1
|
Popoff MR. Overview of Bacterial Protein Toxins from Pathogenic Bacteria: Mode of Action and Insights into Evolution. Toxins (Basel) 2024; 16:182. [PMID: 38668607 PMCID: PMC11054074 DOI: 10.3390/toxins16040182] [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: 02/16/2024] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/29/2024] Open
Abstract
Bacterial protein toxins are secreted by certain bacteria and are responsible for mild to severe diseases in humans and animals. They are among the most potent molecules known, which are active at very low concentrations. Bacterial protein toxins exhibit a wide diversity based on size, structure, and mode of action. Upon recognition of a cell surface receptor (protein, glycoprotein, and glycolipid), they are active either at the cell surface (signal transduction, membrane damage by pore formation, or hydrolysis of membrane compound(s)) or intracellularly. Various bacterial protein toxins have the ability to enter cells, most often using an endocytosis mechanism, and to deliver the effector domain into the cytosol, where it interacts with an intracellular target(s). According to the nature of the intracellular target(s) and type of modification, various cellular effects are induced (cell death, homeostasis modification, cytoskeleton alteration, blockade of exocytosis, etc.). The various modes of action of bacterial protein toxins are illustrated with representative examples. Insights in toxin evolution are discussed.
Collapse
Affiliation(s)
- Michel R Popoff
- Unité des Toxines Bactériennes, Institut Pasteur, Université Paris Cité, CNRS UMR 2001 INSERM U1306, F-75015 Paris, France
| |
Collapse
|
2
|
Zhu Z, Hu Z, Li S, Fang R, Ono HK, Hu DL. Molecular Characteristics and Pathogenicity of Staphylococcus aureus Exotoxins. Int J Mol Sci 2023; 25:395. [PMID: 38203566 PMCID: PMC10778951 DOI: 10.3390/ijms25010395] [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: 11/24/2023] [Revised: 12/24/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
Staphylococcus aureus stands as one of the most pervasive pathogens given its morbidity and mortality worldwide due to its roles as an infectious agent that causes a wide variety of diseases ranging from moderately severe skin infections to fatal pneumonia and sepsis. S. aureus produces a variety of exotoxins that serve as important virulence factors in S. aureus-related infectious diseases and food poisoning in both humans and animals. For example, staphylococcal enterotoxins (SEs) produced by S. aureus induce staphylococcal foodborne poisoning; toxic shock syndrome toxin-1 (TSST-1), as a typical superantigen, induces toxic shock syndrome; hemolysins induce cell damage in erythrocytes and leukocytes; and exfoliative toxin induces staphylococcal skin scalded syndrome. Recently, Panton-Valentine leucocidin, a cytotoxin produced by community-associated methicillin-resistant S. aureus (CA-MRSA), has been reported, and new types of SEs and staphylococcal enterotoxin-like toxins (SEls) were discovered and reported successively. This review addresses the progress of and novel insights into the molecular structure, biological activities, and pathogenicity of both the classic and the newly identified exotoxins produced by S. aureus.
Collapse
Affiliation(s)
- Zhihao Zhu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Zuo Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Shaowen Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Rendong Fang
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China;
| | - Hisaya K. Ono
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Dong-Liang Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| |
Collapse
|
3
|
Ilmain JK, Perelman SS, Panepinto MC, Irnov I, Coudray N, Samhadaneh N, Pironti A, Ueberheide B, Ekiert DC, Bhabha G, Torres VJ. Unlatching of the stem domains in the Staphylococcus aureus pore-forming leukocidin LukAB influences toxin oligomerization. J Biol Chem 2023; 299:105321. [PMID: 37802313 PMCID: PMC10665946 DOI: 10.1016/j.jbc.2023.105321] [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: 05/23/2023] [Revised: 09/22/2023] [Accepted: 09/27/2023] [Indexed: 10/08/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is a serious global pathogen that causes a diverse range of invasive diseases. S. aureus utilizes a family of pore-forming toxins, known as bi-component leukocidins, to evade the host immune response and promote infection. Among these is LukAB (leukocidin A/leukocidin B), a toxin that assembles into an octameric β-barrel pore in the target cell membrane, resulting in host cell death. The established cellular receptor for LukAB is CD11b of the Mac-1 complex. Here, we show that hydrogen voltage-gated channel 1 is also required for the cytotoxicity of all major LukAB variants. We demonstrate that while each receptor is sufficient to recruit LukAB to the plasma membrane, both receptors are required for maximal lytic activity. Why LukAB requires two receptors, and how each of these receptors contributes to pore-formation remains unknown. To begin to resolve this, we performed an alanine scanning mutagenesis screen to identify mutations that allow LukAB to maintain cytotoxicity without CD11b. We discovered 30 mutations primarily localized in the stem domains of LukA and LukB that enable LukAB to exhibit full cytotoxicity in the absence of CD11b. Using crosslinking, electron microscopy, and hydroxyl radical protein footprinting, we show these mutations increase the solvent accessibility of the stem domain, priming LukAB for oligomerization. Together, our data support a model in which CD11b binding unlatches the membrane penetrating stem domains of LukAB, and this change in flexibility promotes toxin oligomerization.
Collapse
Affiliation(s)
- Juliana K Ilmain
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Sofya S Perelman
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Maria C Panepinto
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, New York, USA
| | - Irnov Irnov
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Nicolas Coudray
- Applied Bioinformatics Laboratories, New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA
| | - Nora Samhadaneh
- Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Alejandro Pironti
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, New York, USA; Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, New York, USA; Department of Neurology, Center for Cognitive Neurology, New York University Grossman School of Medicine, New York, New York, USA
| | - Damian C Ekiert
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Department of Host-Microbe Interactions, St Jude Children's Research Hospital, Memphis, Tennessee, USA.
| |
Collapse
|
4
|
Chiu YC, Yeh MC, Wang CH, Chen YA, Chang H, Lin HY, Ho MC, Lin SM. Structural basis for calcium-stimulating pore formation of Vibrio α-hemolysin. Nat Commun 2023; 14:5946. [PMID: 37741869 PMCID: PMC10517994 DOI: 10.1038/s41467-023-41579-x] [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: 05/30/2023] [Accepted: 09/10/2023] [Indexed: 09/25/2023] Open
Abstract
Vibrio α-hemolysins (αHLs) are β-pore-forming toxins secreted by Vibrio pathogens, crucial for the facilitation of bacterial infections through host cell lysis. These toxins are produced as inactive precursors, requiring proteolytic maturation and membrane association for activation within host tissues. Here, we investigate Vibrio campbellii αHL (VcαHL), and establish that its hemolytic activity is significantly stimulated by calcium ions, with an EC50 that aligns with physiological calcium concentrations. Furthermore, we illustrate the vital contribution of calcium ions to the oligomerization of VcαHL on membranes. Using X-ray crystallography and cryo-electron microscopy, we decipher both the immature and assembled structures of VcαHL and elucidate the conformational changes corresponding to toxin assembly. We also identify a calcium-binding module that is integral for VcαHL's calcium-dependent activation. These findings provide insights into the regulatory mechanisms of VcαHL and have the potential to inform the development of targeted therapeutic strategies against Vibrio infections.
Collapse
Affiliation(s)
- Yu-Chuan Chiu
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Min-Chi Yeh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chun-Hsiung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-An Chen
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Hsiang Chang
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Han-You Lin
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Meng-Chiao Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan
| | - Shih-Ming Lin
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan.
- Institute of Tropical Plant Sciences and Microbiology, National Cheng Kung University, Tainan, Taiwan.
| |
Collapse
|
5
|
Pivard M, Caldelari I, Brun V, Croisier D, Jaquinod M, Anzala N, Gilquin B, Teixeira C, Benito Y, Couzon F, Romby P, Moreau K, Vandenesch F. Complex Regulation of Gamma-Hemolysin Expression Impacts Staphylococcus aureus Virulence. Microbiol Spectr 2023; 11:e0107323. [PMID: 37347186 PMCID: PMC10434192 DOI: 10.1128/spectrum.01073-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 05/25/2023] [Indexed: 06/23/2023] Open
Abstract
Staphylococcus aureus gamma-hemolysin CB (HlgCB) is a core-genome-encoded pore-forming toxin that targets the C5a receptor, similar to the phage-encoded Panton-Valentine leucocidin (PVL). Absolute quantification by mass spectrometry of HlgCB in 39 community-acquired pneumonia (CAP) isolates showed considerable variations in the HlgC and HlgB yields between isolates. Moreover, although HlgC and HlgB are encoded on a single operon, their levels were dissociated in 10% of the clinical strains studied. To decipher the molecular basis for the variation in hlgCB expression and protein production among strains, different regulation levels were analyzed in representative clinical isolates and reference strains. Both the HlgCB level and the HlgC/HlgB ratio were found to depend on hlgC promoter activity and mRNA processing and translation. Strikingly, only one single nucleotide polymorphism (SNP) in the 5' untranslated region (UTR) of hlgCB mRNA strongly impaired hlgC translation in the USA300 strain, leading to a strong decrease in the level of HlgC but not in HlgB. Finally, we found that high levels of HlgCB synthesis led to mortality in a rabbit model of pneumonia, correlated with the implication of the role of HlgCB in severe S. aureus CAP. Taken together, this work illustrates the complexity of virulence factor expression in clinical strains and demonstrates a butterfly effect where subtle genomic variations have a major impact on phenotype and virulence. IMPORTANCE S. aureus virulence in pneumonia results in its ability to produce several virulence factors, including the leucocidin PVL. Here, we demonstrate that HlgCB, another leucocidin, which targets the same receptors as PVL, highly contributes to S. aureus virulence in pvl-negative strains. In addition, considerable variations in HlgCB quantities are observed among clinical isolates from patients with CAP. Biomolecular analyses have revealed that a few SNPs in the promoter sequences and only one SNP in the 5' UTR of hlgCB mRNA induce the differential expression of hlgCB, drastically impacting hlgC mRNA translation. This work illustrates the subtlety of regulatory mechanisms in bacteria, especially the sometimes major effects on phenotypes of single nucleotide variation in noncoding regions.
Collapse
Affiliation(s)
- Mariane Pivard
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Virginie Brun
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
- Université Grenoble Alpes, CEA, LETI, Clinatec, Grenoble, France
| | | | - Michel Jaquinod
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
| | | | - Benoît Gilquin
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
- Université Grenoble Alpes, CEA, LETI, Clinatec, Grenoble, France
| | - Chloé Teixeira
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Yvonne Benito
- Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Lyon, France
| | - Florence Couzon
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Karen Moreau
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - François Vandenesch
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
- Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Lyon, France
| |
Collapse
|
6
|
Mayse LA, Movileanu L. Gating of β-Barrel Protein Pores, Porins, and Channels: An Old Problem with New Facets. Int J Mol Sci 2023; 24:12095. [PMID: 37569469 PMCID: PMC10418385 DOI: 10.3390/ijms241512095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
β barrels are ubiquitous proteins in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. These transmembrane proteins (TMPs) execute a wide variety of tasks. For example, they can serve as transporters, receptors, membrane-bound enzymes, as well as adhesion, structural, and signaling elements. In addition, multimeric β barrels are common structural scaffolds among many pore-forming toxins. Significant progress has been made in understanding the functional, structural, biochemical, and biophysical features of these robust and versatile proteins. One frequently encountered fundamental trait of all β barrels is their voltage-dependent gating. This process consists of reversible or permanent conformational transitions between a large-conductance, highly permeable open state and a low-conductance, solute-restrictive closed state. Several intrinsic molecular mechanisms and environmental factors modulate this universal property of β barrels. This review article outlines the typical signatures of voltage-dependent gating. Moreover, we discuss recent developments leading to a better qualitative understanding of the closure dynamics of these TMPs.
Collapse
Affiliation(s)
- Lauren A. Mayse
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
- The BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| |
Collapse
|
7
|
Paternoster C, Tarenzi T, Potestio R, Lattanzi G. Gamma-Hemolysin Components: Computational Strategies for LukF-Hlg2 Dimer Reconstruction on a Model Membrane. Int J Mol Sci 2023; 24:ijms24087113. [PMID: 37108277 PMCID: PMC10138441 DOI: 10.3390/ijms24087113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/07/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
The gamma-hemolysin protein is one of the most common pore-forming toxins expressed by the pathogenic bacterium Staphylococcus aureus. The toxin is used by the pathogen to escape the immune system of the host organism, by assembling into octameric transmembrane pores on the surface of the target immune cell and leading to its death by leakage or apoptosis. Despite the high potential risks associated with Staphylococcus aureus infections and the urgent need for new treatments, several aspects of the pore-formation process from gamma-hemolysin are still unclear. These include the identification of the interactions between the individual monomers that lead to the formation of a dimer on the cell membrane, which represents the unit for further oligomerization. Here, we employed a combination of all-atom explicit solvent molecular dynamics simulations and protein-protein docking to determine the stabilizing contacts that guide the formation of a functional dimer. The simulations and the molecular modeling reveal the importance of the flexibility of specific protein domains, in particular the N-terminus, to drive the formation of the correct dimerization interface through functional contacts between the monomers. The results obtained are compared with the experimental data available in the literature.
Collapse
Affiliation(s)
- Costanza Paternoster
- Department of Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento, Italy
| | - Thomas Tarenzi
- Department of Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento, Italy
| | - Raffaello Potestio
- Department of Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento, Italy
| | - Gianluca Lattanzi
- Department of Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento, Italy
| |
Collapse
|
8
|
Mishra S, Roy A, Dutta S. Cryo-EM-based structural insights into supramolecular assemblies of γ-hemolysin from S. aureus reveal the pore formation mechanism. Structure 2023:S0969-2126(23)00085-0. [PMID: 37019111 DOI: 10.1016/j.str.2023.03.009] [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: 10/15/2022] [Revised: 01/31/2023] [Accepted: 03/10/2023] [Indexed: 04/07/2023]
Abstract
γ-Hemolysin (γ-HL) is a hemolytic and leukotoxic bicomponent β-pore-forming toxin (β-PFT), a potent virulence factor from the Staphylococcus aureus Newman strain. In this study, we performed single-particle cryoelectron microscopy (cryo-EM) of γ-HL in a lipid environment. We observed clustering and square lattice packing of octameric HlgAB pores on the membrane bilayer and an octahedral superassembly of octameric pore complexes that we resolved at resolution of 3.5 Å. Our atomic model further demonstrated the key residues involved in hydrophobic zipping between the rim domains of adjacent octameric complexes, providing additional structural stability in PFTs post oligomerization. We also observed extra densities at the octahedral and octameric interfaces, providing insights into the plausible lipid-binding residues involved for HlgA and HlgB components. Furthermore, the hitherto elusive N-terminal region of HlgA was also resolved in our cryo-EM map, and an overall mechanism of pore formation for bicomponent β-PFTs is proposed.
Collapse
Affiliation(s)
- Suman Mishra
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Anupam Roy
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Somnath Dutta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
| |
Collapse
|
9
|
Bruggisser J, Iacovache I, Musson SC, Degiacomi MT, Posthaus H, Zuber B. Cryo-EM structure of the octameric pore of Clostridium perfringens β-toxin. EMBO Rep 2022; 23:e54856. [PMID: 36215680 PMCID: PMC9724662 DOI: 10.15252/embr.202254856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/05/2022] [Accepted: 09/14/2022] [Indexed: 12/12/2022] Open
Abstract
Clostridium perfringens is one of the most widely distributed and successful pathogens producing an impressive arsenal of toxins. One of the most potent toxins produced is the C. perfringens β-toxin (CPB). This toxin is the main virulence factor of type C strains. We describe the cryo-electron microscopy (EM) structure of CPB oligomer. We show that CPB forms homo-octameric pores like the hetero-oligomeric pores of the bi-component leukocidins, with important differences in the receptor binding region and the N-terminal latch domain. Intriguingly, the octameric CPB pore complex contains a second 16-stranded β-barrel protrusion atop of the cap domain that is formed by the N-termini of the eight protomers. We propose that CPB, together with the newly identified Epx toxins, is a member a new subclass of the hemolysin-like family. In addition, we show that the β-barrel protrusion domain can be modified without affecting the pore-forming ability, thus making the pore particularly attractive for macromolecule sensing and nanotechnology. The cryo-EM structure of the octameric pore of CPB will facilitate future developments in both nanotechnology and basic research.
Collapse
Affiliation(s)
- Julia Bruggisser
- Institute of Animal Pathology, Vetsuisse‐FacultyUniversity of BernBernSwitzerland
| | - Ioan Iacovache
- Institute of Anatomy, Medical FacultyUniversity of BernBernSwitzerland
| | | | | | - Horst Posthaus
- Institute of Animal Pathology, Vetsuisse‐FacultyUniversity of BernBernSwitzerland
| | - Benoît Zuber
- Institute of Anatomy, Medical FacultyUniversity of BernBernSwitzerland
| |
Collapse
|
10
|
Tarenzi T, Lattanzi G, Potestio R. Membrane binding of pore-forming γ-hemolysin components studied at different lipid compositions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183970. [PMID: 35605647 DOI: 10.1016/j.bbamem.2022.183970] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/04/2022] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Methicillin-resistant Staphylococcus aureus is among those pathogens currently posing the highest threat to public health. Its host immune evasion strategy is mediated by pore-forming toxins (PFTs), among which the bi-component γ-hemolysin is one of the most common. The complexity of the porogenesis mechanism by γ-hemolysin poses difficulties in the development of antivirulence therapies targeting PFTs from S. aureus, and sparse and apparently contrasting experimental data have been produced. Here, through a large set of molecular dynamics simulations at different levels of resolution, we investigate the first step of pore formation, and in particular the effect of membrane composition on the ability of γ-hemolysin components, LukF and Hlg2, to steadily adhere to the lipid bilayer in the absence of proteinaceous receptors. Our simulations are in agreement with experimental data of γ-hemolysin pore formation on model membranes, which are here explained on the basis of the bilayer properties. Our computational investigation suggests a possible rationale to explain experimental data on phospholipid binding to the LukF component, and to hypothesise a mechanism by which, on purely lipidic bilayers, the stable anchoring of LukF to the cell surface facilitates Hlg2 binding, through the exposure of its N-terminal region. We expect that further insights on the mechanism of transition between soluble and membrane bound-forms and on the role played by the lipid molecules will contribute to the design of antivirulence agents with enhanced efficacy against methicillin-resistant S. aureus infections.
Collapse
Affiliation(s)
- Thomas Tarenzi
- Department of Physics, University of Trento, Via Sommarive 14, Povo (TN) 38123, Italy; INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, Povo (TN) 38123, Italy.
| | - Gianluca Lattanzi
- Department of Physics, University of Trento, Via Sommarive 14, Povo (TN) 38123, Italy; INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, Povo (TN) 38123, Italy.
| | - Raffaello Potestio
- Department of Physics, University of Trento, Via Sommarive 14, Povo (TN) 38123, Italy; INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, Povo (TN) 38123, Italy.
| |
Collapse
|
11
|
Ghanem N, Kanagami N, Matsui T, Takeda K, Kaneko J, Shiraishi Y, Choe CA, Uchikubo‐Kamo T, Shirouzu M, Hashimoto T, Ogawa T, Matsuura T, Huang P, Yokoyama T, Tanaka Y. Chimeric mutants of staphylococcal hemolysin, which act as both one‐component and two‐component hemolysin, created by grafting the stem domain. FEBS J 2022; 289:3505-3520. [DOI: 10.1111/febs.16354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 12/03/2021] [Accepted: 01/12/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Nouran Ghanem
- Graduate School of Life Sciences Tohoku University Sendai Japan
- Laboratory for Protein Functional and Structural Biology RIKEN Center for Biosystems Dynamics Research Yokohama Japan
| | - Natsuki Kanagami
- Graduate School of Life Sciences Tohoku University Sendai Japan
| | - Takashi Matsui
- Graduate School of Life Sciences Tohoku University Sendai Japan
- School of Science Kitasato University Sagamihara Japan
| | - Kein Takeda
- Department of Microbial Biotechnology Graduate School of Agricultural Science Tohoku University Sendai Japan
| | - Jun Kaneko
- Department of Microbial Biotechnology Graduate School of Agricultural Science Tohoku University Sendai Japan
| | - Yasuyuki Shiraishi
- Pre‐Clinical Research Center Institute of Development, Aging and Cancer Tohoku University Sendai Japan
| | | | - Tomomi Uchikubo‐Kamo
- Laboratory for Protein Functional and Structural Biology RIKEN Center for Biosystems Dynamics Research Yokohama Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology RIKEN Center for Biosystems Dynamics Research Yokohama Japan
| | | | - Tomohisa Ogawa
- Graduate School of Life Sciences Tohoku University Sendai Japan
- Department of Microbial Biotechnology Graduate School of Agricultural Science Tohoku University Sendai Japan
| | - Tomoaki Matsuura
- Department of Biotechnology Graduate School of Engineering Osaka University Suita Japan
| | - Po‐Ssu Huang
- Department of Bioengineering Stanford University CA USA
| | - Takeshi Yokoyama
- Graduate School of Life Sciences Tohoku University Sendai Japan
- Laboratory for Protein Functional and Structural Biology RIKEN Center for Biosystems Dynamics Research Yokohama Japan
| | - Yoshikazu Tanaka
- Graduate School of Life Sciences Tohoku University Sendai Japan
| |
Collapse
|
12
|
Recent Advances in Aptamer‐Based Nanopore Sensing at Single‐Molecule Resolution. Chem Asian J 2022; 17:e202200364. [DOI: 10.1002/asia.202200364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/20/2022] [Indexed: 11/07/2022]
|
13
|
Expression of Staphylococcal Virulence Genes In Situ in Human Skin and Soft Tissue Infections. Antibiotics (Basel) 2022; 11:antibiotics11040527. [PMID: 35453277 PMCID: PMC9032627 DOI: 10.3390/antibiotics11040527] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Staphylococcus aureus, the most common pathogen in skin and soft tissue infections (SSTI), harbors many well-characterized virulence genes. However, the expression of many of them in SSTIs is unknown. In this study, S. aureus virulence genes expressed in SSTI were investigated. Methods: Fifty-three subjects presenting to the outpatient’s care and emergency departments with a purulent SSTI at two medical centers in Wisconsin, USA, were enrolled in the study. Total mRNA was extracted from the purulent or swab materials, made into cDNA and sequenced on MiSeq platform. The relative cDNA counts to gmk and identifications of the transcripts were carried out with respect to USA300 reference genome and using SAMTOOLS v.1.3 and BWA, respectively. Result: A significantly higher cDNA count was observed for many of the virulence and regulatory gene transcripts in the pus samples compared to the swab samples relative to the cDNA counts for gmk, a housekeeping gene. They were for lukS-PV (18.6 vs. 14.2), isaA (13.4 vs. 8.5), ssaA (4.8 vs. 3.1), hlgC (1.4 vs. 1.33), atl (17.7 vs. 8.33), clfA (3.9 vs. 0.83), eno (6.04 vs. 3.16), fnbA (5.93 vs. 0.33), saeS (6.3 vs. 1.33), saeR (5.4 vs. 3.33) and agrC (5.6 vs. 1.5). Conclusions: A relative increase in the transcripts of several toxins, adhesion and regulatory genes with respect to a gmk in purulent materials suggests their role in situ during SSTIs, perhaps in an orchestrated manner.
Collapse
|
14
|
Xiong X, Tian S, Yang P, Lebreton F, Bao H, Sheng K, Yin L, Chen P, Zhang J, Qi W, Ruan J, Wu H, Chen H, Breault DT, Wu H, Earl AM, Gilmore MS, Abraham J, Dong M. Emerging enterococcus pore-forming toxins with MHC/HLA-I as receptors. Cell 2022; 185:1157-1171.e22. [PMID: 35259335 PMCID: PMC8978092 DOI: 10.1016/j.cell.2022.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 12/15/2021] [Accepted: 02/01/2022] [Indexed: 01/12/2023]
Abstract
Enterococci are a part of human microbiota and a leading cause of multidrug resistant infections. Here, we identify a family of Enterococcus pore-forming toxins (Epxs) in E. faecalis, E. faecium, and E. hirae strains isolated across the globe. Structural studies reveal that Epxs form a branch of β-barrel pore-forming toxins with a β-barrel protrusion (designated the top domain) sitting atop the cap domain. Through a genome-wide CRISPR-Cas9 screen, we identify human leukocyte antigen class I (HLA-I) complex as a receptor for two members (Epx2 and Epx3), which preferentially recognize human HLA-I and homologous MHC-I of equine, bovine, and porcine, but not murine, origin. Interferon exposure, which stimulates MHC-I expression, sensitizes human cells and intestinal organoids to Epx2 and Epx3 toxicity. Co-culture with Epx2-harboring E. faecium damages human peripheral blood mononuclear cells and intestinal organoids, and this toxicity is neutralized by an Epx2 antibody, demonstrating the toxin-mediated virulence of Epx-carrying Enterococcus.
Collapse
Affiliation(s)
- Xiaozhe Xiong
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Songhai Tian
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pan Yang
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Francois Lebreton
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Multidrug-Resistant Organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Huan Bao
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Kuanwei Sheng
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115
| | - Linxiang Yin
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pengsheng Chen
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jie Zhang
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Wanshu Qi
- Division of Endocrinology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Jianbin Ruan
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Department of Immunology, University of Connecticut Health School of Medicine, Farmington, CT 06030, USA
| | - Hao Wu
- Vascular Biology Program, Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Hong Chen
- Vascular Biology Program, Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - David T Breault
- Division of Endocrinology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA
| | - Hao Wu
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Ashlee M Earl
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Michael S Gilmore
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Jonathan Abraham
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.
| | - Min Dong
- Department of Urology, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
15
|
Lambey P, Otun O, Cong X, Hoh F, Brunel L, Verdié P, Grison CM, Peysson F, Jeannot S, Durroux T, Bechara C, Granier S, Leyrat C. Structural insights into recognition of chemokine receptors by Staphylococcus aureus leukotoxins. eLife 2022; 11:72555. [PMID: 35311641 PMCID: PMC9005193 DOI: 10.7554/elife.72555] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 03/19/2022] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus (SA) leukocidin ED (LukED) belongs to a family of bicomponent pore forming toxins that play important roles in SA immune evasion and nutrient acquisition. LukED targets specific G protein-coupled chemokine receptors to lyse human erythrocytes (red blood cells) and leukocytes (white blood cells). The first recognition step of receptors is critical for specific cell targeting and lysis. The structural and molecular bases for this mechanism are not well understood but could constitute essential information to guide antibiotic development. Here, we characterized the interaction of LukE with chemokine receptors ACKR1, CCR2, and CCR5 using a combination of structural, pharmacological, and computational approaches. First, crystal structures of LukE in complex with a small molecule mimicking sulfotyrosine side chain (p-cresyl sulfate) and with peptides containing sulfotyrosines issued from receptor sequences revealed the location of receptor sulfotyrosine binding sites in the toxins. Then, by combining previous and novel experimental data with protein docking, classical and accelerated weight histogram (AWH) molecular dynamics we propose models of the ACKR1-LukE and CCR5-LukE complexes. This work provides novel insights into chemokine receptor recognition by leukotoxins and suggests that the conserved sulfotyrosine binding pocket could be a target of choice for future drug development.
Collapse
Affiliation(s)
- Paul Lambey
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Omolade Otun
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Xiaojing Cong
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - François Hoh
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Luc Brunel
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Pascal Verdié
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Claire M Grison
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Fanny Peysson
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Sylvain Jeannot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Thierry Durroux
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cherine Bechara
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Sébastien Granier
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cédric Leyrat
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| |
Collapse
|
16
|
Ulhuq FR, Mariano G. Bacterial pore-forming toxins. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001154. [PMID: 35333704 PMCID: PMC9558359 DOI: 10.1099/mic.0.001154] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/03/2022] [Indexed: 12/11/2022]
Abstract
Pore-forming toxins (PFTs) are widely distributed in both Gram-negative and Gram-positive bacteria. PFTs can act as virulence factors that bacteria utilise in dissemination and host colonisation or, alternatively, they can be employed to compete with rival microbes in polymicrobial niches. PFTs transition from a soluble form to become membrane-embedded by undergoing large conformational changes. Once inserted, they perforate the membrane, causing uncontrolled efflux of ions and/or nutrients and dissipating the protonmotive force (PMF). In some instances, target cells intoxicated by PFTs display additional effects as part of the cellular response to pore formation. Significant progress has been made in the mechanistic description of pore formation for the different PFTs families, but in several cases a complete understanding of pore structure remains lacking. PFTs have evolved recognition mechanisms to bind specific receptors that define their host tropism, although this can be remarkably diverse even within the same family. Here we summarise the salient features of PFTs and highlight where additional research is necessary to fully understand the mechanism of pore formation by members of this diverse group of protein toxins.
Collapse
Affiliation(s)
- Fatima R. Ulhuq
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Giuseppina Mariano
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| |
Collapse
|
17
|
Hesperidin inhibits biofilm formation, virulence and staphyloxanthin synthesis in methicillin resistant Staphylococcus aureus by targeting SarA and CrtM: an in vitro and in silico approach. World J Microbiol Biotechnol 2022; 38:44. [PMID: 35064842 DOI: 10.1007/s11274-022-03232-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/07/2022] [Indexed: 01/20/2023]
Abstract
Methicillin resistant Staphylococcus aureus is considered multidrug resistant bacterium due to developing biofilm formation associated with antimicrobial resistance mechanisms. Therefore, inhibition of biofilm formation is an alternative therapeutic action to control MRSA infections. The present study revealed the non-antibacterial biofilm inhibitory potential of hesperidin against ATCC strain and clinical isolates of S. aureus. Hesperidin is a flavanone glycoside commonly found in citrus fruit. Hesperidin has been shown to exhibits numerous pharmacological activities. The present study aimed to evaluate the antibiofilm and antivirulence potential of hesperidin against MRSA. Results showed that hesperidin treatment significantly impedes lipase, hemolysin, autolysin, autoaggregation and staphyloxanthin production. Reductions of staphyloxanthin production possibly increase the MRSA susceptibility rate to H2O2 oxidative stress condition. In gene expression study revealed that hesperidin treatment downregulated the biofilm-associated gene (sarA), polysaccharide intracellular adhesion gene (icaA and icaD), autolysin (altA), fibronectin-binding protein (fnbA and fnbB) and staphyloxanthin production (crtM). Molecular docking analysis predicted the ability of hesperidin to interact with SarA and CrtM proteins involved in biofilm formation and staphyloxanthin production in MRSA.
Collapse
|
18
|
Sharma M, Singh P. Role of TlyA in the Biology of Uncultivable Mycobacteria. Comb Chem High Throughput Screen 2022; 25:1587-1594. [PMID: 35021968 DOI: 10.2174/1386207325666220111150923] [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: 02/06/2021] [Revised: 10/25/2021] [Accepted: 11/05/2021] [Indexed: 11/22/2022]
Abstract
TlyA proteins are related to distinct functions in a diverse spectrum of bacterial pathogens including mycobacterial spp. There are several annotated proteins function as hemolysin or pore forming molecules that play an important role in the virulence of pathogenic organisms. Many studies reported the dual activity of mycobacterial TlyA as 'hemolysin' and 'S-adenosylmethionine dependent rRNA methylase'. To act as a hemolysin, a sequence must have a signal sequence and transmembrane segment which helps the protein to enter the extracellular environment. Interestingly, the mycobacterial tlyA has neither a traditional signal sequences of general/sec/tat pathways nor any transmembrane segments are present. Still it can reach the extracellular milieu with the help of non-classical signal mechanisms. Also, retention of tlyA in cultivable mycobacterial pathogens (such as Mycobacterium tuberculosis and M. marinum) as well as uncultivated mycobacterial pathogens despite their extreme reductive evolution (such as M. leprae, M. lepromatosis and M. uberis) suggests its crucial role in evolutionary biology of pathogenic mycobacteria. Numerous virulence factors have been characterised from the uncultivable mycobacteria but the information of TlyA protein is still limited in terms of molecular and structural characterisation. The genomic insights offered by comparative analysis of TlyA sequences and its conserved domains reveal its pore forming activity which further confirms its role as a virulence protein, particularly in uncultivable mycobacteria. Therefore, this review presents a comparative analysis of mycobacterial TlyA family by sequence homology and alignment to improve our understanding of this unconventional hemolysin and RNA methyltransferase TlyA of uncultivable mycobacteria.
Collapse
Affiliation(s)
- Mukul Sharma
- ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Pushpendra Singh
- ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| |
Collapse
|
19
|
Lv P, Yang Y, Li S, Tan CS, Ming D. Biological nanopore approach for single‐molecule analysis of nucleobase modifications. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Pengrui Lv
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Yongyi Yang
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Shuang Li
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Cherie S. Tan
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Dong Ming
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
- Department of Biomedical Engineering College of Precision Instruments and Optoelectronics Engineering Tianjin University Tianjin China
| |
Collapse
|
20
|
Correlating biological activity to thermo-structural analysis of the interaction of CTX with synthetic models of macrophage membranes. Sci Rep 2021; 11:23712. [PMID: 34887428 PMCID: PMC8660830 DOI: 10.1038/s41598-021-02552-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/11/2021] [Indexed: 11/10/2022] Open
Abstract
The important pharmacological actions of Crotoxin (CTX) on macrophages, the main toxin in the venom of Crotalus durissus terrificus, and its important participation in the control of different pathophysiological processes, have been demonstrated. The biological activities performed by macrophages are related to signaling mediated by receptors expressed on the membrane surface of these cells or opening and closing of ion channels, generation of membrane curvature and pore formation. In the present work, the interaction of the CTX complex with the cell membrane of macrophages is studied, both using biological cells and synthetic lipid membranes to monitor structural alterations induced by the protein. Here we show that CTX can penetrate THP-1 cells and induce pores only in anionic lipid model membranes, suggesting that a possible access pathway for CTX to the cell is via lipids with anionic polar heads. Considering that the selectivity of the lipid composition varies in different tissues and organs of the human body, the thermostructural studies presented here are extremely important to open new investigations on the biological activities of CTX in different biological systems.
Collapse
|
21
|
Cheung GYC, Bae JS, Otto M. Pathogenicity and virulence of Staphylococcus aureus. Virulence 2021; 12:547-569. [PMID: 33522395 PMCID: PMC7872022 DOI: 10.1080/21505594.2021.1878688] [Citation(s) in RCA: 414] [Impact Index Per Article: 138.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Staphylococcus aureus is one of the most frequent worldwide causes of morbidity and mortality due to an infectious agent. This pathogen can cause a wide variety of diseases, ranging from moderately severe skin infections to fatal pneumonia and sepsis. Treatment of S. aureus infections is complicated by antibiotic resistance and a working vaccine is not available. There has been ongoing and increasing interest in the extraordinarily high number of toxins and other virulence determinants that S. aureus produces and how they impact disease. In this review, we will give an overview of how S. aureus initiates and maintains infection and discuss the main determinants involved. A more in-depth understanding of the function and contribution of S. aureus virulence determinants to S. aureus infection will enable us to develop anti-virulence strategies to counteract the lack of an anti-S. aureus vaccine and the ever-increasing shortage of working antibiotics against this important pathogen.
Collapse
Affiliation(s)
- Gordon Y. C. Cheung
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Justin S. Bae
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
22
|
Molecular insights into mechanisms of GPCR hijacking by Staphylococcus aureus. Proc Natl Acad Sci U S A 2021; 118:2108856118. [PMID: 34663701 DOI: 10.1073/pnas.2108856118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2021] [Indexed: 11/18/2022] Open
Abstract
Atypical chemokine receptor 1 (ACKR1) is a G protein-coupled receptor (GPCR) targeted by Staphylococcus aureus bicomponent pore-forming leukotoxins to promote bacterial growth and immune evasion. Here, we have developed an integrative molecular pharmacology and structural biology approach in order to characterize the effect of leukotoxins HlgA and HlgB on ACKR1 structure and function. Interestingly, using cell-based assays and native mass spectrometry, we found that both components HlgA and HlgB compete with endogenous chemokines through a direct binding with the extracellular domain of ACKR1. Unexpectedly, hydrogen/deuterium exchange mass spectrometry analysis revealed that toxin binding allosterically modulates the intracellular G protein-binding domain of the receptor, resulting in dissociation and/or changes in the architecture of ACKR1-Gαi1 protein complexes observed in living cells. Altogether, our study brings important molecular insights into the initial steps of leukotoxins targeting a host GPCR.
Collapse
|
23
|
Sannigrahi A, Chattopadhyay K. Pore formation by pore forming membrane proteins towards infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:79-111. [PMID: 35034727 DOI: 10.1016/bs.apcsb.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
Collapse
Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
| |
Collapse
|
24
|
Hu H, Liu M, Sun S. Pore-Forming Toxins During Bacterial Infection: Molecular Mechanisms and Potential Therapeutic Targets. DRUG DESIGN DEVELOPMENT AND THERAPY 2021; 15:3773-3781. [PMID: 34522083 PMCID: PMC8434828 DOI: 10.2147/dddt.s322393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/19/2021] [Indexed: 12/17/2022]
Abstract
Bacterial infections are predominantly treated with antibiotics, and resistance to antibiotics is becoming an increasing threat to our health. Pore-forming toxins (PFTs) are virulence factors secreted by many pathogenic bacterial strains, both in acute and chronic infections. They are special membrane-targeting proteins that exert toxic effects by forming pores in the cell membrane. Recent studies have elucidated the structure of PFTs and the detailed molecular mechanisms of their pathogenicity. Here, we discuss recent findings that highlight the regulatory mechanisms and important roles of two types of PFTs, α-PFTs and β-PFTs, in mediating the virulence of bacteria, and the therapeutic potential of targeting PFTs for antibacterial treatment. Therapeutic strategies based on PFTs are highly specific and may alleviate the issue of increasing resistance to antibiotics.
Collapse
Affiliation(s)
- Haijie Hu
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
| | - Min Liu
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
| | - Shuang Sun
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
| |
Collapse
|
25
|
Crisan CV, Chandrashekar H, Everly C, Steinbach G, Hill SE, Yunker PJ, Lieberman RR, Hammer BK. A New Contact Killing Toxin Permeabilizes Cells and Belongs to a Broadly Distributed Protein Family. mSphere 2021; 6:e0031821. [PMID: 34287011 PMCID: PMC8386463 DOI: 10.1128/msphere.00318-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/21/2021] [Indexed: 01/12/2023] Open
Abstract
Vibrio cholerae is an aquatic Gram-negative bacterium that causes severe diarrheal cholera disease when ingested by humans. To eliminate competitor cells in both the external environment and inside hosts, V. cholerae uses the type VI secretion system (T6SS). The T6SS is a macromolecular contact-dependent weapon employed by many Gram-negative bacteria to deliver cytotoxic proteins into adjacent cells. In addition to canonical T6SS gene clusters encoded by all sequenced V. cholerae isolates, strain BGT49 encodes another locus, which we named auxiliary (Aux) cluster 4. The Aux 4 cluster is located on a mobile genetic element and can be used by killer cells to eliminate both V. cholerae and Escherichia coli cells in a T6SS-dependent manner. A putative toxin encoded in the cluster, which we name TpeV (type VI permeabilizing effector Vibrio), shares no homology to known proteins and does not contain motifs or domains indicative of function. Ectopic expression of TpeV in the periplasm of E. coli permeabilizes cells and disrupts the membrane potential. Using confocal microscopy, we confirm that susceptible target cells become permeabilized when competed with killer cells harboring the Aux 4 cluster. We also determine that tpiV, the gene located immediately downstream of tpeV, encodes an immunity protein that neutralizes the toxicity of TpeV. Finally, we show that TpeV homologs are broadly distributed across important human, animal, and plant pathogens and are localized in proximity to other T6SS genes. Our results suggest that TpeV is a toxin that belongs to a large family of T6SS proteins. IMPORTANCE Bacteria live in polymicrobial communities where competition for resources and space is essential for survival. Proteobacteria use the T6SS to eliminate neighboring cells and cause disease. However, the mechanisms by which many T6SS toxins kill or inhibit susceptible target cells are poorly understood. The sequence of the TpeV toxin that we describe here is unlike any previously described protein. We demonstrate that it has antimicrobial activity by permeabilizing cells, eliminating membrane potentials, and causing severe cytotoxicity. TpeV homologs are found near known T6SS genes in human, animal, and plant bacterial pathogens, indicating that the toxin is a representative member of a broadly distributed protein family. We propose that TpeV-like toxins contribute to the fitness of many bacteria. Finally, since antibiotic resistance is a critical global health threat, the discovery of new antimicrobial mechanisms could lead to the development of new treatments against resistant strains.
Collapse
Affiliation(s)
- Cristian V. Crisan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Harshini Chandrashekar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Catherine Everly
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Gabi Steinbach
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Shannon E. Hill
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter J. Yunker
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel R. Lieberman
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Brian K. Hammer
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| |
Collapse
|
26
|
Takeda K, Tanaka Y, Kaneko J. The N-terminal amino-latch region of Hlg2 component of staphylococcal bi-component γ-haemolysin is dispensable for prestem release to form β-barrel pores. J Biochem 2021; 168:349-354. [PMID: 32330256 DOI: 10.1093/jb/mvaa052] [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: 02/18/2020] [Accepted: 04/07/2020] [Indexed: 11/14/2022] Open
Abstract
The contribution of N-terminal regions of staphylococcal bi-component γ-haemolysin toxin components to haemolytic activity towards human erythrocyte cells was investigated in this study. A deletion construct of N-terminal amino acids 1-10 of Hlg2 (Hlg2 ΔN10), which is the S-component protein of γ-haemolysin, had little effect on its haemolytic activity, whereas N-terminal 1-11 amino acid deletion (Hlg2 ΔN11) significantly delayed haemolysis. Moreover, a deletion of N-terminal amino acids 1-17 of LukF, which is the F-component protein of γ-haemolysin, increased its haemolytic activity in combination with either the wild-type or Hlg2 ΔN10. Unlike the N-terminal amino-latch region of staphylococcal α-haemolysin, which is a single component β-barrel pore-forming toxin, the N-terminal regions present in γ-haemolysin components are dispensable for the haemolytic activity of the bi-component toxin. These results strengthen our recent proposal that staphylococcal bi-component γ-haemolysin toxin uses an N-terminal amino-latch independent molecular switch for prestem release during the formation of β-barrel pores.
Collapse
Affiliation(s)
- Kein Takeda
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan
| | - Yoshikazu Tanaka
- Laboratory of Applied Biological Molecular Science, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Jun Kaneko
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan
| |
Collapse
|
27
|
Johnstone BA, Christie MP, Morton CJ, Parker MW. X-ray crystallography shines a light on pore-forming toxins. Methods Enzymol 2021; 649:1-46. [PMID: 33712183 DOI: 10.1016/bs.mie.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A common form of cellular attack by pathogenic bacteria is to secrete pore-forming toxins (PFTs). Capable of forming transmembrane pores in various biological membranes, PFTs have also been identified in a diverse range of other organisms such as sea anemones, earthworms and even mushrooms and trees. The mechanism of pore formation by PFTs is associated with substantial conformational changes in going from the water-soluble to transmembrane states of the protein. The determination of the crystal structures for numerous PFTs has shed much light on our understanding of these proteins. Other than elucidating the atomic structural details of PFTs and the conformational changes that must occur for pore formation, crystal structures have revealed structural homology that has led to the discovery of new PFTs and new PFT families. Here we review some key crystallographic results together with complimentary approaches for studying PFTs. We discuss how these studies have impacted our understanding of PFT function and guided research into biotechnical applications.
Collapse
Affiliation(s)
- Bronte A Johnstone
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michelle P Christie
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Craig J Morton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia; St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia.
| |
Collapse
|
28
|
Vasquez MT, Lubkin A, Reyes-Robles T, Day CJ, Lacey KA, Jennings MP, Torres VJ. Identification of a domain critical for Staphylococcus aureus LukED receptor targeting and lysis of erythrocytes. J Biol Chem 2020; 295:17241-17250. [PMID: 33051210 PMCID: PMC7863875 DOI: 10.1074/jbc.ra120.015757] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/07/2020] [Indexed: 12/14/2022] Open
Abstract
Leukocidin ED (LukED) is a pore-forming toxin produced by Staphylococcus aureus, which lyses host cells and promotes virulence of the bacteria. LukED enables S. aureus to acquire iron by lysing erythrocytes, which depends on targeting the host receptor Duffy antigen receptor for chemokines (DARC). The toxin also targets DARC on the endothelium, contributing to the lethality observed during bloodstream infection in mice. LukED is comprised of two monomers: LukE and LukD. LukE binds to DARC and facilitates hemolysis, but the closely related Panton-Valentine leukocidin S (LukS-PV) does not bind to DARC and is not hemolytic. The interaction of LukE with DARC and the role this plays in hemolysis are incompletely characterized. To determine the domain(s) of LukE that are critical for DARC binding, we studied the hemolytic function of LukE-LukS-PV chimeras, in which areas of sequence divergence (divergence regions, or DRs) were swapped between the toxins. We found that two regions of LukE's rim domain contribute to hemolysis, namely residues 57-75 (DR1) and residues 182-196 (DR4). Interestingly, LukE DR1 is sufficient to render LukS-PV capable of DARC binding and hemolysis. Further, LukE, by binding DARC through DR1, promotes the recruitment of LukD to erythrocytes, likely by facilitating LukED oligomer formation. Finally, we show that LukE targets murine Darc through DR1 in vivo to cause host lethality. These findings expand our biochemical understanding of the LukE-DARC interaction and the role that this toxin-receptor pair plays in S. aureus pathophysiology.
Collapse
Affiliation(s)
- Marilyn T Vasquez
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Ashira Lubkin
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Tamara Reyes-Robles
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Christopher J Day
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Keenan A Lacey
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA.
| |
Collapse
|
29
|
Pore-forming proteins: From defense factors to endogenous executors of cell death. Chem Phys Lipids 2020; 234:105026. [PMID: 33309552 DOI: 10.1016/j.chemphyslip.2020.105026] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Pore-forming proteins (PFPs) and small antimicrobial peptides (AMPs) represent a large family of molecules with the common ability to punch holes in cell membranes to alter their permeability. They play a fundamental role as infectious bacteria's defensive tools against host's immune system and as executors of endogenous machineries of regulated cell death in eukaryotic cells. Despite being highly divergent in primary sequence and 3D structure, specific folds of pore-forming domains have been conserved. In fact, pore formation is considered an ancient mechanism that takes place through a general multistep process involving: membrane partitioning and insertion, oligomerization and pore formation. However, different PFPs and AMPs assemble and form pores following different mechanisms that could end up either in the formation of protein-lined or protein-lipid pores. In this review, we analyze the current findings in the mechanism of action of different PFPs and AMPs that support a wide role of membrane pore formation in nature. We also provide the newest insights into the development of state-of-art techniques that have facilitated the characterization of membrane pores. To understand the physiological role of these peptides/proteins or develop clinical applications, it is essential to uncover the molecular mechanism of how they perforate membranes.
Collapse
|
30
|
Vlaeminck J, Raafat D, Surmann K, Timbermont L, Normann N, Sellman B, van Wamel WJB, Malhotra-Kumar S. Exploring Virulence Factors and Alternative Therapies against Staphylococcus aureus Pneumonia. Toxins (Basel) 2020; 12:toxins12110721. [PMID: 33218049 PMCID: PMC7698915 DOI: 10.3390/toxins12110721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/12/2020] [Accepted: 11/15/2020] [Indexed: 12/13/2022] Open
Abstract
Pneumonia is an acute pulmonary infection associated with high mortality and an immense financial burden on healthcare systems. Staphylococcus aureus is an opportunistic pathogen capable of inducing S. aureus pneumonia (SAP), with some lineages also showing multidrug resistance. Given the high level of antibiotic resistance, much research has been focused on targeting S. aureus virulence factors, including toxins and biofilm-associated proteins, in an attempt to develop effective SAP therapeutics. Despite several promising leads, many hurdles still remain for S. aureus vaccine research. Here, we review the state-of-the-art SAP therapeutics, highlight their pitfalls, and discuss alternative approaches of potential significance and future perspectives.
Collapse
Affiliation(s)
- Jelle Vlaeminck
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
| | - Dina Raafat
- Department of Immunology, Institute of Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany; (D.R.); (N.N.)
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt
| | - Kristin Surmann
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, 17475 Greifswald, Germany;
| | - Leen Timbermont
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
| | - Nicole Normann
- Department of Immunology, Institute of Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany; (D.R.); (N.N.)
| | - Bret Sellman
- Microbiome Discovery, Microbial Sciences, BioPharmaceuticals R & D, AstraZeneca, Gaithersburg, MD 20878, USA;
| | - Willem J. B. van Wamel
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center Rotterdam, 3015 Rotterdam, The Netherlands;
| | - Surbhi Malhotra-Kumar
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
- Correspondence: ; Tel.: +32-3-265-27-52
| |
Collapse
|
31
|
Sugawara S, Takayanagi M, Honda S, Tatsuta T, Fujii Y, Ozeki Y, Ito J, Sato M, Hosono AM. Catfish egg lectin affects influx and efflux rates of sunitinib in human cervical carcinoma HeLa cells. Glycobiology 2020; 30:802-816. [PMID: 32248228 DOI: 10.1093/glycob/cwaa029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 03/24/2020] [Accepted: 03/24/2020] [Indexed: 11/15/2022] Open
Abstract
New treatment protocols are aiming to reduce the dose of the multitargeted tyrosine kinase inhibitor sunitinib, as sunitinib elicits many adverse effects depending on its dosage. Silurus asotus egg lectin (SAL) has been reported to enhance the incorporation of propidium iodide as well as doxorubicin into Burkitt's lymphoma Raji cells through binding to globotriaosylceramide (Gb3) on the cell surface. The objective of this study was to examine whether SAL enhances the cytotoxic effect of sunitinib in Gb3-expressing HeLa cells. Although the treatment with SAL delayed the cell growth and enhanced the propidium iodide uptake, cell death accompanied by membrane collapse was not observed. The viability of sunitinib-treated HeLa cells was significantly reduced when the treatment occurred in combination with SAL compared to their separate usage. Sunitinib uptake significantly increased for 30 min in SAL-treated cells, and this increment was almost completely abolished by the addition of L-rhamnose, a hapten sugar of SAL, but not by D-glucose. After removal of SU from the medium, the intracellular sunitinib level in SAL-treated cells was higher than in untreated cells for 24 h, which was not observed in Gb3-deficient HeLa cells. Furthermore, we observed that SAL promoted the formation of lysosome-like structures, which are LAMP1 positive but not acidic in HeLa cells, which can trap sunitinib. Interestingly, SAL-induced vacuolation in HeLa cells was not observed in another Gb3 positive Raji cells. Our findings suggest that SAL/Gb3 interaction promoted sunitinib uptake and suppressed sunitinib excretion and that sunitinib efficiently exerted cytotoxicity against HeLa cells.
Collapse
Affiliation(s)
- Shigeki Sugawara
- Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Madoka Takayanagi
- Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.,Chemiluminescent Reagents Department, R&D Section, Kagamida Factory, DENKA SEIKEN Co. Ltd., 1359-1 Kagamida, Kigoshi Gosen-shi, Niigata 959-1695, Japan
| | - Shota Honda
- Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Takeo Tatsuta
- Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Yuki Fujii
- Graduate School of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch, Sasebo, Nagasaki 859-3298, Japan
| | - Yasuhiro Ozeki
- Department of Life and Environmental System Science, Laboratory of Glycobiology and Marine Biochemistry, Graduate School of NanoBio Sciences, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan
| | - Jun Ito
- Department of Urology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - Makoto Sato
- Department of Urology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - And Masahiro Hosono
- Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| |
Collapse
|
32
|
The bright and dark sides of protein conformational switches and the unifying forces of infections. Commun Biol 2020; 3:382. [PMID: 32669705 PMCID: PMC7363679 DOI: 10.1038/s42003-020-1115-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/29/2020] [Indexed: 12/19/2022] Open
Abstract
It is now established that a protein can switch between multiple conformations to enable altered functions. Several pathogens including SARS COV2 utilize context-dependent conformational switches of particular proteins to invade host membrane to establish infections. In this perspective, we first discuss the understanding of the conformational switch of a protein towards the productive infections as a dark side of nature. Next, the unexplored binary combination of the sequences of SARS COV2 spike protein and the similarity with diverse pathogen derived proteins have been discussed to obtain novel molecular insights into the process of infection. Sannigrahi et al. discuss conformational switching that allows proteins to alter their conformation, aiding in pathogenesis by enabling cellular entry of viruses and bacterial toxins. Focussing on fusion domain of the Spike glycoprotein of SARS COV2 virus, they identify similar “switching sequences” present in diverse pathogen derived proteins.
Collapse
|
33
|
Inhibition of interaction between Staphylococcus aureus α-hemolysin and erythrocytes membrane by hydrolysable tannins: structure-related activity study. Sci Rep 2020; 10:11168. [PMID: 32636484 PMCID: PMC7341856 DOI: 10.1038/s41598-020-68030-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/11/2020] [Indexed: 01/17/2023] Open
Abstract
The objective of the study was a comparative analysis of the antihemolytic activity against two Staphylococcus aureus strains (8325-4 and NCTC 5655) as well as α-hemolysin and of the membrane modifying action of four hydrolysable tannins with different molecular mass and flexibility: 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-d-glucose (T1), 1,2,3,4,5-penta-O-galloyl-β-d-glucose (T2), 3-O-galloyl-1,2-valoneoyl-β-d-glucose (T3) and 1,2-di-O-galloyl-4,6-valoneoyl-β-d-glucose (T4). We showed that all the compounds studied manifested antihemolytic effects in the range of 5–50 µM concentrations. However, the degree of the reduction of hemolysis by the investigated tannins was not uniform. A valoneoyl group—containing compounds (T3 and T4) were less active. Inhibition of the hemolysis induced by α-hemolysin was also noticed on preincubated with the tannins and subsequently washed erythrocytes. In this case the efficiency again depended on the tannin structure and could be represented by the following order: T1 > T2 > T4 > T3. We also found a relationship between the degree of antihemolytic activity of the tannins studied and their capacity to increase the ordering parameter of the erythrocyte membrane outer layer and to change zeta potential. Overall, our study showed a potential of the T1 and T2 tannins as anti-virulence agents. The results of this study using tannins with different combinations of molecular mass and flexibility shed additional light on the role of tannin structure in activity manifestation.
Collapse
|
34
|
Convergent Evolution of Neutralizing Antibodies to Staphylococcus aureus γ-Hemolysin C That Recognize an Immunodominant Primary Sequence-Dependent B-Cell Epitope. mBio 2020; 11:mBio.00460-20. [PMID: 32546616 PMCID: PMC7298706 DOI: 10.1128/mbio.00460-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus infection is a major public health threat in part due to the spread of antibiotic resistance and repeated failures to develop a protective vaccine. Infection is associated with production of virulence factors that include exotoxins that attack host barriers and cellular defenses, such as the leukocidin (Luk) family of bicomponent pore-forming toxins. To investigate the structural basis of antibody-mediated functional inactivation of Luk toxins, we generated a panel of murine monoclonal antibodies (MAbs) that neutralize host cell killing by the γ-hemolysin HlgCB. Staphylococcus aureus infection is a major public health threat in part due to the spread of antibiotic resistance and repeated failures to develop a protective vaccine. Infection is associated with production of virulence factors that include exotoxins that attack host barriers and cellular defenses, such as the leukocidin (Luk) family of bicomponent pore-forming toxins. To investigate the structural basis of antibody-mediated functional inactivation of Luk toxins, we generated a panel of murine monoclonal antibodies (MAbs) that neutralize host cell killing by the γ-hemolysin HlgCB. By biopanning these MAbs against a phage-display library of random Luk peptide fragments, we identified a small subregion within the rim domain of HlgC as the epitope for all the MAbs. Within the native holotoxin, this subregion folds into a conserved β-hairpin structure, with exposed key residues, His252 and Tyr253, required for antibody binding. On the basis of the phage-display results and molecular modeling, a 15-amino-acid synthetic peptide representing the minimal epitope on HlgC (HlgC241-255) was designed, and preincubation with this peptide blocked antibody-mediated HIgCB neutralization. Immunization of mice with HlgC241-255 or the homologous LukS246-260 subregion peptide elicited serum antibodies that specifically recognized the native holotoxin subunits. Furthermore, serum IgG from patients who were convalescent for invasive S. aureus infection showed neutralization of HlgCB toxin activity ex vivo, which recognized the immunodominant HlgC241-255 peptide and was dependent on His252 and Tyr253 residues. We have thus validated an efficient, rapid, and scalable experimental workflow for identification of immunodominant and immunogenic leukotoxin-neutralizing B-cell epitopes that can be exploited for new S. aureus-protective vaccines and immunotherapies.
Collapse
|
35
|
Liu J, Kozhaya L, Torres VJ, Unutmaz D, Lu M. Structure-based discovery of a small-molecule inhibitor of methicillin-resistant Staphylococcus aureus virulence. J Biol Chem 2020; 295:5944-5959. [PMID: 32179646 PMCID: PMC7196633 DOI: 10.1074/jbc.ra120.012697] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/06/2020] [Indexed: 01/07/2023] Open
Abstract
The rapid emergence and dissemination of methicillin-resistant Staphylococcus aureus (MRSA) strains poses a major threat to public health. MRSA possesses an arsenal of secreted host-damaging virulence factors that mediate pathogenicity and blunt immune defenses. Panton-Valentine leukocidin (PVL) and α-toxin are exotoxins that create lytic pores in the host cell membrane. They are recognized as being important for the development of invasive MRSA infections and are thus potential targets for antivirulence therapies. Here, we report the high-resolution X-ray crystal structures of both PVL and α-toxin in their soluble, monomeric, and oligomeric membrane-inserted pore states in complex with n-tetradecylphosphocholine (C14PC). The structures revealed two evolutionarily conserved phosphatidylcholine-binding mechanisms and their roles in modulating host cell attachment, oligomer assembly, and membrane perforation. Moreover, we demonstrate that the soluble C14PC compound protects primary human immune cells in vitro against cytolysis by PVL and α-toxin and hence may serve as the basis for the development of an antivirulence agent for managing MRSA infections.
Collapse
Affiliation(s)
- Jie Liu
- Public Health Research Institute, Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Lina Kozhaya
- Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Derya Unutmaz
- Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032
| | - Min Lu
- Public Health Research Institute, Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103, To whom correspondence should be addressed:
Public Health Research Institute, Dept. of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Newark, NJ 07103. Tel.:
973-854-3260; E-mail:
| |
Collapse
|
36
|
Unbiased Identification of Immunogenic Staphylococcus aureus Leukotoxin B-Cell Epitopes. Infect Immun 2020; 88:IAI.00785-19. [PMID: 32014894 DOI: 10.1128/iai.00785-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/26/2020] [Indexed: 12/26/2022] Open
Abstract
Unbiased identification of individual immunogenic B-cell epitopes in major antigens of a pathogen remains a technology challenge for vaccine discovery. We therefore developed a platform for rapid phage display screening of deep recombinant libraries consisting of as few as one major pathogen antigen. Using the bicomponent pore-forming leukocidin (Luk) exotoxins of the major pathogen Staphylococcus aureus as a prototype, we randomly fragmented and separately ligated the hemolysin gamma A (HlgA) and LukS genes into a custom-built phage display system, termed pComb-Opti8. Deep sequence analysis of barcoded amplimers of the HlgA and LukS gene fragment libraries demonstrated that biopannng against a cross-reactive anti-Luk monoclonal antibody (MAb) recovered convergent molecular clones with short overlapping homologous sequences. We thereby identified an 11-amino-acid sequence that is highly conserved in four Luk toxin subunits and is ubiquitous in representation within S. aureus clinical isolates. The isolated 11-amino-acid peptide probe was predicted to retain the native three-dimensional (3D) conformation seen within the Luk holotoxin. Indeed, this peptide was recognized by the selecting anti-Luk MAb, and, using mutated peptides, we showed that a particular amino acid side chain was essential for these interactions. Furthermore, murine immunization with this peptide elicited IgG responses that were highly reactive with both the autologous synthetic peptide and the full-length Luk toxin homologues. Thus, using a gene fragment- and phage display-based pipeline, we have identified and validated immunogenic B-cell epitopes that are cross-reactive between members of the pore-forming leukocidin family. This approach could be harnessed to identify novel epitopes for a much-needed S. aureus-protective subunit vaccine.
Collapse
|
37
|
Marchetti M, De Bei O, Bettati S, Campanini B, Kovachka S, Gianquinto E, Spyrakis F, Ronda L. Iron Metabolism at the Interface between Host and Pathogen: From Nutritional Immunity to Antibacterial Development. Int J Mol Sci 2020; 21:E2145. [PMID: 32245010 PMCID: PMC7139808 DOI: 10.3390/ijms21062145] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 02/08/2023] Open
Abstract
Nutritional immunity is a form of innate immunity widespread in both vertebrates and invertebrates. The term refers to a rich repertoire of mechanisms set up by the host to inhibit bacterial proliferation by sequestering trace minerals (mainly iron, but also zinc and manganese). This strategy, selected by evolution, represents an effective front-line defense against pathogens and has thus inspired the exploitation of iron restriction in the development of innovative antimicrobials or enhancers of antimicrobial therapy. This review focuses on the mechanisms of nutritional immunity, the strategies adopted by opportunistic human pathogen Staphylococcus aureus to circumvent it, and the impact of deletion mutants on the fitness, infectivity, and persistence inside the host. This information finally converges in an overview of the current development of inhibitors targeting the different stages of iron uptake, an as-yet unexploited target in the field of antistaphylococcal drug discovery.
Collapse
Affiliation(s)
- Marialaura Marchetti
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
| | - Omar De Bei
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Stefano Bettati
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
- National Institute of Biostructures and Biosystems, 00136 Rome, Italy
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Sandra Kovachka
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Luca Ronda
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
| |
Collapse
|
38
|
Roderer D, Raunser S. Tc Toxin Complexes: Assembly, Membrane Permeation, and Protein Translocation. Annu Rev Microbiol 2019; 73:247-265. [DOI: 10.1146/annurev-micro-102215-095531] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tc toxin complexes are virulence factors of many bacteria, including insect and human pathogens. Tc toxins are composed of three subunits that act together to perforate the host membrane, similar to a syringe, and translocate toxic enzymes into the host cell. The reactions of the toxic enzymes lead to deterioration and ultimately death of the cell. We review recent high-resolution structural and functional data that explain the mechanism of action of this type of bacterial toxin at an unprecedented level of molecular detail. We focus on the steps that are necessary for toxin activation and membrane permeation. This is where the largest conformational transitions appear. Furthermore, we compare the architecture and function of Tc toxins with those of anthrax toxin and vertebrate teneurin.
Collapse
Affiliation(s)
- Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
| |
Collapse
|
39
|
Peng W, de Souza Santos M, Li Y, Tomchick DR, Orth K. High-resolution cryo-EM structures of the E. coli hemolysin ClyA oligomers. PLoS One 2019; 14:e0213423. [PMID: 31048915 PMCID: PMC6497250 DOI: 10.1371/journal.pone.0213423] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/08/2019] [Indexed: 11/29/2022] Open
Abstract
Pore-forming proteins (PFPs) represent a functionally important protein family, that are found in organisms from viruses to humans. As a major branch of PFPs, bacteria pore-forming toxins (PFTs) permeabilize membranes and usually cause the death of target cells. E. coli hemolysin ClyA is the first member with the pore complex structure solved among α-PFTs, employing α-helices as transmembrane elements. ClyA is proposed to form pores composed of various numbers of protomers. With high-resolution cryo-EM structures, we observe that ClyA pore complexes can exist as newly confirmed oligomers of a tridecamer and a tetradecamer, at estimated resolutions of 3.2 Å and 4.3 Å, respectively. The 2.8 Å cryo-EM structure of a dodecamer dramatically improves the existing structural model. Structural analysis indicates that protomers from distinct oligomers resemble each other and neighboring protomers adopt a conserved interaction mode. We also show a stabilized intermediate state of ClyA during the transition process from soluble monomers to pore complexes. Unexpectedly, even without the formation of mature pore complexes, ClyA can permeabilize membranes and allow leakage of particles less than ~400 Daltons. In addition, we are the first to show that ClyA forms pore complexes in the presence of cholesterol within artificial liposomes. These findings provide new mechanistic insights into the dynamic process of pore assembly for the prototypical α-PFT ClyA.
Collapse
Affiliation(s)
- Wei Peng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Yang Li
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| |
Collapse
|
40
|
Haapasalo K, Wollman AJM, de Haas CJC, van Kessel KPM, van Strijp JAG, Leake MC. Staphylococcus aureus toxin LukSF dissociates from its membrane receptor target to enable renewed ligand sequestration. FASEB J 2019; 33:3807-3824. [PMID: 30509126 PMCID: PMC6404581 DOI: 10.1096/fj.201801910r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 10/29/2018] [Indexed: 11/11/2022]
Abstract
Staphylococcus aureus Panton-Valentine leukocidin is a pore-forming toxin targeting the human C5a receptor (hC5aR), enabling this pathogen to battle the immune response by destroying phagocytes through targeted lysis. The mechanisms that contribute to rapid cell lysis are largely unexplored. Here, we show that cell lysis may be enabled by a process of toxins targeting receptor clusters and present indirect evidence for receptor "recycling" that allows multiple toxin pores to be formed close together. With the use of live cell single-molecule super-resolution imaging, Förster resonance energy transfer and nanoscale total internal reflection fluorescence colocalization microscopy, we visualized toxin pore formation in the presence of its natural docking ligand. We demonstrate disassociation of hC5aR from toxin complexes and simultaneous binding of new ligands. This effect may free mobile receptors to amplify hyperinflammatory reactions in early stages of microbial infections and have implications for several other similar bicomponent toxins and the design of new antibiotics.-Haapasalo, K., Wollman, A. J. M., de Haas, C. J. C., van Kessel, K. P. M., van Strijp, J. A. G., Leake, M. C. Staphylococcus aureus toxin LukSF dissociates from its membrane receptor target to enable renewed ligand sequestration.
Collapse
Affiliation(s)
- Karita Haapasalo
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland
| | - Adam J. M. Wollman
- Department of Biology, Biological Physical Sciences Institute, University of York, York, United Kingdom
| | - Carla J. C. de Haas
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Kok P. M. van Kessel
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Jos A. G. van Strijp
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Mark C. Leake
- Department of Biology, Biological Physical Sciences Institute, University of York, York, United Kingdom
- Department of Physics, Biological Physical Sciences Institute, University of York, York, United Kingdom
| |
Collapse
|
41
|
Tam K, Torres VJ. Staphylococcus aureus Secreted Toxins and Extracellular Enzymes. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0039-2018. [PMID: 30873936 PMCID: PMC6422052 DOI: 10.1128/microbiolspec.gpp3-0039-2018] [Citation(s) in RCA: 185] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus is a formidable pathogen capable of causing infections in different sites of the body in a variety of vertebrate animals, including humans and livestock. A major contribution to the success of S. aureus as a pathogen is the plethora of virulence factors that manipulate the host's innate and adaptive immune responses. Many of these immune modulating virulence factors are secreted toxins, cofactors for activating host zymogens, and exoenzymes. Secreted toxins such as pore-forming toxins and superantigens are highly inflammatory and can cause leukocyte cell death by cytolysis and clonal deletion, respectively. Coagulases and staphylokinases are cofactors that hijack the host's coagulation system. Exoenzymes, including nucleases and proteases, cleave and inactivate various immune defense and surveillance molecules, such as complement factors, antimicrobial peptides, and surface receptors that are important for leukocyte chemotaxis. Additionally, some of these secreted toxins and exoenzymes can cause disruption of endothelial and epithelial barriers through cell lysis and cleavage of junction proteins. A unique feature when examining the repertoire of S. aureus secreted virulence factors is the apparent functional redundancy exhibited by the majority of the toxins and exoenzymes. However, closer examination of each virulence factor revealed that each has unique properties that have important functional consequences. This chapter provides a brief overview of our current understanding of the major secreted virulence factors critical for S. aureus pathogenesis.
Collapse
Affiliation(s)
- Kayan Tam
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| |
Collapse
|
42
|
Krueger E, Brown AC. Inhibition of bacterial toxin recognition of membrane components as an anti-virulence strategy. J Biol Eng 2019; 13:4. [PMID: 30820243 PMCID: PMC6380060 DOI: 10.1186/s13036-018-0138-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/27/2018] [Indexed: 12/21/2022] Open
Abstract
Over recent years, the development of new antibiotics has not kept pace with the rate at which bacteria develop resistance to these drugs. For this reason, many research groups have begun to design and study alternative therapeutics, including molecules to specifically inhibit the virulence of pathogenic bacteria. Because many of these pathogenic bacteria release protein toxins, which cause or exacerbate disease, inhibition of the activity of bacterial toxins is a promising anti-virulence strategy. In this review, we describe several approaches to inhibit the initial interactions of bacterial toxins with host cell membrane components. The mechanisms by which toxins interact with the host cell membrane components have been well-studied over the years, leading to the identification of therapeutic targets, which have been exploited in the work described here. We review efforts to inhibit binding to protein receptors and essential membrane lipid components, complex assembly, and pore formation. Although none of these molecules have yet been demonstrated in clinical trials, the in vitro and in vivo results presented here demonstrate their promise as novel alternatives and/or complements to traditional antibiotics.
Collapse
Affiliation(s)
- Eric Krueger
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015 USA
| | - Angela C. Brown
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015 USA
| |
Collapse
|
43
|
Takeda K, Tanaka Y, Abe N, Kaneko J. Intermolecular ionic interactions serve as a possible switch for stem release in the staphylococcal bi-component toxin for β-barrel pore assembly. Toxicon 2018; 155:43-48. [DOI: 10.1016/j.toxicon.2018.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 09/26/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
|
44
|
Tan CS, Fleming AM, Ren H, Burrows CJ, White HS. γ-Hemolysin Nanopore Is Sensitive to Guanine-to-Inosine Substitutions in Double-Stranded DNA at the Single-Molecule Level. J Am Chem Soc 2018; 140:14224-14234. [PMID: 30269492 DOI: 10.1021/jacs.8b08153] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Biological nanopores provide a unique single-molecule sensing platform to detect target molecules based on their specific electrical signatures. The γ-hemolysin (γ-HL) protein produced by Staphylococcus aureus is able to assemble into an octamer nanopore with a ∼2.3 nm diameter β-barrel. Herein, we demonstrate the first application of γ-HL nanopore for DNA structural analysis. To optimize conditions for ion-channel recording, the properties of the γ-HL pore (e.g., conductance, voltage-dependent gating, and ion-selectivity) were characterized at different pH, temperature, and electrolyte concentrations. The optimal condition for DNA analysis using γ-HL corresponds to 3 M KCl, pH 5, and T = 20 °C. The γ-HL protein nanopore is able to translocate dsDNA at about ∼20 bp/ms, and the unique current-signature of captured dsDNA can directly distinguish guanine-to-inosine substitutions at the single-molecule level with ∼99% accuracy. The slow dsDNA threading and translocation processes indicate this wild-type γ-HL channel has potential to detect other base modifications in dsDNA.
Collapse
Affiliation(s)
- Cherie S Tan
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Aaron M Fleming
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Hang Ren
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Cynthia J Burrows
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Henry S White
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| |
Collapse
|
45
|
Peng Z, Takeshita M, Shibata N, Tada H, Tanaka Y, Kaneko J. Rim domain loops of staphylococcal β-pore forming bi-component toxin S-components recognize target human erythrocytes in a coordinated manner. J Biochem 2018; 164:93-102. [PMID: 29474554 DOI: 10.1093/jb/mvy030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/07/2018] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus bi-component pore-forming toxins consist of S- and F-components, and form hetero-octameric beta-barrel pores on target blood cell membranes. Among them, γ-haemolysin (Hlg2 and F-component of Luk (LukF)) and LukED (LukE and LukD) possess haemolytic activity, whereas the Panton-Valentine leukocidin (LukS-PV and LukF-PV) does not lyse human erythrocytes. Here, we focussed on four loop structures in the rim domain of S-component, namely loops -1, -2, -3 and -4, and found that replacement of Loop-4 in both Hlg2 and LukE with that of LukS-PV abolished their haemolytic activity. Furthermore, LukS-PV gained haemolytic activity by Loop-4 exchange with Hlg2 or LukE, suggesting that Loop-4 of these S-components determined erythrocyte specificity. LOOP-1 and -2 enhanced the erythrocytes-binding ability of both components. Although Hlg2 and LukE recognize Duffy antigen receptor for chemokines on human erythrocytes, the ability of Loop-4 was not complementary between Hlg2 and LukE. Exchange of Hlg2 with LukE Loop-4 showed weaker activity than intact Hlg2, and LukE mutant with Hlg2 Loop-4 lost its haemolytic activity in combination of LukD. Interestingly, the haemolytic activities of these Loop-4 exchange mutants were affected by F-component, namely LukF enhanced haemolytic activities of these Hlg2 and LukE Loop-4 mutants, and also haemolytic activity of LukS-PV mutant with LukE Loop-4.
Collapse
Affiliation(s)
- Zhao Peng
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan
| | - Miyu Takeshita
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan
| | - Nao Shibata
- Exploratory Research Laboratories, Tsukuba Research Institute, ONO Pharmaceutical Co., LTD, 17-2 Wadai, Tsukuba 300-4247, Japan
| | - Hideaki Tada
- Exploratory Research Laboratories, Tsukuba Research Institute, ONO Pharmaceutical Co., LTD, 17-2 Wadai, Tsukuba 300-4247, Japan
| | - Yoshikazu Tanaka
- Laboratory of Applied Biological Molecular Science, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Jun Kaneko
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Japan
| |
Collapse
|
46
|
Staphylococcus aureus Toxins and Their Molecular Activity in Infectious Diseases. Toxins (Basel) 2018; 10:toxins10060252. [PMID: 29921792 PMCID: PMC6024779 DOI: 10.3390/toxins10060252] [Citation(s) in RCA: 234] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 12/04/2022] Open
Abstract
Staphylococcus aureus is a microorganism resident in the skin and nasal membranes with a dreadful pathogenic potential to cause a variety of community and hospital-acquired infections. The frequency of these infections is increasing and their treatment is becoming more difficult. The ability of S. aureus to form biofilms and the emergence of multidrug-resistant strains are the main reasons determining the challenge in dealing with these infections. S. aureus' infectious capacity and its success as a pathogen is related to the expression of virulence factors, among which the production of a wide variety of toxins is highlighted. For this reason, a better understanding of S. aureus toxins is needed to enable the development of new strategies to reduce their production and consequently improve therapeutic approaches. This review focuses on understanding the toxin-based pathogenesis of S. aureus and their role on infectious diseases.
Collapse
|
47
|
Bräuning B, Bertosin E, Praetorius F, Ihling C, Schatt A, Adler A, Richter K, Sinz A, Dietz H, Groll M. Structure and mechanism of the two-component α-helical pore-forming toxin YaxAB. Nat Commun 2018; 9:1806. [PMID: 29728606 PMCID: PMC5935710 DOI: 10.1038/s41467-018-04139-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 04/02/2018] [Indexed: 01/30/2023] Open
Abstract
Pore-forming toxins (PFT) are virulence factors that transform from soluble to membrane-bound states. The Yersinia YaxAB system represents a family of binary α-PFTs with orthologues in human, insect, and plant pathogens, with unknown structures. YaxAB was shown to be cytotoxic and likely involved in pathogenesis, though the molecular basis for its two-component lytic mechanism remains elusive. Here, we present crystal structures of YaxA and YaxB, together with a cryo-electron microscopy map of the YaxAB complex. Our structures reveal a pore predominantly composed of decamers of YaxA-YaxB heterodimers. Both subunits bear membrane-active moieties, but only YaxA is capable of binding to membranes by itself. YaxB can subsequently be recruited to membrane-associated YaxA and induced to present its lytic transmembrane helices. Pore formation can progress by further oligomerization of YaxA-YaxB dimers. Our results allow for a comparison between pore assemblies belonging to the wider ClyA-like family of α-PFTs, highlighting diverse pore architectures.
Collapse
Affiliation(s)
- Bastian Bräuning
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Chair of Biochemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany.
| | - Eva Bertosin
- Center for Integrated Protein Science Munich (CIPSM), Department of Physics, Technische Universität München, Am Coulombwall 4a, 85748, Garching, Germany
| | - Florian Praetorius
- Center for Integrated Protein Science Munich (CIPSM), Department of Physics, Technische Universität München, Am Coulombwall 4a, 85748, Garching, Germany
| | - Christian Ihling
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str.4, 06120, Halle/Saale, Germany
| | - Alexandra Schatt
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str.4, 06120, Halle/Saale, Germany
| | - Agnes Adler
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Chair of Biochemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Klaus Richter
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Chair of Biotechnology, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Andrea Sinz
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str.4, 06120, Halle/Saale, Germany
| | - Hendrik Dietz
- Center for Integrated Protein Science Munich (CIPSM), Department of Physics, Technische Universität München, Am Coulombwall 4a, 85748, Garching, Germany
| | - Michael Groll
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Chair of Biochemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| |
Collapse
|
48
|
O'Callaghan RJ. The Pathogenesis of Staphylococcus aureus Eye Infections. Pathogens 2018; 7:pathogens7010009. [PMID: 29320451 PMCID: PMC5874735 DOI: 10.3390/pathogens7010009] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 01/02/2018] [Accepted: 01/04/2018] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus is a major pathogen of the eye able to infect the tear duct, eyelid, conjunctiva, cornea, anterior and posterior chambers, and the vitreous chamber. Of these infections, those involving the cornea (keratitis) or the inner chambers of the eye (endophthalmitis) are the most threatening because of their potential to cause a loss in visual acuity or even blindness. Each of these ocular sites is protected by the constitutive expression of a variety of antimicrobial factors and these defenses are augmented by a protective host response to the organism. Such infections often involve a predisposing factor that weakens the defenses, such as the use of contact lenses prior to the development of bacterial keratitis or, for endophthalmitis, the trauma caused by cataract surgery or intravitreal injection. The structural carbohydrates of the bacterial surface induce an inflammatory response able to reduce the bacterial load, but contribute to the tissue damage. A variety of bacterial secreted proteins including alpha-toxin, beta-toxin, gamma-toxin, Panton-Valentine leukocidin and other two-component leukocidins mediate tissue damage and contribute to the induction of the inflammatory response. Quantitative animal models of keratitis and endophthalmitis have provided insights into the S. aureus virulence and host factors active in limiting such infections.
Collapse
Affiliation(s)
- Richard J O'Callaghan
- Department of Microbiology and Immunology, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216, USA.
| |
Collapse
|
49
|
Molecular mechanisms of action of sphingomyelin-specific pore-forming toxin, lysenin. Semin Cell Dev Biol 2018; 73:188-198. [DOI: 10.1016/j.semcdb.2017.07.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 11/21/2022]
|
50
|
Desikan R, Maiti PK, Ayappa KG. Assessing the Structure and Stability of Transmembrane Oligomeric Intermediates of an α-Helical Toxin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11496-11510. [PMID: 28930630 DOI: 10.1021/acs.langmuir.7b02277] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Protein membrane interactions play an important role in our understanding of diverse phenomena ranging from membrane-assisted protein aggregation to oligomerization and folding. Pore-forming toxins (PFTs) are the primary vehicle for infection by several strains of bacteria. These proteins which are expressed in a water-soluble form (monomers) bind to the target membrane and conformationally transform (protomers) and self-assemble to form a multimer transmembrane pore complex through a process of oligomerization. On the basis of the structure of the transmembrane domains, PFTs are broadly classified into β or α toxins. In contrast to β-PFTs, the paucity of available crystal structures coupled with the amphipathic nature of the transmembrane domains has hindered our understanding of α-PFT pore formation. In this article, we use molecular dynamics (MD) simulations to examine the process of pore formation of the bacterial α-PFT, cytolysin A from Escherichia coli (ClyA) in lipid bilayer membranes. Using atomistic MD simulations ranging from 50 to 500 ns, we show that transmembrane oligomeric intermediates or "arcs" form stable proteolipidic complexes consisting of protein arcs with toroidal lipids lining the free edges. By creating initial conditions where the lipids are contained within the arcs, we study the dynamics of spontaneous lipid evacuation and toroidal edge formation. This process occurs on the time scale of tens of nanoseconds, suggesting that once protomers oligomerize, transmembrane arcs are rapidly stabilized to form functional water channels capable of leakage. Using umbrella sampling with a coarse-grained molecular model, we obtain the free energy of insertion of a single protomer into the membrane. A single inserted protomer has a stabilization free energy of -52.9 ± 1.2 kJ/mol and forms a stable transmembrane water channel capable of leakage. Our simulations reveal that arcs are stable and viable intermediates that can occur during the pore-formation pathway for ClyA.
Collapse
Affiliation(s)
- Rajat Desikan
- Department of Chemical Engineering, ‡Centre for Condensed Matter Theory, Department of Physics, and §Centre for Biosystems Science and Engineering, Indian Institute of Science , Bengaluru, India 560012
| | - Prabal K Maiti
- Department of Chemical Engineering, ‡Centre for Condensed Matter Theory, Department of Physics, and §Centre for Biosystems Science and Engineering, Indian Institute of Science , Bengaluru, India 560012
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, ‡Centre for Condensed Matter Theory, Department of Physics, and §Centre for Biosystems Science and Engineering, Indian Institute of Science , Bengaluru, India 560012
| |
Collapse
|