1
|
Sofer S, Vershinin Z, Mashni L, Zalk R, Shahar A, Eichler J, Grossman-Haham I. Perturbed N-glycosylation of Halobacterium salinarum archaellum filaments leads to filament bundling and compromised cell motility. Nat Commun 2024; 15:5841. [PMID: 38992036 PMCID: PMC11239922 DOI: 10.1038/s41467-024-50277-1] [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: 02/27/2024] [Accepted: 07/03/2024] [Indexed: 07/13/2024] Open
Abstract
The swimming device of archaea-the archaellum-presents asparagine (N)-linked glycans. While N-glycosylation serves numerous roles in archaea, including enabling their survival in extreme environments, how this post-translational modification contributes to cell motility remains under-explored. Here, we report the cryo-EM structure of archaellum filaments from the haloarchaeon Halobacterium salinarum, where archaellins, the building blocks of the archaellum, are N-glycosylated, and the N-glycosylation pathway is well-resolved. We further determined structures of archaellum filaments from two N-glycosylation mutant strains that generate truncated glycans and analyzed their motility. While cells from the parent strain exhibited unidirectional motility, the N-glycosylation mutant strain cells swam in ever-changing directions within a limited area. Although these mutant strain cells presented archaellum filaments that were highly similar in architecture to those of the parent strain, N-linked glycan truncation greatly affected interactions between archaellum filaments, leading to dramatic clustering of both isolated and cell-attached filaments. We propose that the N-linked tetrasaccharides decorating archaellins act as physical spacers that minimize the archaellum filament aggregation that limits cell motility.
Collapse
Affiliation(s)
- Shahar Sofer
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Leen Mashni
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Ran Zalk
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Anat Shahar
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Iris Grossman-Haham
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
Kuiper BP, Schöntag AMC, Oksanen HM, Daum B, Quax TEF. Archaeal virus entry and egress. MICROLIFE 2024; 5:uqad048. [PMID: 38234448 PMCID: PMC10791045 DOI: 10.1093/femsml/uqad048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/08/2023] [Accepted: 01/02/2024] [Indexed: 01/19/2024]
Abstract
Archaeal viruses display a high degree of structural and genomic diversity. Few details are known about the mechanisms by which these viruses enter and exit their host cells. Research on archaeal viruses has lately made significant progress due to advances in genetic tools and imaging techniques, such as cryo-electron tomography (cryo-ET). In recent years, a steady output of newly identified archaeal viral receptors and egress mechanisms has offered the first insight into how archaeal viruses interact with the archaeal cell envelope. As more details about archaeal viral entry and egress are unravelled, patterns are starting to emerge. This helps to better understand the interactions between viruses and the archaeal cell envelope and how these compare to infection strategies of viruses in other domains of life. Here, we provide an overview of recent developments in the field of archaeal viral entry and egress, shedding light onto the most elusive part of the virosphere.
Collapse
Affiliation(s)
- Bastiaan P Kuiper
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Anna M C Schöntag
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Hanna M Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9, FI-00014 Helsinki, Finland
| | - Bertram Daum
- Living Systems Institute, Faculty of Health and Life Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Tessa E F Quax
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| |
Collapse
|
4
|
Kreutzberger MAB, Cvirkaite-Krupovic V, Liu Y, Baquero DP, Liu J, Sonani RR, Calladine CR, Wang F, Krupovic M, Egelman EH. The evolution of archaeal flagellar filaments. Proc Natl Acad Sci U S A 2023; 120:e2304256120. [PMID: 37399404 PMCID: PMC10334743 DOI: 10.1073/pnas.2304256120] [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: 03/14/2023] [Accepted: 06/08/2023] [Indexed: 07/05/2023] Open
Abstract
Flagellar motility has independently arisen three times during evolution: in bacteria, archaea, and eukaryotes. In prokaryotes, the supercoiled flagellar filaments are composed largely of a single protein, bacterial or archaeal flagellin, although these two proteins are not homologous, while in eukaryotes, the flagellum contains hundreds of proteins. Archaeal flagellin and archaeal type IV pilin are homologous, but how archaeal flagellar filaments (AFFs) and archaeal type IV pili (AT4Ps) diverged is not understood, in part, due to the paucity of structures for AFFs and AT4Ps. Despite having similar structures, AFFs supercoil, while AT4Ps do not, and supercoiling is essential for the function of AFFs. We used cryo-electron microscopy to determine the atomic structure of two additional AT4Ps and reanalyzed previous structures. We find that all AFFs have a prominent 10-strand packing, while AT4Ps show a striking structural diversity in their subunit packing. A clear distinction between all AFF and all AT4P structures involves the extension of the N-terminal α-helix with polar residues in the AFFs. Additionally, we characterize a flagellar-like AT4P from Pyrobaculum calidifontis with filament and subunit structure similar to that of AFFs which can be viewed as an evolutionary link, showing how the structural diversity of AT4Ps likely allowed for an AT4P to evolve into a supercoiling AFF.
Collapse
Affiliation(s)
- Mark A. B. Kreutzberger
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
| | | | - Ying Liu
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris75015, France
| | - Diana P. Baquero
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris75015, France
| | - Junfeng Liu
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris75015, France
| | - Ravi R. Sonani
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
| | - Chris R. Calladine
- Department of Engineering, University of Cambridge, CambridgeCB2 1PZ, United Kingdom
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris75015, France
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
| |
Collapse
|
5
|
Sivabalasarma S, de Sousa Machado JN, Albers SV, Jarrell KF. Archaella Isolation. Methods Mol Biol 2023; 2646:183-195. [PMID: 36842116 DOI: 10.1007/978-1-0716-3060-0_16] [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] [Indexed: 02/27/2023]
Abstract
Swimming archaea are propelled by a filamentous structure called the archaellum. The first step for the structural characterization of this filament is its isolation. Here we provide various methods that allow for the isolation of archaella filaments from well-studied archaeal model organisms. Archaella filaments have been successfully extracted from organisms belonging to different archaeal phyla, e.g., euryarchaeal methanogens such as Methanococcus voltae, and crenarchaeal hyperthermoacidophiles like Sulfolobus acidocaldarius. The filament isolation protocols that we provide in this chapter follow one of two strategies: either the filaments are sheared or extracted from whole cells by detergent extraction, prior to further final purification by centrifugation methods.
Collapse
Affiliation(s)
- Shamphavi Sivabalasarma
- 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
| | - João N 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.
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| |
Collapse
|
6
|
Gambelli L, Isupov M, Daum B. Escaping the symmetry trap in helical reconstruction. Faraday Discuss 2022; 240:303-311. [PMID: 35929538 PMCID: PMC9642006 DOI: 10.1039/d2fd00051b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Helical reconstruction is the method of choice for obtaining 3D structures of filaments from electron cryo-microscopy (cryoEM) projections. This approach relies on applying helical symmetry parameters deduced from Fourier-Bessel or real space analysis, such as sub-tomogram averaging. While helical reconstruction continues to provide invaluable structural insights into filaments, its inherent dependence on imposing a pre-defined helical symmetry can also introduce bias. The applied helical symmetry produces structures that are infinitely straight along the filament's axis and can average out biologically important heterogeneities. Here, we describe a simple workflow aimed at overcoming these drawbacks in order to provide truer representations of filamentous structures.
Collapse
Affiliation(s)
- Lavinia Gambelli
- College of Engineering, Mathematics and Physical Sciences, University of ExeterExeterEX4 4QFUK,Living Systems Institute, University of ExeterExeterEX4 4QDUK
| | - Michail N. Isupov
- Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of ExeterExeterEX4 4QDUK
| | - Bertram Daum
- Living Systems Institute, University of ExeterExeterEX4 4QDUK,College of Life and Environmental Sciences, University of ExeterExeterEX4 4QDUK
| |
Collapse
|
7
|
Kreutzberger MAB, Sonani RR, Liu J, Chatterjee S, Wang F, Sebastian AL, Biswas P, Ewing C, Zheng W, Poly F, Frankel G, Luisi BF, Calladine CR, Krupovic M, Scharf BE, Egelman EH. Convergent evolution in the supercoiling of prokaryotic flagellar filaments. Cell 2022; 185:3487-3500.e14. [PMID: 36057255 PMCID: PMC9500442 DOI: 10.1016/j.cell.2022.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/04/2022] [Accepted: 08/04/2022] [Indexed: 02/02/2023]
Abstract
The supercoiling of bacterial and archaeal flagellar filaments is required for motility. Archaeal flagellar filaments have no homology to their bacterial counterparts and are instead homologs of bacterial type IV pili. How these prokaryotic flagellar filaments, each composed of thousands of copies of identical subunits, can form stable supercoils under torsional stress is a fascinating puzzle for which structural insights have been elusive. Advances in cryoelectron microscopy (cryo-EM) make it now possible to directly visualize the basis for supercoiling, and here, we show the atomic structures of supercoiled bacterial and archaeal flagellar filaments. For the bacterial flagellar filament, we identify 11 distinct protofilament conformations with three broad classes of inter-protomer interface. For the archaeal flagellar filament, 10 protofilaments form a supercoil geometry supported by 10 distinct conformations, with one inter-protomer discontinuity creating a seam inside of the curve. Our results suggest that convergent evolution has yielded stable superhelical geometries that enable microbial locomotion.
Collapse
Affiliation(s)
- Mark A B Kreutzberger
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Ravi R Sonani
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Junfeng Liu
- Institut Pasteur, Université Paris Cité, CNRS UMR 6047, Archaeal Virology Unit, 75015 Paris, France
| | - Sharanya Chatterjee
- Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, London, UK
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Amanda L Sebastian
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Priyanka Biswas
- Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, London, UK
| | - Cheryl Ewing
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Frédéric Poly
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA
| | - Gad Frankel
- Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, London, UK
| | - B F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Chris R Calladine
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR 6047, Archaeal Virology Unit, 75015 Paris, France
| | - Birgit E Scharf
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA.
| |
Collapse
|
8
|
Ortega D, Beeby M. How Did the Archaellum Get Its Rotation? Front Microbiol 2022; 12:803720. [PMID: 35558523 PMCID: PMC9087265 DOI: 10.3389/fmicb.2021.803720] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
How new functions evolve fascinates many evolutionary biologists. Particularly captivating is the evolution of rotation in molecular machines, as it evokes familiar machines that we have made ourselves. The archaellum, an archaeal analog of the bacterial flagellum, is one of the simplest rotary motors. It features a long helical propeller attached to a cell envelope-embedded rotary motor. Satisfyingly, the archaellum is one of many members of the large type IV filament superfamily, which includes pili, secretion systems, and adhesins, relationships that promise clues as to how the rotating archaellum evolved from a non-rotary ancestor. Nevertheless, determining exactly how the archaellum got its rotation remains frustratingly elusive. Here we review what is known about how the archaellum got its rotation, what clues exist, and what more is needed to address this question.
Collapse
Affiliation(s)
| | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, United Kingdom
| |
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
Gambelli L, Isupov MN, Conners R, McLaren M, Bellack A, Gold V, Rachel R, Daum B. An archaellum filament composed of two alternating subunits. Nat Commun 2022; 13:710. [PMID: 35132062 PMCID: PMC8821640 DOI: 10.1038/s41467-022-28337-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
Archaea use a molecular machine, called the archaellum, to swim. The archaellum consists of an ATP-powered intracellular motor that drives the rotation of an extracellular filament composed of multiple copies of proteins named archaellins. In many species, several archaellin homologs are encoded in the same operon; however, previous structural studies indicated that archaellum filaments mainly consist of only one protein species. Here, we use electron cryo-microscopy to elucidate the structure of the archaellum from Methanocaldococcus villosus at 3.08 Å resolution. The filament is composed of two alternating archaellins, suggesting that the architecture and assembly of archaella is more complex than previously thought. Moreover, we identify structural elements that may contribute to the filament’s flexibility. The archaellum is a molecular machine used by archaea to swim, consisting of an intracellular motor that drives the rotation of an extracellular filament composed of multiple copies of proteins named archaellins. Here, the authors use electron cryo-microscopy to elucidate the structure of an archaellum, and find that the filament is composed of two alternating archaellins.
Collapse
Affiliation(s)
- Lavinia Gambelli
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK.,College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UK
| | - Michail N Isupov
- Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Rebecca Conners
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK.,College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK.,College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Annett Bellack
- Institute of Microbiology and Archaea Centre, University of Regensburg, 93053, Regensburg, Germany
| | - Vicki Gold
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK.,College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Reinhard Rachel
- Institute of Microbiology and Archaea Centre, University of Regensburg, 93053, Regensburg, Germany
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK. .,College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK.
| |
Collapse
|
11
|
Abstract
Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly in solving the structures of large protein complexes or cellular machineries that play important biological functions. This review focuses on the contribution and future potential of cryo-EM in related emerging applications-enzymatic mechanisms and dynamic processes. Work on these subjects can benefit greatly from the capability of cryo-EM to solve the structures of specific protein complexes in multiple conditions, including variations in the buffer condition, ligands, and temperature, and to capture multiple conformational states, conformational change intermediates, and reaction intermediates. These studies can expand the structural landscape of specific proteins or protein complexes in multiple dimensions and drive new advances in the fields of enzymology and dynamic processes. The advantages and complementarity of cryo-EM relative to X-ray crystallography and nuclear magnetic resonance with regard to these applications are also addressed. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; .,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Wen-Jin Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan;
| | - Meng-Chiao Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; .,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| |
Collapse
|
12
|
Karami Y, López-Castilla A, Ori A, Thomassin JL, Bardiaux B, Malliavin T, Izadi-Pruneyre N, Francetic O, Nilges M. Computational and biochemical analysis of type IV pilus dynamics and stability. Structure 2021; 29:1397-1409.e6. [PMID: 34520738 DOI: 10.1016/j.str.2021.07.008] [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: 04/13/2021] [Revised: 06/14/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022]
Abstract
Type IV pili (T4P) are distinctive dynamic filaments at the surface of many bacteria that can rapidly extend and retract and withstand strong forces. T4P are important virulence factors in many human pathogens, including Enterohemorrhagic Escherichia coli (EHEC). The structure of the EHEC T4P has been determined by integrating nuclear magnetic resonance (NMR) and cryo-electron microscopy data. To better understand pilus assembly, stability, and function, we performed a total of 108 ms all-atom molecular dynamics simulations of wild-type and mutant T4P. Extensive characterization of the conformational landscape of T4P in different conditions of temperature, pH, and ionic strength is complemented with targeted mutagenesis and biochemical analyses. Our simulations and NMR experiments reveal a conserved set of residues defining a calcium-binding site at the interface between three pilin subunits. Calcium binding enhances T4P stability ex vivo and in vitro, supporting the role of this binding site as a potential pocket for drug design.
Collapse
Affiliation(s)
- Yasaman Karami
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Aracelys López-Castilla
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Andrea Ori
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Jenny-Lee Thomassin
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Therese Malliavin
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
The structures of two archaeal type IV pili illuminate evolutionary relationships. Nat Commun 2020; 11:3424. [PMID: 32647180 PMCID: PMC7347861 DOI: 10.1038/s41467-020-17268-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/22/2020] [Indexed: 12/14/2022] Open
Abstract
We have determined the cryo-electron microscopic (cryo-EM) structures of two archaeal type IV pili (T4P), from Pyrobaculum arsenaticum and Saccharolobus solfataricus, at 3.8 Å and 3.4 Å resolution, respectively. This triples the number of high resolution archaeal T4P structures, and allows us to pinpoint the evolutionary divergence of bacterial T4P, archaeal T4P and archaeal flagellar filaments. We suggest that extensive glycosylation previously observed in T4P of Sulfolobus islandicus is a response to an acidic environment, as at even higher temperatures in a neutral environment much less glycosylation is present for Pyrobaculum than for Sulfolobus and Saccharolobus pili. Consequently, the Pyrobaculum filaments do not display the remarkable stability of the Sulfolobus filaments in vitro. We identify the Saccharolobus and Pyrobaculum T4P as host receptors recognized by rudivirus SSRV1 and tristromavirus PFV2, respectively. Our results illuminate the evolutionary relationships among bacterial and archaeal T4P filaments and provide insights into archaeal virus-host interactions. Archaeal type IV pili (T4P) mediate adhesion to surfaces and are receptors for hyperthermophilic archaeal viruses. Here, the authors present the cryo-EM structures of two archaeal T4P from Pyrobaculum arsenaticum and Saccharolobus solfataricus and discuss evolutionary relationships between bacterial T4P, archaeal T4P and archaeal flagellar filaments.
Collapse
|
15
|
Neuhaus A, Selvaraj M, Salzer R, Langer JD, Kruse K, Kirchner L, Sanders K, Daum B, Averhoff B, Gold VAM. Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium. Nat Commun 2020; 11:2231. [PMID: 32376942 PMCID: PMC7203116 DOI: 10.1038/s41467-020-15650-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/19/2020] [Indexed: 12/19/2022] Open
Abstract
Type IV pili are flexible filaments on the surface of bacteria, consisting of a helical assembly of pilin proteins. They are involved in bacterial motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Here, we use cryo-electron microscopy and mass spectrometry to show that the bacterium Thermus thermophilus produces two forms of type IV pilus ('wide' and 'narrow'), differing in structure and protein composition. Wide pili are composed of the major pilin PilA4, while narrow pili are composed of a so-far uncharacterized pilin which we name PilA5. Functional experiments indicate that PilA4 is required for natural transformation, while PilA5 is important for twitching motility.
Collapse
Affiliation(s)
- Alexander Neuhaus
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Muniyandi Selvaraj
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
- Laboratory of Structural Biology, Helsinki Institute of Life Science, 00014 University of Helsinki, Helsinki, Finland
| | - Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
- Structural Studies Division, Medical Research Council-Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave, Cambridge, CB2 0QH, UK
| | - Julian D Langer
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
- Proteomics, Max Planck Institute for Brain Research, Max-von-Laue Str. 4, 60438, Frankfurt am Main, Germany
| | - Kerstin Kruse
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Lennart Kirchner
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Kelly Sanders
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
| |
Collapse
|
16
|
Pyatibratov MG, Syutkin AS, Quax TEF, Melnik TN, Papke RT, Gogarten JP, Kireev II, Surin AK, Beznosov SN, Galeva AV, Fedorov OV. Interaction of two strongly divergent archaellins stabilizes the structure of the Halorubrum archaellum. Microbiologyopen 2020; 9:e1047. [PMID: 32352651 PMCID: PMC7349177 DOI: 10.1002/mbo3.1047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 03/23/2020] [Accepted: 03/28/2020] [Indexed: 12/24/2022] Open
Abstract
Halophilic archaea from the genus Halorubrum possess two extraordinarily diverged archaellin genes, flaB1 and flaB2. To clarify roles for each archaellin, we compared two natural Halorubrum lacusprofundi strains: One of them contains both archaellin genes, and the other has the flaB2 gene only. Both strains synthesize functional archaella; however, the strain, where both archaellins are present, is more motile. In addition, we expressed these archaellins in a Haloferax volcanii strain from which the endogenous archaellin genes were deleted. Three Hfx. volcanii strains expressing Hrr. lacusprofundi archaellins produced functional filaments consisting of only one (FlaB1 or FlaB2) or both (FlaB1/FlaB2) archaellins. All three strains were motile, although there were profound differences in the efficiency of motility. Both native and recombinant FlaB1/FlaB2 filaments have greater thermal stability and resistance to low salinity stress than single‐component filaments. Functional supercoiled Hrr. lacusprofundi archaella can be composed of either single archaellin: FlaB2 or FlaB1; however, the two divergent archaellin subunits provide additional stabilization to the archaellum structure and thus adaptation to a wider range of external conditions. Comparative genomic analysis suggests that the described combination of divergent archaellins is not restricted to Hrr. lacusprofundi, but is occurring also in organisms from other haloarchaeal genera.
Collapse
Affiliation(s)
- Mikhail G Pyatibratov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexey S Syutkin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Tessa E F Quax
- Archaeal Virus-Host Interactions, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Tatjana N Melnik
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Johann Peter Gogarten
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Igor I Kireev
- A.N. Belozersky Institute of Physico-chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Alexey K Surin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.,Pushchino Branch, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.,State Research Center for Applied Microbiology & Biotechnology, Obolensk, Moscow Region, Russia
| | - Sergei N Beznosov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Anna V Galeva
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Oleg V Fedorov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| |
Collapse
|
17
|
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.
Collapse
|
18
|
Beeby M, Ferreira JL, Tripp P, Albers SV, Mitchell DR. Propulsive nanomachines: the convergent evolution of archaella, flagella and cilia. FEMS Microbiol Rev 2020; 44:253-304. [DOI: 10.1093/femsre/fuaa006] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
ABSTRACT
Echoing the repeated convergent evolution of flight and vision in large eukaryotes, propulsive swimming motility has evolved independently in microbes in each of the three domains of life. Filamentous appendages – archaella in Archaea, flagella in Bacteria and cilia in Eukaryotes – wave, whip or rotate to propel microbes, overcoming diffusion and enabling colonization of new environments. The implementations of the three propulsive nanomachines are distinct, however: archaella and flagella rotate, while cilia beat or wave; flagella and cilia assemble at their tips, while archaella assemble at their base; archaella and cilia use ATP for motility, while flagella use ion-motive force. These underlying differences reflect the tinkering required to evolve a molecular machine, in which pre-existing machines in the appropriate contexts were iteratively co-opted for new functions and whose origins are reflected in their resultant mechanisms. Contemporary homologies suggest that archaella evolved from a non-rotary pilus, flagella from a non-rotary appendage or secretion system, and cilia from a passive sensory structure. Here, we review the structure, assembly, mechanism and homologies of the three distinct solutions as a foundation to better understand how propulsive nanomachines evolved three times independently and to highlight principles of molecular evolution.
Collapse
Affiliation(s)
- Morgan Beeby
- Department of Life Sciences, Frankland Road, Imperial College of London, London, SW7 2AZ, UK
| | - Josie L Ferreira
- Department of Life Sciences, Frankland Road, Imperial College of London, London, SW7 2AZ, UK
| | - Patrick Tripp
- Molecular Biology of Archaea, Institute of Biology, University of Freiburg, Schaenzlestrasse 1, 79211 Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology, University of Freiburg, Schaenzlestrasse 1, 79211 Freiburg, Germany
| | - David R Mitchell
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| |
Collapse
|
19
|
The structure of the periplasmic FlaG-FlaF complex and its essential role for archaellar swimming motility. Nat Microbiol 2019; 5:216-225. [PMID: 31844299 DOI: 10.1038/s41564-019-0622-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 10/23/2019] [Indexed: 11/08/2022]
Abstract
Motility structures are vital in all three domains of life. In Archaea, motility is mediated by the archaellum, a rotating type IV pilus-like structure that is a unique nanomachine for swimming motility in nature. Whereas periplasmic FlaF binds the surface layer (S-layer), the structure, assembly and roles of other periplasmic components remain enigmatic, limiting our knowledge of the archaellum's functional interactions. Here, we find that the periplasmic protein FlaG and the association with its paralogue FlaF are essential for archaellation and motility. Therefore, we determine the crystal structure of Sulfolobus acidocaldarius soluble FlaG (sFlaG), which reveals a β-sandwich fold resembling the S-layer-interacting FlaF soluble domain (sFlaF). Furthermore, we solve the sFlaG2-sFlaF2 co-crystal structure, define its heterotetrameric complex in solution by small-angle X-ray scattering and find that mutations that disrupt the complex abolish motility. Interestingly, the sFlaF and sFlaG of Pyrococcus furiosus form a globular complex, whereas sFlaG alone forms a filament, indicating that FlaF can regulate FlaG filament assembly. Strikingly, Sulfolobus cells that lack the S-layer component bound by FlaF assemble archaella but cannot swim. These collective results support a model where a FlaG filament capped by a FlaG-FlaF complex anchors the archaellum to the S-layer to allow motility.
Collapse
|
20
|
Architecture and modular assembly of Sulfolobus S-layers revealed by electron cryotomography. Proc Natl Acad Sci U S A 2019; 116:25278-25286. [PMID: 31767763 PMCID: PMC6911244 DOI: 10.1073/pnas.1911262116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Many bacteria and most archaea are enveloped in S-layers, protective lattices of proteins that are among the most abundant on earth. S-layers define both the cell’s shape and periplasmic space, and play essential roles in cell division, adhesion, biofilm formation, protection against harsh environments and phages, and comprise important virulence factors in pathogenic bacteria. Despite their importance, structural information about archaeal S-layers is sparse. Here, we describe in situ structural data on archaeal S-layers by cutting-edge electron cryotomography. Our results shed light on the function and evolution of archaeal cell walls and thus our understanding of microbial life. They will also inform approaches in nanobiotechnology aiming to engineer S-layers for a vast array of applications. Surface protein layers (S-layers) often form the only structural component of the archaeal cell wall and are therefore important for cell survival. S-layers have a plethora of cellular functions including maintenance of cell shape, osmotic, and mechanical stability, the formation of a semipermeable protective barrier around the cell, and cell–cell interaction, as well as surface adhesion. Despite the central importance of S-layers for archaeal life, their 3-dimensional (3D) architecture is still poorly understood. Here we present detailed 3D electron cryomicroscopy maps of archaeal S-layers from 3 different Sulfolobus strains. We were able to pinpoint the positions and determine the structure of the 2 subunits SlaA and SlaB. We also present a model describing the assembly of the mature S-layer.
Collapse
|