - Ian Hicklin
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Julien Thézé
- Université Clermont Auvergne, INRAE, VetAgro Sup, UMR EPIA, Saint-Genès-Champanelle, France
| | - Jun Takatsuka
- Forestry and Forest Products Research Institute, Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Madoka Nakai
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwai, Fuchu, Tokyo 183-8509, Japan
| | - Elisabeth A Herniou
- Institut de Recherche sur la Biologie de l’Insecte, UMR7261 CNRS-Université de Tours, 20 Avenue Monge, Parc de Grandmont, Tours 37200, France
| | - Anne M Brown
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-Borne Pathogens, Virginia Tech, 1981 Kraft Dr, Blacksburg, VA 24061, USA
- Research and Informatics, University Libraries, Virginia Tech, Blacksburg, VA 24061, USA
| | - Frank O Aylward
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-Borne Pathogens, Virginia Tech, 1981 Kraft Dr, Blacksburg, VA 24061, USA
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Royzenblat SK, Freddolino L. Spatio-temporal organization of the E. coli chromosome from base to cellular length scales. EcoSal Plus 2024:eesp00012022. [PMID: 38864557 DOI: 10.1128/ecosalplus.esp-0001-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 04/17/2024] [Indexed: 06/13/2024]
Abstract
Escherichia coli has been a vital model organism for studying chromosomal structure, thanks, in part, to its small and circular genome (4.6 million base pairs) and well-characterized biochemical pathways. Over the last several decades, we have made considerable progress in understanding the intricacies of the structure and subsequent function of the E. coli nucleoid. At the smallest scale, DNA, with no physical constraints, takes on a shape reminiscent of a randomly twisted cable, forming mostly random coils but partly affected by its stiffness. This ball-of-spaghetti-like shape forms a structure several times too large to fit into the cell. Once the physiological constraints of the cell are added, the DNA takes on overtwisted (negatively supercoiled) structures, which are shaped by an intricate interplay of many proteins carrying out essential biological processes. At shorter length scales (up to about 1 kb), nucleoid-associated proteins organize and condense the chromosome by inducing loops, bends, and forming bridges. Zooming out further and including cellular processes, topological domains are formed, which are flanked by supercoiling barriers. At the megabase-scale both large, highly self-interacting regions (macrodomains) and strong contacts between distant but co-regulated genes have been observed. At the largest scale, the nucleoid forms a helical ellipsoid. In this review, we will explore the history and recent advances that pave the way for a better understanding of E. coli chromosome organization and structure, discussing the cellular processes that drive changes in DNA shape, and what contributes to compaction and formation of dynamic structures, and in turn how bacterial chromatin affects key processes such as transcription and replication.
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Affiliation(s)
- Sonya K Royzenblat
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lydia Freddolino
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
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3
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Mansky J, Wang H, Wagner-Döbler I, Tomasch J. The effect of site-specific recombinases XerCD on the removal of over-replicated chromosomal DNA through outer membrane vesicles in bacteria. Microbiol Spectr 2024; 12:e0234323. [PMID: 38349173 PMCID: PMC10913375 DOI: 10.1128/spectrum.02343-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 01/22/2024] [Indexed: 03/06/2024] Open
Abstract
Outer membrane vesicles (OMVs) are universally produced by Gram-negative bacteria and play important roles in symbiotic and pathogenic interactions. The DNA from the lumen of OMVs from the Alphaproteobacterium Dinoroseobacter shibae was previously shown to be enriched for the region around the terminus of replication ter and specifically for the recognition sequence dif of the two site-specific recombinases XerCD. These enzymes are highly conserved in bacteria and play an important role in the last phase of cell division. Here, we show that a similar enrichment of ter and dif is found in the DNA inside OMVs from Prochlorococcus marinus, Pseudomonas aeruginosa, Vibrio cholerae, and Escherichia coli. The deletion of xerC or xerD in E. coli reduced the enrichment peak directly at the dif sequence, while the enriched DNA region around ter became broader, demonstrating that either enzyme influences the DNA content inside the lumen of OMVs. We propose that the intra-vesicle DNA originated from over-replication repair and the XerCD enzymes might play a role in this process, providing them with a new function in addition to resolving chromosome dimers.IMPORTANCEImprecise termination of replication can lead to over-replicated parts of bacterial chromosomes that have to be excised and removed from the dividing cell. The underlying mechanism is poorly understood. Our data show that outer membrane vesicles (OMVs) from diverse Gram-negative bacteria are enriched for DNA around the terminus of replication ter and the site-specific XerCD recombinases influence this enrichment. Clearing the divisome from over-replicated parts of the bacterial chromosome might be a so far unrecognized and conserved function of OMVs.
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Affiliation(s)
- Johannes Mansky
- Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| | - Hui Wang
- Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| | - Irene Wagner-Döbler
- Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| | - Jürgen Tomasch
- Laboratory of Anoxygenic Phototrophs, Institute of Microbiology of the Czech Academy of Science–Centre Algatech, Třeboň, Czech Republic
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4
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Cornet F, Blanchais C, Dusfour-Castan R, Meunier A, Quebre V, Sekkouri Alaoui H, Boudsoq F, Campos M, Crozat E, Guynet C, Pasta F, Rousseau P, Ton Hoang B, Bouet JY. DNA Segregation in Enterobacteria. EcoSal Plus 2023; 11:eesp00382020. [PMID: 37220081 PMCID: PMC10729935 DOI: 10.1128/ecosalplus.esp-0038-2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/13/2023] [Indexed: 01/28/2024]
Abstract
DNA segregation ensures that cell offspring receive at least one copy of each DNA molecule, or replicon, after their replication. This important cellular process includes different phases leading to the physical separation of the replicons and their movement toward the future daughter cells. Here, we review these phases and processes in enterobacteria with emphasis on the molecular mechanisms at play and their controls.
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Affiliation(s)
- François Cornet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Corentin Blanchais
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Romane Dusfour-Castan
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Alix Meunier
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Valentin Quebre
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Hicham Sekkouri Alaoui
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - François Boudsoq
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Manuel Campos
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Estelle Crozat
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Catherine Guynet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Franck Pasta
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Philippe Rousseau
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Bao Ton Hoang
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
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Abstract
Two decades of metagenomic analyses have revealed that in many environments, small (∼5 kb), single-stranded DNA phages of the family Microviridae dominate the virome. Although the emblematic microvirus phiX174 is ubiquitous in the laboratory, most other microviruses, particularly those of the gokushovirus and amoyvirus lineages, have proven to be much more elusive. This puzzling lack of representative isolates has hindered insights into microviral biology. Furthermore, the idiosyncratic size and nature of their genomes have resulted in considerable misjudgments of their actual abundance in nature. Fortunately, recent successes in microvirus isolation and improved metagenomic methodologies can now provide us with more accurate appraisals of their abundance, their hosts, and their interactions. The emerging picture is that phiX174 and its relatives are rather rare and atypical microviruses, and that a tremendous diversity of other microviruses is ready for exploration.
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Affiliation(s)
- Paul C Kirchberger
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA;
| | - Howard Ochman
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
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6
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Longley R, Robinson A, Liber JA, Bryson AE, Morales DP, LaButti K, Riley R, Mondo SJ, Kuo A, Yoshinaga Y, Daum C, Barry K, Grigoriev IV, Desirò A, Chain PSG, Bonito G. Comparative genomics of Mollicutes-related endobacteria supports a late invasion into Mucoromycota fungi. Commun Biol 2023; 6:948. [PMID: 37723238 PMCID: PMC10507103 DOI: 10.1038/s42003-023-05299-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 08/29/2023] [Indexed: 09/20/2023] Open
Abstract
Diverse members of early-diverging Mucoromycota, including mycorrhizal taxa and soil-associated Mortierellaceae, are known to harbor Mollicutes-related endobacteria (MRE). It has been hypothesized that MRE were acquired by a common ancestor and transmitted vertically. Alternatively, MRE endosymbionts could have invaded after the divergence of Mucoromycota lineages and subsequently spread to new hosts horizontally. To better understand the evolutionary history of MRE symbionts, we generated and analyzed four complete MRE genomes from two Mortierellaceae genera: Linnemannia (MRE-L) and Benniella (MRE-B). These genomes include the smallest known of fungal endosymbionts and showed signals of a tight relationship with hosts including a reduced functional capacity and genes transferred from fungal hosts to MRE. Phylogenetic reconstruction including nine MRE from mycorrhizal fungi revealed that MRE-B genomes are more closely related to MRE from Glomeromycotina than MRE-L from the same host family. We posit that reductions in genome size, GC content, pseudogene content, and repeat content in MRE-L may reflect a longer-term relationship with their fungal hosts. These data indicate Linnemannia and Benniella MRE were likely acquired independently after their fungal hosts diverged from a common ancestor. This work expands upon foundational knowledge on minimal genomes and provides insights into the evolution of bacterial endosymbionts.
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Affiliation(s)
- Reid Longley
- Los Alamos National Laboratory, Los Alamos, NM, USA
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Julian A Liber
- Department of Biology, Duke University, Durham, NC, 27704, USA
| | - Abigail E Bryson
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Kurt LaButti
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Robert Riley
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Stephen J Mondo
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Agricultural Biology, Colorado State University, Fort Collins, CO, 80521, USA
| | - Alan Kuo
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yuko Yoshinaga
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chris Daum
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kerrie Barry
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Igor V Grigoriev
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Alessandro Desirò
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Gregory Bonito
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA.
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA.
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Siguier P, Rousseau P, Cornet F, Chandler M. A subclass of the IS1202 family of bacterial insertion sequences targets XerCD recombination sites. Plasmid 2023; 127:102696. [PMID: 37302728 DOI: 10.1016/j.plasmid.2023.102696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/31/2023] [Accepted: 06/01/2023] [Indexed: 06/13/2023]
Abstract
We describe here a new family of IS which are related to IS1202, originally isolated from Streptococcus pneumoniae in the mid-1990s and previously tagged as an emerging IS family in the ISfinder database. Members of this family have impacted some important properties of their hosts. We describe here another potentially important property of certain family members: specific targeting of xrs recombination sites. The family could be divided into three subgroups based on their transposase sequences and the length on the target repeats (DR) they generate on insertion: subgroup IS1202 (24-29 bp); ISTde1 (15-18 bp); and ISAba32 (5-6 bp). Members of the ISAba32 subgroup were repeatedly found abutting Xer recombinase recombination sites (xrs), separated by an intervening copy of a DR. These xrs sites, present in multiple copies in a number of Acinetobacter plasmids flanking antibiotic resistance genes, were proposed to form a new type of mobile genetic element using the chromosomally-encoded XerCD recombinase for mobility. Transposase alignments identified subgroup-specific indels which may be responsible for the differences in the transposition properties of the three subgroups (i.e. DR length and target specificity). We propose that this collection of IS be classed as a new insertion sequence family: the IS1202 family composed of three subgroups, only one of which specifically targets plasmid-borne xrs. We discuss the implications of xrs targeting for gene mobility.
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Affiliation(s)
- Patricia Siguier
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Integrative, Université de Toulouse, CNRS, UPS, France.
| | - Philippe Rousseau
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Integrative, Université de Toulouse, CNRS, UPS, France
| | - François Cornet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Integrative, Université de Toulouse, CNRS, UPS, France
| | - Michael Chandler
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC, USA.
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Interspecies Horizontal Transfer and Specific Integration of the Mosquitocidal Toxin-Encoding Plasmid pTAND672-2 from Bacillus thuringiensis subsp. israelensis to Lysinibacillus sphaericus. Appl Environ Microbiol 2023; 89:e0165222. [PMID: 36749061 PMCID: PMC9973010 DOI: 10.1128/aem.01652-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
pTAND672-2, a 144-kb resident plasmid of Bacillus thuringiensis serovar israelensis strain TAND672, was sequenced and characterized. This extrachromosomal element carries mosquitocidal toxin-, conjugation-, and recombinase-encoding genes, together with a putative arbitrium system, a genetic module recently discovered in temperate phages controlling lysogeny-lysis transition and in mobile genetic elements (MGEs) where its function remains clarified. Using conjugation experiments, pTAND672-2 is shown to be a novel integrative and conjugative element (ICE), which can horizontally transfer from B. thuringiensis serovar israelensis to Lysinibacillus sphaericus, another mosquitocidal bacterium, where it integrates into the chromosome. Its integration and circularization are reversible and involve a single-cross recombination between 33-bp specific sites, attB in the chromosome of L. sphaericus and attP in pTAND672-2. CDS143, coding for the putative tyrosine integrase Int143 distantly related to site-specific tyrosine Xer recombinases and phage integrases, can mediate the integration of pTAND672-2 to attB. The B. thuringiensis mosquito-killing genes carried by pTAND672-2 are efficiently transcribed and expressed in L. sphaericus, displaying a slight increased toxicity in this bacterium against Aedes albopictus larvae. The occurrence of pTAND672-2-like plasmids within the Bacillus cereus group was also explored and indicated that they all share a similar genetic backbone with diverse plasmid sizes, ranging from 58 to 225 kb. Interestingly, among them, the pEFR-4-4 plasmid of Bacillus paranthracis EFR-4 and p5 of B. thuringiensis BT-59 also display conjugative capability; moreover, like pTAND672-2 displays a chimeric structure between the pCH_133-e- and pBtoxis-like plasmids, pBTHD789-3 also appears to be mosaic of two plasmids. IMPORTANCE Horizontal transfer of mobile genetic elements carrying mosquitocidal toxin genes may play a driving role in the diversity of mosquitocidal bacteria. Here, the 144-kb mosquitocidal toxin-encoding plasmid pTAND672-2 is the first verified integrative and conjugative element (ICE) identified in Bacillus thuringiensis serovar israelensis. The key tyrosine integrase Int143, involved in the specific integration, is distantly related to other tyrosine recombinases. The study also reports the occurrence and potential interspecies transmission of pTAND672-2-like plasmids with varied sizes in B. thuringiensis, Bacillus paranthracis, and Bacillus wiedmannii isolates belonging to the Bacillus cereus group. This study is important for further understanding the evolution and ecology of mosquitocidal bacteria, as well as for providing new direction for the genetic engineering of biopesticides in the control of disease-transmitting mosquitoes.
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Antibiotic Susceptibility, Resistance Gene Determinants and Corresponding Genomic Regions in Lactobacillus amylovorus Isolates Derived from Wild Boars and Domestic Pigs. Microorganisms 2022; 11:microorganisms11010103. [PMID: 36677394 PMCID: PMC9863647 DOI: 10.3390/microorganisms11010103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/04/2023] Open
Abstract
Restrictions on the use of antibiotics in pigs lead to the continuous search for new probiotics serving as an alternative to antibiotics. One of the key parameters for probiotic bacteria selection is the absence of horizontally transmissible resistance genes. The aim of our study was to determine antibiotic susceptibility profiles in 28 Lactobacillus amylovorus isolates derived from the digestive tract of wild boars and farm pigs by means of the broth microdilution method and whole genome sequencing (WGS). We revealed genetic resistance determinants and examined sequences flanking resistance genes in these strains. Our findings indicate that L. amylovorus strains from domestic pigs are predominantly resistant to tetracycline, erythromycin and ampicillin. WGS analysis of horizontally transmissible genes revealed only three genetic determinants (tetW, ermB and aadE) of which all tetW and ermB genes were present only in strains derived from domestic pigs. Sequence analysis of coding sequences (CDS) in the neighborhood of the tetW gene revealed the presence of site-specific recombinase (xerC/D), site-specific DNA recombinase (spoIVCA) or DNA-binding transcriptional regulator (xre), usually directly downstream of the tetW gene. In the case of ermB, CDS for omega transcriptional repressor or mobilization protein were detected upstream of the ermB gene.
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Mobile Element Integration Reveals a Chromosome Dimer Resolution System in Legionellales. mBio 2022; 13:e0217122. [PMID: 36314797 PMCID: PMC9765430 DOI: 10.1128/mbio.02171-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In bacteria, the mechanisms used to repair DNA lesions during genome replication include homologous recombination between sister chromosomes. This can lead to the formation of chromosome dimers if an odd number of crossover events occurs. The dimers must be resolved before cell separation to ensure genomic stability and cell viability. Dimer resolution is achieved by the broadly conserved dif/Xer system, which catalyzes one additional crossover event immediately prior to cell separation. While dif/Xer systems have been characterized or predicted in the vast majority of proteobacteria, no homologs to dif or xer have been identified in the order Legionellales. Here, we report the discovery of a distinct single-recombinase dif/Xer system in the intracellular pathogen Legionella pneumophila. The dif site was uncovered by our analysis of Legionella mobile element-1 (LME-1), which harbors a dif site mimic and integrates into the L. pneumophila genome via site-specific recombination. We demonstrate that lpg1867 (here named xerL) encodes a tyrosine recombinase that is necessary and sufficient for catalyzing recombination at the dif site and that deletion of dif or xerL causes filamentation along with extracellular and intracellular growth defects. We show that the dif/XerL system is present throughout Legionellales and that Coxiella burnetii XerL and its cognate dif site can functionally substitute for the native system in L. pneumophila. Finally, we describe an unexpected link between C. burnetii dif/Xer and the maintenance of its virulence plasmids. IMPORTANCE The maintenance of circular chromosomes depends on the ability to resolve aberrant chromosome dimers after they form. In most proteobacteria, broadly conserved Xer recombinases catalyze single crossovers at short, species-specific dif sites located near the replication terminus. Chromosomal dimerization leads to the formation of two copies of dif within the same molecule, leading to rapid site-specific recombination and conversion back into chromosome monomers. The apparent absence of chromosome dimer resolution mechanisms in Legionellales has been a mystery to date. By studying a phage-like mobile genetic element, LME-1, we have identified a previously unknown single-recombinase dif/Xer system that is not only widespread across Legionellales but whose activity is linked to virulence in two important human pathogens.
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New Wolbachia pipientis Genotype Increasing Heat Stress Resistance of Drosophila melanogaster Host Is Characterized by a Large Chromosomal Inversion. Int J Mol Sci 2022; 23:ijms232416212. [PMID: 36555851 PMCID: PMC9786649 DOI: 10.3390/ijms232416212] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
The maternally transmitted endocellular bacteria Wolbachia is a well-known symbiont of insects, demonstrating both negative and positive effects on host fitness. The previously found Wolbachia strain wMelPlus is characterized by a positive effect on the stress-resistance of its host Drosophila melanogaster, under heat stress conditions. This investigation is dedicated to studying the genomic underpinnings of such an effect. We sequenced two closely related Wolbachia strains, wMelPlus and wMelCS112, assembled their complete genomes, and performed comparative genomic analysis engaging available Wolbachia genomes from the wMel and wMelCS groups. Despite the two strains under study sharing very close gene-composition, we discovered a large (>1/6 of total genome) chromosomal inversion in wMelPlus, spanning through the region that includes the area of the inversion earlier found in the wMel group of Wolbachia genotypes. A number of genes in unique inversion blocks of wMelPlus were identified that might be involved in the induction of a stress-resistant phenotype in the host. We hypothesize that such an inversion could rearrange established genetic regulatory-networks, causing the observed effects of such a complex fly phenotype as a modulation of heat stress resistance. Based on our findings, we propose that wMelPlus be distinguished as a separate genotype of the wMelCS group, named wMelCS3.
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12
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Barbuti MD, Myrbråten IS, Morales Angeles D, Kjos M. The cell cycle of Staphylococcus aureus: An updated review. Microbiologyopen 2022; 12:e1338. [PMID: 36825883 PMCID: PMC9733580 DOI: 10.1002/mbo3.1338] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
As bacteria proliferate, DNA replication, chromosome segregation, cell wall synthesis, and cytokinesis occur concomitantly and need to be tightly regulated and coordinated. Although these cell cycle processes have been studied for decades, several mechanisms remain elusive, specifically in coccus-shaped cells such as Staphylococcus aureus. In recent years, major progress has been made in our understanding of how staphylococci divide, including new, fundamental insights into the mechanisms of cell wall synthesis and division site selection. Furthermore, several novel proteins and mechanisms involved in the regulation of replication initiation or progression of the cell cycle have been identified and partially characterized. In this review, we will summarize our current understanding of the cell cycle processes in the spheroid model bacterium S. aureus, with a focus on recent advances in the understanding of how these processes are regulated.
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Affiliation(s)
- Maria D. Barbuti
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Ine S. Myrbråten
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Danae Morales Angeles
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
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13
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Miele S, Provan JI, Vergne J, Possoz C, Ochsenbein F, Barre FX. The Xer activation factor of TLCΦ expands the possibilities for Xer recombination. Nucleic Acids Res 2022; 50:6368-6383. [PMID: 35657090 PMCID: PMC9226527 DOI: 10.1093/nar/gkac429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 05/03/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
The chromosome dimer resolution machinery of bacteria is generally composed of two tyrosine recombinases, XerC and XerD. They resolve chromosome dimers by adding a crossover between sister copies of a specific site, dif. The reaction depends on a cell division protein, FtsK, which activates XerD by protein-protein interactions. The toxin-linked cryptic satellite phage (TLCΦ) of Vibrio cholerae, which participates in the emergence of cholera epidemic strains, carries a dif-like attachment site (attP). TLCΦ exploits the Xer machinery to integrate into the dif site of its host chromosomes. The TLCΦ integration reaction escapes the control of FtsK because TLCΦ encodes for its own XerD-activation factor, XafT. Additionally, TLCΦ attP is a poor substrate for XerD binding, in apparent contradiction with the high integration efficiency of the phage. Here, we present a sequencing-based methodology to analyse the integration and excision efficiency of thousands of synthetic mini-TLCΦ plasmids with differing attP sites in vivo. This methodology is applicable to the fine-grained analyses of DNA transactions on a wider scale. In addition, we compared the efficiency with which XafT and the XerD-activation domain of FtsK drive recombination reactions in vitro. Our results suggest that XafT not only activates XerD-catalysis but also helps form and/or stabilize synaptic complexes between imperfect Xer recombination sites.
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Affiliation(s)
- Solange Miele
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - James Iain Provan
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - Justine Vergne
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - Christophe Possoz
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - Françoise Ochsenbein
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - François-Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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14
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Benler S, Koonin EV. Recruitment of Mobile Genetic Elements for Diverse Cellular Functions in Prokaryotes. Front Mol Biosci 2022; 9:821197. [PMID: 35402511 PMCID: PMC8987985 DOI: 10.3389/fmolb.2022.821197] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/08/2022] [Indexed: 12/15/2022] Open
Abstract
Prokaryotic genomes are replete with mobile genetic elements (MGE) that span a continuum of replication autonomy. On numerous occasions during microbial evolution, diverse MGE lose their autonomy altogether but, rather than being quickly purged from the host genome, assume a new function that benefits the host, rendering the immobilized MGE subject to purifying selection, and resulting in its vertical inheritance. This mini-review highlights the diversity of the repurposed (exapted) MGE as well as the plethora of cellular functions that they perform. The principal contribution of the exaptation of MGE and their components is to the prokaryotic functional systems involved in biological conflicts, and in particular, defense against viruses and other MGE. This evolutionary entanglement between MGE and defense systems appears to stem both from mechanistic similarities and from similar evolutionary predicaments whereby both MGEs and defense systems tend to incur fitness costs to the hosts and thereby evolve mechanisms for survival including horizontal mobility, causing host addiction, and exaptation for functions beneficial to the host. The examples discussed demonstrate that the identity of an MGE, overall mobility and relationship with the host cell (mutualistic, symbiotic, commensal, or parasitic) are all factors that affect exaptation.
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15
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Gogou C, Japaridze A, Dekker C. Mechanisms for Chromosome Segregation in Bacteria. Front Microbiol 2021; 12:685687. [PMID: 34220773 PMCID: PMC8242196 DOI: 10.3389/fmicb.2021.685687] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/19/2021] [Indexed: 11/13/2022] Open
Abstract
The process of DNA segregation, the redistribution of newly replicated genomic material to daughter cells, is a crucial step in the life cycle of all living systems. Here, we review DNA segregation in bacteria which evolved a variety of mechanisms for partitioning newly replicated DNA. Bacterial species such as Caulobacter crescentus and Bacillus subtilis contain pushing and pulling mechanisms that exert forces and directionality to mediate the moving of newly synthesized chromosomes to the bacterial poles. Other bacteria such as Escherichia coli lack such active segregation systems, yet exhibit a spontaneous de-mixing of chromosomes due to entropic forces as DNA is being replicated under the confinement of the cell wall. Furthermore, we present a synopsis of the main players that contribute to prokaryotic genome segregation. We finish with emphasizing the importance of bottom-up approaches for the investigation of the various factors that contribute to genome segregation.
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Affiliation(s)
- Christos Gogou
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Aleksandre Japaridze
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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16
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Smyshlyaev G, Bateman A, Barabas O. Sequence analysis of tyrosine recombinases allows annotation of mobile genetic elements in prokaryotic genomes. Mol Syst Biol 2021; 17:e9880. [PMID: 34018328 PMCID: PMC8138268 DOI: 10.15252/msb.20209880] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 11/16/2022] Open
Abstract
Mobile genetic elements (MGEs) sequester and mobilize antibiotic resistance genes across bacterial genomes. Efficient and reliable identification of such elements is necessary to follow resistance spreading. However, automated tools for MGE identification are missing. Tyrosine recombinase (YR) proteins drive MGE mobilization and could provide markers for MGE detection, but they constitute a diverse family also involved in housekeeping functions. Here, we conducted a comprehensive survey of YRs from bacterial, archaeal, and phage genomes and developed a sequence-based classification system that dissects the characteristics of MGE-borne YRs. We revealed that MGE-related YRs evolved from non-mobile YRs by acquisition of a regulatory arm-binding domain that is essential for their mobility function. Based on these results, we further identified numerous unknown MGEs. This work provides a resource for comparative analysis and functional annotation of YRs and aids the development of computational tools for MGE annotation. Additionally, we reveal how YRs adapted to drive gene transfer across species and provide a tool to better characterize antibiotic resistance dissemination.
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Affiliation(s)
- Georgy Smyshlyaev
- European Molecular Biology LaboratoryEuropean Bioinformatics Institute (EMBL‐EBI)HinxtonUK
- European Molecular Biology Laboratory (EMBL)Structural and Computational Biology UnitHeidelbergGermany
- Department of Molecular BiologyUniversity of GenevaGenevaSwitzerland
| | - Alex Bateman
- European Molecular Biology LaboratoryEuropean Bioinformatics Institute (EMBL‐EBI)HinxtonUK
| | - Orsolya Barabas
- European Molecular Biology Laboratory (EMBL)Structural and Computational Biology UnitHeidelbergGermany
- Department of Molecular BiologyUniversity of GenevaGenevaSwitzerland
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17
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Piligrimova EG, Kazantseva OA, Kazantsev AN, Nikulin NA, Skorynina AV, Koposova ON, Shadrin AM. Putative plasmid prophages of Bacillus cereus sensu lato may hold the key to undiscovered phage diversity. Sci Rep 2021; 11:7611. [PMID: 33828147 PMCID: PMC8026635 DOI: 10.1038/s41598-021-87111-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/22/2021] [Indexed: 11/26/2022] Open
Abstract
Bacteriophages are bacterial viruses and the most abundant biological entities on Earth. Temperate bacteriophages can form prophages stably maintained in the host population: they either integrate into the host genome or replicate as plasmids in the host cytoplasm. As shown, tailed temperate bacteriophages may form circular plasmid prophages in many bacterial species of the taxa Firmicutes, Gammaproteobacteria and Spirochaetes. The actual number of such prophages is thought to be underestimated for two main reasons: first, in bacterial whole genome-sequencing assemblies, they are difficult to distinguish from actual plasmids; second, there is an absence of experimental studies which are vital to confirm their existence. In Firmicutes, such prophages appear to be especially numerous. In the present study, we identified 23 genomes from species of the Bacillus cereus group that were deposited in GenBank as plasmids and may belong to plasmid prophages with little or no homology to known viruses. We consider these putative prophages worth experimental assays since it will broaden our knowledge of phage diversity and suggest that more attention be paid to such molecules in all bacterial sequencing projects as this will help in identifying previously unknown phages.
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Affiliation(s)
- Emma G Piligrimova
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia.
| | - Olesya A Kazantseva
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Andrey N Kazantsev
- P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Pushchino Radio Astronomy Observatory, Pushchino, 142290, Russia
| | - Nikita A Nikulin
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Anna V Skorynina
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Olga N Koposova
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Andrey M Shadrin
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia.
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18
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Dheekollu J, Wiedmer A, Ayyanathan K, Deakyne JS, Messick TE, Lieberman PM. Cell-cycle-dependent EBNA1-DNA crosslinking promotes replication termination at oriP and viral episome maintenance. Cell 2021; 184:643-654.e13. [PMID: 33482082 DOI: 10.1016/j.cell.2020.12.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/17/2020] [Accepted: 12/15/2020] [Indexed: 02/08/2023]
Abstract
Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that persists as a multicopy episome in proliferating host cells. Episome maintenance is strictly dependent on EBNA1, a sequence-specific DNA-binding protein with no known enzymatic activities. Here, we show that EBNA1 forms a cell cycle-dependent DNA crosslink with the EBV origin of plasmid replication oriP. EBNA1 tyrosine 518 (Y518) is essential for crosslinking to oriP and functionally required for episome maintenance and generation of EBV-transformed lymphoblastoid cell lines (LCLs). Mechanistically, Y518 is required for replication fork termination at oriP in vivo and for formation of SDS-resistant complexes in vitro. EBNA1-DNA crosslinking corresponds to single-strand endonuclease activity specific to DNA structures enriched at replication-termination sites, such as 4-way junctions. These findings reveal that EBNA1 forms tyrosine-dependent DNA-protein crosslinks and single-strand cleavage at oriP required for replication termination and viral episome maintenance.
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19
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Karaboja X, Ren Z, Brandão HB, Paul P, Rudner DZ, Wang X. XerD unloads bacterial SMC complexes at the replication terminus. Mol Cell 2021; 81:756-766.e8. [PMID: 33472056 DOI: 10.1016/j.molcel.2020.12.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 11/24/2022]
Abstract
Bacillus subtilis structural maintenance of chromosomes (SMC) complexes are topologically loaded at centromeric sites adjacent to the replication origin by the partitioning protein ParB. These ring-shaped ATPases then translocate down the left and right chromosome arms while tethering them together. Here, we show that the site-specific recombinase XerD, which resolves chromosome dimers, is required to unload SMC tethers when they reach the terminus. We identify XerD-specific binding sites in the terminus region and show that they dictate the site of unloading in a manner that depends on XerD but not its catalytic residue, its partner protein XerC, or the recombination site dif. Finally, we provide evidence that ParB and XerD homologs perform similar functions in Staphylococcus aureus. Thus, two broadly conserved factors that act at the origin and terminus have second functions in loading and unloading SMC complexes that travel between them.
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Affiliation(s)
- Xheni Karaboja
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Hugo B Brandão
- Graduate Program in Biophysics, Harvard University, Cambridge, MA 02138, USA
| | - Payel Paul
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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20
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Dinoroseobacter shibae Outer Membrane Vesicles Are Enriched for the Chromosome Dimer Resolution Site dif. mSystems 2021; 6:6/1/e00693-20. [PMID: 33436507 PMCID: PMC7901474 DOI: 10.1128/msystems.00693-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Gram-negative bacteria continually form vesicles from their outer membrane (outer membrane vesicles [OMVs]) during normal growth. OMVs frequently contain DNA, and it is unclear how DNA can be shuffled from the cytoplasm to the OMVs. Outer membrane vesicles (OMVs) are universally produced by prokaryotes and play important roles in symbiotic and pathogenic interactions. They often contain DNA, but a mechanism for its incorporation is lacking. Here, we show that Dinoroseobacter shibae, a dinoflagellate symbiont, constitutively secretes OMVs containing DNA. Time-lapse microscopy captured instances of multiple OMV production at the septum during cell division. DNA from the vesicle lumen was up to 22-fold enriched for the region around the terminus of replication (ter). The peak of coverage was located at dif, a conserved 28-bp palindromic sequence required for binding of the site-specific tyrosine recombinases XerC/XerD. These enzymes are activated at the last stage of cell division immediately prior to septum formation when they are bound by the divisome protein FtsK. We suggest that overreplicated regions around the terminus have been repaired by the FtsK-dif-XerC/XerD molecular machinery. The vesicle proteome was clearly dominated by outer membrane and periplasmic proteins. Some of the most abundant vesicle membrane proteins were predicted to be required for direct interaction with peptidoglycan during cell division (LysM, Tol-Pal, Spol, lytic murein transglycosylase). OMVs were 15-fold enriched for the saturated fatty acid 16:00. We hypothesize that constitutive OMV secretion in D. shibae is coupled to cell division. The footprint of the FtsK-dif-XerC/XerD molecular machinery suggests a novel potentially highly conserved route for incorporation of DNA into OMVs. Clearing the division site from small DNA fragments might be an important function of vesicles produced during exponential growth under optimal conditions. IMPORTANCE Gram-negative bacteria continually form vesicles from their outer membrane (outer membrane vesicles [OMVs]) during normal growth. OMVs frequently contain DNA, and it is unclear how DNA can be shuffled from the cytoplasm to the OMVs. We studied OMV cargo in Dinoroseobacter shibae, a symbiont of dinoflagellates, using microscopy and a multi-omics approach. We found that vesicles formed during undisturbed exponential growth contain DNA which is enriched for genes around the replication terminus, specifically, the binding site for an enzyme complex that is activated at the last stage of cell division. We suggest that the enriched genes are the result of overreplication which is repaired by their excision and excretion via membrane vesicles to clear the divisome from waste DNA.
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21
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Lin DL, Traglia GM, Baker R, Sherratt DJ, Ramirez MS, Tolmasky ME. Functional Analysis of the Acinetobacter baumannii XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes. Antibiotics (Basel) 2020; 9:E405. [PMID: 32668667 PMCID: PMC7399989 DOI: 10.3390/antibiotics9070405] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/09/2020] [Accepted: 07/11/2020] [Indexed: 12/12/2022] Open
Abstract
Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The A. baumannii xerC and xerD genes were cloned, and the recombinant clones used to complement the cognate Escherichia coli mutants. The complemented strains supported the resolution of plasmid dimers, and, as is the case with E. coli and Klebsiella pneumoniae plasmids, the activity was enhanced when the cells were grown in a low osmolarity growth medium. Binding experiments showed that the partially purified A. baumannii XerC and XerD proteins (XerCAb and XerDAb) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing A. baumannii plasmids. Incubation with suicide substrates resulted in the covalent attachment of DNA to a recombinase, probably XerCAb, indicating that the first step in the recombination reaction took place. The results described show that XerCAb and XerDAb are functional proteins and support the hypothesis that they participate in horizontal dissemination of resistant genes among bacteria.
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Affiliation(s)
- David L. Lin
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (D.L.L.); (M.S.R.)
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; (R.B.); (D.J.S.)
| | - German M. Traglia
- Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República (UDeLaR), Montevideo 11600, Uruguay;
| | - Rachel Baker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; (R.B.); (D.J.S.)
| | - David J. Sherratt
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; (R.B.); (D.J.S.)
| | - Maria Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (D.L.L.); (M.S.R.)
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (D.L.L.); (M.S.R.)
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; (R.B.); (D.J.S.)
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22
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Comparative Genomic Analysis of Third-Generation-Cephalosporin-Resistant Escherichia coli Harboring the bla CMY-2-Positive IncI1 Group, IncB/O/K/Z, and IncC Plasmids Isolated from Healthy Broilers in Japan. Antimicrob Agents Chemother 2020; 64:AAC.02385-19. [PMID: 32366721 DOI: 10.1128/aac.02385-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 04/09/2020] [Indexed: 12/20/2022] Open
Abstract
The off-label use of third-generation cephalosporins (3GCs) during in ovo vaccination or vaccination of newly hatched chicks has been a common practice worldwide. CMY-2-producing Escherichia coli strains have been disseminated in broiler chicken production. The objective of this study was to determine the epidemiological linkage of bla CMY-2-positive plasmids among broilers both within and outside Japan, because the grandparent stock and parent stock were imported into Japan. We examined the whole-genome sequences of 132 3GC-resistant E. coli isolates collected from healthy broilers during 2002 to 2014. The predominant 3GC resistance gene was bla CMY-2, which was detected in the plasmids of 87 (65.9%) isolates. The main plasmid replicon types were IncI1-Iγ (n = 21; 24.1%), IncI (n = 12; 13.8%), IncB/O/K/Z (n = 28; 32.2%), and IncC (n = 22; 25.3%). Those plasmids were subjected to gene clustering, network analyses, and plasmid multilocus sequence typing (pMLST). The chromosomal DNA of isolates was subjected to MLST and single-nucleotide variant (SNV)-based phylogenetic analysis. MLST and SNV-based phylogenetic analysis revealed high diversity of E. coli isolates. The sequence type 429 (ST429) cluster harboring bla CMY-2-positive IncB/O/K/Z was closely related to isolates from broilers in Germany harboring bla CMY-2-positive IncB/O/K/Z. pST55-IncI, pST12-IncI1-Iγ, and pST3-IncC were prevalent in western Japan. pST12-IncI1-Iγ and pST3-IncC were closely related to plasmids detected in E. coli isolates from chickens in North America, whereas 26 IncB/O/K/Z types were related to those in Europe. These data will be useful to reveal the whole picture of transmission of CMY-2-producing bacteria inside and outside Japan.
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23
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Zhang L, Fu Y, Han X, Xu Q, Weng S, Yan B, Liu L, Hua X, Chen Y, Yu Y. Phenotypic Variation and Carbapenem Resistance Potential in OXA-499-Producing Acinetobacter pittii. Front Microbiol 2020; 11:1134. [PMID: 32582088 PMCID: PMC7296048 DOI: 10.3389/fmicb.2020.01134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/05/2020] [Indexed: 12/17/2022] Open
Abstract
Acinetobacter pittii is increasingly recognized as a clinically important species. Here, we identified a carbapenem-non-resistant A. pittii clinical isolate, A1254, harboring blaOXA–499, blaOXA–826, and blaADC–221. The blaOXA–499 genetic environment in A1254 was identical to that of another OXA-499-producing, but carbapenem-resistant, A. pittii isolate, YMC2010/8/T346, indicating the existence of phenotypic variation among OXA-499-producing A. pittii strains. Under imipenem-selective pressure, the A1254 isolate developed resistance to carbapenems in 60 generations. Two carbapenem-resistant mutants (CAB009 and CAB010) with mutations in the blaOXA–499 promoter region were isolated from two independently evolved populations (CAB001 and CAB004). The CAB009 mutant, with a mutation at position −14 (A to G), exhibited a four-fold higher carbapenem minimum inhibitory concentration (MIC) and a 4.53 ± 0.19 log2 fold change higher expression level of blaOXA–499 than the ancestor strain, A1254. The other mutant, CAB010, with a mutation at position −42 (G to A), showed a two-fold higher carbapenem MIC and a 1.65 ± 0.25 log2 fold change higher blaOXA–499 expression level than the ancestor strain. The blaOXA–499 gene and its promoter region were amplified from the wild-type strain and two mutant isolates and then individually cloned into the pYMAb2-Hygr vector and expressed in Acinetobacter baumannii ATCC 17978, A. pittii LMG 1035, and A. pittii A1254. All the transformed strains were resistant to carbapenem, irrespective of whether they harbored the initial or an evolved promoter sequence, and transformed strains expressing the promoter from the most resistant mutant, CAB009, showed the highest carbapenem MICs, with values of 32–64 μg/ml for imipenem and 128 μg/ml for meropenem. RNA sequencing was performed to confirm the contribution of blaOXA–499 to the development of carbapenem resistance. Although the CAB009 and CAB010 transcriptional patterns were different, blaOXA–499 was the only differentially expressed gene shared by the two mutants. Our results indicate that carbapenem-non-resistant Acinetobacter spp. strains carrying blaOXA genes have the potential to develop carbapenem resistance and need to be further investigated and monitored to prevent treatment failure due to the development of resistance.
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Affiliation(s)
- Linyue Zhang
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Ying Fu
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.,Department of Clinical Laboratory, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Xinhong Han
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Qingye Xu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Shanshan Weng
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Biyong Yan
- Department of Laboratory Medicine, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Lilin Liu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Xiaoting Hua
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Yan Chen
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
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Wang C, Feng Y, Liu L, Wei L, Kang M, Zong Z. Identification of novel mobile colistin resistance gene mcr-10. Emerg Microbes Infect 2020; 9:508-516. [PMID: 32116151 PMCID: PMC7067168 DOI: 10.1080/22221751.2020.1732231] [Citation(s) in RCA: 309] [Impact Index Per Article: 77.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mobile colistin resistance (mcr) genes represent an emerging challenge. Here we describe a novel mcr gene, mcr-10, on an IncFIA plasmid of an Enterobacter roggenkampii clinical strain. mcr-10 has the highest nucleotide identity (79.69%) with mcr-9 and encodes MCR-10 with 82.93% amino acids identical to MCR-9. mcr-10 confers 4-fold increase in colistin MIC (from 1 to 4 mg/L) when cloned into a colistin-susceptible E. roggenkampii strain. By screening GenBank, mcr-10 was found in various Enterobacteriaceae species of countries in four continents, suggesting that this gene has widely spread. MCR-10 shows 79.04% to 83.67% amino acid identity and highly conserved predicted protein structures with chromosomally encoded MCR-like phosphoethanolamine transferases (designated MCR-B here) of various Buttiauxella species. MCR-10, MCR-9 and MCR-B proteins may, therefore, originate from a common ancestor. mcr-10 was adjacent to a site-specific recombinase-encoding gene and was bracketed by IS903 and may be mobilized by site-specific recombination or composite transposon. Our results indicate that mcr-10 is a novel plasmid-borne colistin resistance gene and warrants immediate monitoring and further studies.
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Affiliation(s)
- Chengcheng Wang
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, People's Republic of China.,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Chengdu, People's Republic of China.,Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Yu Feng
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, People's Republic of China.,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Chengdu, People's Republic of China.,Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Lina Liu
- Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Li Wei
- Department of Infection Control, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Mei Kang
- Laboratory of Clinical Microbiology, Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Zhiyong Zong
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, People's Republic of China.,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Chengdu, People's Republic of China.,Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, People's Republic of China.,Department of Infection Control, West China Hospital, Sichuan University, Chengdu, People's Republic of China
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25
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Characterization of the Chromosome Dimer Resolution Site in Caulobacter crescentus. J Bacteriol 2019; 201:JB.00391-19. [PMID: 31548274 DOI: 10.1128/jb.00391-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/13/2019] [Indexed: 01/08/2023] Open
Abstract
Chromosome dimers occur in bacterial cells as a result of the recombinational repair of DNA. In most bacteria, chromosome dimers are resolved by XerCD site-specific recombination at the dif (deletion-induced filamentation) site located in the terminus region of the chromosome. Caulobacter crescentus, a Gram-negative oligotrophic bacterium, also possesses Xer recombinases, called CcXerC and CcXerD, which have been shown to interact with the Escherichia coli dif site in vitro Previous studies on Caulobacter have suggested the presence of a dif site (referred to in this paper as dif1CC ), but no in vitro data have shown any association with this site and the CcXer proteins. Using recursive hidden Markov modeling, another group has proposed a second dif site, which we call dif2CC , which shows more similarity to the dif consensus sequence. Here, by using a combination of in vitro experiments, we compare the affinities and the cleavage abilities of CcXerCD recombinases for both dif sites. Our results show that dif2CC displays a higher affinity for CcXerC and CcXerD and is bound cooperatively by these proteins, which is not the case for the original dif1CC site. Furthermore, dif2CC nicked substrates are more efficiently cleaved by CcXerCD, and deletion of the site results in about 5 to 10% of cells showing an altered cellular morphology.IMPORTANCE Bacteria utilize site-specific recombination for a variety of purposes, including the control of gene expression, acquisition of genetic elements, and the resolution of dimeric chromosomes. Failure to resolve dimeric chromosomes can lead to cell division defects in a percentage of the cell population. The work presented here shows the existence of a chromosomal resolution system in C. crescentus Defects in this resolution system result in the formation of chains of cells. Further understanding of how these cells remain linked together will help in the understanding of how chromosome segregation and cell division are linked in C. crescentus.
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Brovedan M, Repizo GD, Marchiaro P, Viale AM, Limansky A. Characterization of the diverse plasmid pool harbored by the blaNDM-1-containing Acinetobacter bereziniae HPC229 clinical strain. PLoS One 2019; 14:e0220584. [PMID: 31743332 PMCID: PMC6863613 DOI: 10.1371/journal.pone.0220584] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 10/24/2019] [Indexed: 11/18/2022] Open
Abstract
Acinetobacter bereziniae is an environmental microorganism with increasing clinical incidence, and may thus provide a model for a bacterial species bridging the gap between the environment and the clinical setting. A. bereziniae plasmids have been poorly studied, and their characterization could offer clues on the causes underlying the leap between these two different habitats. Here we characterized the whole plasmid content of A. bereziniae HPC229, a clinical strain previously reported to harbor a 44-kbp plasmid, pNDM229, conferring carbapenem and aminoglycoside resistance. We identified five extra plasmids in HPC229 ranging from 114 to 1.3 kbp, including pAbe229-114 (114 kbp) encoding a MOBP111 relaxase and carrying heavy metal resistance, a bacteriophage defense BREX system and four different toxin-antitoxin (TA) systems. Two other replicons, pAbe229-15 (15.4 kbp) and pAbe229-9 (9.1 kbp), both encoding MOBQ1 relaxases and also carrying TA systems, were found. The three latter plasmids contained Acinetobacter Rep_3 superfamily replication initiator protein genes, and functional analysis of their transfer regions revealed the mobilizable nature of them. HPC229 also harbors two smaller plasmids, pAbe229-4 (4.4 kbp) and pAbe229-1 (1.3 kbp), the former bearing a ColE1-type replicon and a TA system, and the latter lacking known replication functions. Comparative sequence analyses against deposited Acinetobacter genomes indicated that the above five HPC229 plasmids were unique, although some regions were also present in other of these genomes. The transfer, replication, and adaptive modules in pAbe229-15, and the stability module in pAbe229-9, were bordered by sites potentially recognized by XerC/XerD site-specific tyrosine recombinases, thus suggesting a potential mechanism for their acquisition. The presence of Rep_3 and ColE1-based replication modules, different mob genes, distinct adaptive functions including resistance to heavy metal and other environmental stressors, as well as antimicrobial resistance genes, and a high content of XerC/XerD sites among HPC229 plasmids provide evidence of substantial links with bacterial species derived from both environmental and clinical habitats.
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Affiliation(s)
- Marco Brovedan
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Guillermo D. Repizo
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Patricia Marchiaro
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Alejandro M. Viale
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
- * E-mail: (AMV); (AL)
| | - Adriana Limansky
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
- * E-mail: (AMV); (AL)
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Ramirez MS, Iriarte A, Reyes-Lamothe R, Sherratt DJ, Tolmasky ME. Small Klebsiella pneumoniae Plasmids: Neglected Contributors to Antibiotic Resistance. Front Microbiol 2019; 10:2182. [PMID: 31616398 PMCID: PMC6764390 DOI: 10.3389/fmicb.2019.02182] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/05/2019] [Indexed: 12/15/2022] Open
Abstract
Klebsiella pneumoniae is the causative agent of community- and, more commonly, hospital-acquired infections. Infections caused by this bacterium have recently become more dangerous due to the acquisition of multiresistance to antibiotics and the rise of hypervirulent variants. Plasmids usually carry genes coding for resistance to antibiotics or virulence factors, and the recent sequence of complete K. pneumoniae genomes showed that most strains harbor many of them. Unlike large plasmids, small, usually high copy number plasmids, did not attract much attention. However, these plasmids may include genes coding for specialized functions, such as antibiotic resistance, that can be expressed at high levels due to gene dosage effect. These genes may be part of mobile elements that not only facilitate their dissemination but also participate in plasmid evolution. Furthermore, high copy number plasmids may also play a role in evolution by allowing coexistence of mutated and non-mutated versions of a gene, which helps to circumvent the constraints imposed by trade-offs after certain genes mutate. Most K. pneumoniae plasmids 25-kb or smaller replicate by the ColE1-type mechanism and many of them are mobilizable. The transposon Tn1331 and derivatives were found in a high percentage of these plasmids. Another transposon that was found in representatives of this group is the bla KPC-containing Tn4401. Common resistance determinants found in these plasmids were aac(6')-Ib and genes coding for β-lactamases including carbapenemases.
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Affiliation(s)
- Maria S. Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Sciences, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, United States
| | - Andrés Iriarte
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Facultad de Medicina, Universidad de la República de Uruguay, Montevideo, Uruguay
| | | | - David J. Sherratt
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Sciences, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, United States
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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28
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Rideau F, Le Roy C, Sagné E, Renaudin H, Pereyre S, Henrich B, Dordet-Frisoni E, Citti C, Lartigue C, Bébéar C. Random transposon insertion in the Mycoplasma hominis minimal genome. Sci Rep 2019; 9:13554. [PMID: 31537861 PMCID: PMC6753208 DOI: 10.1038/s41598-019-49919-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 08/30/2019] [Indexed: 11/09/2022] Open
Abstract
Mycoplasma hominis is an opportunistic human pathogen associated with genital and neonatal infections. Until this study, the lack of a reliable transformation method for the genetic manipulation of M. hominis hindered the investigation of the pathogenicity and the peculiar arginine-based metabolism of this bacterium. A genomic analysis of 20 different M. hominis strains revealed a number of putative restriction-modification systems in this species. Despite the presence of these systems, a reproducible polyethylene glycol (PEG)-mediated transformation protocol was successfully developed in this study for three different strains: two clinical isolates and the M132 reference strain. Transformants were generated by transposon mutagenesis with an efficiency of approximately 10-9 transformants/cell/µg plasmid and were shown to carry single or multiple mini-transposons randomly inserted within their genomes. One M132-mutant was observed to carry a single-copy transposon inserted within the gene encoding P75, a protein potentially involved in adhesion. However, no difference in adhesion was observed in cell-assays between this mutant and the M132 parent strain. Whole genome sequencing of mutants carrying multiple copies of the transposon further revealed the occurrence of genomic rearrangements. Overall, this is the first time that genetically modified strains of M. hominis have been obtained by random mutagenesis using a mini-transposon conferring resistance to tetracycline.
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Affiliation(s)
- Fabien Rideau
- University of Bordeaux, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France.,INRA, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France
| | - Chloé Le Roy
- University of Bordeaux, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France.,INRA, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France
| | - Eveline Sagné
- IHAP, Université de Toulouse, INRA, ENVT, Toulouse, France
| | - Hélène Renaudin
- University of Bordeaux, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France.,INRA, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France
| | - Sabine Pereyre
- University of Bordeaux, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France.,INRA, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France
| | - Birgit Henrich
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University, Düsseldorf, Germany
| | | | | | - Carole Lartigue
- INRA, UMR 1332 de Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, Gironde, France. .,University of Bordeaux, UMR 1332 de Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, Gironde, France.
| | - Cécile Bébéar
- University of Bordeaux, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France. .,INRA, USC-EA3671 Mycoplasmal and Chlamydial Infections in Humans, Bordeaux, France.
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29
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Mindlin S, Petrenko A, Petrova M. Chromium resistance genetic element flanked by XerC/XerD recombination sites and its distribution in environmental and clinical Acinetobacter strains. FEMS Microbiol Lett 2019. [PMID: 29514194 DOI: 10.1093/femsle/fny047] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A novel mobile genetic element has been identified in small plasmids isolated from permafrost strains of Acinetobacter lwoffii. This element, designated the chrAB dif module, contains the chromium resistance genes chrA and chrB, functionally active both in the original host strains and after transfer into Acinetobacter baylyi. The 3011 bp chrAB dif module is flanked by XerC/XerD recombination sites highly homologous to those of the site-specific recombination system dif/Xer. Analysis of public databases revealed almost identical variants of the chrAB dif module in different plasmids in strains of various Acinetobacter species predominantly inhabiting the environment (A. lwoffii, Acinetobacter indicus, Acinetobacter idrijaensis, Acinetobacter shindleri and Acinetobacter nosocomialis). Together with previously described Acinetobacter antibiotic resistance elements, the chrAB dif module defines a new group of mobile elements that rely on the dif/Xer system for their mobility. Our observations suggest an ancient origin of the mobile elements flanked by dif sites and their participation in the mobilization of plasmid genes bearing adaptive functions.
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Affiliation(s)
- Sofia Mindlin
- Russian Academy of Sciences, Institute of Molecular Genetics, Kurchatov sq. 2, Moscow 123182, Russia
| | - Anatoliy Petrenko
- Russian Academy of Sciences, Institute of Molecular Genetics, Kurchatov sq. 2, Moscow 123182, Russia
| | - Mayya Petrova
- Russian Academy of Sciences, Institute of Molecular Genetics, Kurchatov sq. 2, Moscow 123182, Russia
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30
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Midonet C, Miele S, Paly E, Guerois R, Barre FX. The TLCΦ satellite phage harbors a Xer recombination activation factor. Proc Natl Acad Sci U S A 2019; 116:18391-18396. [PMID: 31420511 PMCID: PMC6744903 DOI: 10.1073/pnas.1902905116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The circular chromosomes of bacteria can be concatenated into dimers by homologous recombination. Dimers are solved by the addition of a cross-over at a specific chromosomal site, dif, by 2 related tyrosine recombinases, XerC and XerD. Each enzyme catalyzes the exchange of a specific pair of strands. Some plasmids exploit the Xer machinery for concatemer resolution. Other mobile elements exploit it to integrate into the genome of their host. Chromosome dimer resolution is initiated by XerD. The reaction is under the control of a cell-division protein, FtsK, which activates XerD by a direct contact. Most mobile elements exploit FtsK-independent Xer recombination reactions initiated by XerC. The only notable exception is the toxin-linked cryptic satellite phage of Vibrio cholerae, TLCΦ, which integrates into and excises from the dif site of the primary chromosome of its host by a reaction initiated by XerD. However, the reaction remains independent of FtsK. Here, we show that TLCΦ carries a Xer recombination activation factor, XafT. We demonstrate in vitro that XafT activates XerD catalysis. Correspondingly, we found that XafT specifically interacts with XerD. We further show that integrative mobile elements exploiting Xer (IMEXs) encoding a XafT-like protein are widespread in gamma- and beta-proteobacteria, including human, animal, and plant pathogens.
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Affiliation(s)
- Caroline Midonet
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Université Paris Sud, 91198 Gif sur Yvette, France
| | - Solange Miele
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Université Paris Sud, 91198 Gif sur Yvette, France
| | - Evelyne Paly
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Université Paris Sud, 91198 Gif sur Yvette, France
| | - Raphaël Guerois
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Université Paris Sud, 91198 Gif sur Yvette, France
| | - François-Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Université Paris Sud, 91198 Gif sur Yvette, France
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31
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Timilsina S, Pereira-Martin JA, Minsavage GV, Iruegas-Bocardo F, Abrahamian P, Potnis N, Kolaczkowski B, Vallad GE, Goss EM, Jones JB. Multiple Recombination Events Drive the Current Genetic Structure of Xanthomonas perforans in Florida. Front Microbiol 2019; 10:448. [PMID: 30930868 PMCID: PMC6425879 DOI: 10.3389/fmicb.2019.00448] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/20/2019] [Indexed: 11/23/2022] Open
Abstract
Prior to the identification of Xanthomonas perforans associated with bacterial spot of tomato in 1991, X. euvesicatoria was the only known species in Florida. Currently, X. perforans is the Xanthomonas sp. associated with tomato in Florida. Changes in pathogenic race and sequence alleles over time signify shifts in the dominant X. perforans genotype in Florida. We previously reported recombination of X. perforans strains with closely related Xanthomonas species as a potential driving factor for X. perforans evolution. However, the extent of recombination across the X. perforans genomes was unknown. We used a core genome multilocus sequence analysis approach to identify conserved genes and evaluated recombination-associated evolution of these genes in X. perforans. A total of 1,356 genes were determined to be "core" genes conserved among the 58 X. perforans genomes used in the study. Our approach identified three genetic groups of X. perforans in Florida based on the principal component analysis (PCA) using core genes. Nucleotide variation in 241 genes defined these groups, that are referred as Phylogenetic-group Defining (PgD) genes. Furthermore, alleles of many of these PgD genes showed 100% sequence identity with X. euvesicatoria, suggesting that variation likely has been introduced by recombination at multiple locations throughout the bacterial chromosome. Site-specific recombinase genes along with plasmid mobilization and phage associated genes were observed at different frequencies in the three phylogenetic groups and were associated with clusters of recombinant genes. Our analysis of core genes revealed the extent, source, and mechanisms of recombination events that shaped the current population and genomic structure of X. perforans in Florida.
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Affiliation(s)
- Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
| | | | - Gerald V. Minsavage
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
| | | | - Peter Abrahamian
- Gulf Coast Research and Education Center, University of Florida, Gainesville, FL, United States
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, United States
| | - Bryan Kolaczkowski
- Microbiology and Cell Science, University of Florida, Gainesville, FL, United States
| | - Gary E. Vallad
- Gulf Coast Research and Education Center, University of Florida, Gainesville, FL, United States
| | - Erica M. Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
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Emergence of carbapenem-resistant Acinetobacter pittii carrying the blaOXA-72 gene in the Amazon region, Brazil. Diagn Microbiol Infect Dis 2019; 93:82-84. [DOI: 10.1016/j.diagmicrobio.2018.07.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/15/2018] [Accepted: 07/25/2018] [Indexed: 11/20/2022]
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33
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Binet R, Pettengill EA, Hoffmann M, Hammack TS, Monday SR. Construction of stable fluorescent laboratory control strains for several food safety relevant Enterobacteriaceae. Food Microbiol 2018; 76:553-563. [DOI: 10.1016/j.fm.2017.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/26/2017] [Accepted: 10/27/2017] [Indexed: 02/06/2023]
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34
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Genomic mapping of ST85 bla NDM-1 and bla OXA-94 producing Acinetobacter baumannii isolates from Syrian Civil War Victims. Int J Infect Dis 2018; 74:100-108. [PMID: 30053579 DOI: 10.1016/j.ijid.2018.07.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES The rapid emergence of carbapenem-resistant Acinetobacter baumannii is a global health concern. A comparative genomic analysis was performed on two ST85 A. baumannii strains harboring blaNDM-1 and blaOXA-94 collected in Lebanon from Syrian Civil War victims. METHODS Genome sequencing data of ACMH-6200 and ACMH-6201 were used for in silico extraction of multilocus sequence types (MLST), resistance genes, and virulence factors. Plasmids were genetically mapped in silico and using PCR-based replicon typing (PBRT). The genetic environment of blaNDM-1 and blaOXA-94 was determined, and whole-genome single nucleotide polymorphism (wgSNP) analysis in comparison with 41 publicly available A. baumannii genomes was performed. RESULTS Tn125 carrying blaNDM-1 was truncated by the insertion of ISAba14 downstream of dct, generating ΔTn125. blaOXA-94 was upstream of ISAba13 and ISAba17. Resistance to ceftazidime could be attributed to AmpC cephalosporinase encoded by blaADC-25, and to blaNDM-1 on plasmids. GyrA (S83L) and ParC (S80L) substitutions conferred resistance to fluoroquinolones. wgSNP analysis separated the isolates based on their sequence types. CONCLUSIONS The role of refugees in the transmission of antimicrobial resistance in developing countries is understudied. As such, this study sheds light on the correlation between population mobility and the importation of drug-resistant pathogens. It also highlights the manifold mechanisms underlying antibiotic resistance in A. baumannii.
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35
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Sinha AK, Possoz C, Durand A, Desfontaines JM, Barre FX, Leach DRF, Michel B. Broken replication forks trigger heritable DNA breaks in the terminus of a circular chromosome. PLoS Genet 2018. [PMID: 29522563 PMCID: PMC5862497 DOI: 10.1371/journal.pgen.1007256] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
It was recently reported that the recBC mutants of Escherichia coli, deficient for DNA double-strand break (DSB) repair, have a decreased copy number of their terminus region. We previously showed that this deficit resulted from DNA loss after post-replicative breakage of one of the two sister-chromosome termini at cell division. A viable cell and a dead cell devoid of terminus region were thus produced and, intriguingly, the reaction was transmitted to the following generations. Using genome marker frequency profiling and observation by microscopy of specific DNA loci within the terminus, we reveal here the origin of this phenomenon. We observed that terminus DNA loss was reduced in a recA mutant by the double-strand DNA degradation activity of RecBCD. The terminus-less cell produced at the first cell division was less prone to divide than the one produced at the next generation. DNA loss was not heritable if the chromosome was linearized in the terminus and occurred at chromosome termini that were unable to segregate after replication. We propose that in a recB mutant replication fork breakage results in the persistence of a linear DNA tail attached to a circular chromosome. Segregation of the linear and circular parts of this "σ-replicating chromosome" causes terminus DNA breakage during cell division. One daughter cell inherits a truncated linear chromosome and is not viable. The other inherits a circular chromosome attached to a linear tail ending in the chromosome terminus. Replication extends this tail, while degradation of its extremity results in terminus DNA loss. Repeated generation and segregation of new σ-replicating chromosomes explains the heritability of post-replicative breakage. Our results allow us to determine that in E. coli at each generation, 18% of cells are subject to replication fork breakage at dispersed, potentially random, chromosomal locations.
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Affiliation(s)
- Anurag Kumar Sinha
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (AKS); (BM)
| | - Christophe Possoz
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Adeline Durand
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Jean-Michel Desfontaines
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - François-Xavier Barre
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - David R. F. Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Bénédicte Michel
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (AKS); (BM)
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Cameranesi MM, Morán-Barrio J, Limansky AS, Repizo GD, Viale AM. Site-Specific Recombination at XerC/D Sites Mediates the Formation and Resolution of Plasmid Co-integrates Carrying a blaOXA-58- and Tn aphA6-Resistance Module in Acinetobacter baumannii. Front Microbiol 2018; 9:66. [PMID: 29434581 PMCID: PMC5790767 DOI: 10.3389/fmicb.2018.00066] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/11/2018] [Indexed: 12/21/2022] Open
Abstract
Members of the genus Acinetobacter possess distinct plasmid types which provide effective platforms for the acquisition, evolution, and dissemination of antimicrobial resistance structures. Many plasmid-borne resistance structures are bordered by short DNA sequences providing potential recognition sites for the host XerC and XerD site-specific tyrosine recombinases (XerC/D-like sites). However, whether these sites are active in recombination and how they assist the mobilization of associated resistance structures is still poorly understood. Here we characterized the plasmids carried by Acinetobacter baumannii Ab242, a multidrug-resistant clinical strain belonging to the ST104 (Oxford scheme) which produces an OXA-58 carbapenem-hydrolyzing class-D β-lactamase (CHDL). Plasmid sequencing and characterization of replication, stability, and adaptive modules revealed the presence in Ab242 of three novel plasmids lacking self-transferability functions which were designated pAb242_9, pAb242_12, and pAb242_25, respectively. Among them, only pAb242_25 was found to carry an adaptive module encompassing an ISAba825-blaOXA-58 arrangement accompanied by a TnaphA6 transposon, the whole structure conferring simultaneous resistance to carbapenems and aminoglycosides. Ab242 plasmids harbor several XerC/D-like sites, with most sites found in pAb242_25 located in the vicinity or within the adaptive module described above. Electrotransformation of susceptible A. nosocomialis cells with Ab242 plasmids followed by imipenem selection indicated that the transforming plasmid form was a co-integrate resulting from the fusion of pAb242_25 and pAb242_12. Further characterization by cloning and sequencing studies indicated that a XerC/D site in pAb242_25 and another in pAb242_12 provided the active sister pair for the inter-molecular site-specific recombination reaction mediating the fusion of these two plasmids. Moreover, the resulting co-integrate was found also to undergo intra-molecular resolution at the new pair of XerC/D sites generated during fusion thus regenerating the original pAb242_25 and pAb242_12 plasmids. These observations provide the first evidence indicating that XerC/D-like sites in A. baumannii plasmids can provide active pairs for site-specific recombination mediating inter-molecular fusions and intra-molecular resolutions. The overall results shed light on the evolutionary dynamics of A. baumannii plasmids and the underlying mechanisms of dissemination of genetic structures responsible for carbapenem and other antibiotics resistance among the Acinetobacter clinical population.
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Affiliation(s)
- María M Cameranesi
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Jorgelina Morán-Barrio
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Adriana S Limansky
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Guillermo D Repizo
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Alejandro M Viale
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR), Rosario, Argentina
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Division-induced DNA double strand breaks in the chromosome terminus region of Escherichia coli lacking RecBCD DNA repair enzyme. PLoS Genet 2017; 13:e1006895. [PMID: 28968392 PMCID: PMC5638614 DOI: 10.1371/journal.pgen.1006895] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 10/12/2017] [Accepted: 06/23/2017] [Indexed: 12/27/2022] Open
Abstract
Marker frequency analysis of the Escherichia coli recB mutant chromosome has revealed a deficit of DNA in a specific zone of the terminus, centred on the dif/TerC region. Using fluorescence microscopy of a marked chromosomal site, we show that the dif region is lost after replication completion, at the time of cell division, in one daughter cell only, and that the phenomenon is transmitted to progeny. Analysis by marker frequency and microscopy shows that the position of DNA loss is not defined by the replication fork merging point since it still occurs in the dif/TerC region when the replication fork trap is displaced in strains harbouring ectopic Ter sites. Terminus DNA loss in the recB mutant is also independent of dimer resolution by XerCD at dif and of Topo IV action close to dif. It occurs in the terminus region, at the point of inversion of the GC skew, which is also the point of convergence of specific sequence motifs like KOPS and Chi sites, regardless of whether the convergence of GC skew is at dif (wild-type) or a newly created sequence. In the absence of FtsK-driven DNA translocation, terminus DNA loss is less precisely targeted to the KOPS convergence sequence, but occurs at a similar frequency and follows the same pattern as in FtsK+ cells. Importantly, using ftsIts, ftsAts division mutants and cephalexin treated cells, we show that DNA loss of the dif region in the recB mutant is decreased by the inactivation of cell division. We propose that it results from septum-induced chromosome breakage, and largely contributes to the low viability of the recB mutant. RecBCD protein complex is an important player of DSB repair in bacteria and bacteria that cannot repair DNA double-stranded breaks (DSB) have a low viability. Whole genome sequencing analyses showed a deficit in specific sequences of the chromosome terminus region in recB mutant cells, suggesting terminus DNA degradation during growth. We studied here the phenomenon of terminus DNA loss by whole genome sequencing and microscopy analyses of exponentially growing bacteria. We tested all processes known to take place in the chromosome terminus region for a putative role in DNA loss: replication fork termination, dimer resolution, resolution of catenated chromosomes, and translocation of the chromosome arms in daughter cells during septum formation. None of the mutations that affect these processes prevents the phenomenon. However, we observed that terminus DNA loss is abolished in cells that cannot divide. We propose that in cells defective for RecBCD-mediated DSB repair the terminus region of the chromosome remains in the way of the growing septum during cell division, then septum closure triggers chromosome breakage and, in turn, DNA degradation.
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Lean SS, Yeo CC. Small, Enigmatic Plasmids of the Nosocomial Pathogen, Acinetobacter baumannii: Good, Bad, Who Knows? Front Microbiol 2017; 8:1547. [PMID: 28861061 PMCID: PMC5559437 DOI: 10.3389/fmicb.2017.01547] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has become a serious healthcare concern within a span of two decades due to its ability to rapidly acquire resistance to all classes of antimicrobial compounds. One of the key features of the A. baumannii genome is an open pan genome with a plethora of plasmids, transposons, integrons, and genomic islands, all of which play important roles in the evolution and success of this clinical pathogen, particularly in the acquisition of multidrug resistance determinants. An interesting genetic feature seen in majority of A. baumannii genomes analyzed is the presence of small plasmids that usually ranged from 2 to 10 kb in size, some of which harbor antibiotic resistance genes and homologs of plasmid mobilization genes. These plasmids are often overlooked when compared to their larger, conjugative counterparts that harbor multiple antibiotic resistance genes and transposable elements. In this mini-review, we will examine our current knowledge of these small A. baumannii plasmids and look into their genetic diversity and phylogenetic relationships. Some of these plasmids, such as the Rep-3 superfamily group and the pRAY-type, which has no recognizable replicase genes, are quite widespread among diverse A. baumannii clinical isolates worldwide, hinting at their usefulness to the lifestyle of this pathogen. Other small plasmids especially those from the Rep-1 superfamily are truly enigmatic, encoding only hypothetical proteins of unknown function, leading to the question of whether these small plasmids are “good” or “bad” to their host A. baumannii.
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Affiliation(s)
- Soo Sum Lean
- Saw Swee Hock School of Public Health, National University of SingaporeSingapore, Singapore
| | - Chew Chieng Yeo
- Faculty of Medicine, Biomedical Research Centre, Universiti Sultan Zainal AbidinKuala Terengganu, Malaysia
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Chromosomal Amplification of the blaOXA-58 Carbapenemase Gene in a Proteus mirabilis Clinical Isolate. Antimicrob Agents Chemother 2017; 61:AAC.01697-16. [PMID: 27855079 DOI: 10.1128/aac.01697-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/24/2016] [Indexed: 01/30/2023] Open
Abstract
Horizontal gene transfer may occur between distantly related bacteria, thus leading to genetic plasticity and in some cases to acquisition of novel resistance traits. Proteus mirabilis is an enterobacterial species responsible for human infections that may express various acquired β-lactam resistance genes, including different classes of carbapenemase genes. Here we report a Proteus mirabilis clinical isolate (strain 1091) displaying resistance to penicillin, including temocillin, together with reduced susceptibility to carbapenems and susceptibility to expanded-spectrum cephalosporins. Using biochemical tests, significant carbapenem hydrolysis was detected in P. mirabilis 1091. Since PCR failed to detect acquired carbapenemase genes commonly found in Enterobacteriaceae, we used a whole-genome sequencing approach that revealed the presence of blaOXA-58 class D carbapenemase gene, so far identified only in Acinetobacter species. This gene was located on a 3.1-kb element coharboring a blaAmpC-like gene. Remarkably, these two genes were bracketed by putative XerC-XerD binding sites and inserted at a XerC-XerD site located between the terminase-like small- and large-subunit genes of a bacteriophage. Increased expression of the two bla genes resulted from a 6-time tandem amplification of the element as revealed by Southern blotting. This is the first isolation of a clinical P. mirabilis strain producing OXA-58, a class D carbapenemase, and the first description of a XerC-XerD-dependent insertion of antibiotic resistance genes within a bacteriophage. This study revealed a new role for the XerC-XerD recombinase in bacteriophage biology.
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40
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Bebel A, Karaca E, Kumar B, Stark WM, Barabas O. Structural snapshots of Xer recombination reveal activation by synaptic complex remodeling and DNA bending. eLife 2016; 5. [PMID: 28009253 PMCID: PMC5241119 DOI: 10.7554/elife.19706] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 12/21/2016] [Indexed: 02/06/2023] Open
Abstract
Bacterial Xer site-specific recombinases play an essential genome maintenance role by unlinking chromosome multimers, but their mechanism of action has remained structurally uncharacterized. Here, we present two high-resolution structures of Helicobacter pylori XerH with its recombination site DNA difH, representing pre-cleavage and post-cleavage synaptic intermediates in the recombination pathway. The structures reveal that activation of DNA strand cleavage and rejoining involves large conformational changes and DNA bending, suggesting how interaction with the cell division protein FtsK may license recombination at the septum. Together with biochemical and in vivo analysis, our structures also reveal how a small sequence asymmetry in difH defines protein conformation in the synaptic complex and orchestrates the order of DNA strand exchanges. Our results provide insights into the catalytic mechanism of Xer recombination and a model for regulation of recombination activity during cell division. DOI:http://dx.doi.org/10.7554/eLife.19706.001 Similar to humans, bacteria store their genetic material in the form of DNA and arrange it into structures called chromosomes. In fact, most bacteria have a single circular chromosome. Bacteria multiply by simply dividing in two, and before that happens they must replicate their DNA so that each of the newly formed cells receives one copy of the chromosome. Occasionally, mistakes during the DNA replication process can cause the two chromosomes to become tangled with each other; this prevents them from separating into the newly formed cells. For instance, the chromosomes can become physically connected like links in a chain, or merge into one long string. This kind of tangling can result in cell death, so bacteria encode enzymes called Xer recombinases that can untangle chromosomes. These enzymes separate the chromosomes by cutting and rejoining the DNA strands in a process known as Xer recombination. Although Xer recombinases have been studied in quite some detail, many questions remain unanswered about how they work. How do Xer recombinases interact with DNA? How do they ensure they only work on tangled chromosomes? And how does a protein called FtsK ensure that Xer recombination takes place at the correct time and place? Bebel et al. have now studied the Xer recombinase from a bacterium called Helicobacter pylori, which causes stomach ulcers, using a technique called X-ray crystallography. This enabled the three-dimensional structure of the Xer recombinase to be visualized as it interacted with DNA to form a Xer-DNA complex. Structures of the enzyme before and after it cut the DNA show that Xer-DNA complexes first assemble in an inactive state and are then activated by large conformational changes that make the DNA bend. Bebel et al. propose that the FtsK protein might trigger these changes and help to bend the DNA as it activates Xer recombination. Further work showed that the structures could be used to model and understand Xer recombinases from other species of bacteria. The next step is to analyze how FtsK activates Xer recombinases and to see if this process is universal amongst bacteria. Understanding how this process can be interrupted could help to develop new drugs that can kill harmful bacteria. DOI:http://dx.doi.org/10.7554/eLife.19706.002
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Affiliation(s)
- Aleksandra Bebel
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ezgi Karaca
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Banushree Kumar
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Orsolya Barabas
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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41
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Veiga H, G Pinho M. Staphylococcus aureus requires at least one FtsK/SpoIIIE protein for correct chromosome segregation. Mol Microbiol 2016; 103:504-517. [PMID: 27886417 DOI: 10.1111/mmi.13572] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2016] [Indexed: 11/30/2022]
Abstract
Faithful coordination between bacterial cell division and chromosome segregation in rod-shaped bacteria, such as Escherichia coli and Bacillus subtilis, is dependent on the DNA translocase activity of FtsK/SpoIIIE proteins, which move DNA away from the division site before cytokinesis is completed. However, the role of these proteins in chromosome partitioning has not been well studied in spherical bacteria. Here, it was shown that the two Staphylococcus aureus FtsK/SpoIIIE homologues, SpoIIIE and FtsK, operate in independent pathways to ensure correct chromosome management during cell division. SpoIIIE forms foci at the centre of the closing septum in at least 50% of the cells that are close to complete septum synthesis. FtsK is a multifunctional septal protein with a C-terminal DNA translocase domain that is not required for correct chromosome management in the presence of SpoIIIE. However, lack of both SpoIIIE and FtsK causes severe nucleoid segregation and morphological defects, showing that the two proteins have partially redundant roles in S. aureus.
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Affiliation(s)
- Helena Veiga
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Mariana G Pinho
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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42
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Nivina A, Escudero JA, Vit C, Mazel D, Loot C. Efficiency of integron cassette insertion in correct orientation is ensured by the interplay of the three unpaired features of attC recombination sites. Nucleic Acids Res 2016; 44:7792-803. [PMID: 27496283 PMCID: PMC5027507 DOI: 10.1093/nar/gkw646] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/05/2016] [Accepted: 07/10/2016] [Indexed: 01/29/2023] Open
Abstract
The integron is a bacterial recombination system that allows acquisition, stockpiling and expression of cassettes carrying protein-coding sequences, and is responsible for the emergence and rise of multiresistance in Gram-negative bacteria. The functionality of this system depends on the insertion of promoterless cassettes in correct orientation, allowing their expression from the promoter located upstream of the cassette array. Correct orientation is ensured by strand selectivity of integron integrases for the bottom strand of cassette recombination sites (attC), recombined in form of folded single-stranded hairpins. Here, we investigated the basis of such strand selectivity by comparing recombination of wild-type and mutated attC sites with different lengths, sequences and structures. We show that all three unpaired structural features that distinguish the bottom and top strands contribute to strand selectivity. The localization of Extra-Helical Bases (EHBs) directly favors integrase binding to the bottom strand. The Unpaired Central Spacer (UCS) and the Variable Terminal Structure (VTS) influence strand selectivity indirectly, probably through the stabilization of the bottom strand and the resulting synapse due to the nucleotide skew between the two strands. These results underscore the importance of the single-stranded nature of the attC site that allows such tight control over integron cassette orientation.
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Affiliation(s)
- Aleksandra Nivina
- Institut Pasteur, Bacterial Genome Plasticity Unit, 75724 Paris, France CNRS UMR3525, 75724 Paris, France Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - José Antonio Escudero
- Institut Pasteur, Bacterial Genome Plasticity Unit, 75724 Paris, France CNRS UMR3525, 75724 Paris, France
| | - Claire Vit
- Institut Pasteur, Bacterial Genome Plasticity Unit, 75724 Paris, France CNRS UMR3525, 75724 Paris, France
| | - Didier Mazel
- Institut Pasteur, Bacterial Genome Plasticity Unit, 75724 Paris, France CNRS UMR3525, 75724 Paris, France
| | - Céline Loot
- Institut Pasteur, Bacterial Genome Plasticity Unit, 75724 Paris, France CNRS UMR3525, 75724 Paris, France
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44
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The IntXO-PSL Recombination System Is a Key Component of the Second Maintenance System for Bacillus anthracis Plasmid pXO1. J Bacteriol 2016; 198:1939-1951. [PMID: 27137503 DOI: 10.1128/jb.01004-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/25/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED We previously identified three noncontiguous regions on Bacillus anthracis plasmid pXO1 that comprise a system for accurate plasmid partitioning and maintenance. However, deletion of these regions did not decrease retention of certain shortened pXO1 plasmids during vegetative growth. Using two genetic tools developed for DNA manipulation in B. anthracis (the Cre-loxP and Flp-FRT systems), we found two other noncontiguous pXO1 regions that together are sufficient for plasmid stability. This second pXO1 maintenance system includes the tubZ and tubR genes, characteristic of a type III partitioning system, and the IntXO recombinase gene (GBAA_RS29165), encoding a tyrosine recombinase, along with its adjacent 37-bp perfect stem-loop (PSL) target. Insertion of either the tubZ and tubR genes or the IntXO-PSL system into an unstable mini-pXO1 plasmid did not restore plasmid stability. The need for the two components of the second pXO1 maintenance system follows from the sequential roles of IntXO-PSL in generating monomeric circular daughter pXO1 molecules (thereby presumably preventing dimer catastrophe) and of TubZ/TubR in partitioning the monomers during cell division. We show that the IntXO recombinase deletes DNA regions located between two PSL sites in a manner similar to the actions of the Cre-loxP and Flp-FRT systems. IMPORTANCE Tyrosine recombinases catalyze cutting and joining reactions between short specific DNA sequences. Three types of reactions occur: integration and excision of DNA segments, inversion of DNA segments, and separation of monomeric forms from replicating circular DNA molecules. Here we show that the newly discovered site-specific IntXO-PSL recombinase system that contributes to the maintenance of the B. anthracis plasmid pXO1 can be used for genome engineering in a manner similar to that of the Cre-loxP or Flp-FRT system.
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Zhu K, Hölzel CS, Cui Y, Mayer R, Wang Y, Dietrich R, Didier A, Bassitta R, Märtlbauer E, Ding S. Probiotic Bacillus cereus Strains, a Potential Risk for Public Health in China. Front Microbiol 2016; 7:718. [PMID: 27242738 PMCID: PMC4876114 DOI: 10.3389/fmicb.2016.00718] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/29/2016] [Indexed: 12/14/2022] Open
Abstract
Bacillus cereus is an important cause of foodborne infectious disease and food poisoning. However, B. cereus has also been used as a probiotic in human medicine and livestock production, with low standards of safety assessment. In this study, we evaluated the safety of 15 commercial probiotic B. cereus preparations from China in terms of mislabeling, toxin production, and transferable antimicrobial resistance. Most preparations were incorrectly labeled, as they contained additional bacterial species; one product did not contain viable B. cereus at all. In total, 18 B. cereus group strains-specifically B. cereus and Bacillus thuringiensis-were isolated. Enterotoxin genes nhe, hbl, and cytK1, as well as the ces-gene were assessed by PCR. Enterotoxin production and cytotoxicity were confirmed by ELISA and cell culture assays, respectively. All isolated B. cereus group strains produced the enterotoxin Nhe; 15 strains additionally produced Hbl. Antimicrobial resistance was assessed by microdilution; resistance genes were detected by PCR and further characterized by sequencing, transformation and conjugation assays. Nearly half of the strains harbored the antimicrobial resistance gene tet(45). In one strain, tet(45) was situated on a mobile genetic element-encoding a site-specific recombination mechanism-and was transferable to Staphylococcus aureus and Bacillus subtilis by electro-transformation. In view of the wide and uncontrolled use of these products, stricter regulations for safety assessment, including determination of virulence factors and transferable antimicrobial resistance genes, are urgently needed.
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Affiliation(s)
- Kui Zhu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural UniversityBeijing, China; Department of Veterinary Sciences, Ludwig Maximilian University of MunichOberschleißheim, Germany
| | - Christina S Hölzel
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Yifang Cui
- National Center for Veterinary Drug Safety Evaluation, China Agricultural University Beijing, China
| | - Ricarda Mayer
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Yang Wang
- National Center for Veterinary Drug Safety Evaluation, China Agricultural University Beijing, China
| | - Richard Dietrich
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Andrea Didier
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Rupert Bassitta
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Ludwig Maximilian University of Munich Oberschleißheim, Germany
| | - Shuangyang Ding
- National Center for Veterinary Drug Safety Evaluation, China Agricultural University Beijing, China
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Meinke G, Bohm A, Hauber J, Pisabarro MT, Buchholz F. Cre Recombinase and Other Tyrosine Recombinases. Chem Rev 2016; 116:12785-12820. [PMID: 27163859 DOI: 10.1021/acs.chemrev.6b00077] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tyrosine-type site-specific recombinases (T-SSRs) have opened new avenues for the predictable modification of genomes as they enable precise genome editing in heterologous hosts. These enzymes are ubiquitous in eubacteria, prevalent in archaea and temperate phages, present in certain yeast strains, but barely found in higher eukaryotes. As tools they find increasing use for the generation and systematic modification of genomes in a plethora of organisms. If applied in host organisms, they enable precise DNA cleavage and ligation without the gain or loss of nucleotides. Criteria directing the choice of the most appropriate T-SSR system for genetic engineering include that, whenever possible, the recombinase should act independent of cofactors and that the target sequences should be long enough to be unique in a given genome. This review is focused on recent advancements in our mechanistic understanding of simple T-SSRs and their application in developmental and synthetic biology, as well as in biomedical research.
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Affiliation(s)
- Gretchen Meinke
- Department of Developmental, Molecular & Chemical Biology, Tufts University School of Medicine , Boston, Massachusetts 02111, United States
| | - Andrew Bohm
- Department of Developmental, Molecular & Chemical Biology, Tufts University School of Medicine , Boston, Massachusetts 02111, United States
| | - Joachim Hauber
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology , 20251 Hamburg, Germany
| | | | - Frank Buchholz
- Medical Systems Biology, UCC, Medical Faculty Carl Gustav Carus TU Dresden , 01307 Dresden, Germany
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Unmasking the ancestral activity of integron integrases reveals a smooth evolutionary transition during functional innovation. Nat Commun 2016; 7:10937. [PMID: 26961432 PMCID: PMC4792948 DOI: 10.1038/ncomms10937] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/03/2016] [Indexed: 12/28/2022] Open
Abstract
Tyrosine (Y)-recombinases have evolved to deliver mechanistically different reactions on a variety of substrates, but these evolutionary transitions are poorly understood. Among them, integron integrases are hybrid systems recombining single- and double-stranded DNA partners. These reactions are asymmetric and need a replicative resolution pathway, an exception to the canonical second strand exchange model of Y-recombinases. Integron integrases possess a specific domain for this specialized pathway. Here we show that despite this, integrases are still capable of efficiently operating the ancestral second strand exchange in symmetrical reactions between double-stranded substrates. During these reactions, both strands are reactive and Holliday junction resolution can follow either pathway. A novel deep-sequencing approach allows mapping of the crossover point for the second strand exchange. The persistence of the ancestral activity in integrases illustrates their robustness and shows that innovation towards new recombination substrates and resolution pathways was a smooth evolutionary process. The integron integrases have evolved to perform recombination of single and double stranded DNA. Here the authors show that the ancestral pathway is still functional at double stranded sites, revealing the evolution towards the modern resolution pathway.
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Martínez E, Paly E, Barre FX. CTXφ Replication Depends on the Histone-Like HU Protein and the UvrD Helicase. PLoS Genet 2015; 11:e1005256. [PMID: 25992634 PMCID: PMC4439123 DOI: 10.1371/journal.pgen.1005256] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/29/2015] [Indexed: 02/06/2023] Open
Abstract
The Vibrio cholerae bacterium is the agent of cholera. The capacity to produce the cholera toxin, which is responsible for the deadly diarrhea associated with cholera epidemics, is encoded in the genome of a filamentous phage, CTXφ. Rolling-circle replication (RCR) is central to the life cycle of CTXφ because amplification of the phage genome permits its efficient integration into the genome and its packaging into new viral particles. A single phage-encoded HUH endonuclease initiates RCR of the proto-typical filamentous phages of enterobacteriaceae by introducing a nick at a specific position of the double stranded DNA form of the phage genome. The rest of the process is driven by host factors that are either essential or crucial for the replication of the host genome, such as the Rep SF1 helicase. In contrast, we show here that the histone-like HU protein of V. cholerae is necessary for the introduction of a nick by the HUH endonuclease of CTXφ. We further show that CTXφ RCR depends on a SF1 helicase normally implicated in DNA repair, UvrD, rather than Rep. In addition to CTXφ, we show that VGJφ, a representative member of a second family of vibrio integrative filamentous phages, requires UvrD and HU for RCR while TLCφ, a satellite phage, depends on Rep and is independent from HU. One of the major strategies to prevent Cholera epidemics is the development of oral vaccines based on live attenuated Vibrio cholerae strains. The most promising vaccine strains have been obtained by deletion of the cholera toxin genes, which are harboured in the genome of an integrated phage, CTXϕ. However, they can re-acquire the cholera toxin genes when re-infected by CTXϕ or by hybrid phages between CTXϕ and other vibrio phages, which raised safety concerns about their use. Here, we developed a screening strategy to identify non-essential host factors implicated in CTXϕ replication. We show that the histone-like HU protein and the UvrD helicase are both absolutely required for its replication. We further show that they are essential for the replication of VGJϕ, a representative member of a family of phages that can form hybrids with CTXϕ. Accordingly, we demonstrate that the disruption of the two subunits of HU and/or of UvrD prevents infection of the V. cholerae by CTXϕ and VGJϕ. In addition, we show that it limits CTXϕ horizontal transmission. Taken together, these results indicate that HU- and/or UvrD- cells are promising candidates for the development of safer live attenuated cholera vaccine.
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Affiliation(s)
- Eriel Martínez
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
| | - Evelyne Paly
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
| | - François-Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
- * E-mail:
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