1
|
Cha HJ, He C, Glover DJ, Xu K, Clark DS. STORM Super-Resolution Visualization of Self-Assembled γPFD Chaperone Ultrastructures in Methanocaldococcus jannaschii. NANO LETTERS 2024; 24:6078-6083. [PMID: 38723608 PMCID: PMC11117396 DOI: 10.1021/acs.nanolett.4c01043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/04/2024] [Accepted: 05/07/2024] [Indexed: 05/23/2024]
Abstract
Gamma-prefoldin (γPFD), a unique chaperone found in the extremely thermophilic methanogen Methanocaldococcus jannaschii, self-assembles into filaments in vitro, which so far have been observed using transmission electron microscopy and cryo-electron microscopy. Utilizing three-dimensional stochastic optical reconstruction microscopy (3D-STORM), here we achieve ∼20 nm resolution by precisely locating individual fluorescent molecules, hence resolving γPFD ultrastructure both in vitro and in vivo. Through CF647 NHS ester labeling, we first demonstrate the accurate visualization of filaments and bundles with purified γPFD. Next, by implementing immunofluorescence labeling after creating a 3xFLAG-tagged γPFD strain, we successfully visualize γPFD in M. jannaschii cells. Through 3D-STORM and two-color STORM imaging with DNA, we show the widespread distribution of filamentous γPFD structures within the cell. These findings provide valuable insights into the structure and localization of γPFD, opening up possibilities for studying intriguing nanoscale components not only in archaea but also in other microorganisms.
Collapse
Affiliation(s)
- Hee-Jeong Cha
- Department
of Chemical and Biomolecular Engineering, University of California—Berkeley, Berkeley, California 94720, United States
| | - Changdong He
- Department
of Chemistry, University of California—Berkeley, Berkeley, California 94720, United States
| | - Dominic J. Glover
- School
of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ke Xu
- Department
of Chemistry, University of California—Berkeley, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Douglas S. Clark
- Department
of Chemical and Biomolecular Engineering, University of California—Berkeley, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| |
Collapse
|
2
|
Ithurbide S, de Silva RT, Brown HJ, Shinde V, Duggin IG. A vector system for single and tandem expression of cloned genes and multi-colour fluorescent tagging in Haloferax volcanii. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001461. [PMID: 38787390 PMCID: PMC11165654 DOI: 10.1099/mic.0.001461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024]
Abstract
Archaeal cell biology is an emerging field expected to identify fundamental cellular processes, help resolve the deep evolutionary history of cellular life, and contribute new components and functions in biotechnology and synthetic biology. To facilitate these, we have developed plasmid vectors that allow convenient cloning and production of proteins and fusion proteins with flexible, rigid, or semi-rigid linkers in the model archaeon Haloferax volcanii. For protein subcellular localization studies using fluorescent protein (FP) tags, we created vectors incorporating a range of codon-optimized fluorescent proteins for N- or C-terminal tagging, including GFP, mNeonGreen, mCherry, YPet, mTurquoise2 and mScarlet-I. Obtaining functional fusion proteins can be challenging with proteins involved in multiple interactions, mainly due to steric interference. We demonstrated the use of the new vector system to screen for improved function in cytoskeletal protein FP fusions, and identified FtsZ1-FPs that are functional in cell division and CetZ1-FPs that are functional in motility and rod cell development. Both the type of linker and the type of FP influenced the functionality of the resulting fusions. The vector design also facilitates convenient cloning and tandem expression of two genes or fusion genes, controlled by a modified tryptophan-inducible promoter, and we demonstrated its use for dual-colour imaging of tagged proteins in H. volcanii cells. These tools should promote further development and applications of archaeal molecular and cellular biology and biotechnology.
Collapse
Affiliation(s)
- Solenne Ithurbide
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Roshali T. de Silva
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Hannah J. Brown
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Vinaya Shinde
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Iain G. Duggin
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| |
Collapse
|
3
|
Schiller H, Hong Y, Kouassi J, Rados T, Kwak J, DiLucido A, Safer D, Marchfelder A, Pfeiffer F, Bisson A, Schulze S, Pohlschroder M. Identification of structural and regulatory cell-shape determinants in Haloferax volcanii. Nat Commun 2024; 15:1414. [PMID: 38360755 PMCID: PMC10869688 DOI: 10.1038/s41467-024-45196-0] [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: 03/15/2023] [Accepted: 01/16/2024] [Indexed: 02/17/2024] Open
Abstract
Archaea play indispensable roles in global biogeochemical cycles, yet many crucial cellular processes, including cell-shape determination, are poorly understood. Haloferax volcanii, a model haloarchaeon, forms rods and disks, depending on growth conditions. Here, we used a combination of iterative proteomics, genetics, and live-cell imaging to identify mutants that only form rods or disks. We compared the proteomes of the mutants with wild-type cells across growth phases, thereby distinguishing between protein abundance changes specific to cell shape and those related to growth phases. The results identified a diverse set of proteins, including predicted transporters, transducers, signaling components, and transcriptional regulators, as important for cell-shape determination. Through phenotypic characterization of deletion strains, we established that rod-determining factor A (RdfA) and disk-determining factor A (DdfA) are required for the formation of rods and disks, respectively. We also identified structural proteins, including an actin homolog that plays a role in disk-shape morphogenesis, which we named volactin. Using live-cell imaging, we determined volactin's cellular localization and showed its dynamic polymerization and depolymerization. Our results provide insights into archaeal cell-shape determination, with possible implications for understanding the evolution of cell morphology regulation across domains.
Collapse
Affiliation(s)
- Heather Schiller
- University of Pennsylvania, Department of Biology, Philadelphia, PA, 19104, USA
| | - Yirui Hong
- University of Pennsylvania, Department of Biology, Philadelphia, PA, 19104, USA
| | - Joshua Kouassi
- University of Pennsylvania, Department of Biology, Philadelphia, PA, 19104, USA
| | - Theopi Rados
- Brandeis University, Department of Biology, Waltham, MA, 02453, USA
| | - Jasmin Kwak
- Brandeis University, Department of Biology, Waltham, MA, 02453, USA
| | - Anthony DiLucido
- University of Pennsylvania, Department of Biology, Philadelphia, PA, 19104, USA
| | - Daniel Safer
- University of Pennsylvania, Department of Physiology, Philadelphia, PA, 19104, USA
| | | | - Friedhelm Pfeiffer
- Biology II, Ulm University, 89069, Ulm, Germany
- Computational Biology Group, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Alexandre Bisson
- Brandeis University, Department of Biology, Waltham, MA, 02453, USA.
| | - Stefan Schulze
- University of Pennsylvania, Department of Biology, Philadelphia, PA, 19104, USA.
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, NY, 14623, USA.
| | | |
Collapse
|
4
|
Patro M, Duggin IG, Albers SV, Ithurbide S. "Influence of plasmids, selection markers and auxotrophic mutations on Haloferax volcanii cell shape plasticity". Front Microbiol 2023; 14:1270665. [PMID: 37840741 PMCID: PMC10570808 DOI: 10.3389/fmicb.2023.1270665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Haloferax volcanii and other Haloarchaea can be pleomorphic, adopting different shapes, which vary with growth stages. Several studies have shown that H. volcanii cell shape is sensitive to various external factors including growth media and physical environment. In addition, several studies have noticed that the presence of a recombinant plasmid in the cells is also a factor impacting H. volcanii cell shape, notably by favoring the development of rods in early stages of growth. Here we investigated the reasons for this phenomenon by first studying the impact of auxotrophic mutations on cell shape in strains that are commonly used as genetic backgrounds for selection during strain engineering (namely: H26, H53, H77, H98, and H729) and secondly, by studying the effect of the presence of different plasmids containing selection markers on the cell shape of these strains. Our study showed that most of these auxotrophic strains have variation in cell shape parameters including length, aspect ratio, area and circularity and that the plasmid presence is impacting these parameters too. Our results indicated that ΔhdrB strains and hdrB selection markers have the most influence on H. volcanii cell shape, in addition to the sole presence of a plasmid. Finally, we discuss limitations in studying cell shape in H. volcanii and make recommendations based on our results for improving reproducibility of such studies.
Collapse
Affiliation(s)
- Megha Patro
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Iain G. Duggin
- The Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Solenne Ithurbide
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| |
Collapse
|
5
|
Cezanne A, Hoogenberg B, Baum B. Probing archaeal cell biology: exploring the use of dyes in the imaging of Sulfolobus cells. Front Microbiol 2023; 14:1233032. [PMID: 37731920 PMCID: PMC10508906 DOI: 10.3389/fmicb.2023.1233032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/17/2023] [Indexed: 09/22/2023] Open
Abstract
Archaea are key players in many critical ecological processes. In comparison to eukaryotes and bacteria, however, our understanding of both the cell biology and diversity of archaea remains limited. While archaea inhabit a wide range of environmental conditions, many species are extremophiles, surviving in extreme temperature, salt or pH conditions, making their cell biology hard to study. Recently, our understanding of archaeal cell biology has been advanced significantly by the advent of live cell imaging in extremis as well as the development of genetic tools to exogenously express fluorescent proteins in some mesophilic archaeal model systems, e.g., Haloferax volcanii. However, for most archaeal species, especially thermophilic species or emerging model systems without well characterized genetic tools, live cell imaging remains dependent on fluorescent chemical probes to label and track the dynamics of living cells. While a wide range of fluorescent stains and markers that label different components of the cell are available commercially, their use has usually been optimized for use in a small number of eukaryotic cell systems. Here we report the successes and failures of the application of membrane, DNA, S-layer and cytoplasm markers in live cell imaging of archaea, as well as the optimization of fixation and immunolabelling approaches. We have applied these markers to the thermoacidophilic archaeon Sulfolobus acidocaldarius, but expect some to work in other archaeal species. Furthermore, those procedures that failed in S. acidocaldarius may still prove useful for imaging archaea that grow at a more neutral pH and/or at a less extreme temperature.
Collapse
Affiliation(s)
- Alice Cezanne
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Baukje Hoogenberg
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Buzz Baum
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| |
Collapse
|
6
|
Hartmann P, Schnabl B. Fungal infections and the fungal microbiome in hepatobiliary disorders. J Hepatol 2023; 78:836-851. [PMID: 36565724 PMCID: PMC10033447 DOI: 10.1016/j.jhep.2022.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022]
Abstract
Liver and biliary diseases affect more than a billion people worldwide, with high associated morbidity and mortality. The impact of the intestinal bacterial microbiome on liver diseases has been well established. However, the fungal microbiome, or mycobiome, has been overlooked for a long time. Recently, several studies have shed light on the role of the mycobiome in the development and progression of hepatobiliary diseases. In particular, the fungal genus Candida has been found to be involved in the pathogenesis of multiple hepatobiliary conditions. Herein, we compare colonisation and infection, describe mycobiome findings in the healthy state and across the various hepatobiliary conditions, and point toward communalities. We detail how quantitation of immune responses to fungal antigens can be employed to predict disease severity, e.g. using antibodies to Saccharomyces cerevisiae or specific anti-Candida albicans antibodies. We also show how fungal products (e.g. beta-glucans, candidalysin) activate the host's immune system to exacerbate liver and biliary diseases. Finally, we describe how the gut mycobiome can be modulated to ameliorate hepatobiliary conditions.
Collapse
Affiliation(s)
- Phillipp Hartmann
- Department of Medicine, University of California San Diego, La Jolla, CA, USA; Department of Pediatrics, University of California San Diego, La Jolla, CA, USA; Division of Gastroenterology, Hepatology & Nutrition, Rady Children's Hospital San Diego, San Diego, CA, USA
| | - Bernd Schnabl
- Department of Medicine, University of California San Diego, La Jolla, CA, USA; Department of Medicine, VA San Diego Healthcare System, San Diego, CA, USA.
| |
Collapse
|
7
|
van Wolferen M, Pulschen AA, Baum B, Gribaldo S, Albers SV. The cell biology of archaea. Nat Microbiol 2022; 7:1744-1755. [PMID: 36253512 PMCID: PMC7613921 DOI: 10.1038/s41564-022-01215-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/25/2022] [Indexed: 12/15/2022]
Abstract
The past decade has revealed the diversity and ubiquity of archaea in nature, with a growing number of studies highlighting their importance in ecology, biotechnology and even human health. Myriad lineages have been discovered, which expanded the phylogenetic breadth of archaea and revealed their central role in the evolutionary origins of eukaryotes. These discoveries, coupled with advances that enable the culturing and live imaging of archaeal cells under extreme environments, have underpinned a better understanding of their biology. In this Review we focus on the shape, internal organization and surface structures that are characteristic of archaeal cells as well as membrane remodelling, cell growth and division. We also highlight some of the technical challenges faced and discuss how new and improved technologies will help address many of the key unanswered questions.
Collapse
Affiliation(s)
- Marleen van Wolferen
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Buzz Baum
- Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Simonetta Gribaldo
- Evolutionary Biology of the Microbial Cell Unit, CNRS UMR2001, Department of Microbiology, Institute Pasteur, Paris, France.
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
| |
Collapse
|
8
|
The Viral Susceptibility of the Haloferax Species. Viruses 2022; 14:v14061344. [PMID: 35746816 PMCID: PMC9229481 DOI: 10.3390/v14061344] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/15/2022] [Accepted: 06/17/2022] [Indexed: 11/17/2022] Open
Abstract
Viruses can infect members of all three domains of life. However, little is known about viruses infecting archaea and the mechanisms that determine their host interactions are poorly understood. Investigations of molecular mechanisms of viral infection rely on genetically accessible virus–host model systems. Euryarchaea belonging to the genus Haloferax are interesting models, as a reliable genetic system and versatile microscopy methods are available. However, only one virus infecting the Haloferax species is currently available. In this study, we tested ~100 haloarchaeal virus isolates for their infectivity on 14 Haloferax strains. From this, we identified 10 virus isolates in total capable of infecting Haloferax strains, which represented myovirus or siphovirus morphotypes. Surprisingly, the only susceptible strain of all 14 tested was Haloferax gibbonsii LR2-5, which serves as an auspicious host for all of these 10 viruses. By applying comparative genomics, we shed light on factors determining the host range of haloarchaeal viruses on Haloferax. We anticipate our study to be a starting point in the study of haloarchaeal virus–host interactions.
Collapse
|
9
|
Ithurbide S, Gribaldo S, Albers SV, Pende N. Spotlight on FtsZ-based cell division in Archaea. Trends Microbiol 2022; 30:665-678. [PMID: 35246355 DOI: 10.1016/j.tim.2022.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 12/22/2021] [Accepted: 01/10/2022] [Indexed: 12/15/2022]
Abstract
Compared with the extensive knowledge on cell division in model eukaryotes and bacteria, little is known about how archaea divide. Interestingly, both endosomal sorting complex required for transport (ESCRT)-based and FtsZ-based cell division systems are found in members of the Archaea. In the past couple of years, several studies have started to shed light on FtsZ-based cell division processes in members of the Euryarchaeota. In this review we highlight recent findings in this emerging field of research. We present current knowledge of the cell division machinery of halophiles which relies on two FtsZ proteins, and we compare it with that of methanobacteria, which relies on only one FtsZ. Finally, we discuss how these differences relate to the distinct cell envelopes of these two archaeal model systems.
Collapse
Affiliation(s)
- Solenne Ithurbide
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Simonetta Gribaldo
- Evolutionary Biology of the Microbial Cell Unit, CNRS UMR2001, Department of Microbiology, Institut Pasteur, Paris, France.
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
| | - Nika Pende
- Evolutionary Biology of the Microbial Cell Unit, CNRS UMR2001, Department of Microbiology, Institut Pasteur, Paris, France
| |
Collapse
|
10
|
van Wolferen M, Albers SV. Progress and Challenges in Archaeal Cell Biology. Methods Mol Biol 2022; 2522:365-371. [PMID: 36125763 DOI: 10.1007/978-1-0716-2445-6_24] [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: 06/15/2023]
Abstract
Over the past decades there has been a growing interest in the domain of archaea. In this chapter we highlight the recent advances that have been made in studying the cell biology of archaea. We particularly focus on methods for genetic manipulation and imaging of different archaeal species and discuss the technical limitations at the often-extreme growth conditions. Several ongoing developments will help us overcoming these limitations, thereby facilitating future studies in the existing field of archaeal cell biology.
Collapse
Affiliation(s)
- Marleen van Wolferen
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany.
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany.
| |
Collapse
|
11
|
de Silva RT, Abdul-Halim MF, Pittrich DA, Brown HJ, Pohlschroder M, Duggin IG. Improved growth and morphological plasticity of Haloferax volcanii. MICROBIOLOGY-SGM 2021; 167. [PMID: 33459585 DOI: 10.1099/mic.0.001012] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Some microbes display pleomorphism, showing variable cell shapes in a single culture, whereas others differentiate to adapt to changed environmental conditions. The pleomorphic archaeon Haloferax volcanii commonly forms discoid-shaped ('plate') cells in culture, but may also be present as rods, and can develop into motile rods in soft agar, or longer filaments in certain biofilms. Here we report improvement of H. volcanii growth in both semi-defined and complex media by supplementing with eight trace element micronutrients. With these supplemented media, transient development of plate cells into uniformly shaped rods was clearly observed during the early log phase of growth; cells then reverted to plates for the late log and stationary phases. In media prepared with high-purity water and reagents, without supplemental trace elements, rods and other complex elongated morphologies ('pleomorphic rods') were observed at all growth stages of the culture; the highly elongated cells sometimes displayed a substantial tubule at one or less frequently both poles, as well as unusual tapered and highly curved forms. Polar tubules were observed forming by initial mid-cell narrowing or tubulation, causing a dumbbell-like shape, followed by cell division towards one end. Formation of the uniform early log-phase rods, as well as the pleomorphic rods and tubules were dependent on the function of the tubulin-like cytoskeletal protein, CetZ1. Our results reveal the remarkable morphological plasticity of H. volcanii cells in response to multiple culture conditions, and should facilitate the use of this species in further studies of archaeal biology.
Collapse
Affiliation(s)
- Roshali T de Silva
- The iThree Institute, University of Technology Sydney, New South Wales, 2007, Australia
| | - Mohd F Abdul-Halim
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dorothea A Pittrich
- The iThree Institute, University of Technology Sydney, New South Wales, 2007, Australia
| | - Hannah J Brown
- The iThree Institute, University of Technology Sydney, New South Wales, 2007, Australia
| | | | - Iain G Duggin
- The iThree Institute, University of Technology Sydney, New South Wales, 2007, Australia
| |
Collapse
|
12
|
Cell division in the archaeon Haloferax volcanii relies on two FtsZ proteins with distinct functions in division ring assembly and constriction. Nat Microbiol 2021; 6:594-605. [PMID: 33903747 PMCID: PMC7611241 DOI: 10.1038/s41564-021-00894-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 03/22/2021] [Indexed: 02/02/2023]
Abstract
In bacteria, the tubulin homologue FtsZ assembles a cytokinetic ring, termed the Z ring, and plays a key role in the machinery that constricts to divide the cells. Many archaea encode two FtsZ proteins from distinct families, FtsZ1 and FtsZ2, with previously unclear functions. Here, we show that Haloferax volcanii cannot divide properly without either or both FtsZ proteins, but DNA replication continues and cells proliferate in alternative ways, such as blebbing and fragmentation, via remarkable envelope plasticity. FtsZ1 and FtsZ2 colocalize to form the dynamic division ring. However, FtsZ1 can assemble rings independent of FtsZ2, and stabilizes FtsZ2 in the ring, whereas FtsZ2 functions primarily in the constriction mechanism. FtsZ1 also influenced cell shape, suggesting it forms a hub-like platform at midcell for the assembly of shape-related systems too. Both FtsZ1 and FtsZ2 are widespread in archaea with a single S-layer envelope, but archaea with a pseudomurein wall and division septum only have FtsZ1. FtsZ1 is therefore likely to provide a fundamental recruitment role in diverse archaea, and FtsZ2 is required for constriction of a flexible S-layer envelope, where an internal constriction force might dominate the division mechanism, in contrast with the single-FtsZ bacteria and archaea that divide primarily by wall ingrowth.
Collapse
|
13
|
Schwarzer S, Rodriguez-Franco M, Oksanen HM, Quax TEF. Growth Phase Dependent Cell Shape of Haloarcula. Microorganisms 2021; 9:231. [PMID: 33499340 PMCID: PMC7911496 DOI: 10.3390/microorganisms9020231] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 01/08/2023] Open
Abstract
Several haloarchaea are reported to be pleomorphic, while others exhibit remarkable shapes, such as squares. Recently, Haloferax volcanii was found to alter its morphology during growth. Cells are motile rods in early exponential phase, and immotile plates in stationary phase. It is unknown if this growth phase dependent cell shape alteration is a specific feature of Hfx. volcanii, or conserved amongst haloarchaea. Here, we studied the cell shape and motility of two haloarchaea species Haloarcula hispanica and Haloarcula californiae. With a combination of light and electron microscopy, we observed that both strains undergo a growth phase dependent morphological development, albeit in a slightly different fashion as Hfx. volcanii. For both Haloarcula strains, the cell size is changing throughout growth. Cell shape seems to be related with motility, as highly motile cells on semi-solid agar plates are predominantly rod-shaped. We conclude that the growth phase dependent cell morphology alteration might be a common feature amongst haloarchaea, and that cell shape is generally linked with a motile life style. The conservation of this phenomenon underscores the importance of studies of the molecular mechanisms regulating cell shape in archaea.
Collapse
Affiliation(s)
- Sabine Schwarzer
- Archaeal Virus-Host Interactions, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany;
| | - Marta Rodriguez-Franco
- Cell Biology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany;
| | - Hanna M. Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland;
| | - Tessa E. F. Quax
- Archaeal Virus-Host Interactions, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany;
| |
Collapse
|
14
|
Turkowyd B, Schreiber S, Wörtz J, Segal ES, Mevarech M, Duggin IG, Marchfelder A, Endesfelder U. Establishing Live-Cell Single-Molecule Localization Microscopy Imaging and Single-Particle Tracking in the Archaeon Haloferax volcanii. Front Microbiol 2020; 11:583010. [PMID: 33329447 PMCID: PMC7714787 DOI: 10.3389/fmicb.2020.583010] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/16/2020] [Indexed: 01/30/2023] Open
Abstract
In recent years, fluorescence microscopy techniques for the localization and tracking of single molecules in living cells have become well-established and are indispensable tools for the investigation of cellular biology and in vivo biochemistry of many bacterial and eukaryotic organisms. Nevertheless, these techniques are still not established for imaging archaea. Their establishment as a standard tool for the study of archaea will be a decisive milestone for the exploration of this branch of life and its unique biology. Here, we have developed a reliable protocol for the study of the archaeon Haloferax volcanii. We have generated an autofluorescence-free H. volcanii strain, evaluated several fluorescent proteins for their suitability to serve as single-molecule fluorescence markers and codon-optimized them to work under optimal H. volcanii cultivation conditions. We found that two of them, Dendra2Hfx and PAmCherry1Hfx, provide state-of-the-art single-molecule imaging. Our strategy is quantitative and allows dual-color imaging of two targets in the same field of view (FOV) as well as DNA co-staining. We present the first single-molecule localization microscopy (SMLM) images of the subcellular organization and dynamics of two crucial intracellular proteins in living H. volcanii cells, FtsZ1, which shows complex structures in the cell division ring, and RNA polymerase, which localizes around the periphery of the cellular DNA. This work should provide incentive to develop SMLM strategies for other archaeal organisms in the near future.
Collapse
Affiliation(s)
- Bartosz Turkowyd
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | | | - Julia Wörtz
- Department of Biology II, Ulm University, Ulm, Germany
| | - Ella Shtifman Segal
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Moshe Mevarech
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Iain G. Duggin
- The ithree Institute, University of Technology Sydney, Ultimo, NSW, Australia
| | | | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
- Department of Physics, Mellon College of Science, Carnegie-Mellon University, Pittsburgh, PA, United States
| |
Collapse
|
15
|
Pulschen AA, Mutavchiev DR, Culley S, Sebastian KN, Roubinet J, Roubinet M, Risa GT, van Wolferen M, Roubinet C, Schmidt U, Dey G, Albers SV, Henriques R, Baum B. Live Imaging of a Hyperthermophilic Archaeon Reveals Distinct Roles for Two ESCRT-III Homologs in Ensuring a Robust and Symmetric Division. Curr Biol 2020; 30:2852-2859.e4. [PMID: 32502411 PMCID: PMC7372223 DOI: 10.1016/j.cub.2020.05.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/15/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022]
Abstract
Live-cell imaging has revolutionized our understanding of dynamic cellular processes in bacteria and eukaryotes. Although similar techniques have been applied to the study of halophilic archaea [1-5], our ability to explore the cell biology of thermophilic archaea has been limited by the technical challenges of imaging at high temperatures. Sulfolobus are the most intensively studied members of TACK archaea and have well-established molecular genetics [6-9]. Additionally, studies using Sulfolobus were among the first to reveal striking similarities between the cell biology of eukaryotes and archaea [10-15]. However, to date, it has not been possible to image Sulfolobus cells as they grow and divide. Here, we report the construction of the Sulfoscope, a heated chamber on an inverted fluorescent microscope that enables live-cell imaging of thermophiles. By using thermostable fluorescent probes together with this system, we were able to image Sulfolobus acidocaldarius cells live to reveal tight coupling between changes in DNA condensation, segregation, and cell division. Furthermore, by imaging deletion mutants, we observed functional differences between the two ESCRT-III proteins implicated in cytokinesis, CdvB1 and CdvB2. The deletion of cdvB1 compromised cell division, causing occasional division failures, whereas the ΔcdvB2 exhibited a profound loss of division symmetry, generating daughter cells that vary widely in size and eventually generating ghost cells. These data indicate that DNA separation and cytokinesis are coordinated in Sulfolobus, as is the case in eukaryotes, and that two contractile ESCRT-III polymers perform distinct roles to ensure that Sulfolobus cells undergo a robust and symmetrical division.
Collapse
Affiliation(s)
| | - Delyan R Mutavchiev
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Siân Culley
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Kim Nadine Sebastian
- Molecular Biology of Archaea, Institute of Biology II - Microbiology, University of Freiburg, 79104 Freiburg, Germany
| | | | | | | | - Marleen van Wolferen
- Molecular Biology of Archaea, Institute of Biology II - Microbiology, University of Freiburg, 79104 Freiburg, Germany
| | - Chantal Roubinet
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Uwe Schmidt
- Center for System Biology Dresden (CSBD), 01307 Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), 01307 Dresden, Germany
| | - Gautam Dey
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II - Microbiology, University of Freiburg, 79104 Freiburg, Germany
| | - Ricardo Henriques
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Buzz Baum
- MRC-Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK; Institute for the Physics of Living Systems, UCL, London WC1E 6BT, UK.
| |
Collapse
|
16
|
Gray WT, Govers SK, Xiang Y, Parry BR, Campos M, Kim S, Jacobs-Wagner C. Nucleoid Size Scaling and Intracellular Organization of Translation across Bacteria. Cell 2020; 177:1632-1648.e20. [PMID: 31150626 DOI: 10.1016/j.cell.2019.05.017] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/01/2019] [Accepted: 05/08/2019] [Indexed: 01/10/2023]
Abstract
The scaling of organelles with cell size is thought to be exclusive to eukaryotes. Here, we demonstrate that similar scaling relationships hold for the bacterial nucleoid. Despite the absence of a nuclear membrane, nucleoid size strongly correlates with cell size, independent of changes in DNA amount and across various nutrient conditions. This correlation is observed in diverse bacteria, revealing a near-constant ratio between nucleoid and cell size for a given species. As in eukaryotes, the nucleocytoplasmic ratio in bacteria varies greatly among species. This spectrum of nucleocytoplasmic ratios is independent of genome size, and instead it appears linked to the average population cell size. Bacteria with different nucleocytoplasmic ratios have a cytoplasm with different biophysical properties, impacting ribosome mobility and localization. Together, our findings identify new organizational principles and biophysical features of bacterial cells, implicating the nucleocytoplasmic ratio and cell size as determinants of the intracellular organization of translation.
Collapse
Affiliation(s)
- William T Gray
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Pharmacology, Yale University, New Haven, CT, USA
| | - Sander K Govers
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Yingjie Xiang
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Bradley R Parry
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Manuel Campos
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Sangjin Kim
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT, USA; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, USA.
| |
Collapse
|
17
|
Abdul-Halim MF, Schulze S, DiLucido A, Pfeiffer F, Bisson Filho AW, Pohlschroder M. Lipid Anchoring of Archaeosortase Substrates and Midcell Growth in Haloarchaea. mBio 2020; 11:e00349-20. [PMID: 32209681 PMCID: PMC7157517 DOI: 10.1128/mbio.00349-20] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 02/18/2020] [Indexed: 02/07/2023] Open
Abstract
The archaeal cytoplasmic membrane provides an anchor for many surface proteins. Recently, a novel membrane anchoring mechanism involving a peptidase, archaeosortase A (ArtA), and C-terminal lipid attachment of surface proteins was identified in the model archaeon Haloferax volcanii ArtA is required for optimal cell growth and morphogenesis, and the S-layer glycoprotein (SLG), the sole component of the H. volcanii cell wall, is one of the targets for this anchoring mechanism. However, how exactly ArtA function and regulation control cell growth and morphogenesis is still elusive. Here, we report that archaeal homologs to the bacterial phosphatidylserine synthase (PssA) and phosphatidylserine decarboxylase (PssD) are involved in ArtA-dependent protein maturation. Haloferax volcanii strains lacking either HvPssA or HvPssD exhibited motility, growth, and morphological phenotypes similar to those of an ΔartA mutant. Moreover, we showed a loss of covalent lipid attachment to SLG in the ΔhvpssA mutant and that proteolytic cleavage of the ArtA substrate HVO_0405 was blocked in the ΔhvpssA and ΔhvpssD mutant strains. Strikingly, ArtA, HvPssA, and HvPssD green fluorescent protein (GFP) fusions colocalized to the midcell position of H. volcanii cells, strongly supporting that they are involved in the same pathway. Finally, we have shown that the SLG is also recruited to the midcell before being secreted and lipid anchored at the cell outer surface. Collectively, our data suggest that haloarchaea use the midcell as the main surface processing hot spot for cell elongation, division, and shape determination.IMPORTANCE The subcellular organization of biochemical processes in space and time is still one of the most mysterious topics in archaeal cell biology. Despite the fact that haloarchaea largely rely on covalent lipid anchoring to coat the cell envelope, little is known about how cells coordinate de novo synthesis and about the insertion of this proteinaceous layer throughout the cell cycle. Here, we report the identification of two novel contributors to ArtA-dependent lipid-mediated protein anchoring to the cell surface, HvPssA and HvPssD. ArtA, HvPssA, and HvPssD, as well as SLG, showed midcell localization during growth and cytokinesis, indicating that haloarchaeal cells confine phospholipid processing in order to promote midcell elongation. Our findings have important implications for the biogenesis of the cell surface.
Collapse
Affiliation(s)
| | - Stefan Schulze
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Anthony DiLucido
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Friedhelm Pfeiffer
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Alexandre Wilson Bisson Filho
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | | |
Collapse
|
18
|
Abstract
Replicative DNA helicases are essential cellular enzymes that unwind duplex DNA in front of the replication fork during chromosomal DNA replication. Replicative helicases were discovered, beginning in the 1970s, in bacteria, bacteriophages, viruses, and eukarya, and, in the mid-1990s, in archaea. This year marks the 20th anniversary of the first report on the archaeal replicative helicase, the minichromosome maintenance (MCM) protein. This minireview summarizes 2 decades of work on the archaeal MCM.
Collapse
|
19
|
Kramm K, Endesfelder U, Grohmann D. A Single-Molecule View of Archaeal Transcription. J Mol Biol 2019; 431:4116-4131. [PMID: 31207238 DOI: 10.1016/j.jmb.2019.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/27/2019] [Accepted: 06/06/2019] [Indexed: 01/03/2023]
Abstract
The discovery of the archaeal domain of life is tightly connected to an in-depth analysis of the prokaryotic RNA world. In addition to Carl Woese's approach to use the sequence of the 16S rRNA gene as phylogenetic marker, the finding of Karl Stetter and Wolfram Zillig that archaeal RNA polymerases (RNAPs) were nothing like the bacterial RNAP but are more complex enzymes that resemble the eukaryotic RNAPII was one of the key findings supporting the idea that archaea constitute the third major branch on the tree of life. This breakthrough in transcriptional research 40years ago paved the way for in-depth studies of the transcription machinery in archaea. However, although the archaeal RNAP and the basal transcription factors that fine-tune the activity of the RNAP during the transcription cycle are long known, we still lack information concerning the architecture and dynamics of archaeal transcription complexes. In this context, single-molecule measurements were instrumental as they provided crucial insights into the process of transcription initiation, the architecture of the initiation complex and the dynamics of mobile elements of the RNAP. In this review, we discuss single-molecule approaches suitable to examine molecular mechanisms of transcription and highlight findings that shaped our understanding of the archaeal transcription apparatus. We furthermore explore the possibilities and challenges of next-generation single-molecule techniques, for example, super-resolution microscopy and single-molecule tracking, and ask whether these approaches will ultimately allow us to investigate archaeal transcription in vivo.
Collapse
Affiliation(s)
- Kevin Kramm
- Institute of Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, 35043 Marburg, Germany
| | - Dina Grohmann
- Institute of Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany.
| |
Collapse
|
20
|
Fanalista F, Birnie A, Maan R, Burla F, Charles K, Pawlik G, Deshpande S, Koenderink GH, Dogterom M, Dekker C. Shape and Size Control of Artificial Cells for Bottom-Up Biology. ACS NANO 2019; 13:5439-5450. [PMID: 31074603 PMCID: PMC6543616 DOI: 10.1021/acsnano.9b00220] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 05/10/2019] [Indexed: 05/27/2023]
Abstract
Bottom-up biology is an expanding research field that aims to understand the mechanisms underlying biological processes via in vitro assembly of their essential components in synthetic cells. As encapsulation and controlled manipulation of these elements is a crucial step in the recreation of such cell-like objects, microfluidics is increasingly used for the production of minimal artificial containers such as single-emulsion droplets, double-emulsion droplets, and liposomes. Despite the importance of cell morphology on cellular dynamics, current synthetic-cell studies mainly use spherical containers, and methods to actively shape manipulate these have been lacking. In this paper, we describe a microfluidic platform to deform the shape of artificial cells into a variety of shapes (rods and discs) with adjustable cell-like dimensions below 5 μm, thereby mimicking realistic cell morphologies. To illustrate the potential of our method, we reconstitute three biologically relevant protein systems (FtsZ, microtubules, collagen) inside rod-shaped containers and study the arrangement of the protein networks inside these synthetic containers with physiologically relevant morphologies resembling those found in living cells.
Collapse
Affiliation(s)
- Federico Fanalista
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Anthony Birnie
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Renu Maan
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Federica Burla
- Department
of Living Matter, Biological Soft Matter Group, AMOLF, Science Park
104, 1098 XG Amsterdam, The Netherlands
| | - Kevin Charles
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Grzegorz Pawlik
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Siddharth Deshpande
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Gijsje H. Koenderink
- Department
of Living Matter, Biological Soft Matter Group, AMOLF, Science Park
104, 1098 XG Amsterdam, The Netherlands
| | - Marileen Dogterom
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Department
of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| |
Collapse
|
21
|
Abstract
Archaea are ubiquitous single cellular microorganisms that play important ecological roles in nature. The intracellular organization of archaeal cells is among the unresolved mysteries of archaeal biology. With this work, we show that cells of haloarchaea are polarized. The cellular positioning of proteins involved in chemotaxis and motility is spatially and temporally organized in these cells. This suggests the presence of a specific mechanism responsible for the positioning of macromolecular protein complexes in archaea. Bacteria and archaea exhibit tactical behavior and can move up and down chemical gradients. This tactical behavior relies on a motility structure, which is guided by a chemosensory system. Environmental signals are sensed by membrane-inserted chemosensory receptors that are organized in large ordered arrays. While the cellular positioning of the chemotaxis machinery and that of the flagellum have been studied in detail in bacteria, we have little knowledge about the localization of such macromolecular assemblies in archaea. Although the archaeal motility structure, the archaellum, is fundamentally different from the flagellum, archaea have received the chemosensory machinery from bacteria and have connected this system with the archaellum. Here, we applied a combination of time-lapse imaging and fluorescence and electron microscopy using the model euryarchaeon Haloferax volcanii and found that archaella were specifically present at the cell poles of actively dividing rod-shaped cells. The chemosensory arrays also had a polar preference, but in addition, several smaller arrays moved freely in the lateral membranes. In the stationary phase, rod-shaped cells became round and chemosensory arrays were disassembled. The positioning of archaella and that of chemosensory arrays are not interdependent and likely require an independent form of positioning machinery. This work showed that, in the rod-shaped haloarchaeal cells, the positioning of the archaellum and of the chemosensory arrays is regulated in time and in space. These insights into the cellular organization of H. volcanii suggest the presence of an active mechanism responsible for the positioning of macromolecular protein complexes in archaea.
Collapse
|