1
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Chatterjee P, Garcia MA, Cote JA, Yun K, Legerme GP, Habib R, Tripepi M, Young C, Kulp D, Dyall-Smith M, Pohlschroder M. Involvement of ArlI, ArlJ, and CirA in archaeal type IV pilin-mediated motility regulation. J Bacteriol 2024; 206:e0008924. [PMID: 38819156 DOI: 10.1128/jb.00089-24] [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: 03/05/2024] [Accepted: 05/06/2024] [Indexed: 06/01/2024] Open
Abstract
Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established; however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that the deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon Haloferax volcanii non-motile. In this study, we used ethyl methanesulfonate mutagenesis and a motility assay to identify motile suppressors of the ∆pilA[1-6] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, arlI and arlJ. In trans expression of arlI and arlJ mutant constructs in the respective multi-deletion strains ∆pilA[1-6]∆arlI and ∆pilA[1-6]∆arlJ confirmed their role in suppressing the ∆pilA[1-6] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in cirA, a gene encoding a proposed regulatory protein. A deletion of cirA resulted in hypermotility, while cirA expression in trans in wild-type cells led to decreased motility. Moreover, quantitative real-time PCR analysis revealed that in wild-type cells, higher expression levels of arlI, arlJ, and the archaellin gene arlA1 were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ∆cirA cells, which form rods during both early- and mid-log phases, exhibited similar expression levels of arl genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.IMPORTANCEArchaea are close relatives of eukaryotes and play crucial ecological roles. Certain behaviors, such as swimming motility, are thought to be important for archaeal environmental adaptation. Archaella, the archaeal motility appendages, are evolutionarily distinct from bacterial flagella, and the regulatory mechanisms driving archaeal motility are largely unknown. Previous research has linked the loss of type IV pili subunits to archaeal motility suppression. This study reveals three Haloferax volcanii proteins involved in pilin-mediated motility regulation, offering a deeper understanding of motility regulation in this understudied domain while also paving the way for uncovering novel mechanisms that govern archaeal motility. Understanding archaeal cellular processes will help elucidate the ecological roles of archaea as well as the evolution of these processes across domains.
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Affiliation(s)
- Priyanka Chatterjee
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Marco A Garcia
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jacob A Cote
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kun Yun
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Georgio P Legerme
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rumi Habib
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Manuela Tripepi
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Criston Young
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniel Kulp
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Mike Dyall-Smith
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany
- Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
| | - Mecky Pohlschroder
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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2
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Gaines MC, Sivabalasarma S, Isupov MN, Haque RU, McLaren M, Hanus C, Gold VAM, Albers SV, Daum B. CryoEM reveals the structure of an archaeal pilus involved in twitching motility. Nat Commun 2024; 15:5050. [PMID: 38877033 PMCID: PMC11178815 DOI: 10.1038/s41467-024-45831-w] [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: 08/08/2023] [Accepted: 02/02/2024] [Indexed: 06/16/2024] Open
Abstract
Amongst the major types of archaeal filaments, several have been shown to closely resemble bacterial homologues of the Type IV pili (T4P). Within Sulfolobales, member species encode for three types of T4P, namely the archaellum, the UV-inducible pilus system (Ups) and the archaeal adhesive pilus (Aap). Whereas the archaellum functions primarily in swimming motility, and the Ups in UV-induced cell aggregation and DNA-exchange, the Aap plays an important role in adhesion and twitching motility. Here, we present a cryoEM structure of the Aap of the archaeal model organism Sulfolobus acidocaldarius. We identify the component subunit as AapB and find that while its structure follows the canonical T4P blueprint, it adopts three distinct conformations within the pilus. The tri-conformer Aap structure that we describe challenges our current understanding of pilus structure and sheds new light on the principles of twitching motility.
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Affiliation(s)
- Matthew C Gaines
- Living Systems Institute, University of Exeter, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK
| | - Shamphavi Sivabalasarma
- Institute of Biology, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Michail N Isupov
- Henry Wellcome Building for Biocatalysis, Department of Biosciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Risat Ul Haque
- Living Systems Institute, University of Exeter, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK
| | - Cyril Hanus
- Institute of Psychiatry and Neurosciences of Paris, Inserm UMR1266 - Université Paris Cité, Paris, France
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK
| | - Sonja-Verena Albers
- Institute of Biology, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBBS, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, UK.
- Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK.
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3
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St John E, Reysenbach AL. Genomic comparison of deep-sea hydrothermal genera related to Aeropyrum, Thermodiscus and Caldisphaera, and proposed emended description of the family Acidilobaceae. Syst Appl Microbiol 2024; 47:126507. [PMID: 38703419 DOI: 10.1016/j.syapm.2024.126507] [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: 12/15/2023] [Revised: 03/02/2024] [Accepted: 04/17/2024] [Indexed: 05/06/2024]
Abstract
Deep-sea hydrothermal vents host archaeal and bacterial thermophilic communities, including taxonomically and functionally diverse Thermoproteota. Despite their prevalence in high-temperature submarine communities, Thermoproteota are chronically under-represented in genomic databases and issues have emerged regarding their nomenclature, particularly within the Aeropyrum-Thermodiscus-Caldisphaera. To resolve some of these problems, we identified 47 metagenome-assembled genomes (MAGs) within this clade, from 20 previously published deep-sea hydrothermal vent and submarine volcano metagenomes, and 24 MAGs from public databases. Using phylogenomic analysis, Genome Taxonomy Database Toolkit (GTDB-Tk) taxonomic assessment, 16S rRNA gene phylogeny, average amino acid identity (AAI) and functional gene patterns, we re-evaluated of the taxonomy of the Aeropyrum-Thermodiscus-Caldisphaera. At least nine genus-level clades were identified with two or more MAGs. In accordance with SeqCode requirements and recommendations, we propose names for three novel genera, viz. Tiamatella incendiivivens, Hestiella acidicharens and Calypsonella navitae. A fourth genus was also identified related to Thermodiscus maritimus, for which no available sequenced genome exists. We propose the novel species Thermodiscus eudorianus to describe our high-quality Thermodiscus MAG, which represents the type genome for the genus. All three novel genera and T. eudorianus are likely anaerobic heterotrophs, capable of fermenting protein-rich carbon sources, while some Tiamatella, Calypsonella and T. eudorianus may also reduce polysulfides, thiosulfate, sulfur and/or selenite, and the likely acidophile, Hestiella, may reduce nitrate and/or perchlorate. Based on phylogenomic evidence, we also propose the family Acidilobaceae be amended to include Caldisphaera, Aeropyrum, Thermodiscus and Stetteria and the novel genera described here.
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Affiliation(s)
- Emily St John
- Center for Life in Extreme Environments, Portland State University, Portland, OR 97201, USA.
| | - Anna-Louise Reysenbach
- Center for Life in Extreme Environments, Portland State University, Portland, OR 97201, USA.
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4
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Chatterjee P, Garcia MA, Cote JA, Yun K, Legerme GP, Habib R, Tripepi M, Young C, Kulp D, Dyall-Smith M, Pohlschroder M. Involvement of ArlI, ArlJ, and CirA in Archaeal Type-IV Pilin-Mediated Motility Regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583388. [PMID: 38562816 PMCID: PMC10983859 DOI: 10.1101/2024.03.04.583388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established, however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon Haloferax volcanii non-motile. In this study, we used EMS mutagenesis and a motility assay to identify motile suppressors of the ΔpilA[1-6] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, arlI and arlJ. Overexpression of these arlI and arlJ mutant constructs in the respective multi-deletion strains ΔpilA[1-6]ΔarlI and ΔpilA[1-6]ΔarlJ confirmed their role in suppressing the ΔpilA[1-6] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in cirA, a gene encoding a proposed regulatory protein. A deletion of cirA resulted in hypermotility, while cirA overexpression in wild-type cells led to decreased motility. Moreover, qRT-PCR analysis revealed that in wild-type cells, higher expression levels of arlI, arlJ, and the archaellin gene arlA1 were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ΔcirA cells, which form rods during both early and mid-log phases, exhibited similar expression levels of arl genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.
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Affiliation(s)
- Priyanka Chatterjee
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, USA
| | - Marco A. Garcia
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
| | - Jacob A. Cote
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, USA
| | - Kun Yun
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
| | | | - Rumi Habib
- Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, USA
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia PA, USA
| | - Manuela Tripepi
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
| | - Criston Young
- University of Pennsylvania, Department of Biology, Philadelphia PA, USA
| | - Daniel Kulp
- Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, USA
- Vaccine and Immunotherapy Center, The Wistar Institute, Philadelphia PA, USA
| | - Mike Dyall-Smith
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsreid, Germany
- Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
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5
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de Oliveira BFR, Yusuff Y. Culturing enigmatic marine bacteria. Nat Microbiol 2024; 9:6-7. [PMID: 38177298 DOI: 10.1038/s41564-023-01567-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Affiliation(s)
| | - Yahyah Yusuff
- Department of Microbiology, University of Ilorin, Ilorin, Nigeria.
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6
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Stöckl R, Nißl L, Reichelt R, Rachel R, Grohmann D, Grünberger F. The transcriptional regulator EarA and intergenic terminator sequences modulate archaellation in Pyrococcus furiosus. Front Microbiol 2023; 14:1241399. [PMID: 38029142 PMCID: PMC10665913 DOI: 10.3389/fmicb.2023.1241399] [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: 06/16/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
The regulation of archaellation, the formation of archaeal-specific cell appendages called archaella, is crucial for the motility, adhesion, and survival of archaeal organisms. Although the heavily archaellated and highly motile Pyrococcus furiosus is a key model organism for understanding the production and function of archaella in Euryarchaea, the transcriptional regulation of archaellum assembly is so far unknown. Here we show that the transcription factor EarA is the master regulator of the archaellum (arl) operon transcription, which is further modulated by intergenic transcription termination signals. EarA deletion or overexpression strains demonstrate that EarA is essential for archaellation in P. furiosus and governs the degree of archaellation. Providing a single-molecule update on the transcriptional landscape of the arl operon in P. furiosus, we identify sequence motifs for EarA binding upstream of the arl operon and intergenic terminator sequences as critical elements for fine-tuning the expression of the multicistronic arl cluster. Furthermore, transcriptome re-analysis across different Thermococcales species demonstrated a heterogeneous production of major archaellins, suggesting a more diverse composition of archaella than previously recognized. Overall, our study provides novel insights into the transcriptional regulation of archaellation and highlights the essential role of EarA in Pyrococcus furiosus. These findings advance our understanding of the mechanisms governing archaellation and have implications for the functional diversity of archaella.
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Affiliation(s)
- Richard Stöckl
- Institute of Microbiology and Archaea Centre, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Laura Nißl
- Institute of Microbiology and Archaea Centre, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Robert Reichelt
- Institute of Microbiology and Archaea Centre, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Reinhard Rachel
- Centre for Electron Microscopy, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Dina Grohmann
- Institute of Microbiology and Archaea Centre, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Felix Grünberger
- Institute of Microbiology and Archaea Centre, Faculty for Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
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7
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Lim Y, Seo JH, Giovannoni SJ, Kang I, Cho JC. Cultivation of marine bacteria of the SAR202 clade. Nat Commun 2023; 14:5098. [PMID: 37607927 PMCID: PMC10444878 DOI: 10.1038/s41467-023-40726-8] [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: 04/04/2023] [Accepted: 08/07/2023] [Indexed: 08/24/2023] Open
Abstract
Bacteria of the SAR202 clade, within the phylum Chloroflexota, are ubiquitously distributed in the ocean but have not yet been cultivated in the lab. It has been proposed that ancient expansions of catabolic enzyme paralogs broadened the spectrum of organic compounds that SAR202 bacteria could oxidize, leading to transformations of the Earth's carbon cycle. Here, we report the successful cultivation of SAR202 bacteria from surface seawater using dilution-to-extinction culturing. The growth of these strains is very slow (0.18-0.24 day-1) and is inhibited by exposure to light. The genomes, of ca. 3.08 Mbp, encode archaella (archaeal motility structures) and multiple sets of enzyme paralogs, including 80 genes coding for enolase superfamily enzymes and 44 genes encoding NAD(P)-dependent dehydrogenases. We propose that these enzyme paralogs participate in multiple parallel pathways for non-phosphorylative catabolism of sugars and sugar acids. Indeed, we demonstrate that SAR202 strains can utilize several substrates that are metabolized through the predicted pathways, such as sugars ʟ-fucose and ʟ-rhamnose, as well as their lactone and acid forms.
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Affiliation(s)
- Yeonjung Lim
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, Republic of Korea
- Center for Molecular and Cell Biology, Inha University, Incheon, 22212, Republic of Korea
| | - Ji-Hui Seo
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, Republic of Korea
| | | | - Ilnam Kang
- Center for Molecular and Cell Biology, Inha University, Incheon, 22212, Republic of Korea.
| | - Jang-Cheon Cho
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, Republic of Korea.
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8
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Kelly J, Vinogradov E, Robotham A, Tessier L, Logan SM, Jarrell KF. Characterizing the N- and O-linked glycans of the PGF-CTERM sorting domain-containing S-layer protein of Methanoculleus marisnigri. Glycobiology 2022; 32:629-644. [PMID: 35481895 DOI: 10.1093/glycob/cwac019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/28/2022] [Accepted: 03/09/2022] [Indexed: 01/05/2023] Open
Abstract
The glycosylation of structural proteins is a widespread posttranslational modification in Archaea. Although only a handful of archaeal N-glycan structures have been determined to date, it is evident that the diversity of structures expressed is greater than in the other domains of life. Here, we report on our investigation of the N- and O-glycan modifications expressed by Methanoculleus marisnigri, a mesophilic methanogen from the Order Methanomicrobiales. Unusually, mass spectrometry (MS) analysis of purified archaella revealed no evidence for N- or O-glycosylation of the constituent archaellins, In contrast, the S-layer protein, identified as a PGF-CTERM sorting domain-containing protein encoded by MEMAR_RS02690, is both N- and O-glycosylated. Two N-glycans were identified by NMR and MS analysis: a trisaccharide α-GlcNAc-4-β-GlcNAc3NGaAN-4-β-Glc-Asn where the second residue is 2-N-acetyl, 3-N-glyceryl-glucosamide and a disaccharide β-GlcNAc3NAcAN-4-β-Glc-Asn, where the terminal residue is 2,3 di-N-acetyl-glucosamide. The same trisaccharide was also found N-linked to a type IV pilin. The S-layer protein is also extensively modified in the threonine-rich region near the C-terminus with O-glycans composed exclusively of hexoses. While the S-layer protein has a predicted PGF-CTERM processing site, no evidence of a truncated and lipidated C-terminus, the expected product of processing by an archaeosortase, was found. Finally, NMR also identified a polysaccharide expressed by M. marisnigri and composed of a repeating tetrasaccharide unit of [-2-β-Ribf-3-α-Rha2OMe-3-α-Rha - 2-α-Rha-]. This is the first report of N- and O-glycosylation in an archaeon from the Order Methanomicrobiales.
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Affiliation(s)
- John Kelly
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Evgeny Vinogradov
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Anna Robotham
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Luc Tessier
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Susan M Logan
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Ken F Jarrell
- Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
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9
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Nuno de Sousa Machado J, Albers SV, Daum B. Towards Elucidating the Rotary Mechanism of the Archaellum Machinery. Front Microbiol 2022; 13:848597. [PMID: 35387068 PMCID: PMC8978795 DOI: 10.3389/fmicb.2022.848597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
Motile archaea swim by means of a molecular machine called the archaellum. This structure consists of a filament attached to a membrane-embedded motor. The archaellum is found exclusively in members of the archaeal domain, but the core of its motor shares homology with the motor of type IV pili (T4P). Here, we provide an overview of the different components of the archaellum machinery and hypothetical models to explain how rotary motion of the filament is powered by the archaellum motor.
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Affiliation(s)
- João Nuno de Sousa Machado
- Molecular Biology of Archaea, Faculty of Biology, Institute of Biology II, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Faculty of Biology, Institute of Biology II, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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10
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Holmes DE, Zhou J, Ueki T, Woodard T, Lovley DR. Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer. mBio 2021; 12:e0234421. [PMID: 34607451 PMCID: PMC8546582 DOI: 10.1128/mbio.02344-21] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Direct interspecies electron transfer (DIET) between bacteria and methanogenic archaea appears to be an important syntrophy in both natural and engineered methanogenic environments. However, the electrical connections on the outer surface of methanogens and the subsequent processing of electrons for carbon dioxide reduction to methane are poorly understood. Here, we report that the genetically tractable methanogen Methanosarcina acetivorans can grow via DIET in coculture with Geobacter metallireducens serving as the electron-donating partner. Comparison of gene expression patterns in M. acetivorans grown in coculture versus pure-culture growth on acetate revealed that transcripts for the outer-surface multiheme c-type cytochrome MmcA were higher during DIET-based growth. Deletion of mmcA inhibited DIET. The high aromatic amino acid content of M. acetivorans archaellins suggests that they might assemble into electrically conductive archaella. A mutant that could not express archaella was deficient in DIET. However, this mutant grew in DIET-based coculture as well as the archaellum-expressing parental strain in the presence of granular activated carbon, which was previously shown to serve as a substitute for electrically conductive pili as a conduit for long-range interspecies electron transfer in other DIET-based cocultures. Transcriptomic data suggesting that the membrane-bound Rnf, Fpo, and HdrED complexes also play a role in DIET were incorporated into a charge-balanced model illustrating how electrons entering the cell through MmcA can yield energy to support growth from carbon dioxide reduction. The results are the first genetics-based functional demonstration of likely outer-surface electrical contacts for DIET in a methanogen. IMPORTANCE The conversion of organic matter to methane plays an important role in the global carbon cycle and is an effective strategy for converting wastes to a useful biofuel. The reduction of carbon dioxide to methane accounts for approximately a third of the methane produced in anaerobic soils and sediments as well as waste digesters. Potential electron donors for carbon dioxide reduction are H2 or electrons derived from direct interspecies electron transfer (DIET) between bacteria and methanogens. Elucidating the relative importance of these electron donors has been difficult due to a lack of information on the electrical connections on the outer surfaces of methanogens and how they process the electrons received from DIET. Transcriptomic patterns and gene deletion phenotypes reported here provide insight into how a group of Methanosarcina organisms that play an important role in methane production in soils and sediments participate in DIET.
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Affiliation(s)
- Dawn E. Holmes
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Science, Western New England University, Springfield, Massachusetts, USA
| | - Jinjie Zhou
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Trevor Woodard
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
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