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Dagar J, Maurya S, Antil S, Abraham JS, Somasundaram S, Lal R, Makhija S, Toteja R. Symbionts of Ciliates and Ciliates as Symbionts. Indian J Microbiol 2024; 64:304-317. [PMID: 39010998 PMCID: PMC11246404 DOI: 10.1007/s12088-024-01203-y] [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: 05/31/2023] [Accepted: 01/06/2024] [Indexed: 07/17/2024] Open
Abstract
Endosymbiotic relationships between ciliates and others are critical for their ecological roles, physiological adaptations, and evolutionary implications. These can be obligate and facultative. Symbionts often provide essential nutrients, contribute to the ciliate's metabolism, aid in digestion, and offer protection against predators or environmental stressors. In turn, ciliates provide a protected environment and resources for their symbionts, facilitating their survival and proliferation. Ultrastructural and full-cycle rRNA approaches are utilized to identify these endosymbionts. Fluorescence in situ hybridization using "species- and group-specific probes" which are complementary to the genetic material (DNA or RNA) of a particular species or group of interest represent convenient tools for their detection directly in the environment. A systematic survey of these endosymbionts has been conducted using both traditional and metagenomic approaches. Ciliophora and other protists have a wide range of prokaryotic symbionts, which may contain potentially pathogenic bacteria. Ciliates can establish symbiotic relationships with a variety of hosts also, ranging from protists to metazoans. Understanding ciliate symbiosis can provide useful insights into the complex relationships that drive microbial communities and ecosystems in general.
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Affiliation(s)
- Jyoti Dagar
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
| | - Swati Maurya
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
| | - Sandeep Antil
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
| | | | | | - Rup Lal
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
| | - Seema Makhija
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
| | - Ravi Toteja
- Acharya Narendra Dev College, University of Delhi, New Delhi, India
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2
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Lehman SS, Verhoeve VI, Driscoll TP, Beckmann JF, Gillespie JJ. Metagenome diversity illuminates the origins of pathogen effectors. mBio 2024; 15:e0075923. [PMID: 38564675 PMCID: PMC11077975 DOI: 10.1128/mbio.00759-23] [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: 03/27/2023] [Accepted: 02/12/2024] [Indexed: 04/04/2024] Open
Abstract
Recent metagenome-assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. The discovery of basal lineages (novel families Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles exposed an evolutionary timepoint for the transition to host dependency, which seemingly occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales vir homolog (rvh) type IV secretion system and purportedly use rvh to kill congener microbes rather than parasitize host cells as described for later-evolving rickettsial pathogens. MAG analysis also substantially increased diversity for the genus Rickettsia and delineated a sister lineage (the novel genus Tisiphia) that stands to inform on the emergence of human pathogens from protist and invertebrate endosymbionts. Herein, we probed Rickettsiales MAG and genomic diversity for the distribution of Rickettsia rvh effectors to ascertain their origins. A sparse distribution of most Rickettsia rvh effectors outside of Rickettsiaceae lineages illuminates unique rvh evolution from basal extracellular species and other rickettsial families. Remarkably, nearly every effector was found in multiple divergent forms with variable architectures, indicating profound roles for gene duplication and recombination in shaping effector repertoires in Rickettsia pathogens. Lateral gene transfer plays a prominent role in shaping the rvh effector landscape, as evinced by the discovery of many effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchange between Rickettsia and Legionella species. Our study exemplifies how MAGs can yield insight into pathogen effector origins, particularly how effector architectures might become tailored to the discrete host cell functions of different eukaryotic hosts.IMPORTANCEWhile rickettsioses are deadly vector-borne human diseases, factors distinguishing Rickettsia pathogens from the innumerable bevy of environmental rickettsial endosymbionts remain lacking. Recent metagenome-assembled genome (MAG) studies revealed evolutionary timepoints for rickettsial transitions to host dependency. The rvh type IV secretion system was likely repurposed from congener killing in basal extracellular species to parasitizing host cells in later-evolving pathogens. Our analysis of MAG diversity for over two dozen rvh effectors unearthed their presence in some non-pathogens. However, most effectors were found in multiple divergent forms with variable architectures, indicating gene duplication and recombination-fashioned effector repertoires of Rickettsia pathogens. Lateral gene transfer substantially shaped pathogen effector arsenals, evinced by the discovery of effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchanges between Rickettsia and Legionella species. Our study exemplifies how MAGs yield insight into pathogen effector origins and evolutionary processes tailoring effectors to eukaryotic host cell biology.
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Affiliation(s)
- Stephanie S. Lehman
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Victoria I. Verhoeve
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Timothy P. Driscoll
- Department of Biology, West Virginia University, Morgantown, West Virginia, USA
| | - John F. Beckmann
- Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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3
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Hollender M, Sałek M, Karlicki M, Karnkowska A. Single-cell genomics revealed Candidatus Grellia alia sp. nov. as an endosymbiont of Eutreptiella sp. (Euglenophyceae). Protist 2024; 175:126018. [PMID: 38325049 DOI: 10.1016/j.protis.2024.126018] [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: 09/12/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/09/2024]
Abstract
Though endosymbioses between protists and prokaryotes are widespread, certain host lineages have received disproportionate attention what may indicate either a predisposition to such interactions or limited studies on certain protist groups due to lack of cultures. The euglenids represent one such group in spite of microscopic observations showing intracellular bacteria in some strains. Here, we perform a comprehensive molecular analysis of a previously identified endosymbiont in the Eutreptiella sp. CCMP3347 using a single cell approach and bulk culture sequencing. The genome reconstruction of this endosymbiont allowed the description of a new endosymbiont Candidatus Grellia alia sp. nov. from the family Midichloriaceae. Comparative genomics revealed a remarkably complete conjugative type IV secretion system present in three copies on the plasmid sequences of the studied endosymbiont, a feature missing in the closely related Grellia incantans. This study addresses the challenge of limited host cultures with endosymbionts by showing that the genomes of endosymbionts reconstructed from single host cells have the completeness and contiguity that matches or exceeds those coming from bulk cultures. This paves the way for further studies of endosymbionts in euglenids and other protist groups. The research also provides the opportunity to study the diversity of endosymbionts in natural populations.
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Affiliation(s)
- Metody Hollender
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland
| | - Marta Sałek
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland
| | - Michał Karlicki
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland
| | - Anna Karnkowska
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland.
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4
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Castelli M, Nardi T, Gammuto L, Bellinzona G, Sabaneyeva E, Potekhin A, Serra V, Petroni G, Sassera D. Host association and intracellularity evolved multiple times independently in the Rickettsiales. Nat Commun 2024; 15:1093. [PMID: 38321113 PMCID: PMC10847448 DOI: 10.1038/s41467-024-45351-7] [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: 12/14/2022] [Accepted: 01/18/2024] [Indexed: 02/08/2024] Open
Abstract
The order Rickettsiales (Alphaproteobacteria) encompasses multiple diverse lineages of host-associated bacteria, including pathogens, reproductive manipulators, and mutualists. Here, in order to understand how intracellularity and host association originated in this order, and whether they are ancestral or convergently evolved characteristics, we built a large and phylogenetically-balanced dataset that includes de novo sequenced genomes and a selection of published genomic and metagenomic assemblies. We perform detailed functional reconstructions that clearly indicates "late" and parallel evolution of obligate host-association in different Rickettsiales lineages. According to the depicted scenario, multiple independent horizontal acquisitions of transporters led to the progressive loss of biosynthesis of nucleotides, amino acids and other metabolites, producing distinct conditions of host-dependence. Each clade experienced a different pattern of evolution of the ancestral arsenal of interaction apparatuses, including development of specialised effectors involved in the lineage-specific mechanisms of host cell adhesion and/or invasion.
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Affiliation(s)
- Michele Castelli
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Tiago Nardi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | | | - Greta Bellinzona
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Elena Sabaneyeva
- Department of Cytology and Histology, Saint Petersburg State University, Petersburg, Russia
| | - Alexey Potekhin
- Department of Microbiology, Saint Petersburg State University, Petersburg, Russia
- Research Department for Limnology, University of Innsbruck, Mondsee, Austria
| | | | | | - Davide Sassera
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
- IRCCS Policlinico San Matteo, Pavia, Italy.
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5
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Song Q, Zhao F, Hou L, Miao M. Cellular interactions and evolutionary origins of endosymbiotic relationships with ciliates. THE ISME JOURNAL 2024; 18:wrae117. [PMID: 38916437 PMCID: PMC11253213 DOI: 10.1093/ismejo/wrae117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 05/26/2024] [Accepted: 06/21/2024] [Indexed: 06/26/2024]
Abstract
As unicellular predators, ciliates engage in close associations with diverse microbes, laying the foundation for the establishment of endosymbiosis. Originally heterotrophic, ciliates demonstrate the ability to acquire phototrophy by phagocytizing unicellular algae or by sequestering algal plastids. This adaptation enables them to gain photosynthate and develop resistance to unfavorable environmental conditions. The integration of acquired phototrophy with intrinsic phagotrophy results in a trophic mode known as mixotrophy. Additionally, ciliates can harbor thousands of bacteria in various intracellular regions, including the cytoplasm and nucleus, exhibiting species specificity. Under prolonged and specific selective pressure within hosts, bacterial endosymbionts evolve unique lifestyles and undergo particular reductions in metabolic activities. Investigating the research advancements in various endosymbiotic cases within ciliates will contribute to elucidate patterns in cellular interaction and unravel the evolutionary origins of complex traits.
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Affiliation(s)
- Qi Song
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
| | - Fangqing Zhao
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
- Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, No. 1 Xiangshan Road, Hangzhou 310024, China
| | - Lina Hou
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
| | - Miao Miao
- Medical School, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing 100049, China
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6
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Giovannini M, Petroni G, Castelli M. Novel evolutionary insights on the interactions of the Holosporales (Alphaproteobacteria) with eukaryotic hosts from comparative genomics. Environ Microbiol 2024; 26:e16562. [PMID: 38173299 DOI: 10.1111/1462-2920.16562] [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: 06/12/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024]
Abstract
Holosporales are an alphaproteobacterial order engaging in obligate and complex associations with eukaryotes, in particular protists. The functional and evolutionary features of those interactions are still largely undisclosed. Here, we sequenced the genomes of two members of the species Bealeia paramacronuclearis (Holosporales, Holosporaceae) intracellularly associated with the ciliate protist Paramecium, which resulted in high correspondence. Consistent with the short-branched early-divergent phylogenetic position, Bealeia presents a larger functional repertoire than other Holosporaceae, comparable to those of other Holosporales families, particularly for energy metabolism and motility. Our analyses indicate that different Holosporales likely experienced at least partly autonomous genome reduction and adaptation to host interactions, for example regarding dependence on host biotin driven by multiple independent horizontal acquisitions of transporters. Among Alphaproteobacteria, this is reminiscent of the convergently evolved Rickettsiales, which however appear more diverse, possibly due to a probably more ancient origin. We identified in Bealeia and other Holosporales the plasmid-encoded putative genetic determinants of R-bodies, which may be involved in a killer trait towards symbiont-free hosts. While it is not clear whether these genes are ancestral or recently horizontally acquired, an intriguing and peculiar role of R-bodies is suggested in the evolution of the interactions of multiple Holosporales with their hosts.
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Affiliation(s)
| | | | - Michele Castelli
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
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7
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Lu M, Ji Y, Zhao H, Wang W, Tian J, Duan C, Qin X, Guo Y, Chen G, Lei F, Meng C, Li K. Circulation of multiple Rickettsiales bacteria in ticks from Sichuan province, Southwest China. Microb Pathog 2023; 183:106313. [PMID: 37625661 DOI: 10.1016/j.micpath.2023.106313] [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: 01/07/2023] [Revised: 02/17/2023] [Accepted: 08/19/2023] [Indexed: 08/27/2023]
Abstract
During 2021, 403 ticks including Haemaphysalis qinghaiensis, Ixodes ovatus, Ixodes acutitarsus, and Rhipicephalus microplus were collected from three sites (590, 310, and 576 km away from each other) in Sichuan Province, China. A total of nine Rickettsiales species were identified in them, including three Rickettsia spp., five Anaplasma spp., and one Ehrlichia sp. Anaplasma ovis and a novel Rickettsia sp. named "Candidatus Rickettsia liangshanensis" were characterized in I. ovatus ticks from Liangshan, with positive rates of 11.11% and 45.56%, respectively. Anaplasma capra (13.33%) and Anaplasma bovis (15.33%) were detected in H. qinghaiensis ticks from Maerkang. Phylogenetic analysis based on 16S rRNA, gltA, and groEL gene sequences indicated that the A. bovis strains were divided into two groups. Additionally, a novel Ehrlichia species named "Candidatus Ehrlichia maerkangensis" was identified. It is closely related to "Candidatus Ehrlichia zunyiensis" which was previously reported in Berylmys bowersi rats from Zunyi City, Southwest China. In R. microplus from Mianyang, "Candidatus Rickettsia jingxinensis" was detected with a high prevalence (92.99%). Notably, a variant of R. raoultii was identified in I. acutitarsus (33.33%). This may be the first Rickettsiales bacterium reported in I. acutitarsus. Our results reveal the remarkable biodiversity of Rickettsiales in this area. Some of these bacteria are human pathogens, indicating the potential exposure risk to local people.
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Affiliation(s)
- Miao Lu
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Changping District, Beijing City, China
| | - Yuqi Ji
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China
| | - Hongqing Zhao
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Changping District, Beijing City, China
| | - Wen Wang
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Changping District, Beijing City, China
| | - Junhua Tian
- Wuhan Center for Disease Control and Prevention, 430024, Wuhan City, Hubei Province, China
| | - Chengyu Duan
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China
| | - Xincheng Qin
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Changping District, Beijing City, China
| | - Yawen Guo
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China
| | - Gaosong Chen
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China
| | - Fuyu Lei
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China
| | - Chao Meng
- College of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, 271016, Tai'an City, Shandong Province, China.
| | - Kun Li
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Changping District, Beijing City, China.
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8
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Gillespie JJ, Salje J. Orientia and Rickettsia: different flowers from the same garden. Curr Opin Microbiol 2023; 74:102318. [PMID: 37080115 DOI: 10.1016/j.mib.2023.102318] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/22/2023]
Abstract
Recent discoveries of basal extracellular Rickettsiales have illuminated divergent evolutionary paths to host dependency in later-evolving lineages. Family Rickettsiaceae, primarily comprised of numerous protist- and invertebrate-associated species, also includes human pathogens from two genera, Orientia and Rickettsia. Once considered sister taxa, these bacteria form distinct lineages with newly appreciated lifestyles and morphological traits. Contrasting other rickettsial human pathogens in Family Anaplasmataceae, Orientia and Rickettsia species do not reside in host-derived vacuoles and lack glycolytic potential. With only a few described mechanisms, strategies for commandeering host glycolysis to support cytosolic growth remain to be discovered. While regulatory systems for this unique mode of intracellular parasitism are unclear, conjugative transposons unique to Orientia and Rickettsia species provide insights that are critical for determining how these obligate intracellular pathogens overtake eukaryotic cytosol.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, USA.
| | - Jeanne Salje
- Department of Biochemistry, Department of Pathology, and Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.
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9
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Verhoeve VI, Lehman SS, Driscoll TP, Beckmann JF, Gillespie JJ. Metagenome diversity illuminates origins of pathogen effectors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.26.530123. [PMID: 36909625 PMCID: PMC10002696 DOI: 10.1101/2023.02.26.530123] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Recent metagenome assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. Discovery of basal lineages (Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles reveals an evolutionary timepoint for the transition to host dependency, which occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales vir homolog (rvh) type IV secretion system (T4SS) and purportedly use rvh to kill congener microbes rather than parasitize host cells as described for derived rickettsial pathogens. MAG analysis also substantially increased diversity for genus Rickettsia and delineated a basal lineage (Tisiphia) that stands to inform on the rise of human pathogens from protist and invertebrate endosymbionts. Herein, we probed Rickettsiales MAG and genomic diversity for the distribution of Rickettsia rvh effectors to ascertain their origins. A sparse distribution of most Rickettsia rvh effectors outside of Rickettsiaceae lineages indicates unique rvh evolution from basal extracellular species and other rickettsial families. Remarkably, nearly every effector was found in multiple divergent forms with variable architectures, illuminating profound roles for gene duplication and recombination in shaping effector repertoires in Rickettsia pathogens. Lateral gene transfer plays a prominent role shaping the rvh effector landscape, as evinced by the discover of many effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchange between Rickettsia and Legionella species. Our study exemplifies how MAGs can provide incredible insight on the origins of pathogen effectors and how their architectural modifications become tailored to eukaryotic host cell biology.
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Affiliation(s)
- Victoria I Verhoeve
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Stephanie S Lehman
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Timothy P Driscoll
- Department of Biology, West Virginia University, Morgantown, West Virginia, USA
| | - John F Beckmann
- Microbiology and Immunology, University of South Alabama, Mobile, AL, USA
| | - Joseph J Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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10
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Oren A. Candidatus List No. 4: Lists of names of prokaryotic Candidatus taxa. Int J Syst Evol Microbiol 2022; 72. [PMID: 36748458 DOI: 10.1099/ijsem.0.005545] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, 9190401 Jerusalem, Israel
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11
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Identification of the bacteria associated to the phycosphere of the Chlorella-like strain SEC_LI_ChL_1. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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12
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Together forever: Inseparable partners of the symbiotic system Paramecium multimicronucleatum/Ca. Trichorickettsia mobilis. Symbiosis 2022. [DOI: 10.1007/s13199-022-00854-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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13
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George EE, Tashyreva D, Kwong WK, Okamoto N, Horák A, Husnik F, Lukeš J, Keeling PJ. Gene Transfer Agents in Bacterial Endosymbionts of Microbial Eukaryotes. Genome Biol Evol 2022; 14:6615375. [PMID: 35738252 PMCID: PMC9254644 DOI: 10.1093/gbe/evac099] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2022] [Indexed: 11/14/2022] Open
Abstract
Gene transfer agents (GTAs) are virus-like structures that package and transfer prokaryotic DNA from donor to recipient prokaryotic cells. Here, we describe widespread GTA gene clusters in the highly reduced genomes of bacterial endosymbionts from microbial eukaryotes (protists). Homologs of the GTA capsid and portal complexes were initially found to be present in several highly reduced alphaproteobacterial endosymbionts of diplonemid protists (Rickettsiales and Rhodospirillales). Evidence of GTA expression was found in polyA-enriched metatranscriptomes of the diplonemid hosts and their endosymbionts, but due to biases in the polyA-enrichment methods, levels of GTA expression could not be determined. Examining the genomes of closely related bacteria revealed that the pattern of retained GTA head/capsid complexes with missing tail components was common across Rickettsiales and Holosporaceae (Rhodospirillales), all obligate symbionts with a wide variety of eukaryotic hosts. A dN/dS analysis of Rickettsiales and Holosporaceae symbionts revealed that purifying selection is likely the main driver of GTA evolution in symbionts, suggesting they remain functional, but the ecological function of GTAs in bacterial symbionts is unknown. In particular, it is unclear how increasing horizontal gene transfer in small, largely clonal endosymbiont populations can explain GTA retention, and, therefore, the structures may have been repurposed in endosymbionts for host interactions. Either way, their widespread retention and conservation in endosymbionts of diverse eukaryotes suggests an important role in symbiosis.
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Affiliation(s)
- Emma E George
- University of British Columbia, Department of Botany, Vancouver, V6T 1Z4, Canada
| | - Daria Tashyreva
- Institute of Parasitology, Biology Center, Czech Academy of Sciences, 370 05 České Budějovice (Budweis), Czech Republic
| | - Waldan K Kwong
- University of British Columbia, Department of Botany, Vancouver, V6T 1Z4, Canada.,Instituto Gulbenkian de Ciência, 6, 2780-156 Oeiras, Portugal
| | - Noriko Okamoto
- University of British Columbia, Department of Botany, Vancouver, V6T 1Z4, Canada.,Hakai Institute, Quadra Island, British Columbia, Canada
| | - Aleš Horák
- Institute of Parasitology, Biology Center, Czech Academy of Sciences, 370 05 České Budějovice (Budweis), Czech Republic.,University of South Bohemia, Faculty of Sciences, 370 05 České Budějovice (Budweis), Czech Republic
| | - Filip Husnik
- University of British Columbia, Department of Botany, Vancouver, V6T 1Z4, Canada.,Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan
| | - Julius Lukeš
- Institute of Parasitology, Biology Center, Czech Academy of Sciences, 370 05 České Budějovice (Budweis), Czech Republic.,University of South Bohemia, Faculty of Sciences, 370 05 České Budějovice (Budweis), Czech Republic
| | - Patrick J Keeling
- University of British Columbia, Department of Botany, Vancouver, V6T 1Z4, Canada
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14
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Davison HR, Pilgrim J, Wybouw N, Parker J, Pirro S, Hunter-Barnett S, Campbell PM, Blow F, Darby AC, Hurst GDD, Siozios S. Genomic diversity across the Rickettsia and 'Candidatus Megaira' genera and proposal of genus status for the Torix group. Nat Commun 2022; 13:2630. [PMID: 35551207 PMCID: PMC9098888 DOI: 10.1038/s41467-022-30385-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/29/2022] [Indexed: 11/09/2022] Open
Abstract
Members of the bacterial genus Rickettsia were originally identified as causative agents of vector-borne diseases in mammals. However, many Rickettsia species are arthropod symbionts and close relatives of ‘Candidatus Megaira’, which are symbiotic associates of microeukaryotes. Here, we clarify the evolutionary relationships between these organisms by assembling 26 genomes of Rickettsia species from understudied groups, including the Torix group, and two genomes of ‘Ca. Megaira’ from various insects and microeukaryotes. Our analyses of the new genomes, in comparison with previously described ones, indicate that the accessory genome diversity and broad host range of Torix Rickettsia are comparable to those of all other Rickettsia combined. Therefore, the Torix clade may play unrecognized roles in invertebrate biology and physiology. We argue this clade should be given its own genus status, for which we propose the name ‘Candidatus Tisiphia’. The bacterial genus Rickettsia includes vector-borne pathogens and arthropod symbionts that are close relatives of symbionts of microeukaryotes classified under the genus ‘Candidatus Megaira’. Here, Davison et al. clarify the evolutionary relationships between these organisms by assembling 28 genomes of understudied species, and propose that a distinct clade known as Torix Rickettsia should be considered a separate genus.
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Affiliation(s)
- Helen R Davison
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Jack Pilgrim
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Nicky Wybouw
- Terrestrial Ecology Unit, Department of Biology, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Joseph Parker
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Boulevard, Pasadena, CA, 91125, USA
| | | | - Simon Hunter-Barnett
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Paul M Campbell
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK.,School of Health and Life Sciences, Faculty of Biology Medicine and Health, the University of Manchester, Manchester, UK
| | - Frances Blow
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK.,Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Alistair C Darby
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Gregory D D Hurst
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Stefanos Siozios
- Institute of Infection, Veterinary and Ecological sciences, University of Liverpool, Liverpool, L69 7ZB, UK.
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15
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The 'other' Rickettsiales: an overview of the family ' Candidatus Midichloriaceae'. Appl Environ Microbiol 2022; 88:e0243221. [PMID: 35108076 DOI: 10.1128/aem.02432-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The family 'Candidatus Midichloriaceae' constitutes the most diverse but least studied lineage within the important order of intracellular bacteria Rickettsiales. Midichloriaceae endosymbionts are found in many hosts, including terrestrial arthropods, aquatic invertebrates, and protists. Representatives of the family are not documented to be pathogenic, but some are associated with diseased fish or corals. Different genera display a range of unusual features, such as full sets of flagellar genes without visible flagella, or the ability to invade host mitochondria. Since studies on 'Ca. Midichloriaceae' tend to focus on the host, the family is rarely addressed as a unit and we therefore lack a coherent picture of its diversity. Here we provide four new midichloriaceae genomes and we survey molecular and ecological data from the entire family. Features like genome size, ecological context, and host transitions vary considerably even among closely related midichloriaceae, suggesting a high frequency of such shifts, incomplete sampling, or both. Important functional traits involved in energy metabolism, flagella and secretion systems were independently reduced multiple times with no obvious correspondence to host or habitat, corroborating the idea that many features of these 'professional symbionts' are largely independent of host identity. Finally, despite 'Ca. Midichloriaceae' being predominantly studied in ticks, our analyses show that the clade is mainly aquatic, with a few terrestrial offshoots. This highlights the importance of considering aquatic hosts, and protists in particular, when reconstructing the evolution of these endosymbionts and by extension all Rickettsiales. Importance Among endosymbiotic bacterial lineages, few are as intensely studied as Rickettsiales, which include the causative agents of spotted fever, typhus, and anaplasmosis. And yet, an important subgroup called 'Candidatus Midichloriaceae' receives little attention despite accounting for a third of the diversity of Rickettsiales and harbouring a wide range of bacteria with unique features, like the ability to infect mitochondria. Midichloriaceae are found in many hosts, from ticks to corals to unicellular protozoa, and studies on them tend to focus on the host groups. Here, for the first time since the establishment of this clade, we address the genomics, evolution, and ecology of 'Ca. Midichloriaceae' as a whole, highlighting trends and patterns, the remaining gaps in our knowledge, and its importance for the understanding of symbiotic processes in intracellular bacteria.
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16
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Castelli M, Lanzoni O, Giovannini M, Lebedeva N, Gammuto L, Sassera D, Melekhin M, Potekhin A, Fokin S, Petroni G. 'Candidatus Gromoviella agglomerans', a novel intracellular Holosporaceae parasite of the ciliate Paramecium showing marked genome reduction. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:34-49. [PMID: 34766443 DOI: 10.1111/1758-2229.13021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Holosporales are an alphaproteobacterial lineage encompassing bacteria obligatorily associated with multiple diverse eukaryotes. For most representatives, little is known on the interactions with their hosts. In this study, we characterized a novel Holosporales symbiont of the ciliate Paramecium polycaryum. This bacterium inhabits the host cytoplasm, frequently forming quite large aggregates. Possibly due to such aggregates, host cells sometimes displayed lethal division defects. The symbiont was also able to experimentally stably infect another Paramecium polycaryum strain. The bacterium is phylogenetically related with symbionts of other ciliates and diplonemids, forming a putatively fast-evolving clade within the family Holosporaceae. Similarly to many close relatives, it presents a very small genome (<600 kbp), and, accordingly, a limited predicted metabolism, implying a heavy dependence on Paramecium, thanks also to some specialized membrane transporters. Characterized features, including the presence of specific secretion systems, are overall suggestive of a mild parasitic effect on the host. From an evolutionary perspective, a potential ancestral trend towards pronounced genome reduction and possibly linked to parasitism could be inferred, at least among fast-evolving Holosporaceae, with some lineage-specific traits. Interestingly, similar convergent features could be observed in other host-associated lineages, in particular Rickettsiales among Alphaproteobacteria.
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Affiliation(s)
- Michele Castelli
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
| | - Olivia Lanzoni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
- Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland
| | | | - Natalia Lebedeva
- Centre of Core Facilities "Culture Collections of Microorganisms", Saint Petersburg State University, Saint Petersburg, Russia
| | | | - Davide Sassera
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
| | - Maksim Melekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
- Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Saint Petersburg, Russia
| | - Alexey Potekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
- Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Saint Petersburg, Russia
| | - Sergei Fokin
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
- Department of Invertebrate Zoology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Giulio Petroni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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17
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Flemming FE, Grosser K, Schrallhammer M. Natural Shifts in Endosymbionts' Occurrence and Relative Frequency in Their Ciliate Host Population. Front Microbiol 2022; 12:791615. [PMID: 35087493 PMCID: PMC8787144 DOI: 10.3389/fmicb.2021.791615] [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] [Received: 10/08/2021] [Accepted: 12/14/2021] [Indexed: 11/13/2022] Open
Abstract
The role of bacterial endosymbionts harbored by heterotrophic Paramecium species is complex. Obligate intracellular bacteria supposedly always inflict costs as the host is the only possible provider of resources. However, several experimental studies have shown that paramecia carrying bacterial endosymbionts can benefit from their infection. Here, we address the question which endosymbionts occur in natural paramecia populations isolated from a small lake over a period of 5 years and which factors might explain observed shifts and persistence in the symbionts occurrence. One hundred and nineteen monoclonal strains were investigated and approximately two-third harbored intracellular bacteria. The majority of infected paramecia carried the obligate endosymbiotic "Candidatus Megaira polyxenophila", followed by Caedimonas varicaedens, and Holospora undulata. The latter was only detected in a single strain. While "Ca. M. polyxenophila" was observed in seven out of 13 samplings, C. varicaedens presence was limited to a single sampling occasion. After the appearance of C. varicaedens, "Ca. M. polyxenophila" prevalence dramatically dropped with some delay but recovered to original levels at the end of our study. Potential mechanisms explaining these observations include differences in infectivity, host range, and impact on host fitness as well as host competitive capacities. Growth experiments revealed fitness advantages for infected paramecia harboring "Ca. M. polyxenophila" as well as C. varicaedens. Furthermore, we showed that cells carrying C. varicaedens gain a competitive advantage from the symbiosis-derived killer trait. Other characteristics like infectivity and overlapping host range were taken into consideration, but the observed temporal persistence of "Ca. M. polyxenophila" is most likely explained by the positive effect this symbiont provides to its host.
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Affiliation(s)
- Felicitas E. Flemming
- Microbiology, Institute of Biology II, Albert Ludwig University of Freiburg, Freiburg, Germany
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