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Nakagawa S, Imachi H, Shimamura S, Yanaka S, Yagi H, Yagi-Utsumi M, Sakai H, Kato S, Ohkuma M, Kato K, Takai K. Characterization of protein glycosylation in an Asgard archaeon. BBA ADVANCES 2024; 6:100118. [PMID: 39081798 PMCID: PMC11284389 DOI: 10.1016/j.bbadva.2024.100118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/30/2024] [Accepted: 07/10/2024] [Indexed: 08/02/2024] Open
Abstract
Archaeal cells are typically enveloped by glycosylated S-layer proteins. Archaeal protein glycosylation provides valuable insights not only into their adaptation to their niches but also into their evolutionary trajectory. Notably, thermophilic Thermoproteota modify proteins with N-glycans that include two GlcNAc units at the reducing end, resembling the "core structure" preserved across eukaryotes. Recently, Asgard archaea, now classified as members of the phylum Promethearchaeota, have offered unprecedented opportunities for understanding the role of archaea in eukaryogenesis. Despite the presence of genes indicative of protein N-glycosylation in this archaeal group, these have not been experimentally investigated. Here we performed a glycoproteome analysis of the firstly isolated Asgard archaeon Promethearchaeum syntrophicum. Over 700 different proteins were identified through high-resolution LC-MS/MS analysis, however, there was no evidence of either the presence or glycosylation of putative S-layer proteins. Instead, N-glycosylation in this archaeon was primarily observed in an extracellular solute-binding protein, possibly related to chemoreception or transmembrane transport of oligopeptides. The glycan modification occurred on an asparagine residue located within the conserved N-X-S/T sequon, consistent with the pattern found in other archaea, bacteria, and eukaryotes. Unexpectedly, three structurally different N-glycans lacking the conventional core structure were identified in this archaeon, presenting unique compositions that included atypical sugars. Notably, one of these sugars was likely HexNAc modified with a threonine residue, similar to modifications previously observed in mesophilic methanogens within the Methanobacteriati. Our findings advance our understanding of Asgard archaea physiology and evolutionary dynamics.
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Affiliation(s)
- Satoshi Nakagawa
- Laboratory of Marine Environmental Microbiology, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 273-0061, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Hiroyuki Imachi
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 273-0061, Japan
| | - Shigeru Shimamura
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 273-0061, Japan
| | - Saeko Yanaka
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuhoku, Nagoya 467-8603, Japan
- Institute for Molecular Science (IMS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Hirokazu Yagi
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuhoku, Nagoya 467-8603, Japan
| | - Maho Yagi-Utsumi
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuhoku, Nagoya 467-8603, Japan
- Institute for Molecular Science (IMS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Hiroyuki Sakai
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Shingo Kato
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
- Submarine Resources Research Center, JAMSTEC, Yokosuka 273-0061, Japan
| | - Moriya Ohkuma
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Koichi Kato
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuhoku, Nagoya 467-8603, Japan
- Institute for Molecular Science (IMS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Ken Takai
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 273-0061, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
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2
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Santin YG, Sogues A, Bourigault Y, Remaut HK, Laloux G. Lifecycle of a predatory bacterium vampirizing its prey through the cell envelope and S-layer. Nat Commun 2024; 15:3590. [PMID: 38678033 PMCID: PMC11055950 DOI: 10.1038/s41467-024-48042-5] [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: 11/09/2023] [Accepted: 04/16/2024] [Indexed: 04/29/2024] Open
Abstract
Predatory bacteria feed upon other bacteria in various environments. Bdellovibrio exovorus is an obligate epibiotic predator that attaches on the prey cell surface, where it grows and proliferates. Although the mechanisms allowing feeding through the prey cell envelope are unknown, it has been proposed that the prey's proteinaceous S-layer may act as a defensive structure against predation. Here, we use time-lapse and cryo-electron microscopy to image the lifecycle of B. exovorus feeding on Caulobacter crescentus. We show that B. exovorus proliferates by non-binary division, primarily generating three daughter cells. Moreover, the predator feeds on C. crescentus regardless of the presence of an S-layer, challenging its assumed protective role against predators. Finally, we show that apparently secure junctions are established between prey and predator outer membranes.
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Affiliation(s)
- Yoann G Santin
- de Duve Institute, UCLouvain, 75 avenue Hippocrate, 1200, Brussels, Belgium
| | - Adrià Sogues
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Yvann Bourigault
- de Duve Institute, UCLouvain, 75 avenue Hippocrate, 1200, Brussels, Belgium
| | - Han K Remaut
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Géraldine Laloux
- de Duve Institute, UCLouvain, 75 avenue Hippocrate, 1200, Brussels, Belgium.
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3
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Zhang C, Joseph AM, Casini L, Collier J, Badrinarayanan A, Manley S. Chromosome organization shapes replisome dynamics in Caulobacter crescentus. Nat Commun 2024; 15:3460. [PMID: 38658616 PMCID: PMC11043382 DOI: 10.1038/s41467-024-47849-6] [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: 08/28/2023] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
DNA replication in bacteria takes place on highly compacted chromosomes, where segregation, transcription, and repair must occur simultaneously. Within this dynamic environment, colocalization of sister replisomes has been observed in many bacterial species, driving the hypothesis that a physical linker may tether them together. However, replisome splitting has also been reported in many of the same species, leaving the principles behind replisome organization a long-standing puzzle. Here, by tracking the replisome β-clamp subunit in live Caulobacter crescentus, we find that rapid DNA segregation can give rise to a second focus which resembles a replisome, but does not replicate DNA. Sister replisomes can remain colocalized, or split apart to travel along DNA separately upon disruption of chromosome inter-arm alignment. Furthermore, chromosome arm-specific replication-transcription conflicts differentially modify replication speed on the two arms, facilitate the decoupling of the two replisomes. With these observations, we conclude that the dynamic chromosome organization flexibly shapes the organization of sister replisomes, and we outline principles which can help to reconcile previously conflicting models of replisome architecture.
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Affiliation(s)
- Chen Zhang
- Laboratory of Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Asha Mary Joseph
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Laurent Casini
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Anjana Badrinarayanan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Suliana Manley
- Laboratory of Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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4
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Herdman M, Isbilir B, von Kügelgen A, Schulze U, Wainman A, Bharat TAM. Cell cycle dependent coordination of surface layer biogenesis in Caulobacter crescentus. Nat Commun 2024; 15:3355. [PMID: 38637514 PMCID: PMC11026435 DOI: 10.1038/s41467-024-47529-5] [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: 06/23/2023] [Accepted: 04/04/2024] [Indexed: 04/20/2024] Open
Abstract
Surface layers (S-layers) are proteinaceous, two-dimensional paracrystalline arrays that constitute a major component of the cell envelope in many prokaryotic species. In this study, we investigated S-layer biogenesis in the bacterial model organism Caulobacter crescentus. Fluorescence microscopy revealed localised incorporation of new S-layer at the poles and mid-cell, consistent with regions of cell growth in the cell cycle. Light microscopy and electron cryotomography investigations of drug-treated bacteria revealed that localised S-layer insertion is retained when cell division is inhibited, but is disrupted upon dysregulation of MreB or lipopolysaccharide. We further uncovered that S-layer biogenesis follows new peptidoglycan synthesis and localises to regions of high cell wall turnover. Finally, correlated cryo-light microscopy and electron cryotomographic analysis of regions of S-layer insertion showed the presence of discontinuities in the hexagonal S-layer lattice, contrasting with other S-layers completed by defined symmetric defects. Our findings present insights into how C. crescentus cells form an ordered S-layer on their surface in coordination with the biogenesis of other cell envelope components.
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Affiliation(s)
- Matthew Herdman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Buse Isbilir
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Andriko von Kügelgen
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Ulrike Schulze
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Tanmay A M Bharat
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK.
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5
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Fioravanti A, Mathelie-Guinlet M, Dufrêne YF, Remaut H. The Bacillus anthracis S-layer is an exoskeleton-like structure that imparts mechanical and osmotic stabilization to the cell wall. PNAS NEXUS 2022; 1:pgac121. [PMID: 36714836 PMCID: PMC9802277 DOI: 10.1093/pnasnexus/pgac121] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 08/02/2022] [Indexed: 02/05/2023]
Abstract
Surface layers (S-layers) are 2D paracrystalline protein monolayers covering the cell envelope of many prokaryotes and archaea. Proposed functions include a role in cell support, as scaffolding structure, as molecular sieve, or as virulence factor. Bacillus anthracis holds two S-layers, composed of Sap or EA1, which interchange in early and late exponential growth phase. We previously found that acute disruption of B. anthracis Sap S-layer integrity, by means of nanobodies, results in severe morphological cell surface defects and cell collapse. Remarkably, this loss of function is due to the destruction of the Sap lattice structure rather than detachment of monomers from the cell surface. Here, we combine force nanoscopy and light microscopy observations to probe the contribution of the S-layer to the mechanical, structural, and functional properties of the cell envelope, which have been so far elusive. Our experiments reveal that cells with a compromised S-layer lattice show a decreased compressive stiffness and elastic modulus. Furthermore, we find that S-layer integrity is required to resist cell turgor under hypotonic conditions. These results present compelling experimental evidence indicating that the S-layers can serve as prokaryotic exoskeletons that support the cell wall in conferring rigidity and mechanical stability to bacterial cells.
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Affiliation(s)
- Antonella Fioravanti
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Marion Mathelie-Guinlet
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte L7.07.07, B-1348 Louvain-la-Neuve, Belgium
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte L7.07.07, B-1348 Louvain-la-Neuve, Belgium
| | - Han Remaut
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
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6
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Pierrat X, Pham A, Wong JPH, Al-Mayyah Z, Persat A. Engineering Agrobacterium tumefaciens Adhesion to Target Cells. ACS Synth Biol 2022; 11:2662-2671. [PMID: 35881049 DOI: 10.1021/acssynbio.2c00069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Agrobacterium tumefaciens is a plant pathogen commonly repurposed for genetic modification of crops. Despite its versatility, it remains inefficient at transferring DNA to many hosts, including to animal cells. Like many pathogens, physical contact between A. tumefaciens and host cells promotes infection efficacy. Thus, improving the strength and specificity of A. tumefaciens to target cells has the potential for enhancing DNA transfer for biotechnological and therapeutic purposes. Here, we demonstrate a methodology for engineering genetically encoded exogeneous adhesins at the surface of A. tumefaciens. We identified an autotransporter gene we named Aat that is predicted to show canonical β-barrel and passenger domains. We engineered the β-barrel scaffold and linker (Aatβ) to display synthetic adhesins susceptible to rewire A. tumefaciens to alternative host targets. As a proof of concept, we leveraged the versatility of a VHH domain to rewire A. tumefaciens adhesion to yeast and mammalian hosts displaying a GFP target receptor. Finally, to demonstrate how synthetic A. tumefaciens adhesion can improve transfer to host cells, we showed improved protein translocation into HeLa cells using a sensitive split luciferase reporter system. Engineering A. tumefaciens adhesion has therefore a strong potential in generating complex heterogeneous cellular assemblies and in improving DNA transfer efficiency against non-natural hosts.
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Affiliation(s)
- Xavier Pierrat
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Alix Pham
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Jeremy P H Wong
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Zainebe Al-Mayyah
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Alexandre Persat
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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7
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Al-Husini N, Tomares DT, Pfaffenberger ZJ, Muthunayake NS, Samad MA, Zuo T, Bitar O, Aretakis JR, Bharmal MHM, Gega A, Biteen JS, Childers WS, Schrader JM. BR-Bodies Provide Selectively Permeable Condensates that Stimulate mRNA Decay and Prevent Release of Decay Intermediates. Mol Cell 2020; 78:670-682.e8. [PMID: 32343944 PMCID: PMC7245546 DOI: 10.1016/j.molcel.2020.04.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 12/16/2019] [Accepted: 03/30/2020] [Indexed: 12/22/2022]
Abstract
Biomolecular condensates play a key role in organizing RNAs and proteins into membraneless organelles. Bacterial RNP-bodies (BR-bodies) are a biomolecular condensate containing the RNA degradosome mRNA decay machinery, but the biochemical function of such organization remains poorly defined. Here, we define the RNA substrates of BR-bodies through enrichment of the bodies followed by RNA sequencing (RNA-seq). We find that long, poorly translated mRNAs, small RNAs, and antisense RNAs are the main substrates, while rRNA, tRNA, and other conserved non-coding RNAs (ncRNAs) are excluded from these bodies. BR-bodies stimulate the mRNA decay rate of enriched mRNAs, helping to reshape the cellular mRNA pool. We also observe that BR-body formation promotes complete mRNA decay, avoiding the buildup of toxic endo-cleaved mRNA decay intermediates. The combined selective permeability of BR-bodies for both enzymes and substrates together with the stimulation of the sub-steps of mRNA decay provide an effective organization strategy for bacterial mRNA decay.
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MESH Headings
- Caulobacter crescentus/genetics
- Caulobacter crescentus/growth & development
- Caulobacter crescentus/metabolism
- Endoribonucleases/genetics
- Endoribonucleases/metabolism
- Escherichia coli/genetics
- Escherichia coli/growth & development
- Escherichia coli/metabolism
- Humans
- Multienzyme Complexes/genetics
- Multienzyme Complexes/metabolism
- Organelles/genetics
- Organelles/metabolism
- Polyribonucleotide Nucleotidyltransferase/genetics
- Polyribonucleotide Nucleotidyltransferase/metabolism
- RNA Helicases/genetics
- RNA Helicases/metabolism
- RNA Stability
- RNA, Antisense/genetics
- RNA, Antisense/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Small Untranslated/genetics
- RNA, Small Untranslated/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
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Affiliation(s)
- Nadra Al-Husini
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Dylan T Tomares
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | | | | - Mohammad A Samad
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Tiancheng Zuo
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Obaidah Bitar
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - James R Aretakis
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | | | - Alisa Gega
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Julie S Biteen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - W Seth Childers
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | - Jared M Schrader
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
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8
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A bacterial surface layer protein exploits multistep crystallization for rapid self-assembly. Proc Natl Acad Sci U S A 2019; 117:388-394. [PMID: 31848245 PMCID: PMC6955313 DOI: 10.1073/pnas.1909798116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Many microbes assemble a crystalline protein layer on their outer surface as an additional barrier and communication platform between the cell and its environment. Surface layer proteins efficiently crystallize to continuously coat the cell, and this trait has been utilized to design functional macromolecular nanomaterials. Here, we report that rapid crystallization of a bacterial surface layer protein occurs through a multistep pathway involving a crystalline intermediate. Upon calcium binding, sequential changes occur in the structure and arrangement of the protein, which are captured by time-resolved small angle X-ray scattering and transmission electron cryo-microscopy. We demonstrate that a specific domain is responsible for enhancing the rate of self-assembly, unveiling possible evolutionary mechanisms to enhance the kinetics of 2D protein crystallization. Surface layers (S-layers) are crystalline protein coats surrounding microbial cells. S-layer proteins (SLPs) regulate their extracellular self-assembly by crystallizing when exposed to an environmental trigger. However, molecular mechanisms governing rapid protein crystallization in vivo or in vitro are largely unknown. Here, we demonstrate that the Caulobacter crescentus SLP readily crystallizes into sheets in vitro via a calcium-triggered multistep assembly pathway. This pathway involves 2 domains serving distinct functions in assembly. The C-terminal crystallization domain forms the physiological 2-dimensional (2D) crystal lattice, but full-length protein crystallizes multiple orders of magnitude faster due to the N-terminal nucleation domain. Observing crystallization using a time course of electron cryo-microscopy (Cryo-EM) imaging reveals a crystalline intermediate wherein N-terminal nucleation domains exhibit motional dynamics with respect to rigid lattice-forming crystallization domains. Dynamic flexibility between the 2 domains rationalizes efficient S-layer crystal nucleation on the curved cellular surface. Rate enhancement of protein crystallization by a discrete nucleation domain may enable engineering of kinetically controllable self-assembling 2D macromolecular nanomaterials.
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9
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A Caulobacter crescentus Microbicide Protects from Vaginal Infection with HIV-1 JR-CSF in Humanized Bone Marrow-Liver-Thymus Mice. J Virol 2019; 93:JVI.00614-19. [PMID: 31243127 PMCID: PMC6714793 DOI: 10.1128/jvi.00614-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/12/2019] [Indexed: 02/01/2023] Open
Abstract
Human immunodeficiency virus (HIV) disproportionally infects young women in sub-Saharan Africa. Current HIV-1 prevention options have had limited success among women, suggesting that alternative, female-controlled prevention options need to be developed. Microbicides that can be applied to the vaginal tract are a promising prevention option. In this study, we describe the testing of 15 potential candidates for inhibition of HIV-1 infection in a humanized mouse model of HIV-1 infection. Four of these candidates were able to provide significant protection from vaginal infection with HIV-1, with the most successful candidate protecting 75% of the mice from infection. This study describes the preclinical testing of a new strategy that could be a safe and effective option for HIV-1 prevention in women. Over 2 million people are infected with HIV-1 annually. Approximately half of these new infections occur in women residing in low-income countries, where their access to and control over HIV-1 preventative measures are often limited, indicating that female-controlled prevention options for HIV-1 are urgently needed. Microbicides that can be topically applied to the vaginal tract in advance of sexual activity represent a promising female-controlled prevention option for HIV-1. We have previously described the development of an HIV-1-specific microbicide using the surface or S-layer recombinant protein display capabilities of the nonpathogenic, freshwater bacterium Caulobacter crescentus. Recombinant C. crescentus bacteria were created that displayed proteins that interfere with the HIV-1 attachment and entry process and that were able to provide significant protection of TZM-bl cells from infection with HIV-1 pseudovirus. These studies have been expanded to investigate if these recombinant C. crescentus bacteria are able to maintain efficacy with replication-competent HIV-1 and both TZM-bl cells and human peripheral blood mononuclear cells (PBMCs). In addition, we utilized the humanized bone marrow-liver-thymus (BLT) mouse model to determine if vaginal application of recombinant C. crescentus at the time of HIV-1JR-CSF infection could provide protection from HIV-1 infection. Recombinant C. crescentus bacteria expressing Griffithsin, GB virus C E2 protein, elafin, α-1-antitrypsin, indolicidin, and the fusion inhibitor T-1249 were able to protect 40 to 75% of the BLT mice from vaginal infection with HIV-1JR-CSF, with C. crescentus bacteria expressing Griffithsin being the most effective. Taken together, these data suggest that a C. crescentus-based microbicide could be a safe and effective method for HIV-1 prevention. IMPORTANCE Human immunodeficiency virus (HIV) disproportionally infects young women in sub-Saharan Africa. Current HIV-1 prevention options have had limited success among women, suggesting that alternative, female-controlled prevention options need to be developed. Microbicides that can be applied to the vaginal tract are a promising prevention option. In this study, we describe the testing of 15 potential candidates for inhibition of HIV-1 infection in a humanized mouse model of HIV-1 infection. Four of these candidates were able to provide significant protection from vaginal infection with HIV-1, with the most successful candidate protecting 75% of the mice from infection. This study describes the preclinical testing of a new strategy that could be a safe and effective option for HIV-1 prevention in women.
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10
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Topologically-guided continuous protein crystallization controls bacterial surface layer self-assembly. Nat Commun 2019; 10:2731. [PMID: 31227690 PMCID: PMC6588578 DOI: 10.1038/s41467-019-10650-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/16/2019] [Indexed: 12/22/2022] Open
Abstract
Many bacteria and most archaea possess a crystalline protein surface layer (S-layer), which surrounds their growing and topologically complicated outer surface. Constructing a macromolecular structure of this scale generally requires localized enzymatic machinery, but a regulatory framework for S-layer assembly has not been identified. By labeling, superresolution imaging, and tracking the S-layer protein (SLP) from C. crescentus, we show that 2D protein self-assembly is sufficient to build and maintain the S-layer in living cells by efficient protein crystal nucleation and growth. We propose a model supported by single-molecule tracking whereby randomly secreted SLP monomers diffuse on the lipopolysaccharide (LPS) outer membrane until incorporated at the edges of growing 2D S-layer crystals. Surface topology creates crystal defects and boundaries, thereby guiding S-layer assembly. Unsupervised assembly poses challenges for therapeutics targeting S-layers. However, protein crystallization as an evolutionary driver rationalizes S-layer diversity and raises the potential for biologically inspired self-assembling macromolecular nanomaterials. Bacteria assemble the surface layer (S-layer), a crystalline protein coat surrounding the curved surface, using protein self-assembly. Here authors image native and purified RsaA, the S-layer protein from C. crescentus, and show that protein crystallization alone is sufficient to assemble and maintain the S-layer in vivo.
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Absolute Measurements of mRNA Translation in Caulobacter crescentus Reveal Important Fitness Costs of Vitamin B 12 Scavenging. mSystems 2019; 4:4/4/e00170-19. [PMID: 31138672 PMCID: PMC6538847 DOI: 10.1128/msystems.00170-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Caulobacter crescentus is a model system of the bacterial cell cycle culminating in asymmetric cell division, with each daughter cell inheriting a distinct set of proteins. While a genetic network of master transcription factors coordinates the cell cycle timing of transcription for nearly 20% of Caulobacter genes, we lack knowledge of how many of each protein “part” encoded in the genome are synthesized. Therefore, to determine the absolute production rates across the genome, we performed ribosome profiling, providing, for the first time, a quantitative resource with measurements of each protein “part” needed to generate daughter cells. This resource furthers the goal of a systems-level understanding of the genetic network controlling asymmetric cell division. To highlight the utility of this data set, we probe the protein synthesis cost of a B12 utilization pathway and provide new insights into Caulobacter’s adaptation to its natural environments. Caulobacter crescentus is a model for the bacterial cell cycle which culminates in asymmetric cell division, yet little is known about the absolute levels of protein synthesis of the cellular parts needed to complete the cell cycle. Here we utilize ribosome profiling to provide absolute measurements of mRNA translation in C. crescentus, providing an important resource with quantitative genome-wide measurements of protein output across individual genes. Analysis of protein synthesis rates revealed ∼4.5% of cellular protein synthesis is for genes related to vitamin B12 import (btuB) and B12-independent methionine biosynthesis (metE) when grown in common growth media lacking B12. While its facultative B12 lifestyle provides a fitness advantage in the absence of B12, we find that it provides a fitness disadvantage of the cells in the presence of B12, potentially explaining why many Caulobacter species have lost the metE gene and become obligates for B12. IMPORTANCECaulobacter crescentus is a model system of the bacterial cell cycle culminating in asymmetric cell division, with each daughter cell inheriting a distinct set of proteins. While a genetic network of master transcription factors coordinates the cell cycle timing of transcription for nearly 20% of Caulobacter genes, we lack knowledge of how many of each protein “part” encoded in the genome are synthesized. Therefore, to determine the absolute production rates across the genome, we performed ribosome profiling, providing, for the first time, a quantitative resource with measurements of each protein “part” needed to generate daughter cells. This resource furthers the goal of a systems-level understanding of the genetic network controlling asymmetric cell division. To highlight the utility of this data set, we probe the protein synthesis cost of a B12 utilization pathway and provide new insights into Caulobacter’s adaptation to its natural environments. Author Video: An author video summary of this article is available.
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Charrier M, Li D, Mann VR, Yun L, Jani S, Rad B, Cohen BE, Ashby PD, Ryan KR, Ajo-Franklin CM. Engineering the S-Layer of Caulobacter crescentus as a Foundation for Stable, High-Density, 2D Living Materials. ACS Synth Biol 2019; 8:181-190. [PMID: 30577690 DOI: 10.1021/acssynbio.8b00448] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Materials synthesized by organisms, such as bones and wood, combine the ability to self-repair with remarkable mechanical properties. This multifunctionality arises from the presence of living cells within the material and hierarchical assembly of different components across nanometer to micron scales. While creating engineered analogues of these natural materials is of growing interest, our ability to hierarchically order materials using living cells largely relies on engineered 1D protein filaments. Here, we lay the foundation for bottom-up assembly of engineered living material composites in 2D along the cell body using a synthetic biology approach. We engineer the paracrystalline surface-layer (S-layer) of Caulobacter crescentus to display SpyTag peptides that form irreversible isopeptide bonds to SpyCatcher-modified proteins, nanocrystals, and biopolymers on the extracellular surface. Using flow cytometry and confocal microscopy, we show that attachment of these materials to the cell surface is uniform, specific, and covalent, and its density can be controlled on the basis of the insertion location within the S-layer protein, RsaA. Moreover, we leverage the irreversible nature of this attachment to demonstrate via SDS-PAGE that the engineered S-layer can display a high density of materials, reaching 1 attachment site per 288 nm2. Finally, we show that ligation of quantum dots to the cell surface does not impair cell viability, and this composite material remains intact over a period of 2 weeks. Taken together, this work provides a platform for self-organization of soft and hard nanomaterials on a cell surface with precise control over 2D density, composition, and stability of the resulting composite, and is a key step toward building hierarchically ordered engineered living materials with emergent properties.
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Generation of a Dual-Target, Safe, Inexpensive Microbicide that Protects Against HIV-1 and HSV-2 Disease. Sci Rep 2018; 8:2786. [PMID: 29434285 PMCID: PMC5809452 DOI: 10.1038/s41598-018-21134-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/22/2018] [Indexed: 01/17/2023] Open
Abstract
HSV-2 infection is a significant health problem and a major co-morbidity factor for HIV-1 acquisition, increasing risk of infection 2-4 fold. Condom based prevention strategies for HSV-2 and HIV-1 have not been effective at stopping the HIV-1 pandemic, indicating that alternative prevention strategies need to be investigated. We have previously developed an inexpensive HIV-1 specific microbicide that utilizes the S-layer mediated display capabilities of Caulobacter crescentus, and have shown that recombinant C. crescentus displaying HIV entry blocking proteins are able to provide significant protection from HIV-1 infection in vitro. Here we demonstrate that recombinant C. crescentus are safe for topical application and describe 5 new recombinant C. crescentus that provide protection from HIV-1 infection in vitro. Further, we demonstrate protection from disease following intravaginal infection with HSV-2 in a murine model using C. crescentus expressing the anti-viral lectins Cyanovirin-N and Griffithsin, as well as α-1-antitrypsin and indolicidin. Interestingly, C. crescentus alone significantly reduced HSV-2 replication in vaginal lavage fluid. Protection from HSV-2 disease was strongly associated with early cytokine production in the vaginal tract. Our data support the potential for a dual-target microbicide that can protect against both HIV-1 and HSV-2, which could have an enormous impact on public health.
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Herrmann J, Jabbarpour F, Bargar PG, Nomellini JF, Li PN, Lane TJ, Weiss TM, Smit J, Shapiro L, Wakatsuki S. Environmental Calcium Controls Alternate Physical States of the Caulobacter Surface Layer. Biophys J 2017; 112:1841-1851. [PMID: 28494955 PMCID: PMC5425405 DOI: 10.1016/j.bpj.2017.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/28/2017] [Accepted: 04/06/2017] [Indexed: 11/23/2022] Open
Abstract
Surface layers (S-layers) are paracrystalline, proteinaceous structures found in most archaea and many bacteria. Often the outermost cell envelope component, S-layers serve diverse functions including aiding pathogenicity and protecting against predators. We report that the S-layer of Caulobacter crescentus exhibits calcium-mediated structural plasticity, switching irreversibly between an amorphous aggregate state and the crystalline state. This finding invalidates the common assumption that S-layers serve only as static wall-like structures. In vitro, the Caulobacter S-layer protein, RsaA, enters the aggregate state at physiological temperatures and low divalent calcium ion concentrations. At higher concentrations, calcium ions stabilize monomeric RsaA, which can then transition to the two-dimensional crystalline state. Caulobacter requires micromolar concentrations of calcium for normal growth and development. Without an S-layer, Caulobacter is even more sensitive to changes in environmental calcium concentration. Therefore, this structurally dynamic S-layer responds to environmental conditions as an ion sensor and protects Caulobacter from calcium deficiency stress, a unique mechanism of bacterial adaptation. These findings provide a biochemical and physiological basis for RsaA's calcium-binding behavior, which extends far beyond calcium's commonly accepted role in aiding S-layer biogenesis or oligomerization and demonstrates a connection to cellular fitness.
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Affiliation(s)
- Jonathan Herrmann
- Department of Structural Biology, Stanford University, Stanford, California; Bioscience Division, SLAC National Accelerator Laboratory, Menlo Park, California.
| | - Fatemeh Jabbarpour
- Department of Structural Biology, Stanford University, Stanford, California
| | | | - John F Nomellini
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Po-Nan Li
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Thomas J Lane
- Bioscience Division, SLAC National Accelerator Laboratory, Menlo Park, California
| | - Thomas M Weiss
- Bioscience Division, SLAC National Accelerator Laboratory, Menlo Park, California
| | - John Smit
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lucy Shapiro
- Department of Developmental Biology, Stanford University, Stanford, California.
| | - Soichi Wakatsuki
- Department of Structural Biology, Stanford University, Stanford, California; Bioscience Division, SLAC National Accelerator Laboratory, Menlo Park, California.
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Jones MD, Chan ACK, Nomellini JF, Murphy MEP, Smit J. Surface-layer protein from Caulobacter crescentus: expression, purification and X-ray crystallographic analysis. Acta Crystallogr F Struct Biol Commun 2016; 72:677-80. [PMID: 27599857 PMCID: PMC5012206 DOI: 10.1107/s2053230x16011638] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/16/2016] [Indexed: 11/10/2022] Open
Abstract
Protein surface layers are self-assembling, paracrystalline lattices on the surface of many prokaryotes. Surface-layer proteins have not benefited from widespread structural analysis owing to their resistance to crystallization. Here, the successful expression of a truncated version of RsaA, the surface-layer protein from Caulobacter crescentus, from a Caulobacter protein-expression system is reported. The purification, crystallization and initial X-ray diffraction analysis of the truncated RsaA, the largest surface-layer protein studied to date and the first from a Gram-negative bacterium, are also reported.
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Affiliation(s)
- Michael D. Jones
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Anson C. K. Chan
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - John F. Nomellini
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Michael E. P. Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - John Smit
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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OmpW of Caulobacter crescentus Functions as an Outer Membrane Channel for Cations. PLoS One 2015; 10:e0143557. [PMID: 26606672 PMCID: PMC4659666 DOI: 10.1371/journal.pone.0143557] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/05/2015] [Indexed: 11/30/2022] Open
Abstract
Caulobacter crescentus is an oligotrophic bacterium that lives in dilute organic environments such as soil and freshwater. This bacterium represents an interesting model for cellular differentiation and regulation because daughter cells after division have different forms: one is motile while the other is non-motile and can adhere to surfaces. Interestingly, the known genome of C. crescentus does not contain genes predicted to code for outer membrane porins of the OmpF/C general diffusion type present in enteric bacteria or those coding for specific porins selective for classes of substrates. Instead, genes coding for 67 TonB-dependent outer membrane receptors have been identified, suggesting that active transport of specific nutrients may be the norm. Here, we report that high channel-forming activity was observed with crude outer membrane extracts of C. crescentus in lipid bilayer experiments, indicating that the outer membrane of C. crescentus contained an ion-permeable channel with a single-channel conductance of about 120 pS in 1M KCl. The channel-forming protein with an apparent molecular mass of about 20 kDa was purified to homogeneity. Partial protein sequencing of the protein indicated it was a member of the OmpW family of outer membrane proteins from Gram-negative bacteria. This channel was not observed in reconstitution experiments with crude outer membrane extracts of an OmpW deficient C. crescentus mutant. Biophysical analysis of the C. crescentus OmpW suggested that it has features that are special for general diffusion porins of Gram-negative outer membranes because it was not a wide aqueous channel. Furthermore, OmpW of C. crescentus seems to be different to known OmpW porins and has a preference for ions, in particular cations. A putative model for OmpW of C. crescentus was built on the basis of the known 3D-structures of OmpW of Escherichia coli and OprG of Pseudomonas aeruginosa using homology modeling. A comparison of the two known structures with the model of OmpW of C. crescentus suggested that it has a more hydrophilic interior and possibly a larger diameter.
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Habibi N. Immobilization of bacterial S-layer proteins from Caulobacter crescentus on iron oxide-based nanocomposite: synthesis and spectroscopic characterization of zincite-coated Fe₂O₃ nanoparticles. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 125:359-362. [PMID: 24566114 DOI: 10.1016/j.saa.2014.01.084] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/10/2014] [Accepted: 01/16/2014] [Indexed: 06/03/2023]
Abstract
Zinc oxide was coated on Fe2O3 nanoparticles using sol-gel spin-coating. Caulobacter crescentus have a crystalline surface layer (S-layer), which consist of one protein or glycoprotein species. The immobilization of bacterial S-layers obtained from C. crescentus on zincite-coated nanoparticles of iron oxide was investigated. The SDS PAGE results of S-layers isolated from C. crescentus showed the weight of 50 KDa. Nanoparticles of the Fe2O3 and zinc oxide were synthesized by a sol-gel technique. Fe2O3 nanoparticles with an average size of 50 nm were successfully prepared by the proper deposition of zinc oxide onto iron oxide nanoparticles surface annealed at 450 °C. The samples were characterized by field-emission scanning electron microscope (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR).
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Affiliation(s)
- Neda Habibi
- Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran.
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18
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Farr C, Nomellini JF, Ailon E, Shanina I, Sangsari S, Cavacini LA, Smit J, Horwitz MS. Development of an HIV-1 Microbicide Based on Caulobacter crescentus: Blocking Infection by High-Density Display of Virus Entry Inhibitors. PLoS One 2013; 8:e65965. [PMID: 23840383 PMCID: PMC3686833 DOI: 10.1371/journal.pone.0065965] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 05/02/2013] [Indexed: 01/23/2023] Open
Abstract
The HIV/AIDS pandemic remains an enormous global health concern. Despite effective prevention options, 2.6 million new infections occur annually, with women in developing countries accounting for more than half of these infections. New prevention strategies that can be used by women are urgently needed. Topical microbicides specific for HIV-1 represent a promising prevention strategy. Conceptually, using harmless bacteria to display peptides or proteins capable of blocking entry provides an inexpensive approach to microbicide development. To avoid the potential pitfalls of engineering commensal bacteria, our strategy is to genetically display infection inhibitors on a non-native bacterium and rely on topical application of stabilized bacteria before potential virus exposure. Due to the high density cell-surface display capabilities and the inherent low toxicity of the bacterium, the S-layer mediated protein display capabilities of the non-pathogenic bacterium Caulobacter crescentus has been exploited for this approach. We have demonstrated that C. crescentus displaying MIP1α or CD4 interfered with the virus entry pathway and provided significant protection from HIV-1 pseudovirus representing clade B in a standard single cycle infection assay. Here we have expanded our C. crescentus based microbicide approach with additional and diverse classes of natural and synthetic inhibitors of the HIV-1 entry pathway. All display constructs provided variable but significant protection from HIV-1 infection; some with protection as high as 70%. Further, we describe protection from infection with additional viral clades. These findings indicate the significant potential for engineering C. crescentus to be an effective and readily adaptable HIV-1 microbicide platform.
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Affiliation(s)
- Christina Farr
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - John F. Nomellini
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Evan Ailon
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Iryna Shanina
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Sassan Sangsari
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Lisa A. Cavacini
- Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - John Smit
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Marc S. Horwitz
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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The bacterial surface layer provides protection against antimicrobial peptides. Appl Environ Microbiol 2012; 78:5452-6. [PMID: 22635987 DOI: 10.1128/aem.01493-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This report describes a previously unrecognized role for bacterial surface layers as barriers that confer protection against antimicrobial peptides. As antimicrobial peptides exist in natural environments, S-layers may provide a bacterial survival mechanism that has been selected for through evolution.
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Gandham L, Nomellini JF, Smit J. Evaluating secretion and surface attachment of SapA, an S-layer-associated metalloprotease of Caulobacter crescentus. Arch Microbiol 2012; 194:865-77. [DOI: 10.1007/s00203-012-0819-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 03/23/2012] [Accepted: 04/23/2012] [Indexed: 11/30/2022]
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21
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Cao Y, Johnson HM, Bazemore-Walker CR. Improved enrichment and proteomic identification of outer membrane proteins from a Gram-negative bacterium: Focus on Caulobacter crescentus. Proteomics 2011; 12:251-62. [DOI: 10.1002/pmic.201100288] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Revised: 10/16/2011] [Accepted: 11/02/2011] [Indexed: 01/12/2023]
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Enhanced neutralization of HIV by antibodies displayed on the S-layer of Caulobacter crescentus. Antimicrob Agents Chemother 2011; 55:5547-52. [PMID: 21896905 DOI: 10.1128/aac.00509-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Innovative methods of prevention are needed to stop the more than two million new HIV-1 infections annually, particularly in women. Local application of anti-HIV antibodies has been shown to be effective at preventing infection in nonhuman primates; however, the concentrations needed are cost prohibitive. Display of antibodies on a particulate platform will likely prolong effectiveness of these anti-HIV agents and lower the cost of goods. Here, we demonstrate that the bacterium Caulobacter crescentus and its highly expressed surface-layer (S-layer) protein can provide this antibody display platform. Caulobacters displaying protein G, alone or with CD4 codisplay, successfully captured HIV-1-specific antibodies and demonstrated functional neutralization. Compared to soluble antibodies, a neutralizing anti-HIV antibody displayed on Caulobacter was as effective or more effective at neutralizing diverse HIV-1 isolates. Moreover, when an antibody reactive with an epitope induced by CD4 binding (CD4i) was codisplayed with CD4, there was significant enhancement in HIV-1 neutralization. These results suggest that caulobacters displaying anti-HIV antibodies offer a distinct improvement in the use of antibodies as microbicides. Furthermore, these reagents can specifically evaluate anti-HIV antibodies in concert with other HIV-1 blocking agents to assess the most suitable tools for conversion to scFvs, allowing for direct display within the S-layer protein and further reducing cost of goods. In summary, C. crescentus, which can be easily produced and chemically stabilized at low cost, is well suited for engineering as an effective platform, offering an inexpensive way to produce and deliver HIV-1-specific microbicides.
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Analysis of the intact surface layer of Caulobacter crescentus by cryo-electron tomography. J Bacteriol 2010; 192:5855-65. [PMID: 20833802 DOI: 10.1128/jb.00747-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The surface layers (S layers) of those bacteria and archaea that elaborate these crystalline structures have been studied for 40 years. However, most structural analysis has been based on electron microscopy of negatively stained S-layer fragments separated from cells, which can introduce staining artifacts and allow rearrangement of structures prone to self-assemble. We present a quantitative analysis of the structure and organization of the S layer on intact growing cells of the Gram-negative bacterium Caulobacter crescentus using cryo-electron tomography (CET) and statistical image processing. Instead of the expected long-range order, we observed different regions with hexagonally organized subunits exhibiting short-range order and a broad distribution of periodicities. Also, areas of stacked double layers were found, and these increased in extent when the S-layer protein (RsaA) expression level was elevated by addition of multiple rsaA copies. Finally, we combined high-resolution amino acid residue-specific Nanogold labeling and subtomogram averaging of CET volumes to improve our understanding of the correlation between the linear protein sequence and the structure at the 2-nm level of resolution that is presently available. The results support the view that the U-shaped RsaA monomer predicted from negative-stain tomography proceeds from the N terminus at one vertex, corresponding to the axis of 3-fold symmetry, to the C terminus at the opposite vertex, which forms the prominent 6-fold symmetry axis. Such information will help future efforts to analyze subunit interactions and guide selection of internal sites for display of heterologous protein segments.
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