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Torrance EL, Burton C, Diop A, Bobay LM. Evolution of homologous recombination rates across bacteria. Proc Natl Acad Sci U S A 2024; 121:e2316302121. [PMID: 38657048 PMCID: PMC11067023 DOI: 10.1073/pnas.2316302121] [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: 09/19/2023] [Accepted: 03/08/2024] [Indexed: 04/26/2024] Open
Abstract
Bacteria are nonsexual organisms but are capable of exchanging DNA at diverse degrees through homologous recombination. Intriguingly, the rates of recombination vary immensely across lineages where some species have been described as purely clonal and others as "quasi-sexual." However, estimating recombination rates has proven a difficult endeavor and estimates often vary substantially across studies. It is unclear whether these variations reflect natural variations across populations or are due to differences in methodologies. Consequently, the impact of recombination on bacterial evolution has not been extensively evaluated and the evolution of recombination rate-as a trait-remains to be accurately described. Here, we developed an approach based on Approximate Bayesian Computation that integrates multiple signals of recombination to estimate recombination rates. We inferred the rate of recombination of 162 bacterial species and one archaeon and tested the robustness of our approach. Our results confirm that recombination rates vary drastically across bacteria; however, we found that recombination rate-as a trait-is conserved in several lineages but evolves rapidly in others. Although some traits are thought to be associated with recombination rate (e.g., GC-content), we found no clear association between genomic or phenotypic traits and recombination rate. Overall, our results provide an overview of recombination rate, its evolution, and its impact on bacterial evolution.
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Affiliation(s)
- Ellis L Torrance
- Department of Biology, University of North Carolina, Greensboro, NC 27412
| | - Corey Burton
- Department of Biology, University of North Carolina, Greensboro, NC 27412
| | - Awa Diop
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695
| | - Louis-Marie Bobay
- Department of Biology, University of North Carolina, Greensboro, NC 27412
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695
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2
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Nautiyal A, Thakur M. Prokaryotic DNA Crossroads: Holliday Junction Formation and Resolution. ACS OMEGA 2024; 9:12515-12538. [PMID: 38524412 PMCID: PMC10956419 DOI: 10.1021/acsomega.3c09866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 02/04/2024] [Accepted: 02/09/2024] [Indexed: 03/26/2024]
Abstract
Cells are continually exposed to a multitude of internal and external stressors, which give rise to various types of DNA damage. To protect the integrity of their genetic material, cells are equipped with a repertoire of repair proteins that engage in various repair mechanisms, facilitated by intricate networks of protein-protein and protein-DNA interactions. Among these networks is the homologous recombination (HR) system, a molecular repair mechanism conserved in all three domains of life. On one hand, HR ensures high-fidelity, template-dependent DNA repair, while on the other hand, it results in the generation of combinatorial genetic variations through allelic exchange. Despite substantial progress in understanding this pathway in bacteria, yeast, and humans, several critical questions remain unanswered, including the molecular processes leading to the exchange of DNA segments, the coordination of protein binding, conformational switching during branch migration, and the resolution of Holliday Junctions (HJs). This Review delves into our current understanding of the HR pathway in bacteria, shedding light on the roles played by various proteins or their complexes at different stages of HR. In the first part of this Review, we provide a brief overview of the end resection processes and the strand-exchange reaction, offering a concise depiction of the mechanisms that culminate in the formation of HJs. In the latter half, we expound upon the alternative methods of branch migration and HJ resolution more comprehensively and holistically, considering the historical research timelines. Finally, when we consolidate our knowledge about HR within the broader context of genome replication and the emergence of resistant species, it becomes evident that the HR pathway is indispensable for the survival of bacteria in diverse ecological niches.
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Affiliation(s)
- Astha Nautiyal
- Department
of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Manoj Thakur
- Sri
Venkateswara College, Benito Juarez Road, University of Delhi, New Delhi 110021, India
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3
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Konstantinidis KT. Sequence-discrete species for prokaryotes and other microbes: A historical perspective and pending issues. MLIFE 2023; 2:341-349. [PMID: 38818268 PMCID: PMC10989153 DOI: 10.1002/mlf2.12088] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/04/2023] [Accepted: 10/08/2023] [Indexed: 06/01/2024]
Abstract
Whether prokaryotes, and other microorganisms, form distinct clusters that can be recognized as species remains an issue of paramount theoretical as well as practical consequence in identifying, regulating, and communicating about these organisms. In the past decade, comparisons of thousands of genomes of isolates and hundreds of metagenomes have shown that prokaryotic diversity may be predominantly organized in such sequence-discrete clusters, albeit organisms of intermediate relatedness between the identified clusters are also frequently found. Accumulating evidence suggests, however, that the latter "intermediate" organisms show enough ecological and/or functional distinctiveness to be considered different species. Notably, the area of discontinuity between clusters often-but not always-appears to be around 85%-95% genome-average nucleotide identity, consistently among different taxa. More recent studies have revealed remarkably similar diversity patterns for viruses and microbial eukaryotes as well. This high consistency across taxa implies a specific mechanistic process that underlies the maintenance of the clusters. The underlying mechanism may be a substantial reduction in the efficiency of homologous recombination, which mediates (successful) horizontal gene transfer, around 95% nucleotide identity. Deviations from the 95% threshold (e.g., species showing lower intraspecies diversity) may be caused by ecological differentiation that imposes barriers to otherwise frequent gene transfer. While this hypothesis that clusters are driven by ecological differentiation coupled to recombination frequency (i.e., higher recombination within vs. between groups) is appealing, the supporting evidence remains anecdotal. The data needed to rigorously test the hypothesis toward advancing the species concept are also outlined.
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Affiliation(s)
- Konstantinos T. Konstantinidis
- School of Civil and Environmental Engineering, and School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
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Feodorova VA, Zaitsev SS, Lyapina AM, Kichemazova NV, Saltykov YV, Khizhnyakova MA, Evstifeev VV, Larionova OS. Whole genome sequencing characteristics of Chlamydia psittaci caprine AMK-16 strain, a promising killed whole cell veterinary vaccine candidate against chlamydia infection. PLoS One 2023; 18:e0293612. [PMID: 37903115 PMCID: PMC10615304 DOI: 10.1371/journal.pone.0293612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/16/2023] [Indexed: 11/01/2023] Open
Abstract
Chlamydia psittaci is a primary zoonotic pathogen with a broad host range causing severe respiratory and reproductive system infection in animals and humans. To reduce the global burden of C. psittaci-associated diseases on animal welfare and health and to control the pathogen spread in husbandry, effective vaccines based on promising vaccine candidate(s) are required. Recently, the caprine C. psittaci AMK-16 strain (AMK-16) demonstrated a high level of protection (up to 80-100%) in outbred mice and pregnant rabbits immunized with these formaldehyde-inactivated bacteria against experimental chlamydial wild-type infection. This study investigated the molecular characteristics of AMK-16 by whole-genome sequencing followed by molecular typing, phylogenetic analysis and detection of main immunodominant protein(s) eliciting the immune response in mouse model. Similarly to other C. psittaci, AMK-16 harbored an extrachromosomal plasmid. The whole-genome phylogenetic analysis proved that AMK-16 strain belonging to ST28 clustered with only C. psittaci but not with Chlamydia abortus strains. However, AMK-16 possessed the insert which resulted from the recombination event as the additional single chromosome region of a 23,100 bp size with higher homology to C. abortus (98.38-99.94%) rather than to C. psittaci (92.06-92.55%). At least six of 16 CDSs were absent in AMK-16 plasticity zone and 41 CDSs in other loci compared with the reference C. psittaci 6BC strain. Two SNPs identified in the AMK-16 ompA sequence resulted in MOMP polymorphism followed by the formation of a novel genotype/subtype including three other C. psittaci strains else. AMK-16 MOMP provided marked specific cellular and humoral immune response in 100% of mice immunized with the inactivated AMK-16 bacteria. Both DnaK and GrpE encoded by the recombination region genes were less immunoreactive, inducing only a negligible T-cell murine immune response, while homologous antibodies could be detected in 50% and 30% of immunized mice, respectively. Thus, AMK-16 could be a promising vaccine candidate for the development of a killed whole cell vaccine against chlamydiosis in livestock.
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Affiliation(s)
- Valentina A. Feodorova
- Laboratory for Fundamental and Applied Research, Department for Microbiology and Biotechnology, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Sergey S. Zaitsev
- Laboratory for Fundamental and Applied Research, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Anna M. Lyapina
- Laboratory for Fundamental and Applied Research, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Natalya V. Kichemazova
- Laboratory for Fundamental and Applied Research, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Yury V. Saltykov
- Laboratory for Fundamental and Applied Research, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Mariya A. Khizhnyakova
- Laboratory for Fundamental and Applied Research, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
| | - Vitaliy V. Evstifeev
- Laboratory of Viral and Chlamydial Infections, Federal Center for Toxicological, Radiation and Biological Safety, Kazan, Russia
- Department of Microbiology, Virology and Immunology, Kazan State Academy of Veterinary Medicine by N.E. Bauman, Kazan City, Russia
| | - Olga S. Larionova
- Laboratory for Fundamental and Applied Research, Department for Microbiology and Biotechnology, Saratov State University of Genetics, Biotechnology and Engineering Named After N.I. Vavilov, Saratov, Russia
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Shikov AE, Savina IA, Nizhnikov AA, Antonets KS. Recombination in Bacterial Genomes: Evolutionary Trends. Toxins (Basel) 2023; 15:568. [PMID: 37755994 PMCID: PMC10534446 DOI: 10.3390/toxins15090568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/02/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023] Open
Abstract
Bacterial organisms have undergone homologous recombination (HR) and horizontal gene transfer (HGT) multiple times during their history. These processes could increase fitness to new environments, cause specialization, the emergence of new species, and changes in virulence. Therefore, comprehensive knowledge of the impact and intensity of genetic exchanges and the location of recombination hotspots on the genome is necessary for understanding the dynamics of adaptation to various conditions. To this end, we aimed to characterize the functional impact and genomic context of computationally detected recombination events by analyzing genomic studies of any bacterial species, for which events have been detected in the last 30 years. Genomic loci where the transfer of DNA was detected pertained to mobile genetic elements (MGEs) housing genes that code for proteins engaged in distinct cellular processes, such as secretion systems, toxins, infection effectors, biosynthesis enzymes, etc. We found that all inferences fall into three main lifestyle categories, namely, ecological diversification, pathogenesis, and symbiosis. The latter primarily exhibits ancestral events, thus, possibly indicating that adaptation appears to be governed by similar recombination-dependent mechanisms.
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Affiliation(s)
- Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (I.A.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Iuliia A. Savina
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (I.A.S.); (A.A.N.)
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (I.A.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (I.A.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
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Shikov AE, Merkushova AV, Savina IA, Nizhnikov AA, Antonets KS. The man, the plant, and the insect: shooting host specificity determinants in Serratia marcescens pangenome. Front Microbiol 2023; 14:1211999. [PMID: 38029097 PMCID: PMC10656689 DOI: 10.3389/fmicb.2023.1211999] [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: 04/25/2023] [Accepted: 08/21/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Serratia marcescens is most commonly known as an opportunistic pathogen causing nosocomial infections. It, however, was shown to infect a wide range of hosts apart from vertebrates such as insects or plants as well, being either pathogenic or growth-promoting for the latter. Despite being extensively studied in terms of virulence mechanisms during human infections, there has been little evidence of which factors determine S. marcescens host specificity. On that account, we analyzed S. marcescens pangenome to reveal possible specificity factors. Methods We selected 73 high-quality genome assemblies of complete level and reconstructed the respective pangenome and reference phylogeny based on core genes alignment. To find an optimal pipeline, we tested current pangenomic tools and obtained several phylogenetic inferences. The pangenome was rich in its accessory component and was considered open according to the Heaps' law. We then applied the pangenome-wide associating method (pan-GWAS) and predicted positively associated gene clusters attributed to three host groups, namely, humans, insects, and plants. Results According to the results, significant factors relating to human infections included transcriptional regulators, lipoproteins, ABC transporters, and membrane proteins. Host preference toward insects, in its turn, was associated with diverse enzymes, such as hydrolases, isochorismatase, and N-acetyltransferase with the latter possibly exerting a neurotoxic effect. Finally, plant infection may be conducted through type VI secretion systems and modulation of plant cell wall synthesis. Interestingly, factors associated with plants also included putative growth-promoting proteins like enzymes performing xenobiotic degradation and releasing ammonium irons. We also identified overrepresented functional annotations within the sets of specificity factors and found that their functional characteristics fell into separate clusters, thus, implying that host adaptation is represented by diverse functional pathways. Finally, we found that mobile genetic elements bore specificity determinants. In particular, prophages were mainly associated with factors related to humans, while genetic islands-with insects and plants, respectively. Discussion In summary, functional enrichments coupled with pangenomic inferences allowed us to hypothesize that the respective host preference is carried out through distinct molecular mechanisms of virulence. To the best of our knowledge, the presented research is the first to identify specific genomic features of S. marcescens assemblies isolated from different hosts at the pangenomic level.
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Affiliation(s)
- Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
- Faculty of Biology, St. Petersburg State University, St. Petersburg, Russia
| | - Anastasiya V. Merkushova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
| | - Iuliia A. Savina
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
- Faculty of Biology, St. Petersburg State University, St. Petersburg, Russia
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
- Faculty of Biology, St. Petersburg State University, St. Petersburg, Russia
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7
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Merkushova AV, Shikov AE, Nizhnikov AA, Antonets KS. For Someone, You Are the Whole World: Host-Specificity of Salmonella enterica. Int J Mol Sci 2023; 24:13670. [PMID: 37761974 PMCID: PMC10530738 DOI: 10.3390/ijms241813670] [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: 08/08/2023] [Revised: 08/27/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023] Open
Abstract
Salmonella enterica is a bacterial pathogen known to cause gastrointestinal infections in diverse hosts, including humans and animals. Despite extensive knowledge of virulence mechanisms, understanding the factors driving host specificity remains limited. In this study, we performed a comprehensive pangenome-wide analysis of S. enterica to identify potential loci determining preference towards certain hosts. We used a dataset of high-quality genome assemblies grouped into 300 reference clusters with a special focus on four host groups: humans, pigs, cattle, and birds. The reconstructed pangenome was shown to be open and enriched with the accessory component implying high genetic diversity. Notably, phylogenetic inferences did not correspond to the distribution of affected hosts, as large compact phylogenetic groups were absent. By performing a pangenome-wide association study, we identified potential host specificity determinants. These included multiple genes encoding proteins involved in distinct infection stages, e.g., secretion systems, surface structures, transporters, transcription regulators, etc. We also identified antibiotic resistance loci in host-adapted strains. Functional annotation corroborated the results obtained with significant enrichments related to stress response, antibiotic resistance, ion transport, and surface or extracellular localization. We suggested categorizing the revealed specificity factors into three main groups: pathogenesis, resistance to antibiotics, and propagation of mobile genetic elements (MGEs).
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Affiliation(s)
- Anastasiya V. Merkushova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
| | - Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
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8
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Hsu TY, Nzabarushimana E, Wong D, Luo C, Beiko RG, Langille M, Huttenhower C, Nguyen LH, Franzosa EA. Profiling novel lateral gene transfer events in the human microbiome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.08.552500. [PMID: 37609252 PMCID: PMC10441418 DOI: 10.1101/2023.08.08.552500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Lateral gene transfer (LGT) is an important mechanism for genome diversification in microbial populations, including the human microbiome. While prior work has surveyed LGT events in human-associated microbial isolate genomes, the scope and dynamics of novel LGT events arising in personal microbiomes are not well understood, as there are no widely adopted computational methods to detect, quantify, and characterize LGT from complex microbial communities. We addressed this by developing, benchmarking, and experimentally validating a computational method (WAAFLE) to profile novel LGT events from assembled metagenomes. Applying WAAFLE to >2K human metagenomes from diverse body sites, we identified >100K putative high-confidence but previously uncharacterized LGT events (~2 per assembled microbial genome-equivalent). These events were enriched for mobile elements (as expected), as well as restriction-modification and transport functions typically associated with the destruction of foreign DNA. LGT frequency was quantifiably influenced by biogeography, the phylogenetic similarity of the involved taxa, and the ecological abundance of the donor taxon. These forces manifest as LGT networks in which hub species abundant in a community type donate unequally with their close phylogenetic neighbors. Our findings suggest that LGT may be a more ubiquitous process in the human microbiome than previously described. The open-source WAAFLE implementation, documentation, and data from this work are available at http://huttenhower.sph.harvard.edu/waafle.
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Affiliation(s)
- Tiffany Y Hsu
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Etienne Nzabarushimana
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Dennis Wong
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Chengwei Luo
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Robert G Beiko
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Morgan Langille
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Curtis Huttenhower
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Long H Nguyen
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Eric A Franzosa
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
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9
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Tourasse NJ, Jolley KA, Kolstø AB, Økstad OA. Core genome multilocus sequence typing scheme for Bacillus cereus group bacteria. Res Microbiol 2023; 174:104050. [PMID: 36893969 DOI: 10.1016/j.resmic.2023.104050] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/24/2023] [Accepted: 02/28/2023] [Indexed: 03/09/2023]
Abstract
Core genome multilocus sequence typing (cgMLST) employs a strategy where the set of orthologous genes common to all members of a group of organisms are used for phylogenetic analysis of the group members. The Bacillus cereus group consists of species with pathogenicity towards insect species as well as warm-blooded animals including humans. While B. cereus is an opportunistic pathogen linked to a range of human disease conditions, including emesis and diarrhoea, Bacillus thuringiensis is an entomopathogenic species with toxicity toward insect larvae, and therefore used as a biological pesticide worldwide. Bacillus anthracis is a classical obligate pathogen causing anthrax, an acute lethal condition in herbivores as well as humans, and which is endemic in many parts of the world. The group also includes a range of additional species, and B. cereus group bacteria have been subject to analysis with a wide variety of phylogenetic typing systems. Here we present, based on analyses of 173 complete genomes from B. cereus group species available in public databases, the identification of a set of 1568 core genes which were used to create a core genome multilocus typing scheme for the group which is implemented in the PubMLST system as an open online database freely available to the community. The new cgMLST system provides unprecedented resolution over existing phylogenetic analysis schemes covering the B. cereus group.
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Affiliation(s)
- Nicolas J Tourasse
- Department of Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway; University of Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, F-33000 Bordeaux, France.
| | | | - Anne-Brit Kolstø
- Department of Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway.
| | - Ole Andreas Økstad
- Department of Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway.
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10
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hgtseq: A Standard Pipeline to Study Horizontal Gene Transfer. Int J Mol Sci 2022; 23:ijms232314512. [PMID: 36498841 PMCID: PMC9738810 DOI: 10.3390/ijms232314512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/14/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Horizontal gene transfer (HGT) is well described in prokaryotes: it plays a crucial role in evolution, and has functional consequences in insects and plants. However, less is known about HGT in humans. Studies have reported bacterial integrations in cancer patients, and microbial sequences have been detected in data from well-known human sequencing projects. Few of the existing tools for investigating HGT are highly automated. Thanks to the adoption of Nextflow for life sciences workflows, and to the standards and best practices curated by communities such as nf-core, fully automated, portable, and scalable pipelines can now be developed. Here we present nf-core/hgtseq to facilitate the analysis of HGT from sequencing data in different organisms. We showcase its performance by analysing six exome datasets from five mammals. Hgtseq can be run seamlessly in any computing environment and accepts data generated by existing exome and whole-genome sequencing projects; this will enable researchers to expand their analyses into this area. Fundamental questions are still open about the mechanisms and the extent or role of horizontal gene transfer: by releasing hgtseq we provide a standardised tool which will enable a systematic investigation of this phenomenon, thus paving the way for a better understanding of HGT.
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Choi Y, Ahn S, Park M, Lee S, Cho S, Kim H. HGTree v2.0: a comprehensive database update for horizontal gene transfer (HGT) events detected by the tree-reconciliation method. Nucleic Acids Res 2022; 51:D1010-D1018. [PMID: 36350646 PMCID: PMC9825516 DOI: 10.1093/nar/gkac929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
HGTree is a database that provides horizontal gene transfer (HGT) event information on 2472 prokaryote genomes using the tree-reconciliation method. HGTree was constructed in 2015, and a large number of prokaryotic genomes have been additionally published since then. To cope with the rapid rise of prokaryotic genome data, we present HGTree v2.0 (http://hgtree2.snu.ac.kr), a newly updated version of our HGT database with much more extensive data, including a total of 20 536 completely sequenced non-redundant prokaryotic genomes, and more reliable HGT information results curated with various steps. As a result, HGTree v2.0 has a set of expanded data results of 6 361 199 putative horizontally transferred genes integrated with additional functional information such as the KEGG pathway, virulence factors and antimicrobial resistance. Furthermore, various visualization tools in the HGTree v2.0 database website provide intuitive biological insights, allowing the users to investigate their genomes of interest.
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Affiliation(s)
| | | | - Myeongkyu Park
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 08826, Republic of Korea
| | | | - Seoae Cho
- eGnome Inc., Seoul 05836, Republic of Korea
| | - Heebal Kim
- To whom correspondence should be addressed. Tel: +82 2 880 4803; Fax: +82 2 883 8812;
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12
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Using Genomes and Evolutionary Analyses to Screen for Host-Specificity and Positive Selection in the Plant Pathogen Xylella fastidiosa. Appl Environ Microbiol 2022; 88:e0122022. [PMID: 36094203 PMCID: PMC9499020 DOI: 10.1128/aem.01220-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Xylella fastidiosa infects several economically important crops in the Americas, and it also recently emerged in Europe. Here, using a set of Xylella genomes reflective of the genus-wide diversity, we performed a pan-genome analysis based on both core and accessory genes for two purposes: (i) to test associations between genetic divergence and plant host species and (ii) to identify positively selected genes that are potentially involved in arms-race dynamics. For the former, tests yielded significant evidence for the specialization of X. fastidiosa to plant host species. This observation contributes to a growing literature suggesting that the phylogenetic history of X. fastidiosa lineages affects the host range. For the latter, our analyses uncovered evidence of positive selection across codons for 5.3% (67 of 1,257) of the core genes and 5.4% (201 of 3,691) of the accessory genes. These genes are candidates to encode interacting factors with plant and insect hosts. Most of these genes had unknown functions, but we did identify some tractable candidates, including nagZ_2, which encodes a beta-glucosidase that is important for Neisseria gonorrhoeae biofilm formation; cya, which modulates gene expression in pathogenic bacteria, and barA, a membrane associated histidine kinase that has roles in cell division, metabolism, and pili formation. IMPORTANCEXylella fastidiosa causes devasting diseases to several critical crops. Because X. fastidiosa colonizes and infects many plant species, it is important to understand whether the genome of X. fastidiosa has genetic determinants that underlie specialization to specific host plants. We analyzed genome sequences of X. fastidiosa to investigate evolutionary relationships and to test for evidence of positive selection on specific genes. We found a significant signal between genome diversity and host plants, consistent with bacterial specialization to specific plant hosts. By screening for positive selection, we identified both core and accessory genes that may affect pathogenicity, including genes involved in biofilm formation.
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