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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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2
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Gaines MC, Isupov MN, Sivabalasarma S, Haque RU, McLaren M, Mollat CL, Tripp P, Neuhaus A, Gold VAM, Albers SV, Daum B. Electron cryo-microscopy reveals the structure of the archaeal thread filament. Nat Commun 2022; 13:7411. [PMID: 36456543 PMCID: PMC9715654 DOI: 10.1038/s41467-022-34652-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 11/02/2022] [Indexed: 12/05/2022] Open
Abstract
Pili are filamentous surface extensions that play roles in bacterial and archaeal cellular processes such as adhesion, biofilm formation, motility, cell-cell communication, DNA uptake and horizontal gene transfer. The model archaeaon Sulfolobus acidocaldarius assembles three filaments of the type-IV pilus superfamily (archaella, archaeal adhesion pili and UV-inducible pili), as well as a so-far uncharacterised fourth filament, named "thread". Here, we report on the cryo-EM structure of the archaeal thread. The filament is highly glycosylated and consists of subunits of the protein Saci_0406, arranged in a head-to-tail manner. Saci_0406 displays structural similarity, but low sequence homology, to bacterial type-I pilins. Thread subunits are interconnected via donor strand complementation, a feature reminiscent of bacterial chaperone-usher pili. However, despite these similarities in overall architecture, archaeal threads appear to have evolved independently and are likely assembled by a distinct mechanism.
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Affiliation(s)
- Matthew C Gaines
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Michail N Isupov
- Henry Wellcome Building for Biocatalysis, Department of Biosciences, Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, Exeter, UK
| | - Shamphavi Sivabalasarma
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Risat Ul Haque
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Clara L Mollat
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
| | - Patrick Tripp
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
| | - Alexander Neuhaus
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Sonja-Verena Albers
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, 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, Stocker Road, EX4 4QD, Exeter, UK.
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK.
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3
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Jarrell KF, Albers SV, Machado JNDS. A comprehensive history of motility and Archaellation in Archaea. FEMS MICROBES 2021; 2:xtab002. [PMID: 37334237 PMCID: PMC10117864 DOI: 10.1093/femsmc/xtab002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/18/2021] [Indexed: 08/24/2023] Open
Abstract
Each of the three Domains of life, Eukarya, Bacteria and Archaea, have swimming structures that were all originally called flagella, despite the fact that none were evolutionarily related to either of the other two. Surprisingly, this was true even in the two prokaryotic Domains of Bacteria and Archaea. Beginning in the 1980s, evidence gradually accumulated that convincingly demonstrated that the motility organelle in Archaea was unrelated to that found in Bacteria, but surprisingly shared significant similarities to type IV pili. This information culminated in the proposal, in 2012, that the 'archaeal flagellum' be assigned a new name, the archaellum. In this review, we provide a historical overview on archaella and motility research in Archaea, beginning with the first simple observations of motile extreme halophilic archaea a century ago up to state-of-the-art cryo-tomography of the archaellum motor complex and filament observed today. In addition to structural and biochemical data which revealed the archaellum to be a type IV pilus-like structure repurposed as a rotating nanomachine (Beeby et al. 2020), we also review the initial discoveries and subsequent advances using a wide variety of approaches to reveal: complex regulatory events that lead to the assembly of the archaellum filaments (archaellation); the roles of the various archaellum proteins; key post-translational modifications of the archaellum structural subunits; evolutionary relationships; functions of archaella other than motility and the biotechnological potential of this fascinating structure. The progress made in understanding the structure and assembly of the archaellum is highlighted by comparing early models to what is known today.
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Affiliation(s)
- Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Sonja-Verena Albers
- Institute for Biology II- Microbiology, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany
| | - J Nuno de Sousa Machado
- Institute for Biology II- Microbiology, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Albertstraße 19A, 79104, Freiburg, Germany
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Effect of changes at the conserved + 3 position of mature archaellins on in vitro cleavage by the pre-archaellin peptidase FlaK of Methanococcus maripaludis. Arch Microbiol 2020; 202:1669-1675. [PMID: 32285165 DOI: 10.1007/s00203-020-01873-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/28/2020] [Accepted: 04/01/2020] [Indexed: 10/24/2022]
Abstract
Archaea swim using archaella that are domain-specific rotary type IV pilus-like appendages. The structural components of the archaellum filament are archaellins, initially made as preproteins with type IV pilin-like signal peptides which are removed by signal peptidases that are homologues of prepilin peptidases that remove signal peptides from type IV pilins. N-terminal sequences of archaellins, including the signal peptide cleavage site, are conserved and various positions have been previously shown to be critical for signal peptide removal. Archaellins have an absolute conservation of glycine at the + 3 position from the signal peptide cleavage site. To investigate its role in signal peptide cleavage, I used archaellin variants in which the + 3 glycine was mutated to all other possibilities in in vitro cleavage reactions. Cleavage was observed with ten different amino acids at the + 3 position, indicating that the observed glycine conservation is not required for this essential processing step.
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5
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Phylogenetic distribution of the euryarchaeal archaellum regulator EarA and complementation of a Methanococcus maripaludis ∆earA mutant with heterologous earA homologues. Microbiology (Reading) 2017; 163:804-815. [DOI: 10.1099/mic.0.000464] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Pohlschroder M, Esquivel RN. Archaeal type IV pili and their involvement in biofilm formation. Front Microbiol 2015; 6:190. [PMID: 25852657 PMCID: PMC4371748 DOI: 10.3389/fmicb.2015.00190] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/20/2015] [Indexed: 12/13/2022] Open
Abstract
Type IV pili are ancient proteinaceous structures present on the cell surface of species in nearly all bacterial and archaeal phyla. These filaments, which are required for a diverse array of important cellular processes, are assembled employing a conserved set of core components. While type IV pilins, the structural subunits of pili, share little sequence homology, their signal peptides are structurally conserved allowing for in silico prediction. Recently, in vivo studies in model archaea representing the euryarchaeal and crenarchaeal kingdoms confirmed that several of these pilins are incorporated into type IV adhesion pili. In addition to facilitating surface adhesion, these in vivo studies also showed that several predicted pilins are required for additional functions that are critical to biofilm formation. Examples include the subunits of Sulfolobus acidocaldarius Ups pili, which are induced by exposure to UV light and promote cell aggregation and conjugation, and a subset of the Haloferax volcanii adhesion pilins, which play a critical role in microcolony formation while other pilins inhibit this process. The recent discovery of novel pilin functions such as the ability of haloarchaeal adhesion pilins to regulate swimming motility may point to novel regulatory pathways conserved across prokaryotic domains. In this review, we will discuss recent advances in our understanding of the functional roles played by archaeal type IV adhesion pili and their subunits, with particular emphasis on their involvement in biofilm formation.
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Affiliation(s)
| | - Rianne N Esquivel
- Department of Biology, University of Pennsylvania Philadelphia, PA, USA
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7
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Giménez MI, Cerletti M, De Castro RE. Archaeal membrane-associated proteases: insights on Haloferax volcanii and other haloarchaea. Front Microbiol 2015; 6:39. [PMID: 25774151 PMCID: PMC4343526 DOI: 10.3389/fmicb.2015.00039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/12/2015] [Indexed: 11/17/2022] Open
Abstract
The function of membrane proteases range from general house-keeping to regulation of cellular processes. Although the biological role of these enzymes in archaea is poorly understood, some of them are implicated in the biogenesis of the archaeal cell envelope and surface structures. The membrane-bound ATP-dependent Lon protease is essential for cell viability and affects membrane carotenoid content in Haloferax volcanii. At least two different proteases are needed in this archaeon to accomplish the posttranslational modifications of the S-layer glycoprotein. The rhomboid protease RhoII is involved in the N-glycosylation of the S-layer protein with a sulfoquinovose-containing oligosaccharide while archaeosortase ArtA mediates the proteolytic processing coupled-lipid modification of this glycoprotein facilitating its attachment to the archaeal cell surface. Interestingly, two different signal peptidase I homologs exist in H. volcanii, Sec11a and Sec11b, which likely play distinct physiological roles. Type IV prepilin peptidase PibD processes flagellin/pilin precursors, being essential for the biogenesis and function of the archaellum and other cell surface structures in H. volcanii.
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Affiliation(s)
- María I Giménez
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas Mar del Plata, Argentina
| | - Micaela Cerletti
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas Mar del Plata, Argentina
| | - Rosana E De Castro
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas Mar del Plata, Argentina
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8
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Abstract
Recent studies on archaeal motility have shown that the archaeal motility structure is unique in several aspects. Although it fulfills the same swimming function as the bacterial flagellum, it is evolutionarily and structurally related to the type IV pilus. This was the basis for the recent proposal to term the archaeal motility structure the "archaellum." This review illustrates the key findings that led to the realization that the archaellum was a novel motility structure and presents the current knowledge about the structural composition, mechanism of assembly and regulation, and the posttranslational modifications of archaella.
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Affiliation(s)
- Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg , Freiburg, Germany ; Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology , Marburg, Germany
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University , Kingston, ON, Canada
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9
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Nair DB, Jarrell KF. Pilin Processing Follows a Different Temporal Route than That of Archaellins in Methanococcus maripaludis. Life (Basel) 2015; 5:85-101. [PMID: 25569238 PMCID: PMC4390842 DOI: 10.3390/life5010085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 12/26/2014] [Indexed: 11/16/2022] Open
Abstract
Methanococcus maripaludis has two different surface appendages: type IV-like pili and archaella. Both structures are believed to be assembled using a bacterial type IV pilus mechanism. Each structure is composed of multiple subunits, either pilins or archaellins. Both pilins and archaellins are made initially as preproteins with type IV pilin-like signal peptides, which must be removed by a prepilin peptidase-like enzyme. This enzyme is FlaK for archaellins and EppA for pilins. In addition, both pilins and archaellins are modified with N-linked glycans. The archaellins possess an N-linked tetrasaccharide while the pilins have a pentasaccharide which consists of the archaellin tetrasaccharide but with an additional sugar, an unidentified hexose, attached to the linking sugar. In this report, we show that archaellins can be processed by FlaK in the absence of N-glycosylation and N-glycosylation can occur on archaellins that still retain their signal peptides. In contrast, pilins are not glycosylated unless they have been acted on by EppA to have the signal peptide removed. However, EppA can still remove signal peptides from non-glycosylated pilins. These findings indicate that there is a difference in the order of the posttranslational modifications of pilins and archaellins even though both are type IV pilin-like proteins.
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Affiliation(s)
- Divya B Nair
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
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10
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Antranikian G, Bonch-Osmolovskaya E, Atomi H, Oren A, Adams MW, Santos H. International conference on extremophiles 2014. Extremophiles 2014; 18:789-90. [PMID: 25159180 DOI: 10.1007/s00792-014-0690-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Garabed Antranikian
- Institute of Technical Microbiology, Hamburg University of Technology (TUHH), Kasernenstr. 12, 21073, Hamburg, Germany,
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