1
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Jones AA, Snow CD. Porous protein crystals: synthesis and applications. Chem Commun (Camb) 2024; 60:5790-5803. [PMID: 38756076 DOI: 10.1039/d4cc00183d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Large-pore protein crystals (LPCs) are an emerging class of biomaterials. The inherent diversity of proteins translates to a diversity of crystal lattice structures, many of which display large pores and solvent channels. These pores can, in turn, be functionalized via directed evolution and rational redesign based on the known crystal structures. LPCs possess extremely high solvent content, as well as extremely high surface area to volume ratios. Because of these characteristics, LPCs continue to be explored in diverse applications including catalysis, targeted therapeutic delivery, templating of nanostructures, structural biology. This Feature review article will describe several of the existing platforms in detail, with particular focus on LPC synthesis approaches and reported applications.
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Affiliation(s)
- Alec Arthur Jones
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523-1301, USA.
| | - Christopher D Snow
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523-1301, USA.
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523-1301, USA
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2
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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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3
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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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4
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Sun J, Rutherford ST, Silhavy TJ, Huang KC. Physical properties of the bacterial outer membrane. Nat Rev Microbiol 2022; 20:236-248. [PMID: 34732874 PMCID: PMC8934262 DOI: 10.1038/s41579-021-00638-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2021] [Indexed: 11/09/2022]
Abstract
It has long been appreciated that the Gram-negative outer membrane acts as a permeability barrier, but recent studies have uncovered a more expansive and versatile role for the outer membrane in cellular physiology and viability. Owing to recent developments in microfluidics and microscopy, the structural, rheological and mechanical properties of the outer membrane are becoming apparent across multiple scales. In this Review, we discuss experimental and computational studies that have revealed key molecular factors and interactions that give rise to the spatial organization, limited diffusivity and stress-bearing capacity of the outer membrane. These physical properties suggest broad connections between cellular structure and physiology, and we explore future prospects for further elucidation of the implications of outer membrane construction for cellular fitness and survival.
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Affiliation(s)
- Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Steven T. Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA 94080, USA,To whom correspondence should be addressed: , ,
| | - Thomas J. Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,To whom correspondence should be addressed: , ,
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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5
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Simon P, Pompe W, Gruner D, Sturm E, Ostermann K, Matys S, Vogel M, Rödel G. Nested Formation of Calcium Carbonate Polymorphs in a Bacterial Surface Membrane with a Graded Nanoconfinement: An Evolutionary Strategy to Ensure Bacterial Survival. ACS Biomater Sci Eng 2022; 8:526-539. [PMID: 34995442 PMCID: PMC8848282 DOI: 10.1021/acsbiomaterials.1c01280] [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] [Indexed: 11/29/2022]
Abstract
![]()
It is the intention
of this study to elucidate the nested formation
of calcium carbonate polymorphs or polyamorphs in the different nanosized
compartments. With these observations, it can be concluded how the
bacteria can survive in a harsh environment with high calcium carbonate
supersaturation. The mechanisms of calcium carbonate precipitation
at the surface membrane and at the underlying cell wall membrane of
the thermophilic soil bacterium Geobacillus stearothermophilus DSM 13240 have been revealed by high-resolution transmission electron
microscopy and atomic force microscopy. In this Gram-positive bacterium,
nanopores in the surface layer (S-layer) and in the supporting cell
wall polymers are nucleation sites for metastable calcium carbonate
polymorphs and polyamorphs. In order to observe the different metastable
forms, various reaction times and a low reaction temperature (4 °C)
have been chosen. Calcium carbonate polymorphs nucleate in the confinement
of nanosized pores (⌀ 3–5 nm) of the S-layer. The hydrous
crystalline calcium carbonate (ikaite) is formed initially with [110]
as the favored growth direction. It transforms into the anhydrous
metastable vaterite by a solid-state transition. In a following reaction
step, calcite is precipitated, caused by dissolution of vaterite in
the aqueous solution. In the larger pores of the cell wall (⌀
20–50 nm), hydrated amorphous calcium carbonate is grown, which
transforms into metastable monohydrocalcite, aragonite, or calcite.
Due to the sequence of reaction steps via various metastable phases,
the bacteria gain time for chipping the partially mineralized S-layer,
and forming a fresh S-layer (characteristic growth time about 20 min).
Thus, the bacteria can survive in solutions with high calcium carbonate
supersaturation under the conditions of forced biomineralization.
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Affiliation(s)
- Paul Simon
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Wolfgang Pompe
- Institute of Materials Science, Technische Universität Dresden, Helmholtzstraße 7, 01069 Dresden, Germany
| | - Denise Gruner
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany.,Polymeric Microsystems, Technische Universität Dresden, Helmholtzstraße 100, 01069 Dresden, Germany
| | - Elena Sturm
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany.,Physical Chemistry, University of Konstanz, POB 714, D-78457 Konstanz, Germany
| | - Kai Ostermann
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
| | - Sabine Matys
- Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzener Landstraße 400, 01328 Dresden, Germany
| | - Manja Vogel
- Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzener Landstraße 400, 01328 Dresden, Germany
| | - Gerhard Rödel
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
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6
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Chang MP, Huang W, Mai DJ. Monomer‐scale design of functional protein polymers using consensus repeat sequences. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Marina P. Chang
- Department of Materials Science and Engineering Stanford University Stanford California USA
| | - Winnie Huang
- Department of Chemical Engineering Stanford University Stanford California USA
| | - Danielle J. Mai
- Department of Chemical Engineering Stanford University Stanford California USA
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7
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von Kügelgen A, Tang H, Hardy GG, Kureisaite-Ciziene D, Brun YV, Stansfeld PJ, Robinson CV, Bharat TAM. In Situ Structure of an Intact Lipopolysaccharide-Bound Bacterial Surface Layer. Cell 2020; 180:348-358.e15. [PMID: 31883796 PMCID: PMC6978808 DOI: 10.1016/j.cell.2019.12.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/22/2019] [Accepted: 12/04/2019] [Indexed: 12/15/2022]
Abstract
Most bacterial and all archaeal cells are encapsulated by a paracrystalline, protective, and cell-shape-determining proteinaceous surface layer (S-layer). On Gram-negative bacteria, S-layers are anchored to cells via lipopolysaccharide. Here, we report an electron cryomicroscopy structure of the Caulobacter crescentus S-layer bound to the O-antigen of lipopolysaccharide. Using native mass spectrometry and molecular dynamics simulations, we deduce the length of the O-antigen on cells and show how lipopolysaccharide binding and S-layer assembly is regulated by calcium. Finally, we present a near-atomic resolution in situ structure of the complete S-layer using cellular electron cryotomography, showing S-layer arrangement at the tip of the O-antigen. A complete atomic structure of the S-layer shows the power of cellular tomography for in situ structural biology and sheds light on a very abundant class of self-assembling molecules with important roles in prokaryotic physiology with marked potential for synthetic biology and surface-display applications.
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Affiliation(s)
- Andriko von Kügelgen
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom; Central Oxford Structural Microscopy and Imaging Centre, South Parks Road, Oxford OX1 3RE, United Kingdom
| | - Haiping Tang
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3TA, United Kingdom
| | - Gail G Hardy
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Département de microbiologie, infectiologie et immunologie, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3TA, United Kingdom
| | - Tanmay A M Bharat
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom; Central Oxford Structural Microscopy and Imaging Centre, South Parks Road, Oxford OX1 3RE, United Kingdom.
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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: 12] [Impact Index Per Article: 2.4] [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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Li PN, Herrmann J, Wakatsuki S, van den Bedem H. Transport Properties of Nanoporous, Chemically Forced Biological Lattices. J Phys Chem B 2019; 123:10331-10342. [PMID: 31721579 DOI: 10.1021/acs.jpcb.9b05882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Permselective nanochannels are ubiquitous in biological systems, controlling ion transport and maintaining a potential difference across a cell surface. Surface layers (S-layers) are proteinaceous, generally charged lattices punctuated with nanoscale pores that form the outermost cell envelope component of virtually all archaea and many bacteria. Ammonia oxidizing archaea (AOA) obtain their energy exclusively from oxidizing ammonia directly below the S-layer lattice, but how the charged surfaces and nanochannels affect availability of NH4+ at the reaction site is unknown. Here, we examine the electrochemical properties of negatively charged S-layers for asymmetrically forced ion transport governed by Michaelis-Menten kinetics at ultralow concentrations. Our 3-dimensional electrodiffusion reaction simulations revealed that a negatively charged S-layer can invert the potential across the nanochannel to favor chemically forced NH4+ transport, analogous to polarity switching in nanofluidic field-effect transistors. Polarity switching was not observed when only the interior of the nanochannels was charged. We found that S-layer charge, nanochannel geometry, and enzymatic turnover rate are finely tuned to elevate NH4+ concentration at the active site, potentially enabling AOA to occupy nutrient-poor ecological niches. Strikingly, and in contrast to voltage-biased systems, magnitudes of the co- and counterion currents in the charged nanochannels were nearly equal and amplified disproportionally to the NH4+ current. Our simulations suggest that engineered arrays of crystalline proteinaceous membranes could find unique applications in industrial energy conversion or separation processes.
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Affiliation(s)
- Po-Nan Li
- Department of Electrical Engineering , Stanford University , 318 Campus Drive , Stanford , California 94305 , United States.,Biosciences Division, SLAC National Accelerator Laboratory , Stanford University , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Jonathan Herrmann
- Department of Structural Biology , Stanford University , 318 Campus Drive , Stanford , California 94305 , United States
| | - Soichi Wakatsuki
- Biosciences Division, SLAC National Accelerator Laboratory , Stanford University , 2575 Sand Hill Road , Menlo Park , California 94025 , United States.,Department of Structural Biology , Stanford University , 318 Campus Drive , Stanford , California 94305 , United States
| | - Henry van den Bedem
- Biosciences Division, SLAC National Accelerator Laboratory , Stanford University , 2575 Sand Hill Road , Menlo Park , California 94025 , United States.,Department of Bioengineering and Therapeutic Sciences , University of California San Francisco , 1700 Fourth Street , San Francisco , California 94158 , United States
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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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11
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Stankeviciute G, Guan Z, Goldfine H, Klein EA. Caulobacter crescentus Adapts to Phosphate Starvation by Synthesizing Anionic Glycoglycerolipids and a Novel Glycosphingolipid. mBio 2019; 10:e00107-19. [PMID: 30940701 PMCID: PMC6445935 DOI: 10.1128/mbio.00107-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/15/2019] [Indexed: 11/20/2022] Open
Abstract
Caulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure. The stalk is an extension of the Gram-negative envelope containing inner and outer membranes as well as a peptidoglycan cell wall. Cellular elongation requires a 6- to 7-fold increase in membrane synthesis, yet phosphate limitation would preclude the incorporation of additional phospholipids. In the place of phospholipids, C. crescentus can synthesize several glycolipid species, including a novel glycosphingolipid (GSL-2). While glycosphingolipids are ubiquitous in eukaryotes, the presence of GSL-2 in C. crescentus is surprising since GSLs had previously been found only in Sphingomonas species, in which they play a role in outer membrane integrity. In this paper, we identify three proteins required for GSL-2 synthesis: CcbF catalyzes the first step in ceramide synthesis, while Sgt1 and Sgt2 sequentially glycosylate ceramides to produce GSL-2. Unlike in Sphingomonas, GSLs are nonessential in C. crescentus; however, the presence of ceramides does contribute to phage resistance and susceptibility to the cationic antimicrobial peptide polymyxin B. The identification of a novel lipid species specifically produced upon phosphate starvation suggests that bacteria may be able to synthesize a wider variety of lipids in response to stresses than previously observed. Uncovering these lipids and their functional relevance will provide greater insight into microbial physiology and environmental adaptation.IMPORTANCE Bacteria adapt to environmental changes in a variety of ways, including altering their cell shape. Caulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure containing both inner and outer membranes. While we generally think of cellular membranes being composed largely of phospholipids, cellular elongation occurs when environmental phosphate, and therefore phospholipid synthesis, is limited. In order to adapt to these environmental constraints, C. crescentus synthesizes several glycolipid species, including a novel glycosphingolipid. This finding is significant because glycosphingolipids, while ubiquitous in eukaryotes, are extremely rare in bacteria. In this paper, we identify three proteins required for GSL-2 synthesis and demonstrate that they contribute to phage resistance. These findings suggest that bacteria may synthesize a wider variety of lipids in response to stresses than previously observed.
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Affiliation(s)
- Gabriele Stankeviciute
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA
| | - Howard Goldfine
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Eric A Klein
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey, USA
- Department of Biology, Rutgers University-Camden, Camden, New Jersey, USA
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12
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Nutrient transport suggests an evolutionary basis for charged archaeal surface layer proteins. ISME JOURNAL 2018; 12:2389-2402. [PMID: 29899515 DOI: 10.1038/s41396-018-0191-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 04/11/2018] [Accepted: 04/14/2018] [Indexed: 01/17/2023]
Abstract
Surface layers (S-layers) are two-dimensional, proteinaceous, porous lattices that form the outermost cell envelope component of virtually all archaea and many bacteria. Despite exceptional sequence diversity, S-layer proteins (SLPs) share important characteristics such as their ability to form crystalline sheets punctuated with nano-scale pores, and their propensity for charged amino acids, leading to acidic or basic isoelectric points. However, the precise function of S-layers, or the role of charged SLPs and how they relate to cellular metabolism is unknown. Nano-scale lattices affect the diffusion behavior of low-concentration solutes, even if they are significantly smaller than the pore size. Here, we offer a rationale for charged S-layer proteins in the context of the structural evolution of S-layers. Using the ammonia-oxidizing archaea (AOA) as a model for S-layer geometry, and a 2D electrodiffusion reaction computational framework to simulate diffusion and consumption of the charged solute ammonium (NH4+), we find that the characteristic length scales of nanoporous S-layers elevate the concentration of NH4+ in the pseudo-periplasmic space. Our simulations suggest an evolutionary, mechanistic basis for S-layer charge and shed light on the unique ability of some AOA to oxidize ammonia in environments with nanomolar NH4+ availability, with broad implications for comparisons of ecologically distinct populations.
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13
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Tolar BB, Herrmann J, Bargar JR, van den Bedem H, Wakatsuki S, Francis CA. Integrated structural biology and molecular ecology of N-cycling enzymes from ammonia-oxidizing archaea. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:484-491. [PMID: 28677304 DOI: 10.1111/1758-2229.12567] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 06/01/2017] [Accepted: 06/25/2017] [Indexed: 06/07/2023]
Abstract
Knowledge of the molecular ecology and environmental determinants of ammonia-oxidizing organisms is critical to understanding and predicting the global nitrogen (N) and carbon cycles, but an incomplete biochemical picture hinders in vitro studies of N-cycling enzymes. Although an integrative structural and dynamic characterization at the atomic scale would advance our understanding of function tremendously, structural knowledge of key N-cycling enzymes from ecologically relevant ammonia oxidizers is unfortunately extremely limited. Here, we discuss the challenges and opportunities for examining the ecology of ammonia-oxidizing organisms, particularly uncultivated Thaumarchaeota, through (meta)genome-driven structural biology of the enzymes ammonia monooxygenase (AMO) and nitrite reductase (NirK).
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Affiliation(s)
- Bradley B Tolar
- Department of Earth System Science, Stanford University, Stanford, CA 94305, USA
| | - Jonathan Herrmann
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - John R Bargar
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Henry van den Bedem
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Soichi Wakatsuki
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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