1
|
Pierro A, Bonucci A, Magalon A, Belle V, Mileo E. Impact of Cellular Crowding on Protein Structural Dynamics Investigated by EPR Spectroscopy. Chem Rev 2024; 124:9873-9898. [PMID: 39213496 DOI: 10.1021/acs.chemrev.3c00951] [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: 09/04/2024]
Abstract
The study of how the intracellular medium influences protein structural dynamics and protein-protein interactions is a captivating area of research for scientists aiming to comprehend biomolecules in their native environment. As the cellular environment can hardly be reproduced in vitro, direct investigation of biomolecules within cells has attracted growing interest in the past two decades. Among magnetic resonances, site-directed spin labeling coupled to electron paramagnetic resonance spectroscopy (SDSL-EPR) has emerged as a powerful tool for studying the structural properties of biomolecules directly in cells. Since the first in-cell EPR experiment was reported in 2010, substantial progress has been made, and this Review provides a detailed overview of the developments and applications of this spectroscopic technique. The strategies available for preparing a cellular sample and the EPR methods that can be applied to cells will be discussed. The array of spin labels available, along with their strengths and weaknesses in cellular contexts, will also be described. Several examples will illustrate how in-cell EPR can be applied to different biological systems and how the cellular environment affects the structural and dynamic properties of different proteins. Lastly, the Review will focus on the future developments expected to expand the capabilities of this promising technique.
Collapse
Affiliation(s)
- Annalisa Pierro
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Alessio Bonucci
- Aix Marseille University, CNRS, Bioénergétique et Ingénierie des Protéines (BIP), IMM, IM2B, Marseille, France
| | - Axel Magalon
- Aix Marseille University, CNRS, Laboratoire de Chimie Bactérienne (LCB), IMM, IM2B, Marseille, France
| | - Valérie Belle
- Aix Marseille University, CNRS, Bioénergétique et Ingénierie des Protéines (BIP), IMM, IM2B, Marseille, France
| | - Elisabetta Mileo
- Aix Marseille University, CNRS, Bioénergétique et Ingénierie des Protéines (BIP), IMM, IM2B, Marseille, France
| |
Collapse
|
2
|
Liu M, Cheng JH, Zhao H, Yu C, Wu J. Targeting the outer membrane of gram-negative foodborne pathogens for food safety: compositions, functions, and disruption strategies. Crit Rev Food Sci Nutr 2024:1-14. [PMID: 39213149 DOI: 10.1080/10408398.2024.2397462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Foodborne pathogens are a major threat to both food safety and public health. The current trend toward fresh and less processed foods and the misuse of antibiotics in food production have made controlling these pathogens even more challenging. The outer membrane has been employed as a practical target to combat foodborne Gram-negative pathogens due to its accessibility and importance. In this review, the compositions of the outer membrane are extensively described firstly, to offer a thorough overview of this target. Current strategies for disrupting the outer membrane are also discussed, with emphasized on their mechanism of action. The disruption of the outer membrane structure, whether caused by severe damage of the lipid bilayer or by interference with the biosynthesis pathway, has been demonstrated to represent an effective antimicrobial strategy. Interference with the outer membrane-mediated functions of barrier, efflux and adhesion also contributes to the fight against Gram-negative pathogens. Their potential for control of foodborne pathogens in the production chain are also proposed. However, it is possible that multiple components in the food matrix may act as a protective barrier against microorganisms, and it is often the case that contamination is not caused by a single microorganism. Further investigation is needed to determine the effectiveness and safety of these methods in more complex systems, and it may be advisable to consider a multi-technology combined approach. Additionally, further studies on outer membranes are necessary to discover more promising mechanisms of action.
Collapse
Affiliation(s)
- Mengyuan Liu
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, China
| | - Jun-Hu Cheng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, China
| | - Haigang Zhao
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- ChemPartner PharmaTech Co., Ltd., Jiangmen, China
| | - Chongchong Yu
- Beijing Key Laboratory of Big Data Technology for Food Safety, Beijing Technology and Business University, Beijing, China
| | - Jingzhu Wu
- Beijing Key Laboratory of Big Data Technology for Food Safety, Beijing Technology and Business University, Beijing, China
| |
Collapse
|
3
|
Gupta M, Johnson ANT, Cruz ER, Costa EJ, Guest RL, Li SHJ, Hart EM, Nguyen T, Stadlmeier M, Bratton BP, Silhavy TJ, Wingreen NS, Gitai Z, Wühr M. Global protein turnover quantification in Escherichia coli reveals cytoplasmic recycling under nitrogen limitation. Nat Commun 2024; 15:5890. [PMID: 39003262 PMCID: PMC11246515 DOI: 10.1038/s41467-024-49920-8] [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: 07/05/2023] [Accepted: 06/25/2024] [Indexed: 07/15/2024] Open
Abstract
Protein turnover is critical for proteostasis, but turnover quantification is challenging, and even in well-studied E. coli, proteome-wide measurements remain scarce. Here, we quantify the turnover rates of ~3200 E. coli proteins under 13 conditions by combining heavy isotope labeling with complement reporter ion quantification and find that cytoplasmic proteins are recycled when nitrogen is limited. We use knockout experiments to assign substrates to the known cytoplasmic ATP-dependent proteases. Surprisingly, none of these proteases are responsible for the observed cytoplasmic protein degradation in nitrogen limitation, suggesting that a major proteolysis pathway in E. coli remains to be discovered. Lastly, we show that protein degradation rates are generally independent of cell division rates. Thus, we present broadly applicable technology for protein turnover measurements and provide a rich resource for protein half-lives and protease substrates in E. coli, complementary to genomics data, that will allow researchers to study the control of proteostasis.
Collapse
Affiliation(s)
- Meera Gupta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Alex N T Johnson
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Edward R Cruz
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Eli J Costa
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Randi L Guest
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | | | - Elizabeth M Hart
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Thao Nguyen
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Michael Stadlmeier
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Benjamin P Bratton
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
- Vanderbilt Institute of Infection, Immunology and Inflammation, Nashville, TN, USA
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Ned S Wingreen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Martin Wühr
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
| |
Collapse
|
4
|
Hatton N, Nabarro J, Yates NDJ, Parkin A, Wilson LG, Baumann CG, Fascione MA. Mannose-Presenting "Glyco-Colicins" Convert the Bacterial Cell Surface into a Multivalent Adsorption Site for Adherent Bacteria. JACS AU 2024; 4:2122-2129. [PMID: 38938796 PMCID: PMC11200225 DOI: 10.1021/jacsau.4c00365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 06/29/2024]
Abstract
Biofilm formation is integral to the pathogenesis of numerous adherent bacteria and contributes to antimicrobial resistance (AMR). The rising threat of AMR means the need to develop novel nonbactericidal antiadhesion approaches against such bacteria is more urgent than ever. Both adherent-invasive Escherichia coli (AIEC, implicated in inflammatory bowel disease) and uropathogenic E. coli (UPEC, responsible for ∼80% of urinary tract infections) adhere to terminal mannose sugars on epithelial glycoproteins through the FimH adhesin on their type 1 pilus. Although mannose-based inhibitors have previously been explored to inhibit binding of adherent bacteria to epithelial cells, this approach has been limited by monovalent carbohydrate-protein interactions. Herein, we pioneer a novel approach to this problem through the preparation of colicin E9 bioconjugates that bind to the abundant BtuB receptor in the outer membrane of bacteria, which enables multivalent presentation of functional motifs on the cell surface. We show these bioconjugates label the surface of live E. coli and furthermore demonstrate that mannose-presenting "glyco-colicins" induce E. coli aggregation, thereby using the bacteria, itself, as a multivalent platform for mannose display, which triggers binding to adjacent FimH-presenting bacteria.
Collapse
Affiliation(s)
- Natasha
E. Hatton
- Department
of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Joe Nabarro
- Department
of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | | | - Alison Parkin
- Department
of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Laurence G. Wilson
- Department
of Physics, University of York, York, YO10 5DD, United Kingdom
| | | | - Martin A. Fascione
- Department
of Chemistry, University of York, York, YO10 5DD, United Kingdom
| |
Collapse
|
5
|
Costan SA, Ryan PM, Kim H, Wolgemuth CW, Riedel-Kruse IH. Biophysical characterization of synthetic adhesins for predicting and tuning engineered living material properties. MATTER 2024; 7:2125-2143. [PMID: 39165662 PMCID: PMC11335339 DOI: 10.1016/j.matt.2024.03.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Bacterial synthetic multicellular systems are promising platforms for engineered living materials (ELMs) for medical, biosynthesis, environmental, and smart materials applications. Recent advancements in genetically encoded adhesion toolkits have enabled precise manipulation of cell-cell adhesion and the design and patterning of self-assembled multicellular materials. However, in contrast to gene regulation in synthetic biology, the characterization and control of synthetic adhesins remains limited. Here, we demonstrate the quantitative characterization of a bacterial synthetic adhesion toolbox through various biophysical methods. We determine key parameters, including number of adhesins per cell, in-membrane diffusion constant, production and decay rates, and bond-breaking force between adhesins. With these parameters, we demonstrate the bottom-up prediction and quantitative tuning of macroscopic ELM properties (tensile strength) and, furthermore, that cells inside ELMs are connected only by a small fraction of available adhesins. These results enable the rational engineering, characterization, and modeling of other synthetic and natural adhesins and multicellular consortia.
Collapse
Affiliation(s)
- Stefana A. Costan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Paul M. Ryan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - Honesty Kim
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Charles W. Wolgemuth
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
- Department of Applied Mathematics, University of Arizona, Tucson, AZ 85721, USA
| | - Ingmar H. Riedel-Kruse
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
- Department of Applied Mathematics, University of Arizona, Tucson, AZ 85721, USA
- Lead contact
| |
Collapse
|
6
|
Fivenson EM, Dubois L, Bernhardt TG. Co-ordinated assembly of the multilayered cell envelope of Gram-negative bacteria. Curr Opin Microbiol 2024; 79:102479. [PMID: 38718542 DOI: 10.1016/j.mib.2024.102479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 06/11/2024]
Abstract
Bacteria surround themselves with complex cell envelopes to maintain their integrity and protect against external insults. The envelope of Gram-negative organisms is multilayered, with two membranes sandwiching the periplasmic space that contains the peptidoglycan cell wall. Understanding how this complicated surface architecture is assembled during cell growth and division is a major fundamental problem in microbiology. Additionally, because the envelope is an important antibiotic target and determinant of intrinsic antibiotic resistance, understanding the mechanisms governing its assembly is relevant to therapeutic development. In the last several decades, most of the factors required to build the Gram-negative envelope have been identified. However, surprisingly, little is known about how the biogenesis of the different cell surface layers is co-ordinated. Here, we provide an overview of recent work that is beginning to uncover the links connecting the different envelope biosynthetic pathways and assembly machines to ensure uniform envelope growth.
Collapse
Affiliation(s)
- Elayne M Fivenson
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, United States
| | - Laurent Dubois
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, United States
| | - Thomas G Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, United States; Howard Hughes Medical Institute, Boston, United States.
| |
Collapse
|
7
|
Xu Y, Wang X, Zaal EA, Berkers CR, Lorent JH, Heise T, Cox R, Pieters RJ, Breukink E. Specific labeling of newly synthesized lipopolysaccharide via metabolic incorporation of azido-galactose. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159467. [PMID: 38382574 DOI: 10.1016/j.bbalip.2024.159467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/12/2024] [Accepted: 02/17/2024] [Indexed: 02/23/2024]
Abstract
Gram-negative bacteria possess an asymmetric outer membrane (OM) primarily composed of lipopolysaccharides (LPS) on the outer leaflet and phospholipids on the inner leaflet. The outer membrane functions as an effective permeability barrier to compounds such as antibiotics. Studying LPS biosynthesis is therefore helpful to explore novel strategies for new antibiotic development. Metabolic glycan labeling of the bacterial surface has emerged as a powerful method to investigate LPS biosynthesis. However, the previously reported methods of labeling LPS are based on radioactivity or difficult-to-produce analogs of bacterial sugars. In this study, we report on the incorporation of azido galactose into the LPS of the Gram-negative bacteria Escherichia coli and Salmonella typhi via metabolic labeling. As a common sugar analog, azido galactose successfully labeled both O-antigen and core of Salmonella LPS, but not E. coli LPS. This labeling of Salmonella LPS, as shown by SDS-PAGE analysis and fluorescence microscopy, differs from the previously reported labeling of either O-antigen or core of LPS. Our findings are useful for studying LPS biogenesis pathways in Gram-negative bacteria like Salmonella. In addition, our approach is helpful for screening for agents that target LPS biosynthesis as it allows for the detection of newly synthesized LPS that appears in the OM. Furthermore, this approach may also aid in isolating chemically modified LPS for vaccine development or immunotherapy.
Collapse
Affiliation(s)
- Yang Xu
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Xiaoqi Wang
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Esther A Zaal
- Division of Cell Biology, Metabolism & Cancer, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, the Netherlands
| | - Celia R Berkers
- Division of Cell Biology, Metabolism & Cancer, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, the Netherlands
| | - Joseph H Lorent
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Torben Heise
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, the Netherlands
| | - Ruud Cox
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Roland J Pieters
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, the Netherlands
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
| |
Collapse
|
8
|
Zanetti-Domingues LC, Hirsch M, Wang L, Eastwood TA, Baker K, Mulvihill DP, Radford S, Horne J, White P, Bateman B. Toward quantitative super-resolution methods for cryo-CLEM. Methods Cell Biol 2024; 187:249-292. [PMID: 38705627 DOI: 10.1016/bs.mcb.2024.02.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Cryogenic ultrastructural imaging techniques such as cryo-electron tomography have produced a revolution in how the structure of biological systems is investigated by enabling the determination of structures of protein complexes immersed in a complex biological matrix within vitrified cell and model organisms. However, so far, the portfolio of successes has been mostly limited to highly abundant complexes or to structures that are relatively unambiguous and easy to identify through electron microscopy. In order to realize the full potential of this revolution, researchers would have to be able to pinpoint lower abundance species and obtain functional annotations on the state of objects of interest which would then be correlated to ultrastructural information to build a complete picture of the structure-function relationships underpinning biological processes. Fluorescence imaging at cryogenic conditions has the potential to be able to meet these demands. However, wide-field images acquired at low numeric aperture (NA) using air immersion objective have a low resolving power and cannot provide accurate enough three-dimensional (3D) localization to enable the assignment of functional annotations to individual objects of interest or target sample debulking to ensure the preservation of the structures of interest. It is therefore necessary to develop super-resolved cryo-fluorescence workflows capable of fulfilling this role and enabling new biological discoveries. In this chapter, we present the current state of development of two super-resolution cryogenic fluorescence techniques, superSIL-STORM and astigmatism-based 3D STORM, show their application to a variety of biological systems and discuss their advantages and limitations. We further discuss the future applicability to cryo-CLEM workflows though examples of practical application to the study of membrane protein complexes both in mammalian cells and in Escherichia coli.
Collapse
Affiliation(s)
- Laura C Zanetti-Domingues
- CLF Octopus Facility, UKRI-Science and Technology Facilities Council, R92, Rutherford Appleton Laboratory, Didcot, United Kingdom.
| | - Michael Hirsch
- CLF Octopus Facility, UKRI-Science and Technology Facilities Council, R92, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Lin Wang
- CLF Octopus Facility, UKRI-Science and Technology Facilities Council, R92, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Tara A Eastwood
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Karen Baker
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Sheena Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, Leeds, United Kingdom
| | - Jim Horne
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, Leeds, United Kingdom
| | - Paul White
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, Leeds, United Kingdom
| | - Benji Bateman
- CLF Octopus Facility, UKRI-Science and Technology Facilities Council, R92, Rutherford Appleton Laboratory, Didcot, United Kingdom
| |
Collapse
|
9
|
George A, Patil AG, Mahalakshmi R. ATP-independent assembly machinery of bacterial outer membranes: BAM complex structure and function set the stage for next-generation therapeutics. Protein Sci 2024; 33:e4896. [PMID: 38284489 PMCID: PMC10804688 DOI: 10.1002/pro.4896] [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: 09/18/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 01/30/2024]
Abstract
Diderm bacteria employ β-barrel outer membrane proteins (OMPs) as their first line of communication with their environment. These OMPs are assembled efficiently in the asymmetric outer membrane by the β-Barrel Assembly Machinery (BAM). The multi-subunit BAM complex comprises the transmembrane OMP BamA as its functional subunit, with associated lipoproteins (e.g., BamB/C/D/E/F, RmpM) varying across phyla and performing different regulatory roles. The ability of BAM complex to recognize and fold OM β-barrels of diverse sizes, and reproducibly execute their membrane insertion, is independent of electrochemical energy. Recent atomic structures, which captured BAM-substrate complexes, show the assembly function of BamA can be tailored, with different substrate types exhibiting different folding mechanisms. Here, we highlight common and unique features of its interactome. We discuss how this conserved protein complex has evolved the ability to effectively achieve the directed assembly of diverse OMPs of wide-ranging sizes (8-36 β-stranded monomers). Additionally, we discuss how darobactin-the first natural membrane protein inhibitor of Gram-negative bacteria identified in over five decades-selectively targets and specifically inhibits BamA. We conclude by deliberating how a detailed deduction of BAM complex-associated regulation of OMP biogenesis and OM remodeling will open avenues for the identification and development of effective next-generation therapeutics against Gram-negative pathogens.
Collapse
Affiliation(s)
- Anjana George
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
| | - Akanksha Gajanan Patil
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological SciencesIndian Institute of Science Education and ResearchBhopalIndia
| |
Collapse
|
10
|
Dunstan RA, Hay ID, Lithgow T. Defining Membrane Protein Localization by Isopycnic Density Gradients. Methods Mol Biol 2024; 2715:91-98. [PMID: 37930523 DOI: 10.1007/978-1-0716-3445-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Bacterial membrane proteins account for around one-third of the proteome in many species and can represent much more than half of the mass of the membranes. Classic techniques in cell biology can be applied to characterize bacterial membranes and their membrane protein constituents, and here we describe a protocol for the purification of outer membranes and inner membranes from Escherichia coli. This allows for compositional analysis of the membranes as well as functional analyses. The procedure can be applied with minor modifications to other bacterial species including those carrying capsular polysaccharide attached to the outer membrane.
Collapse
Affiliation(s)
- Rhys A Dunstan
- Centre to Impact AMR, Monash University, Melbourne, VIC, Australia
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Iain D Hay
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Trevor Lithgow
- Centre to Impact AMR, Monash University, Melbourne, VIC, Australia.
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
| |
Collapse
|
11
|
Lee Upton S, Tay JW, Schwartz DK, Sousa MC. Similarly slow diffusion of BAM and SecYEG complexes in live E. coli cells observed with 3D spt-PALM. Biophys J 2023; 122:4382-4394. [PMID: 37853695 PMCID: PMC10698321 DOI: 10.1016/j.bpj.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 09/05/2023] [Accepted: 10/16/2023] [Indexed: 10/20/2023] Open
Abstract
The β-barrel assembly machinery (BAM) complex is responsible for inserting outer membrane proteins (OMPs) into the Escherichia coli outer membrane. The SecYEG translocon inserts inner membrane proteins into the inner membrane and translocates both soluble proteins and nascent OMPs into the periplasm. Recent reports describe Sec possibly playing a direct role in OMP biogenesis through interactions with the soluble polypeptide transport-associated (POTRA) domains of BamA (the central OMP component of BAM). Here we probe the diffusion behavior of these protein complexes using photoactivatable super-resolution localization microscopy and single-particle tracking in live E. coli cells of BAM and SecYEG components BamA and SecE and compare them to other outer and inner membrane proteins. To accurately measure trajectories on the highly curved cell surface, three-dimensional tracking was performed using double-helix point-spread function microscopy. All proteins tested exhibit two diffusive modes characterized by "slow" and "fast" diffusion coefficients. We implement a diffusion coefficient analysis as a function of the measurement lag time to separate positional uncertainty from true mobility. The resulting true diffusion coefficients of the slow and fast modes showed a complete immobility of full-length BamA constructs in the time frame of the experiment, whereas the OMP OmpLA displayed a slow diffusion consistent with the high viscosity of the outer membrane. The periplasmic POTRA domains of BamA were found to anchor BAM to other cellular structures and render it immobile. However, deletion of individual distal POTRA domains resulted in increased mobility, suggesting that these domains are required for the full set of cellular interactions. SecE diffusion was much slower than that of the inner membrane protein PgpB and was more like OMPs and BamA. Strikingly, SecE diffused faster upon POTRA domain deletion. These results are consistent with the existence of a BAM-SecYEG trans-periplasmic assembly in live E. coli cells.
Collapse
Affiliation(s)
- Stephen Lee Upton
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado
| | - Jian Wei Tay
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Daniel Keith Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado
| | | |
Collapse
|
12
|
Törk L, Moffatt CB, Bernhardt TG, Garner EC, Kahne D. Single-molecule dynamics show a transient lipopolysaccharide transport bridge. Nature 2023; 623:814-819. [PMID: 37938784 PMCID: PMC10842706 DOI: 10.1038/s41586-023-06709-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/04/2023] [Indexed: 11/09/2023]
Abstract
Gram-negative bacteria are surrounded by two membranes. A special feature of the outer membrane is its asymmetry. It contains lipopolysaccharide (LPS) in the outer leaflet and phospholipids in the inner leaflet1-3. The proper assembly of LPS in the outer membrane is required for cell viability and provides Gram-negative bacteria intrinsic resistance to many classes of antibiotics. LPS biosynthesis is completed in the inner membrane, so the LPS must be extracted, moved across the aqueous periplasm that separates the two membranes and translocated through the outer membrane where it assembles on the cell surface4. LPS transport and assembly requires seven conserved and essential LPS transport components5 (LptA-G). This system has been proposed to form a continuous protein bridge that provides a path for LPS to reach the cell surface6,7, but this model has not been validated in living cells. Here, using single-molecule tracking, we show that Lpt protein dynamics are consistent with the bridge model. Half of the inner membrane Lpt proteins exist in a bridge state, and bridges persist for 5-10 s, showing that their organization is highly dynamic. LPS facilitates Lpt bridge formation, suggesting a mechanism by which the production of LPS can be directly coupled to its transport. Finally, the bridge decay kinetics suggest that there may be two different types of bridges, whose stability differs according to the presence (long-lived) or absence (short-lived) of LPS. Together, our data support a model in which LPS is both a substrate and a structural component of dynamic Lpt bridges that promote outer membrane assembly.
Collapse
Affiliation(s)
- Lisa Törk
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Caitlin B Moffatt
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Thomas G Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Boston, MA, USA
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
| |
Collapse
|
13
|
Kobayashi M, Noguchi H, Sato G, Watanabe C, Fujiwara K, Yanagisawa M. Phase-Separated Giant Liposomes for Stable Elevation of α-Hemolysin Concentration in Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11481-11489. [PMID: 37531551 DOI: 10.1021/acs.langmuir.3c02019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Staphylococcus aureus α-hemolysin (αHL) is one of the most popular proteins in nanopore experiments within lipid membranes. Higher concentrations of αHL within the lipid membrane are desirable to enhance the mass transport capacity through nanopores. However, the reconstitution of αHL at high concentrations is associated with the problem of membrane lytic disruption. In this study, we present a method that effectively increases αHL concentration while maintaining membrane stability. This method is achieved by using phase-separated giant liposomes, where coexisting liquid-disordered (Ld) and liquid-ordered phases (Lo) are enriched in unsaturated lipids and saturated lipids with cholesterol (Chol), respectively. Fluorescence observation of αHL in liposomes revealed that the presence of Chol facilitates αHL insertion into the membrane. Despite the preferential localization of αHL in the Ld phase rather than the Lo phase, the coexistence of both Lo and Ld phases prevents membrane disruption in the presence of concentrated αHL. We have explained this stabilization mechanism considering the lower membrane tension exhibited by phase-separated liposomes compared to homogeneous liposomes. Under hypertonic conditions, we have successfully increased the local concentration of αHL by invagination of the lipid-only region in the Ld phase, leaving αHL behind. This method exhibits potential for the reconstitution of various nanochannels and membrane proteins that prefer the Ld phase over the Lo phase, thus enabling the production of giant liposomes at high concentrations and the replication of the membrane-crowding condition observed in cells.
Collapse
Affiliation(s)
- Mizuki Kobayashi
- Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
- Graduate School of Arts and Sciences, Komaba Institute for Science, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
| | - Hiroshi Noguchi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Graduate School of Science, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Gaku Sato
- Department of Biosciences and Informatics, Keio University, Kohoku-ku, Yokohama 223-8522, Japan
| | - Chiho Watanabe
- Graduate School of Arts and Sciences, Komaba Institute for Science, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
- School of Integrated Arts and Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama, Higashi, Hiroshima 739-8521, Japan
| | - Kei Fujiwara
- Department of Biosciences and Informatics, Keio University, Kohoku-ku, Yokohama 223-8522, Japan
| | - Miho Yanagisawa
- Graduate School of Arts and Sciences, Komaba Institute for Science, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
- Graduate School of Science, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
| |
Collapse
|
14
|
Abellon-Ruiz J, Jana K, Silale A, Frey AM, Baslé A, Trost M, Kleinekathöfer U, van den Berg B. BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B 12 uptake in gut Bacteroides. Nat Commun 2023; 14:4714. [PMID: 37543597 PMCID: PMC10404256 DOI: 10.1038/s41467-023-40427-2] [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: 11/25/2022] [Accepted: 07/27/2023] [Indexed: 08/07/2023] Open
Abstract
Vitamin B12 (cobalamin) is required for most human gut microbes, many of which are dependent on scavenging to obtain this vitamin. Since bacterial densities in the gut are extremely high, competition for this keystone micronutrient is severe. Contrasting with Enterobacteria, members of the dominant genus Bacteroides often encode several BtuB vitamin B12 outer membrane transporters together with a conserved array of surface-exposed B12-binding lipoproteins. Here we show that the BtuB transporters from Bacteroides thetaiotaomicron form stable, pedal bin-like complexes with surface-exposed BtuG lipoprotein lids, which bind B12 with high affinities. Closing of the BtuG lid following B12 capture causes destabilisation of the bound B12 by a conserved BtuB extracellular loop, causing translocation of the vitamin to BtuB and subsequent transport. We propose that TonB-dependent, lipoprotein-assisted small molecule uptake is a general feature of Bacteroides spp. that is important for the success of this genus in colonising the human gut.
Collapse
Affiliation(s)
- Javier Abellon-Ruiz
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Kalyanashis Jana
- School of Science, Constructor University, Campus Ring 1, 28759, Bremen, Germany
| | - Augustinas Silale
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Andrew M Frey
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Arnaud Baslé
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Matthias Trost
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | | | - Bert van den Berg
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| |
Collapse
|
15
|
Hockenberry A, Radiom M, Arnoldini M, Turgay Y, Dunne M, Adamcik J, Stadtmueller B, Mezzenga R, Ackermann M, Slack E. Nanoscale clustering by O-antigen-Secretory Immunoglobulin-A binding limits outer membrane diffusion by encaging individual Salmonella cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.13.548943. [PMID: 37503073 PMCID: PMC10369997 DOI: 10.1101/2023.07.13.548943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Secreted immunoglobulins, predominantly SIgA, influence the colonization and pathogenicity of mucosal bacteria. While part of this effect can be explained by SIgA-mediated bacterial aggregation, we have an incomplete picture of how SIgA binding influences cells independently of aggregation. Here we show that akin to microscale crosslinking of cells, SIgA targeting the Salmonella Typhimurium O-antigen extensively crosslinks the O-antigens on the surface of individual bacterial cells at the nanoscale. This crosslinking results in an essentially immobilized bacterial outer membrane. Membrane immobilization, combined with Bam-complex mediated outer membrane protein insertion results in biased inheritance of IgA-bound O-antigen, concentrating SIgA-bound O-antigen at the oldest poles during cell growth. By combining empirical measurements and simulations, we show that this SIgA-driven biased inheritance increases the rate at which phase-varied daughter cells become IgA-free: a process that can accelerate IgA escape via phase-variation of O-antigen structure. Our results show that O-antigen-crosslinking by SIgA impacts workings of the bacterial outer membrane, helping to mechanistically explain how SIgA may exert aggregation-independent effects on individual microbes colonizing the mucosae.
Collapse
|
16
|
Wimalasiri VW, Jurczak KA, Wieliniec MK, Nilaweera TD, Nakamoto RK, Cafiso DS. A disulfide chaperone knockout facilitates spin labeling and pulse EPR spectroscopy of outer membrane transporters. Protein Sci 2023; 32:e4704. [PMID: 37312651 PMCID: PMC10288552 DOI: 10.1002/pro.4704] [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: 02/17/2023] [Revised: 05/18/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023]
Abstract
Pulse EPR measurements provide information on distances and distance distributions in proteins but require the incorporation of pairs of spin labels that are usually attached to engineered cysteine residues. In previous work, we demonstrated that efficient in vivo labeling of the Escherichia coli outer membrane vitamin B12 transporter, BtuB, could only be achieved using strains defective in the periplasmic disulfide bond formation (Dsb) system. Here, we extend these in vivo measurements to FecA, the E. coli ferric citrate transporter. As seen for BtuB, pairs of cysteines cannot be labeled when the protein is present in a standard expression strain. However, incorporating plasmids that permit an arabinose induced expression of FecA into a strain defective in the thiol disulfide oxidoreductase, DsbA, enables efficient spin-labeling and pulse EPR of FecA in cells. A comparison of the measurements made on FecA in cells with measurements made in reconstituted phospholipid bilayers suggests that the cellular environment alters the behavior of the extracellular loops of FecA. In addition to these in situ EPR measurements, the use of a DsbA minus strain for the expression of BtuB improves the EPR signals and pulse EPR data obtained in vitro from BtuB that is labeled, purified, and reconstituted into phospholipid bilayers. The in vitro data also indicate the presence of intermolecular BtuB-BtuB interactions, which had not previously been observed in a reconstituted bilayer system. This result suggests that in vitro EPR measurements on other outer membrane proteins would benefit from protein expression in a DsbA minus strain.
Collapse
Affiliation(s)
- Viranga W. Wimalasiri
- Department of Chemistry and Center for Membrane BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Kinga A. Jurczak
- Department of Chemistry and Center for Membrane BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Monika K. Wieliniec
- Department of Chemistry and Center for Membrane BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Thushani D. Nilaweera
- Department of Chemistry and Center for Membrane BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
- Present address:
Genetics and Biochemistry BranchNational Institute of Diabetes and Digestive and Kidney DiseasesBethesdaMarylandUSA
| | - Robert K. Nakamoto
- Department of Molecular Physiology and Biological PhysicsUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - David S. Cafiso
- Department of Chemistry and Center for Membrane BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
| |
Collapse
|
17
|
White JBR, Silale A, Feasey M, Heunis T, Zhu Y, Zheng H, Gajbhiye A, Firbank S, Baslé A, Trost M, Bolam DN, van den Berg B, Ranson NA. Outer membrane utilisomes mediate glycan uptake in gut Bacteroidetes. Nature 2023:10.1038/s41586-023-06146-w. [PMID: 37286596 DOI: 10.1038/s41586-023-06146-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 04/27/2023] [Indexed: 06/09/2023]
Abstract
Bacteroidetes are abundant members of the human microbiota, utilizing a myriad of diet- and host-derived glycans in the distal gut1. Glycan uptake across the bacterial outer membrane of these bacteria is mediated by SusCD protein complexes, comprising a membrane-embedded barrel and a lipoprotein lid, which is thought to open and close to facilitate substrate binding and transport. However, surface-exposed glycan-binding proteins and glycoside hydrolases also play critical roles in the capture, processing and transport of large glycan chains. The interactions between these components in the outer membrane are poorly understood, despite being crucial for nutrient acquisition by our colonic microbiota. Here we show that for both the levan and dextran utilization systems of Bacteroides thetaiotaomicron, the additional outer membrane components assemble on the core SusCD transporter, forming stable glycan-utilizing machines that we term utilisomes. Single-particle cryogenic electron microscopy structures in the absence and presence of substrate reveal concerted conformational changes that demonstrate the mechanism of substrate capture, and rationalize the role of each component in the utilisome.
Collapse
Affiliation(s)
- Joshua B R White
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Augustinas Silale
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Matthew Feasey
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Tiaan Heunis
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Yiling Zhu
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Hong Zheng
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Akshada Gajbhiye
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Susan Firbank
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Arnaud Baslé
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Matthias Trost
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - David N Bolam
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Bert van den Berg
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
| | - Neil A Ranson
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| |
Collapse
|
18
|
Overly Cottom C, Stephenson R, Wilson L, Noinaj N. Targeting BAM for Novel Therapeutics against Pathogenic Gram-Negative Bacteria. Antibiotics (Basel) 2023; 12:679. [PMID: 37107041 PMCID: PMC10135246 DOI: 10.3390/antibiotics12040679] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 04/29/2023] Open
Abstract
The growing emergence of multidrug resistance in bacterial pathogens is an immediate threat to human health worldwide. Unfortunately, there has not been a matching increase in the discovery of new antibiotics to combat this alarming trend. Novel contemporary approaches aimed at antibiotic discovery against Gram-negative bacterial pathogens have expanded focus to also include essential surface-exposed receptors and protein complexes, which have classically been targeted for vaccine development. One surface-exposed protein complex that has gained recent attention is the β-barrel assembly machinery (BAM), which is conserved and essential across all Gram-negative bacteria. BAM is responsible for the biogenesis of β-barrel outer membrane proteins (β-OMPs) into the outer membrane. These β-OMPs serve essential roles for the cell including nutrient uptake, signaling, and adhesion, but can also serve as virulence factors mediating pathogenesis. The mechanism for how BAM mediates β-OMP biogenesis is known to be dynamic and complex, offering multiple modes for inhibition by small molecules and targeting by larger biologics. In this review, we introduce BAM and establish why it is a promising and exciting new therapeutic target and present recent studies reporting novel compounds and vaccines targeting BAM across various bacteria. These reports have fueled ongoing and future research on BAM and have boosted interest in BAM for its therapeutic promise in combatting multidrug resistance in Gram-negative bacterial pathogens.
Collapse
Affiliation(s)
- Claire Overly Cottom
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Robert Stephenson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lindsey Wilson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Nicholas Noinaj
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
- Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
19
|
Surveying membrane landscapes: a new look at the bacterial cell surface. Nat Rev Microbiol 2023:10.1038/s41579-023-00862-w. [PMID: 36828896 DOI: 10.1038/s41579-023-00862-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 02/26/2023]
Abstract
Recent studies applying advanced imaging techniques are changing the way we understand bacterial cell surfaces, bringing new knowledge on everything from single-cell heterogeneity in bacterial populations to their drug sensitivity and mechanisms of antimicrobial resistance. In both Gram-positive and Gram-negative bacteria, the outermost surface of the bacterial cell is being imaged at nanoscale; as a result, topographical maps of bacterial cell surfaces can be constructed, revealing distinct zones and specific features that might uniquely identify each cell in a population. Functionally defined assembly precincts for protein insertion into the membrane have been mapped at nanoscale, and equivalent lipid-assembly precincts are suggested from discrete lipopolysaccharide patches. As we review here, particularly for Gram-negative bacteria, the applications of various modalities of nanoscale imaging are reawakening our curiosity about what is conceptually a 3D cell surface landscape: what it looks like, how it is made and how it provides resilience to respond to environmental impacts.
Collapse
|
20
|
Hodges FJ, Torres VVL, Cunningham AF, Henderson IR, Icke C. Redefining the bacterial Type I protein secretion system. Adv Microb Physiol 2023; 82:155-204. [PMID: 36948654 DOI: 10.1016/bs.ampbs.2022.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type I secretion systems (T1SS) are versatile molecular machines for protein transport across the Gram-negative cell envelope. The archetypal Type I system mediates secretion of the Escherichia coli hemolysin, HlyA. This system has remained the pre-eminent model of T1SS research since its discovery. The classic description of a T1SS is composed of three proteins: an inner membrane ABC transporter, a periplasmic adaptor protein and an outer membrane factor. According to this model, these components assemble to form a continuous channel across the cell envelope, an unfolded substrate molecule is then transported in a one-step mechanism, directly from the cytosol to the extracellular milieu. However, this model does not encapsulate the diversity of T1SS that have been characterized to date. In this review, we provide an updated definition of a T1SS, and propose the subdivision of this system into five subgroups. These subgroups are categorized as T1SSa for RTX proteins, T1SSb for non-RTX Ca2+-binding proteins, T1SSc for non-RTX proteins, T1SSd for class II microcins, and T1SSe for lipoprotein secretion. Although often overlooked in the literature, these alternative mechanisms of Type I protein secretion offer many avenues for biotechnological discovery and application.
Collapse
Affiliation(s)
- Freya J Hodges
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Von Vergel L Torres
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Adam F Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Ian R Henderson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Christopher Icke
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| |
Collapse
|
21
|
Abstract
This review focuses on nonlytic outer membrane vesicles (OMVs), a subtype of bacterial extracellular vesicles (BEVs) produced by Gram-negative organisms focusing on the mechanisms of their biogenesis, cargo, and function. Throughout, we highlight issues concerning the characterization of OMVs and distinguishing them from other types of BEVs. We also highlight the shortcomings of commonly used methodologies for the study of BEVs that impact the interpretation of their functionality and suggest solutions to standardize protocols for OMV studies.
Collapse
Affiliation(s)
| | - Simon R. Carding
- Quadram Institute Bioscience, Norwich, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom
| |
Collapse
|
22
|
Kikuchi Y, Toyofuku M, Ichinaka Y, Kiyokawa T, Obana N, Nomura N, Taoka A. Physical Properties and Shifting of the Extracellular Membrane Vesicles Attached to Living Bacterial Cell Surfaces. Microbiol Spectr 2022; 10:e0216522. [PMID: 36383005 PMCID: PMC9769862 DOI: 10.1128/spectrum.02165-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 11/02/2022] [Indexed: 11/18/2022] Open
Abstract
Bacterial cells release nanometer-sized extracellular membrane vesicles (MVs) to deliver cargo molecules for use in mediating various biological processes. However, the detailed processes of transporting these cargos from MVs to recipient cells remain unclear because of the lack of imaging techniques to image nanometer-sized fragile vesicles in a living bacterial cell surface. Herein, we quantitatively demonstrated that the direct binding of MV to the cell surface significantly promotes hydrophobic quorum-sensing signal (C16-HSL) transportation to the recipient cells. Moreover, we analyzed the MV-binding process in the Paracoccus denitrificans cell surface using high-speed atomic force microscopy phase imaging. Although MV shapes were unaltered after binding to the cell surface, the physical properties of a group of single MV particles were shifted. Additionally, the phase shift values of MVs were higher than that of the cell's surfaces upon binding, whereas the phase shift values of the group of MVs were decreased during observation. The shifting physical properties occurred irreversibly only once for each MV during the observations. The decreasing phase shift values indicated alterations of chemical components in the MVs as well, thereby suggesting the dynamic process in which single MV particles deliver their hydrophobic cargo into the recipient cell. IMPORTANCE Compared to the increasing knowledge about MV release mechanisms from donor cells, the mechanism by which recipient cells receive cargo from MVs remains unknown. Herein, we have successfully imaged single MV-binding processes in living bacterial cell surfaces. Accordingly, we confirmed the shift in the MV hydrophobic properties after landing on the cell surface. Our results showed the detailed states and the attaching process of a single MV into the cell surface and can aid the development of a new model for MV reception into Gram-negative bacterial cell surfaces. The insight provided by this study is significant for understanding MV-mediated cell-cell communication mechanisms. Moreover, the AFM technique presented for nanometer-scaled mapping of dynamic physical properties alteration on a living cell could be applied for the analyses of various biological phenomena occurring on the cell surface, and it gives us a new view into the understanding of the phenotypes of the bacterial cell surface.
Collapse
Affiliation(s)
- Yousuke Kikuchi
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Japan
| | - Masanori Toyofuku
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
- Suntory Rising Stars Encouragement Program in Life Sciences (SunRiSE), Seika, Kyoto, Japan
| | - Yuki Ichinaka
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
| | - Tatsunori Kiyokawa
- Graduate of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Nozomu Obana
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
- Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Azuma Taoka
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Japan
| |
Collapse
|
23
|
Webby MN, Oluwole AO, Pedebos C, Inns PG, Olerinyova A, Prakaash D, Housden NG, Benn G, Sun D, Hoogenboom BW, Kukura P, Mohammed S, Robinson CV, Khalid S, Kleanthous C. Lipids mediate supramolecular outer membrane protein assembly in bacteria. SCIENCE ADVANCES 2022; 8:eadc9566. [PMID: 36322653 PMCID: PMC9629720 DOI: 10.1126/sciadv.adc9566] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
β Barrel outer membrane proteins (OMPs) cluster into supramolecular assemblies that give function to the outer membrane (OM) of Gram-negative bacteria. How such assemblies form is unknown. Here, through photoactivatable cross-linking into the Escherichia coli OM, coupled with simulations, and biochemical and biophysical analysis, we uncover the basis for OMP clustering in vivo. OMPs are typically surrounded by an annular shell of asymmetric lipids that mediate higher-order complexes with neighboring OMPs. OMP assemblies center on the abundant porins OmpF and OmpC, against which low-abundance monomeric β barrels, such as TonB-dependent transporters, are packed. Our study reveals OMP-lipid-OMP complexes to be the basic unit of supramolecular OMP assembly that, by extending across the entire cell surface, couples the requisite multifunctionality of the OM to its stability and impermeability.
Collapse
Affiliation(s)
- Melissa N. Webby
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Abraham O. Oluwole
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford OX1 3QZ, UK
| | - Conrado Pedebos
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Patrick G. Inns
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Anna Olerinyova
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Dheeraj Prakaash
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Nicholas G. Housden
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Georgina Benn
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Dawei Sun
- Structural Biology, Genentech Inc., South San Francisco, USA
| | - Bart W. Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
- Department of Physics and Astronomy, University College London, WC1E 6BT London, UK
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Shabaz Mohammed
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3QZ, UK
- Mechanistic Proteomics, Rosalind Franklin Institute, Harwell Campus, Didcot OX11 OFA, UK
| | - Carol V. Robinson
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford OX1 3QZ, UK
| | - Syma Khalid
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Colin Kleanthous
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| |
Collapse
|
24
|
Svirina A, Chamachi N, Schlierf M. Single‐molecule approaches reveal outer membrane protein biogenesis dynamics. Bioessays 2022; 44:e2200149. [DOI: 10.1002/bies.202200149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Anna Svirina
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
| | - Neharika Chamachi
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
| | - Michael Schlierf
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
- Cluster of Excellence Physics of Life Technische Universität Dresden Dresden Germany
| |
Collapse
|
25
|
Watkins DW, Williams SL, Collinson I. A bacterial secretosome for regulated envelope biogenesis and quality control? MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36260397 DOI: 10.1099/mic.0.001255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Gram-negative bacterial envelope is the first line of defence against environmental stress and antibiotics. Therefore, its biogenesis is of considerable fundamental interest, as well as a challenge to address the growing problem of antimicrobial resistance. All bacterial proteins are synthesised in the cytosol, so inner- and outer-membrane proteins, and periplasmic residents have to be transported to their final destinations via specialised protein machinery. The Sec translocon, a ubiquitous integral inner-membrane (IM) complex, is key to this process as the major gateway for protein transit from the cytosol to the cell envelope; this can be achieved during their translation, or afterwards. Proteins need to be directed into the inner-membrane (usually co-translational), otherwise SecA utilises ATP and the proton-motive-force (PMF) to drive proteins across the membrane post-translationally. These proteins are then picked up by chaperones for folding in the periplasm, or delivered to the β-barrel assembly machinery (BAM) for incorporation into the outer-membrane. The core hetero-trimeric SecYEG-complex forms the hub for an extensive network of interactions that regulate protein delivery and quality control. Here, we conduct a biochemical exploration of this 'secretosome' -a very large, versatile and inter-changeable assembly with the Sec-translocon at its core; featuring interactions that facilitate secretion (SecDF), inner- and outer-membrane protein insertion (respectively, YidC and BAM), protein folding and quality control (e.g. PpiD, YfgM and FtsH). We propose the dynamic interplay amongst these, and other factors, act to ensure efficient envelope biogenesis, regulated to accommodate the requirements of cell elongation and division. We believe this organisation is critical for cell wall biogenesis and remodelling and thus its perturbation could be a means for the development of anti-microbials.
Collapse
Affiliation(s)
- Daniel W Watkins
- School of Biochemistry, University of Bristol, BS8 1TD, UK.,Present address: CytoSeek, Science Creates Old Market, Midland Road, Bristol, BS20JZ, UK
| | | | - Ian Collinson
- School of Biochemistry, University of Bristol, BS8 1TD, UK
| |
Collapse
|
26
|
Xiang S, Pinto C, Baldus M. Divide and Conquer: A Tailored Solid‐state NMR Approach to Study Large Membrane Protein Complexes. Angew Chem Int Ed Engl 2022; 61:e202203319. [PMID: 35712982 PMCID: PMC9540533 DOI: 10.1002/anie.202203319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Indexed: 11/18/2022]
Abstract
Membrane proteins are known to exert many essential biological functions by forming complexes in cell membranes. An example refers to the β‐barrel assembly machinery (BAM), a 200 kDa pentameric complex containing BAM proteins A–E that catalyzes the essential process of protein insertion into the outer membrane of gram‐negative bacteria. While progress has been made in capturing three‐dimensional structural snapshots of the BAM complex, the role of the lipoprotein BamC in the complex assembly in functional lipid bilayers has remained unclear. We have devised a component‐selective preparation scheme to directly study BamC as part of the entire BAM complex in lipid bilayers. Combination with proton‐detected solid‐state NMR methods allowed us to probe the structure, dynamics, and supramolecular topology of full‐length BamC embedded in the entire complex in lipid bilayers. Our approach may help decipher how individual proteins contribute to the dynamic formation and functioning of membrane protein complexes in membranes.
Collapse
Affiliation(s)
- ShengQi Xiang
- NMR Spectroscopy Bijvoet Center for Biomolecular Research Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands
- MOE Key Lab for Cellular Dynamics School of Life Sciences University of Science and Technology of China 96 Jinzhai Road Hefei 230026 Anhui China
| | - Cecilia Pinto
- NMR Spectroscopy Bijvoet Center for Biomolecular Research Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands
- Current address: Department of Bionanoscience Kavli Institute of Nanoscience Delft University of Technology Van der Maasweg 9 2629 H. Z. Delft The Netherlands
| | - Marc Baldus
- NMR Spectroscopy Bijvoet Center for Biomolecular Research Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands
| |
Collapse
|
27
|
Xiang S, Pinto C, Baldus M. Divide and Conquer: A Tailored Solid‐state NMR Approach to Study Large Membrane Protein Complexes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- ShengQi Xiang
- University of Science and Technology of China, Anhui, MOE Key lab for Cellular Dynamics CHINA
| | - Cecilia Pinto
- Delft University of Technology: Technische Universiteit Delft Department of Bionanoscience NETHERLANDS
| | - Marc Baldus
- Utrecht University Bijvoet Center for Biomolecular Research Padualaan 8 3584 Utrecht NETHERLANDS
| |
Collapse
|
28
|
Dynamic interplay between the periplasmic chaperone SurA and the BAM complex in outer membrane protein folding. Commun Biol 2022; 5:560. [PMID: 35676411 PMCID: PMC9177699 DOI: 10.1038/s42003-022-03502-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 05/18/2022] [Indexed: 12/12/2022] Open
Abstract
Correct folding of outer membrane proteins (OMPs) into the outer membrane of Gram-negative bacteria depends on delivery of unfolded OMPs to the β-barrel assembly machinery (BAM). How unfolded substrates are presented to BAM remains elusive, but the major OMP chaperone SurA is proposed to play a key role. Here, we have used hydrogen deuterium exchange mass spectrometry (HDX-MS), crosslinking, in vitro folding and binding assays and computational modelling to show that the core domain of SurA and one of its two PPIase domains are key to the SurA-BAM interaction and are required for maximal catalysis of OMP folding. We reveal that binding causes changes in BAM and SurA conformation and/or dynamics distal to the sites of binding, including at the BamA β1-β16 seam. We propose a model for OMP biogenesis in which SurA plays a crucial role in OMP delivery and primes BAM to accept substrates for folding. Interaction of the outer membrane protein (OMP) chaperone SurA and the OMP folding catalyst BAM results in changes in the conformational ensembles of both species, suggesting a mechanism for delivery of OMPs to BAM in Gram-negative bacteria.
Collapse
|
29
|
Mamou G, Corona F, Cohen-Khait R, Housden NG, Yeung V, Sun D, Sridhar P, Pazos M, Knowles TJ, Kleanthous C, Vollmer W. Peptidoglycan maturation controls outer membrane protein assembly. Nature 2022; 606:953-959. [PMID: 35705811 PMCID: PMC9242858 DOI: 10.1038/s41586-022-04834-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 05/05/2022] [Indexed: 11/12/2022]
Abstract
Linkages between the outer membrane of Gram-negative bacteria and the peptidoglycan layer are crucial for the maintenance of cellular integrity and enable survival in challenging environments1–5. The function of the outer membrane is dependent on outer membrane proteins (OMPs), which are inserted into the membrane by the β-barrel assembly machine6,7 (BAM). Growing Escherichia coli cells segregate old OMPs towards the poles by a process known as binary partitioning, the basis of which is unknown8. Here we demonstrate that peptidoglycan underpins the spatiotemporal organization of OMPs. Mature, tetrapeptide-rich peptidoglycan binds to BAM components and suppresses OMP foldase activity. Nascent peptidoglycan, which is enriched in pentapeptides and concentrated at septa9, associates with BAM poorly and has little effect on its activity, leading to preferential insertion of OMPs at division sites. The synchronization of OMP biogenesis with cell wall growth results in the binary partitioning of OMPs as cells divide. Our study reveals that Gram-negative bacteria coordinate the assembly of two major cell envelope layers by rendering OMP biogenesis responsive to peptidoglycan maturation, a potential vulnerability that could be exploited in future antibiotic design. Peptidoglycan stem peptides in the Gram-negative bacterial cell wall regulate the insertion of essential outer membrane proteins, thus representing a potential target for antibiotic design.
Collapse
Affiliation(s)
- Gideon Mamou
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Federico Corona
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.,Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ruth Cohen-Khait
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Nicholas G Housden
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Vivian Yeung
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Dawei Sun
- Structural Biology, Genentech, South San Francisco, CA, USA
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Manuel Pazos
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.,Department of Molecular Biology, Center of Molecular Biology 'Severo Ochoa' (UAM-CSIC), Autonomous University of Madrid, Madrid, Spain
| | | | - Colin Kleanthous
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK.
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.
| |
Collapse
|
30
|
|
31
|
Ginez LD, Osorio A, Vázquez-Ramírez R, Arenas T, Mendoza L, Camarena L, Poggio S. Changes in fluidity of the E. coli outer membrane in response to temperature, divalent cations and polymyxin-B show two different mechanisms of membrane fluidity adaptation. FEBS J 2022; 289:3550-3567. [PMID: 35038363 DOI: 10.1111/febs.16358] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/23/2021] [Accepted: 01/13/2022] [Indexed: 12/28/2022]
Abstract
The outer membrane (OM) is an essential component of the Gram-negative bacterial cell envelope. Restricted diffusion of integral OM proteins and lipopolysaccharide (LPS) that constitute the outer leaflet of the OM support a model in which the OM is in a semi-crystalline state. The low fluidity of the OM has been suggested to be an important property of this membrane that even contributes to cell rigidity. The LPS characteristics strongly determine the properties of the OM and the LPS layer fluidity has been measured using different techniques that require specific conditions or are technically challenging. Here, we characterize the Escherichia coli LPS fluidity by evaluating the lateral diffusion of the styryl dye FM4-64FX in fluorescence recovery after photobleaching experiments. This technique allowed us to determine the effect of different conditions and genetic backgrounds on the LPS fluidity. Our results show that a fraction of the LPS can slowly diffuse and that the fluidity of the LPS layer adapts by modifying the diffusion of the LPS and the fraction of mobile LPS molecules.
Collapse
Affiliation(s)
- Luis David Ginez
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Aurora Osorio
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Ricardo Vázquez-Ramírez
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Thelma Arenas
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Luis Mendoza
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Laura Camarena
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| | - Sebastian Poggio
- Departamento Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
| |
Collapse
|
32
|
Doyle MT, Bernstein HD. Function of the Omp85 Superfamily of Outer Membrane Protein Assembly Factors and Polypeptide Transporters. Annu Rev Microbiol 2022; 76:259-279. [PMID: 35650668 DOI: 10.1146/annurev-micro-033021-023719] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Omp85 protein superfamily is found in the outer membrane (OM) of all gram-negative bacteria and eukaryotic organelles of bacterial origin. Members of the family catalyze both the membrane insertion of β-barrel proteins and the translocation of proteins across the OM. Although the mechanism(s) by which these proteins function is unclear, striking new insights have emerged from recent biochemical and structural studies. In this review we discuss the entire Omp85 superfamily but focus on the function of the best-studied member, BamA, which is an essential and highly conserved component of the bacterial barrel assembly machinery (BAM). Because BamA has multiple functions that overlap with those of other Omp85 proteins, it is likely the prototypical member of the Omp85 superfamily. Furthermore, BamA has become a protein of great interest because of the recent discovery of small-molecule inhibitors that potentially represent an important new class of antibiotics. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Matthew Thomas Doyle
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA; ,
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA; ,
| |
Collapse
|
33
|
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: 93] [Impact Index Per Article: 46.5] [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.
Collapse
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.
| |
Collapse
|
34
|
Doyle MT, Jimah JR, Dowdy T, Ohlemacher SI, Larion M, Hinshaw JE, Bernstein HD. Cryo-EM structures reveal multiple stages of bacterial outer membrane protein folding. Cell 2022; 185:1143-1156.e13. [PMID: 35294859 DOI: 10.1016/j.cell.2022.02.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/01/2021] [Accepted: 02/13/2022] [Indexed: 02/08/2023]
Abstract
Transmembrane β barrel proteins are folded into the outer membrane (OM) of Gram-negative bacteria by the β barrel assembly machinery (BAM) via a poorly understood process that occurs without known external energy sources. Here, we used single-particle cryo-EM to visualize the folding dynamics of a model β barrel protein (EspP) by BAM. We found that BAM binds the highly conserved "β signal" motif of EspP to correctly orient β strands in the OM during folding. We also found that the folding of EspP proceeds via "hybrid-barrel" intermediates in which membrane integrated β sheets are attached to the essential BAM subunit, BamA. The structures show an unprecedented deflection of the membrane surrounding the EspP intermediates and suggest that β sheets progressively fold toward BamA to form a β barrel. Along with in vivo experiments that tracked β barrel folding while the OM tension was modified, our results support a model in which BAM harnesses OM elasticity to accelerate β barrel folding.
Collapse
Affiliation(s)
- Matthew Thomas Doyle
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - John R Jimah
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tyrone Dowdy
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shannon I Ohlemacher
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mioara Larion
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jenny E Hinshaw
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
35
|
Khalid S, Schroeder C, Bond PJ, Duncan AL. What have molecular simulations contributed to understanding of Gram-negative bacterial cell envelopes? MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35294337 PMCID: PMC9558347 DOI: 10.1099/mic.0.001165] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacterial cell envelopes are compositionally complex and crowded and while highly dynamic in some areas, their molecular motion is very limited, to the point of being almost static in others. Therefore, it is no real surprise that studying them at high resolution across a range of temporal and spatial scales requires a number of different techniques. Details at atomistic to molecular scales for up to tens of microseconds are now within range for molecular dynamics simulations. Here we review how such simulations have contributed to our current understanding of the cell envelopes of Gram-negative bacteria.
Collapse
Affiliation(s)
- Syma Khalid
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Cyril Schroeder
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Peter J Bond
- Bioinformatics Institute (A*STAR), Singapore 138671, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| |
Collapse
|
36
|
Budiardjo SJ, Stevens JJ, Calkins AL, Ikujuni AP, Wimalasena VK, Firlar E, Case DA, Biteen JS, Kaelber JT, Slusky JSG. Colicin E1 opens its hinge to plug TolC. eLife 2022; 11:73297. [PMID: 35199644 PMCID: PMC9020818 DOI: 10.7554/elife.73297] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 02/21/2022] [Indexed: 12/02/2022] Open
Abstract
The double membrane architecture of Gram-negative bacteria forms a barrier that is impermeable to most extracellular threats. Bacteriocin proteins evolved to exploit the accessible, surface-exposed proteins embedded in the outer membrane to deliver cytotoxic cargo. Colicin E1 is a bacteriocin produced by, and lethal to, Escherichia coli that hijacks the outer membrane proteins (OMPs) TolC and BtuB to enter the cell. Here, we capture the colicin E1 translocation domain inside its membrane receptor, TolC, by high-resolution cryo-electron microscopy to obtain the first reported structure of a bacteriocin bound to TolC. Colicin E1 binds stably to TolC as an open hinge through the TolC pore—an architectural rearrangement from colicin E1’s unbound conformation. This binding is stable in live E. coli cells as indicated by single-molecule fluorescence microscopy. Finally, colicin E1 fragments binding to TolC plug the channel, inhibiting its native efflux function as an antibiotic efflux pump, and heightening susceptibility to three antibiotic classes. In addition to demonstrating that these protein fragments are useful starting points for developing novel antibiotic potentiators, this method could be expanded to other colicins to inhibit other OMP functions. Bacteria are constantly warring with each other for space and resources. As a result, they have developed a range of molecular weapons to poison, damage or disable other cells. For instance, bacteriocins are proteins that can latch onto structures at the surface of enemy bacteria and push toxins through their outer membrane. Bacteria are increasingly resistant to antibiotics, representing a growing concern for modern healthcare. One way that they are able to survive is by using ‘efflux pumps’ studded through their external membranes to expel harmful drugs before these can cause damage. Budiardjo et al. wanted to test whether bacteriocins could interfere with this defence mechanism by blocking efflux pumps. Bacteriocins are usually formed of binding elements (which recognise specific target proteins) and of a ‘killer tail’ that can stab the cell. Experiments showed that the binding parts of a bacteriocin could effectively ‘plug’ efflux pumps in Escherichia coli bacteria: high-resolution molecular microscopy revealed how the bacteriocin fragment binds to the pump, while fluorescent markers showed that it attached to the surface of E. coli and stopped the efflux pumps from working. As a result, lower amounts of antibiotics were necessary to kill the bacteria when bacteriocins were present. The work by Budiardjo et al. could lead to new ways to combat bacteria that will reduce the need for current antibiotics. In the future, bacteriocins could also be harnessed to target other proteins than efflux pumps, allowing scientists to manipulate a range of bacterial processes.
Collapse
Affiliation(s)
- S Jimmy Budiardjo
- Center for Computational Biology, University of Kansas, Lawrence, United States
| | - Jacqueline J Stevens
- Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Anna L Calkins
- Department of Chemistry, University of Michigan, Ann Arbor, United States
| | - Ayotunde P Ikujuni
- Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | | | - Emre Firlar
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, United States
| | - David A Case
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, United States
| | - Julie S Biteen
- Department of Chemistry, University of Michigan, Ann Arbor, United States
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, United States
| | - Joanna S G Slusky
- Center for Computational Biology, University of Kansas, Lawrence, United States
| |
Collapse
|
37
|
Vendrell-Fernández S, Lozano-Picazo P, Cuadros-Sánchez P, Tejero-Ojeda MM, Giraldo R. Conversion of the OmpF Porin into a Device to Gather Amyloids on the E. coli Outer Membrane. ACS Synth Biol 2022; 11:655-667. [PMID: 34852197 DOI: 10.1021/acssynbio.1c00347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protein amyloids are ubiquitous in natural environments. They typically originate from microbial secretions or spillages from mammals infected by prions, currently raising concerns about their infectivity and toxicity in contexts such as gut microbiota or soils. Exploiting the self-assembly potential of amyloids for their scavenging, here, we report the insertion of an amyloidogenic sequence stretch from a bacterial prion-like protein (RepA-WH1) in one of the extracellular loops (L5) of the abundant Escherichia coli outer membrane porin OmpF. The expression of this grafted porin enables bacterial cells to trap on their envelopes the same amyloidogenic sequence when provided as an extracellular free peptide. Conversely, when immobilized on a surface as bait, the full-length prion-like protein including the amyloidogenic peptide can catch bacteria displaying the L5-grafted OmpF. Polyphenolic molecules known to inhibit amyloid assembly interfere with peptide recognition by the engineered OmpF, indicating that this is compatible with the kind of homotypic interactions expected for amyloid assembly. Our study suggests that synthetic porins may provide suitable scaffolds for engineering biosensor and clearance devices to tackle the threat posed by pathogenic amyloids.
Collapse
Affiliation(s)
- Sol Vendrell-Fernández
- Department of Microbial Biotechnology, National Centre for Biotechnology (CSIC), c/ Darwin 3, Campus Cantoblanco, 28049 Madrid, Spain
| | - Paloma Lozano-Picazo
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), c/ Ramiro de Maeztu 9, Campus Moncloa, 28040 Madrid, Spain
| | - Paula Cuadros-Sánchez
- Department of Microbial Biotechnology, National Centre for Biotechnology (CSIC), c/ Darwin 3, Campus Cantoblanco, 28049 Madrid, Spain
| | - María M. Tejero-Ojeda
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), c/ Ramiro de Maeztu 9, Campus Moncloa, 28040 Madrid, Spain
| | - Rafael Giraldo
- Department of Microbial Biotechnology, National Centre for Biotechnology (CSIC), c/ Darwin 3, Campus Cantoblanco, 28049 Madrid, Spain
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), c/ Ramiro de Maeztu 9, Campus Moncloa, 28040 Madrid, Spain
| |
Collapse
|
38
|
Vermaas JV, Mayne CG, Shinn E, Tajkhorshid E. Assembly and Analysis of Cell-Scale Membrane Envelopes. J Chem Inf Model 2022; 62:602-617. [PMID: 34910495 PMCID: PMC8903035 DOI: 10.1021/acs.jcim.1c01050] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The march toward exascale computing will enable routine molecular simulation of larger and more complex systems, for example, simulation of entire viral particles, on the scale of approximately billions of atoms─a simulation size commensurate with a small bacterial cell. Anticipating the future hardware capabilities that will enable this type of research and paralleling advances in experimental structural biology, efforts are currently underway to develop software tools, procedures, and workflows for constructing cell-scale structures. Herein, we describe our efforts in developing and implementing an efficient and robust workflow for construction of cell-scale membrane envelopes and embedding membrane proteins into them. A new approach for construction of massive membrane structures that are stable during the simulations is built on implementing a subtractive assembly technique coupled with the development of a structure concatenation tool (fastmerge), which eliminates overlapping elements based on volumetric criteria rather than adding successive molecules to the simulation system. Using this approach, we have constructed two "protocells" consisting of MARTINI coarse-grained beads to represent cellular membranes, one the size of a cellular organelle and another the size of a small bacterial cell. The membrane envelopes constructed here remain whole during the molecular dynamics simulations performed and exhibit water flux only through specific proteins, demonstrating the success of our methodology in creating tight cell-like membrane compartments. Extended simulations of these cell-scale structures highlight the propensity for nonspecific interactions between adjacent membrane proteins leading to the formation of protein microclusters on the cell surface, an insight uniquely enabled by the scale of the simulations. We anticipate that the experiences and best practices presented here will form the basis for the next generation of cell-scale models, which will begin to address the addition of soluble proteins, nucleic acids, and small molecules essential to the function of a cell.
Collapse
Affiliation(s)
- Josh V. Vermaas
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401
| | - Christopher G. Mayne
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Eric Shinn
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| |
Collapse
|
39
|
Hermansen S, Linke D, Leo JC. Transmembrane β-barrel proteins of bacteria: From structure to function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:113-161. [PMID: 35034717 DOI: 10.1016/bs.apcsb.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The outer membrane of Gram-negative bacteria is a specialized organelle conferring protection to the cell against various environmental stresses and resistance to many harmful compounds. The outer membrane has a number of unique features, including an asymmetric lipid bilayer, the presence of lipopolysaccharides and an individual proteome. The vast majority of the integral transmembrane proteins in the outer membrane belongs to the family of β-barrel proteins. These evolutionarily related proteins share a cylindrical, anti-parallel β-sheet core fold spanning the outer membrane. The loops and accessory domains attached to the β-barrel allow for a remarkable versatility in function for these proteins, ranging from diffusion pores and transporters to enzymes and adhesins. We summarize the current knowledge on β-barrel structure and folding and give an overview of their functions, evolution, and potential as drug targets.
Collapse
Affiliation(s)
- Simen Hermansen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Jack C Leo
- Antimicrobial resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.
| |
Collapse
|
40
|
Mandela E, Stubenrauch CJ, Ryoo D, Hwang H, Cohen EJ, Torres VVL, Deo P, Webb CT, Huang C, Schittenhelm RB, Beeby M, Gumbart JC, Lithgow T, Hay ID. Adaptation of the periplasm to maintain spatial constraints essential for cell envelope processes and cell viability. eLife 2022; 11:73516. [PMID: 35084330 PMCID: PMC8824477 DOI: 10.7554/elife.73516] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/21/2022] [Indexed: 11/17/2022] Open
Abstract
The cell envelope of Gram-negative bacteria consists of two membranes surrounding a periplasm and peptidoglycan layer. Molecular machines spanning the cell envelope depend on spatial constraints and load-bearing forces across the cell envelope and surface. The mechanisms dictating spatial constraints across the cell envelope remain incompletely defined. In Escherichia coli, the coiled-coil lipoprotein Lpp contributes the only covalent linkage between the outer membrane and the underlying peptidoglycan layer. Using proteomics, molecular dynamics, and a synthetic lethal screen, we show that lengthening Lpp to the upper limit does not change the spatial constraint but is accommodated by other factors which thereby become essential for viability. Our findings demonstrate E. coli expressing elongated Lpp does not simply enlarge the periplasm in response, but the bacteria accommodate by a combination of tilting Lpp and reducing the amount of the covalent bridge. By genetic screening, we identified all of the genes in E. coli that become essential in order to enact this adaptation, and by quantitative proteomics discovered that very few proteins need to be up- or down-regulated in steady-state levels in order to accommodate the longer Lpp. We observed increased levels of factors determining cell stiffness, a decrease in membrane integrity, an increased membrane vesiculation and a dependance on otherwise non-essential tethers to maintain lipid transport and peptidoglycan biosynthesis. Further this has implications for understanding how spatial constraint across the envelope controls processes such as flagellum-driven motility, cellular signaling, and protein translocation
Collapse
Affiliation(s)
- Eric Mandela
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | | | - David Ryoo
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, United States
| | - Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Eli J Cohen
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Pankaj Deo
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Chaille T Webb
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Cheng Huang
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Ralf B Schittenhelm
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Morgan Beeby
- Department of Life Sciencesa, Imperial College London, London, United Kingdom
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, United States
| | - Trevor Lithgow
- Department of Microbiology, Monash University, Melbourne, Australia
| | - Iain D Hay
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| |
Collapse
|
41
|
Tan WB, Chng SS. Genetic interaction mapping highlights key roles of the Tol-Pal complex. Mol Microbiol 2022; 117:921-936. [PMID: 35066953 DOI: 10.1111/mmi.14882] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 01/20/2022] [Accepted: 01/20/2022] [Indexed: 11/30/2022]
Abstract
The conserved Tol-Pal trans-envelope complex is important for outer membrane (OM) stability and cell division in Gram-negative bacteria. It is proposed to mediate OM constriction during cell division via cell wall tethering. Yet, recent studies suggest the complex has additional roles in OM lipid homeostasis and septal wall separation. How Tol-Pal facilitates all these processes is unclear. To gain insights into its function(s), we applied transposon-insertion sequencing, and report here a detailed network of genetic interactions with the tol-pal locus in Escherichia coli. We found one positive and >20 negative strong interactions based on fitness. Disruption osmoregulated-periplasmic glucan biosynthesis restores fitness and OM barrier function, but not proper division, in tol-pal mutants. In contrast, deleting genes involved in OM homeostasis and cell wall remodeling cause synthetic growth defects in strains lacking Tol-Pal, especially exacerbating OM barrier and/or division phenotypes. Notably, the ΔtolA mutant having additional defects in OM protein assembly (ΔbamB) exhibited severe division phenotypes, even when single mutants divided normally; this highlights the possibility for OM phenotypes to indirectly impact cell division. Overall, our work underscores the intricate nature of Tol-Pal function, and reinforces its key roles in cell wall-OM tethering, cell wall remodeling, and in particular, OM homeostasis.
Collapse
Affiliation(s)
- Wee Boon Tan
- Department of Chemistry, National University of Singapore, Singapore.,Singapore Center for Environmental Life Sciences Engineering, National University of Singapore (SCELSE-NUS), Singapore
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore.,Singapore Center for Environmental Life Sciences Engineering, National University of Singapore (SCELSE-NUS), Singapore
| |
Collapse
|
42
|
Gopinath A, Joseph B. Conformational Flexibility of the Protein Insertase BamA in the Native Asymmetric Bilayer Elucidated by ESR Spectroscopy. Angew Chem Int Ed Engl 2022; 61:e202113448. [PMID: 34761852 PMCID: PMC9299766 DOI: 10.1002/anie.202113448] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Indexed: 12/15/2022]
Abstract
The β-barrel assembly machinery (BAM) consisting of the central β-barrel BamA and four other lipoproteins mediates the folding of the majority of the outer membrane proteins. BamA is placed in an asymmetric bilayer and its lateral gate is suggested to be the functional hotspot. Here we used in situ pulsed electron-electron double resonance spectroscopy to characterize BamA in the native outer membrane. In the detergent micelles, the data is consistent with mainly an inward-open conformation of BamA. The native membrane considerably enhanced the conformational heterogeneity. The lateral gate and the extracellular loop 3 exist in an equilibrium between different conformations. The outer membrane provides a favorable environment for occupying multiple conformational states independent of the lipoproteins. Our results reveal a highly dynamic behavior of the lateral gate and other key structural elements and provide direct evidence for the conformational modulation of a membrane protein in situ.
Collapse
Affiliation(s)
- Aathira Gopinath
- Institute of BiophysicsDepartment of PhysicsCenter for Biomolecular Magnetic Resonance (BMRZ)Goethe University FrankfurtMax-von-Laue-Str. 160438Frankfurt/MainGermany
| | - Benesh Joseph
- Institute of BiophysicsDepartment of PhysicsCenter for Biomolecular Magnetic Resonance (BMRZ)Goethe University FrankfurtMax-von-Laue-Str. 160438Frankfurt/MainGermany
| |
Collapse
|
43
|
Wang B, Zhong C, Tieleman DP. Supramolecular Organization of SARS-CoV and SARS-CoV-2 Virions Revealed by Coarse-Grained Models of Intact Virus Envelopes. J Chem Inf Model 2022; 62:176-186. [PMID: 34911299 PMCID: PMC8691453 DOI: 10.1021/acs.jcim.1c01240] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Indexed: 12/12/2022]
Abstract
The coronavirus disease 19 (COVID-19) pandemic is causing a global health crisis and has already caused a devastating societal and economic burden. The pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has a high sequence and architecture identity with SARS-CoV, but far more people have been infected by SARS-CoV-2. Here, combining the structural data from cryo-electron microscopy and structure prediction, we constructed bottom-up Martini coarse-grained models of intact SARS-CoV and SARS-CoV-2 envelopes. Microsecond molecular dynamics simulations were performed, allowing us to explore their dynamics and supramolecular organization. Both SARS-CoV and SARS-CoV-2 envelopes present a spherical morphology, with structural proteins forming multiple string-like islands in the membrane and clusters between the heads of spike proteins. Critical differences between the SARS-CoV and SARS-CoV-2 envelopes are the interaction pattern between the spike proteins and the flexibility of the spike proteins. Our models provide structural and dynamic insights into the SARS virus envelopes and could be used for further investigation, such as drug design and membrane fusion and fission processes.
Collapse
Affiliation(s)
- Beibei Wang
- Centre for Advanced Materials Research, Advanced
Institute of Natural Sciences, Beijing Normal University at
Zhuhai, No. 18 Jinfeng Road, Zhuhai 519087, Guangdong,
China
| | - Changqing Zhong
- Centre for Informational Biology, School of Life
Science and Technology, University of Electronic Science and Technology of
China, 2006 Xiyuan Avenue, Chengdu 611731, Sichuan,
China
| | - D. Peter Tieleman
- Department of Biological Sciences and Centre for
Molecular Simulation, University of Calgary, 2500 University
Drive North West, Calgary T2N 1N4, Alberta, Canada
| |
Collapse
|
44
|
Acinetobacter baumannii Can Survive with an Outer Membrane Lacking Lipooligosaccharide Due to Structural Support from Elongasome Peptidoglycan Synthesis. mBio 2021; 12:e0309921. [PMID: 34844428 PMCID: PMC8630537 DOI: 10.1128/mbio.03099-21] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gram-negative bacteria resist external stresses due to cell envelope rigidity, which is provided by two membranes and a peptidoglycan layer. The outer membrane (OM) surface contains lipopolysaccharide (LPS; contains O-antigen) or lipooligosaccharide (LOS). LPS/LOS are essential in most Gram-negative bacteria and may contribute to cellular rigidity. Acinetobacter baumannii is a useful tool for testing these hypotheses as it can survive without LOS. Previously, our group found that strains with naturally high levels of penicillin binding protein 1A (PBP1A) could not become LOS deficient unless the gene encoding it was deleted, highlighting the relevance of peptidoglycan biosynthesis and suggesting that high PBP1A levels were toxic during LOS deficiency. Transposon sequencing and follow-up analysis found that axial peptidoglycan synthesis by the elongasome and a peptidoglycan recycling enzyme, ElsL, were vital in LOS-deficient cells. The toxicity of high PBP1A levels during LOS deficiency was clarified to be due to a negative impact on elongasome function. Our data suggest that during LOS deficiency, the strength of the peptidoglycan specifically imparted by elongasome synthesis becomes essential, supporting that the OM and peptidoglycan contribute to cell rigidity.
Collapse
|
45
|
Müller M, Gräbnitz F, Barandun N, Shen Y, Wendt F, Steiner SN, Severin Y, Vetterli SU, Mondal M, Prudent JR, Hofmann R, van Oostrum M, Sarott RC, Nesvizhskii AI, Carreira EM, Bode JW, Snijder B, Robinson JA, Loessner MJ, Oxenius A, Wollscheid B. Light-mediated discovery of surfaceome nanoscale organization and intercellular receptor interaction networks. Nat Commun 2021; 12:7036. [PMID: 34857745 PMCID: PMC8639842 DOI: 10.1038/s41467-021-27280-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 11/09/2021] [Indexed: 12/18/2022] Open
Abstract
The molecular nanoscale organization of the surfaceome is a fundamental regulator of cellular signaling in health and disease. Technologies for mapping the spatial relationships of cell surface receptors and their extracellular signaling synapses would unlock theranostic opportunities to target protein communities and the possibility to engineer extracellular signaling. Here, we develop an optoproteomic technology termed LUX-MS that enables the targeted elucidation of acute protein interactions on and in between living cells using light-controlled singlet oxygen generators (SOG). By using SOG-coupled antibodies, small molecule drugs, biologics and intact viral particles, we demonstrate the ability of LUX-MS to decode ligand receptor interactions across organisms and to discover surfaceome receptor nanoscale organization with direct implications for drug action. Furthermore, by coupling SOG to antigens we achieved light-controlled molecular mapping of intercellular signaling within functional immune synapses between antigen-presenting cells and CD8+ T cells providing insights into T cell activation with spatiotemporal specificity. LUX-MS based decoding of surfaceome signaling architectures thereby provides a molecular framework for the rational development of theranostic strategies. The spatial organization of cell surface receptors is critical for cell signaling and drug action. Here, the authors develop an optoproteomic method for mapping surface protein interactions, revealing cellular responses to antibodies, drugs and viral particles as well as immunosynapse signaling events.
Collapse
Affiliation(s)
- Maik Müller
- Department of Health Sciences and Technology (D-HEST), ETH Zurich, Institute of Translational Medicine (ITM), Zurich, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Fabienne Gräbnitz
- Department of Biology, ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | - Niculò Barandun
- Department of Biology, ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | - Yang Shen
- Institute of Food Nutrition and Health, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Fabian Wendt
- Department of Health Sciences and Technology (D-HEST), ETH Zurich, Institute of Translational Medicine (ITM), Zurich, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Sebastian N Steiner
- Department of Health Sciences and Technology (D-HEST), ETH Zurich, Institute of Translational Medicine (ITM), Zurich, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Yannik Severin
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | | | - Milon Mondal
- Chemistry Department, University of Zurich, Zurich, Switzerland
| | | | - Raphael Hofmann
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Marc van Oostrum
- Department of Health Sciences and Technology (D-HEST), ETH Zurich, Institute of Translational Medicine (ITM), Zurich, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Roman C Sarott
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Alexey I Nesvizhskii
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Erick M Carreira
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Jeffrey W Bode
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Berend Snijder
- Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland.,Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - John A Robinson
- Chemistry Department, University of Zurich, Zurich, Switzerland
| | - Martin J Loessner
- Institute of Food Nutrition and Health, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Annette Oxenius
- Department of Biology, ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | - Bernd Wollscheid
- Department of Health Sciences and Technology (D-HEST), ETH Zurich, Institute of Translational Medicine (ITM), Zurich, Switzerland. .,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland.
| |
Collapse
|
46
|
Gopinath A, Joseph B. Conformational Flexibility of the Protein Insertase BamA in the Native Asymmetric Bilayer Elucidated by ESR Spectroscopy. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202113448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Aathira Gopinath
- Institute of Biophysics Department of Physics Center for Biomolecular Magnetic Resonance (BMRZ) Goethe University Frankfurt Max-von-Laue-Str. 1 60438 Frankfurt/Main Germany
| | - Benesh Joseph
- Institute of Biophysics Department of Physics Center for Biomolecular Magnetic Resonance (BMRZ) Goethe University Frankfurt Max-von-Laue-Str. 1 60438 Frankfurt/Main Germany
| |
Collapse
|
47
|
Quantification and surface localization of the hemolysin A type 1 secretion system at the endogenous level and under conditions of overexpression. Appl Environ Microbiol 2021; 88:e0189621. [PMID: 34851699 DOI: 10.1128/aem.01896-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Secretion systems are essential for Gram-negative bacteria as these nanomachineries allow a communication with the outside world by exporting proteins into the extracellular space or directly into the cytosol of a host cell. For example, type one secretion systems (T1SS) secrete a broad range of substrates across both membranes into the extracellular space. One well-known example is the hemolysin A (HlyA) T1SS from Escherichia coli (E. coli), which consists of an ABC transporter (HlyB), a membrane fusion protein (HlyD), the outer membrane protein TolC and the substrate HlyA, a member of the family of RTX (repeats in toxins) toxins. Here, we determined the amount of TolC at the endogenous level (parental strain, UTI89) and under conditions of overexpression (T7 expression system, BL21(DE3)-BD). The overall amount of TolC was not influenced by the overexpression of the HlyBD complex. Moving one step further, we determined the localization of the HlyA T1SS by super-resolution microscopy. In contrast to other bacterial secretion systems, no polarization was observed with respect to endogenous or overexpression levels. Additionally, the cell growth and division cycle did not influence the polarization. Most importantly, the size of the observed T1SS clusters did not correlate with the recently proposed outer membrane islands. These data indicate that T1SS cluster at the outer membrane generating domains of so far not described identity. Importance Uropathogenic Escherichia coli (UPEC) strains cause about 110 million urinary tract infections each year worldwide representing a global burden to the healthcare system. UPEC secrete many virulence factors among these the TX toxin hemolysin A via a cognate T1SS into the extracellular space. In this study, we determined the endogenous copy number of the HlyA T1SS in UTI89 and analyzed the surface localization in BL21(DE3)-BD and UTI89, respectively. With approximately 800 copies of the T1SS in UTI89, this is one of the highest expressed bacterial secretion systems. Furthermore and in clear contrast to other secretion systems, no polarized surface localization was detected. Finally, quantitative analysis of the super-resolution data revealed that clusters of the HlyA T1SS are not related to the recently identified outer membrane protein islands. These data provide insights into the quantitative molecular architecture of the HlyA T1SS.
Collapse
|
48
|
Thoma J, Burmann BM. Architects of their own environment: How membrane proteins shape the Gram-negative cell envelope. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:1-34. [PMID: 35034716 DOI: 10.1016/bs.apcsb.2021.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gram-negative bacteria are surrounded by a complex multilayered cell envelope, consisting of an inner and an outer membrane, and separated by the aqueous periplasm, which contains a thin peptidoglycan cell wall. These bacteria employ an arsenal of highly specialized membrane protein machineries to ensure the correct assembly and maintenance of the membranes forming the cell envelope. Here, we review the diverse protein systems, which perform these functions in Escherichia coli, such as the folding and insertion of membrane proteins, the transport of lipoproteins and lipopolysaccharide within the cell envelope, the targeting of phospholipids, and the regulation of mistargeted envelope components. Some of these protein machineries have been known for a long time, yet still hold surprises. Others have only recently been described and some are still missing pieces or yet remain to be discovered.
Collapse
Affiliation(s)
- Johannes Thoma
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Göteborg, Sweden; Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
| | - Björn M Burmann
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Göteborg, Sweden; Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| |
Collapse
|
49
|
Phase separation in the outer membrane of Escherichia coli. Proc Natl Acad Sci U S A 2021; 118:2112237118. [PMID: 34716276 DOI: 10.1073/pnas.2112237118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/20/2021] [Indexed: 11/18/2022] Open
Abstract
Gram-negative bacteria are surrounded by a protective outer membrane (OM) with phospholipids in its inner leaflet and lipopolysaccharides (LPS) in its outer leaflet. The OM is also populated with many β-barrel outer-membrane proteins (OMPs), some of which have been shown to cluster into supramolecular assemblies. However, it remains unknown how abundant OMPs are organized across the entire bacterial surface and how this relates to the lipids in the membrane. Here, we reveal how the OM is organized from molecular to cellular length scales, using atomic force microscopy to visualize the OM of live bacteria, including engineered Escherichia coli strains and complemented by specific labeling of abundant OMPs. We find that a predominant OMP in the E. coli OM, the porin OmpF, forms a near-static network across the surface, which is interspersed with barren patches of LPS that grow and merge with other patches during cell elongation. Embedded within the porin network is OmpA, which forms noncovalent interactions to the underlying cell wall. When the OM is destabilized by mislocalization of phospholipids to the outer leaflet, a new phase appears, correlating with bacterial sensitivity to harsh environments. We conclude that the OM is a mosaic of phase-separated LPS-rich and OMP-rich regions, the maintenance of which is essential to the integrity of the membrane and hence to the lifestyle of a gram-negative bacterium.
Collapse
|
50
|
Schoppe J, Schubert E, Apelbaum A, Yavavli E, Birkholz O, Stephanowitz H, Han Y, Perz A, Hofnagel O, Liu F, Piehler J, Raunser S, Ungermann C. Flexible open conformation of the AP-3 complex explains its role in cargo recruitment at the Golgi. J Biol Chem 2021; 297:101334. [PMID: 34688652 PMCID: PMC8591511 DOI: 10.1016/j.jbc.2021.101334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/15/2021] [Accepted: 09/21/2021] [Indexed: 01/17/2023] Open
Abstract
Vesicle formation at endomembranes requires the selective concentration of cargo by coat proteins. Conserved adapter protein complexes at the Golgi (AP-3), the endosome (AP-1), or the plasma membrane (AP-2) with their conserved core domain and flexible ear domains mediate this function. These complexes also rely on the small GTPase Arf1 and/or specific phosphoinositides for membrane binding. The structural details that influence these processes, however, are still poorly understood. Here we present cryo-EM structures of the full-length stable 300 kDa yeast AP-3 complex. The structures reveal that AP-3 adopts an open conformation in solution, comparable to the membrane-bound conformations of AP-1 or AP-2. This open conformation appears to be far more flexible than AP-1 or AP-2, resulting in compact, intermediate, and stretched subconformations. Mass spectrometrical analysis of the cross-linked AP-3 complex further indicates that the ear domains are flexibly attached to the surface of the complex. Using biochemical reconstitution assays, we also show that efficient AP-3 recruitment to the membrane depends primarily on cargo binding. Once bound to cargo, AP-3 clustered and immobilized cargo molecules, as revealed by single-molecule imaging on polymer-supported membranes. We conclude that its flexible open state may enable AP-3 to bind and collect cargo at the Golgi and could thus allow coordinated vesicle formation at the trans-Golgi upon Arf1 activation.
Collapse
Affiliation(s)
- Jannis Schoppe
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Evelyn Schubert
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Amir Apelbaum
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Erdal Yavavli
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Oliver Birkholz
- Department of Biology/Chemistry, Biophysics Section, Osnabrück University, Osnabrück, Germany
| | - Heike Stephanowitz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Campus Berlin-Buch, Berlin, Germany
| | - Yaping Han
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Angela Perz
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Fan Liu
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Campus Berlin-Buch, Berlin, Germany
| | - Jacob Piehler
- Department of Biology/Chemistry, Biophysics Section, Osnabrück University, Osnabrück, Germany; Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Dortmund, Germany.
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany; Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany.
| |
Collapse
|