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Batt SM, Abrahams KA, Besra GS. Top five unanswered questions in bacterial cell wall research. Cell Surf 2024; 11:100122. [PMID: 38425882 PMCID: PMC10902140 DOI: 10.1016/j.tcsw.2024.100122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/15/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024] Open
Affiliation(s)
| | | | - Gurdyal S. Besra
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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2
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Brown CM, Marrink SJ. Modeling membranes in situ. Curr Opin Struct Biol 2024; 87:102837. [PMID: 38744147 DOI: 10.1016/j.sbi.2024.102837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/26/2024] [Accepted: 04/23/2024] [Indexed: 05/16/2024]
Abstract
Molecular dynamics simulations of cellular membranes have come a long way-from simple model lipid bilayers to multicomponent systems capturing the crowded and complex nature of real cell membranes. In this opinionated minireview, we discuss the current challenge to simulate the dynamics of membranes in their native environment, in situ, with the prospect of reaching the level of whole cells and cell organelles using an integrative modeling framework.
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Affiliation(s)
- Chelsea M Brown
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands. https://twitter.com/chelseabrowncg
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands. s.j.marrinkrug.nl
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3
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Kitzmiller CE, Cheng TY, Prandi J, Sparks IL, Moody DB, Morita YS. Detergent-induced quantitatively limited formation of diacyl phosphatidylinositol dimannoside in Mycobacterium smegmatis. J Lipid Res 2024; 65:100533. [PMID: 38522749 DOI: 10.1016/j.jlr.2024.100533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/16/2024] [Accepted: 03/19/2024] [Indexed: 03/26/2024] Open
Abstract
Mycobacterial plasma membrane, together with the peptidoglycan-arabinogalactan cell wall and waxy outer membrane, creates a robust permeability barrier against xenobiotics. The fact that several antituberculosis drugs target plasma membrane-embedded enzymes underscores the importance of the plasma membrane in bacterial physiology and pathogenesis. Nevertheless, its accurate phospholipid composition remains undefined, with conflicting reports on the abundance of phosphatidylinositol mannosides (PIMs), physiologically important glycolipids evolutionarily conserved among mycobacteria and related bacteria. Some studies indicate cardiolipin, phosphatidylethanolamine, and phosphatidylinositol as dominant structural phospholipids. Conversely, some suggest PIMs dominate the plasma membrane. A striking example of the latter is the use of reverse micelle extraction, showing diacyl phosphatidylinositol dimannoside (Ac2PIM2) as the most abundant phospholipid in a model organism, Mycobacterium smegmatis. Our recent work reveals a rapid response mechanism to membrane-fluidizing stress in mycobacterial plasma membrane: monoacyl phosphatidylinositol dimannoside and hexamannoside (AcPIM2 and AcPIM6) are converted to diacyl forms (Ac2PIM2 and Ac2PIM6). Given the dynamic nature of PIMs, we aimed to resolve the conflicting data in the literature. We show that unstressed M. smegmatis lacks an Ac2PIM2-dominated plasma membrane. Ac2PIM2 accumulation is induced by experimental conditions involving sodium docusate, a component of the reverse micellar solution. Using chemically synthesized PIMs as standards, we accurately quantified phospholipid ratio in M. smegmatis through liquid chromatography-mass spectrometry, revealing that mycobacterial plasma membrane is dominated by cardiolipin, phosphatidylethanolamine, and phosphatidylinositol. PIMs are quantitatively minor but responsive to environmental stresses in M. smegmatis. Our study paves the way for accurate modeling of mycobacterial plasma membrane.
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Affiliation(s)
| | - Tan-Yun Cheng
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jacques Prandi
- Institut de Pharmacologie et de Biologie Structurale, CNRS, UPS, Université de Toulouse, Toulouse, France
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - D Branch Moody
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA.
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4
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Guzmán L, Cambier CJ, Cheng TY, Naqvi KF, Shiloh MU, Moody DB, Bertozzi CR. Bioorthogonal Metabolic Labeling of the Virulence Factor Phenolic Glycolipid in Mycobacteria. ACS Chem Biol 2024; 19:707-717. [PMID: 38442242 PMCID: PMC10949201 DOI: 10.1021/acschembio.3c00724] [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: 11/28/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/07/2024]
Abstract
Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid that varies among clinical Mycobacterium tuberculosis strains. PGL is also found in Mycobacterium marinum, where it promotes infection of zebrafish through effects on the innate immune system. Given the important role this lipid plays in the host-pathogen relationship, tools for profiling its abundance, spatial distribution, and dynamics are needed. Here, we report a strategy for imaging PGL in live mycobacteria using bioorthogonal metabolic labeling. We functionalized the PGL precursor p-hydroxybenzoic acid (pHB) with an azide group (3-azido pHB). When fed to mycobacteria, 3-azido pHB was incorporated into the cell surface, which could then be visualized via the bioorthogonal conjugation of a fluorescent probe. We confirmed that 3-azido pHB incorporates into PGL using mass spectrometry methods and demonstrated selectivity for PGL-producing M. marinum and M. tuberculosis strains. Finally, we applied this metabolic labeling strategy to study the dynamics of PGL within the mycobacterial membrane. This new tool enables visualization of PGL that may facilitate studies of mycobacterial pathogenesis.
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Affiliation(s)
- Lindsay
E. Guzmán
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - C. J. Cambier
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Tan-Yun Cheng
- Brigham
and Women’s Hospital, Division of Rheumatology, Inflammation
and Immunity, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Kubra F. Naqvi
- Department
of Internal Medicine, University of Texas
Southwestern Medical Center, Dallas, Texas 75390, United States
- Department
of Microbiology, University of Texas Southwestern
Medical Center, Dallas, Texas 75390, United States
| | - Michael U. Shiloh
- Department
of Internal Medicine, University of Texas
Southwestern Medical Center, Dallas, Texas 75390, United States
- Department
of Microbiology, University of Texas Southwestern
Medical Center, Dallas, Texas 75390, United States
| | - D. Branch Moody
- Brigham
and Women’s Hospital, Division of Rheumatology, Inflammation
and Immunity, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Carolyn R. Bertozzi
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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5
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Brown T, Chavent M, Im W. Molecular Modeling and Simulation of the Mycobacterial Cell Envelope: From Individual Components to Cell Envelope Assemblies. J Phys Chem B 2023; 127:10941-10949. [PMID: 38091517 PMCID: PMC10758119 DOI: 10.1021/acs.jpcb.3c06136] [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: 09/12/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/29/2023]
Abstract
Unlike typical Gram-positive bacteria, the cell envelope of mycobacteria is unique and composed of a mycobacterial outer membrane, also known as the mycomembrane, a peptidoglycan layer, and a mycobacterial inner membrane, which is analogous to that of Gram-negative bacteria. Despite its importance, however, our understanding of this complex cell envelope is rudimentary at best. Thus, molecular modeling and simulation of such an envelope can benefit the scientific community by proposing new hypotheses about the biophysical properties of its different layers. In this Perspective, we present recent advances in molecular modeling and simulation of the mycobacterial cell envelope from individual components to cell envelope assemblies. We also show how modeling other types of cell envelopes, such as that of Escherichia coli, may help modeling part of the mycobacterial envelopes. We hope that the studies presented here are just the beginning of the road and more and more new modeling and simulation studies help us to understand crucial questions related to mycobacteria such as antibiotic resistance or bacterial survival in the host.
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Affiliation(s)
- Turner Brown
- Department
of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Matthieu Chavent
- Institut
de Pharmacologie et Biologie Structurale, CNRS, Université
de Toulouse, 205 Route de Narbonne, 31400 Toulouse, France
| | - Wonpil Im
- Department
of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
- Departments
of Biological Sciences and Chemistry, Lehigh
University, Bethlehem, Pennsylvania 18015, United States
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6
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Khalid S, Brandner AF, Juraschko N, Newman KE, Pedebos C, Prakaash D, Smith IPS, Waller C, Weerakoon D. Computational microbiology of bacteria: Advancements in molecular dynamics simulations. Structure 2023; 31:1320-1327. [PMID: 37875115 DOI: 10.1016/j.str.2023.09.012] [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: 07/27/2023] [Revised: 09/04/2023] [Accepted: 09/28/2023] [Indexed: 10/26/2023]
Abstract
Microbiology is traditionally considered within the context of wet laboratory methodologies. Computational techniques have a great potential to contribute to microbiology. Here, we describe our loose definition of "computational microbiology" and provide a short survey focused on molecular dynamics simulations of bacterial systems that fall within this definition. It is our contention that increased compositional complexity and realistic levels of molecular crowding within simulated systems are key for bridging the divide between experimental and computational microbiology.
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Affiliation(s)
- Syma Khalid
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, UK; School of Chemistry, University of Southampton, SO17 1BJ Southampton, UK.
| | - Astrid F Brandner
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, UK
| | - Nikolai Juraschko
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, UK; Artificial Intelligence and Informatics, The Rosalind Franklin Institute, Didcot, UK
| | - Kahlan E Newman
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, UK
| | - Conrado Pedebos
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, UK; Programa de Pós-Graduação em Biociências (PPGBio), Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Porto Alegre, Brazil
| | - Dheeraj Prakaash
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, UK
| | - Iain P S Smith
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, UK
| | - Callum Waller
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, UK
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7
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Li Y, Acharya A, Yang L, Liu J, Tajkhorshid E, Zgurskaya HI, Jackson M, Gumbart JC. Insights into substrate transport and water permeation in the mycobacterial transporter MmpL3. Biophys J 2023; 122:2342-2352. [PMID: 36926696 PMCID: PMC10257117 DOI: 10.1016/j.bpj.2023.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 02/04/2023] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
Mycobacteria, such as Mycobacterium tuberculosis, are characterized by a uniquely thick and waxy cell envelope that consists of two membranes, with a variety of mycolates comprising their outer membrane (OM). The protein Mycobacterial membrane protein Large 3 (MmpL3) is responsible for the transport of a primary OM component, trehalose monomycolate (TMM), from the inner (cytoplasmic) membrane (IM) to the periplasmic space, a process driven by the proton gradient. Although multiple structures of MmpL3 with bound substrates have been solved, the exact pathway(s) for TMM or proton transport remains elusive. Here, employing molecular dynamics simulations we investigate putative pathways for either transport species. We hypothesized that MmpL3 will cycle through similar conformational states as the related transporter AcrB, which we used as targets for modeling the conformation of MmpL3. A continuous water pathway through the transmembrane region was found in one of these states, illustrating a putative pathway for protons. Additional equilibrium simulations revealed that TMM can diffuse from the membrane into a binding pocket in MmpL3 spontaneously. We also found that acetylation of TMM, which is required for transport, makes it more stable within MmpL3's periplasmic cavity compared with the unacetylated form.
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Affiliation(s)
- Yupeng Li
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Atanu Acharya
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia
| | - Lixinhao Yang
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - Jinchan Liu
- Department of Molecular Biophysics and Biochemistry (MB&B), Yale University, New Haven, Connecticut
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia.
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