1
|
Sawyer TK, Aral E, Staros JV, Bobst CE, Garman SC. Human Saposin B Ligand Binding and Presentation to α-Galactosidase A. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.584535. [PMID: 38617236 PMCID: PMC11014568 DOI: 10.1101/2024.04.04.584535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Sphingolipid activator protein B (saposin B; SapB) is an essential activator of globotriaosylceramide (Gb3) catabolism by α-galactosidase A. However, the manner by which SapB stimulates α-galactosidase A activity remains unknown. To uncover the molecular mechanism of SapB presenting Gb3 to α-galactosidase A, we subjected the fluorescent substrate globotriaosylceramide-nitrobenzoxidazole (Gb3-NBD) to a series of biochemical and structural assays involving SapB. First, we showed that SapB stably binds Gb3-NBD using a fluorescence equilibrium binding assay, isolates Gb3-NBD from micelles, and facilitates α-galactosidase A cleavage of Gb3-NBD in vitro. Second, we crystallized SapB in the presence of Gb3-NBD and validated the ligand-bound assembly. Third, we captured transient interactions between SapB and α-galactosidase A by chemical cross-linking. Finally, we determined the crystal structure of SapB bound to α-galactosidase A. These findings establish general principles for molecular recognition in saposin:hydrolase complexes and highlight the utility of NBD reporter lipids in saposin biochemistry and structural biology.
Collapse
Affiliation(s)
- Thomas K Sawyer
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Efecan Aral
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - James V Staros
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Cedric E Bobst
- Mass Spectrometry Core Facility, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Scott C Garman
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| |
Collapse
|
2
|
Gershberg J, Morhaim M, Rostrovsky I, Eichler J, Sal-Man N. The sequence of events of enteropathogenic E. coli's type III secretion system translocon assembly. iScience 2024; 27:109108. [PMID: 38375228 PMCID: PMC10875159 DOI: 10.1016/j.isci.2024.109108] [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: 08/23/2023] [Revised: 12/17/2023] [Accepted: 01/31/2024] [Indexed: 02/21/2024] Open
Abstract
Many bacterial pathogens employ the type III secretion system (T3SS), a specialized complex that transports effector proteins that manipulate various cellular processes. The T3SS forms a translocon pore within the host-cell membrane consisting of two secreted proteins that transition from a soluble state into a transmembrane complex. Still, the exact sequence of events leading to the formation of a membranous functional pore remains uncertain. Here, we utilized the translocon proteins of enteropathogenic E. coli (EPEC) to investigate the sequence of those steps leading to translocon assembly, including self-oligomerization, hetero-oligomerization, interprotein interaction, and membrane insertion. We found that in EPEC, EspD (SctE) plays a dominant role in pore formation as it assembles into an oligomeric state, regardless of pH, membrane contact, or the presence of EspB (SctB). Subsequently, EspB subunits integrate into EspD homo-oligomers to create EspB-EspD hetero-oligomers that adopt a transmembrane orientation to create a functional pore complex.
Collapse
Affiliation(s)
- Jenia Gershberg
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - May Morhaim
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Irina Rostrovsky
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Neta Sal-Man
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
3
|
Guo H, Geddes EJ, Opperman TJ, Heuck AP. Cell-Based Assay to Determine Type 3 Secretion System Translocon Assembly in Pseudomonas aeruginosa Using Split Luciferase. ACS Infect Dis 2023; 9:2652-2664. [PMID: 37978950 DOI: 10.1021/acsinfecdis.3c00482] [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] [Indexed: 11/19/2023]
Abstract
Multi-drug-resistant Pseudomonas aeruginosa poses a serious threat to hospitalized patients. This organism expresses an arsenal of virulence factors that enables it to readily establish infections and disseminate in the host. The Type 3 secretion system (T3SS) and its associated effectors play a crucial role in the pathogenesis of P. aeruginosa, making them attractive targets for the development of novel therapeutic agents. The T3SS translocon, composed of PopD and PopB, is an essential component of the T3SS secretion apparatus. In the properly assembled translocon, the N-terminus of PopD protrudes into the cytoplasm of the target mammalian cell, which can be exploited as a molecular indicator of functional translocon assembly. In this article, we describe a novel whole-cell-based assay that employs the split NanoLuc luciferase detection system to provide a readout for translocon assembly. The assay demonstrates a favorable signal/noise ratio (13.6) and robustness (Z' = 0.67), making it highly suitable for high-throughput screening of small-molecule inhibitors targeting T3SS translocon assembly.
Collapse
Affiliation(s)
- Hanling Guo
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Emily J Geddes
- Microbiotix, Inc., Worcester, Massachusetts 01605, United States
| | | | - Alejandro P Heuck
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| |
Collapse
|
4
|
Farag SI, Francis MK, Gurung JM, Wai SN, Stenlund H, Francis MS, Nadeem A. Macrophage innate immune responses delineate between defective translocon assemblies produced by Yersinia pseudotuberculosis YopD mutants. Virulence 2023; 14:2249790. [PMID: 37621095 PMCID: PMC10461508 DOI: 10.1080/21505594.2023.2249790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 06/11/2023] [Accepted: 08/13/2023] [Indexed: 08/26/2023] Open
Abstract
Translocon pores formed in the eukaryotic cell membrane by a type III secretion system facilitate the translocation of immune-modulatory effector proteins into the host cell interior. The YopB and YopD proteins produced and secreted by pathogenic Yersinia spp. harboring a virulence plasmid-encoded type III secretion system perform this pore-forming translocator function. We had previously characterized in vitro T3SS function and in vivo pathogenicity of a number of strains encoding sited-directed point mutations in yopD. This resulted in the classification of mutants into three different classes based upon the severity of the phenotypic defects. To investigate the molecular and functional basis for these defects, we explored the effectiveness of RAW 264.7 cell line to respond to infection by representative YopD mutants of all three classes. Signature cytokine profiles could separate the different YopD mutants into distinct categories. The activation and suppression of certain cytokines that function as central innate immune response modulators correlated well with the ability of mutant bacteria to alter anti-phagocytosis and programmed cell death pathways. These analyses demonstrated that sub-optimal translocon pores impact the extent and magnitude of host cell responsiveness, and this limits the capacity of pathogenic Yersinia spp. to fortify against attack by both early and late arms of the host innate immune response.
Collapse
Affiliation(s)
- Salah I. Farag
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Monika K. Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Jyoti M. Gurung
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Hans Stenlund
- Department of Plant Physiology, Umeå Plant Science Centre (UPSC), Umeå University, Umeå, Sweden
- Swedish Metabolomics Centre (SMC), Umeå, Sweden
| | - Matthew S. Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Aftab Nadeem
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| |
Collapse
|
5
|
Chen P, Goldberg MB. Recent insights into type-3 secretion system injectisome structure and mechanism of human enteric pathogens. Curr Opin Microbiol 2023; 71:102232. [PMID: 36368294 PMCID: PMC10510281 DOI: 10.1016/j.mib.2022.102232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/06/2022] [Accepted: 10/19/2022] [Indexed: 11/10/2022]
Abstract
Type-3 secretion system injectisomes are multiprotein complexes that translocate bacterial effector proteins from the cytoplasm of gram-negative bacteria directly into the cytosol of eukaryotic host cells. These systems are present in more than 30 bacterial species, including numerous human, animal, and plant pathogens. We review recent discoveries of structural and molecular mechanisms of effector protein translocation through the injectisomes and recent advances in the understanding of mechanisms of activation of effector protein secretion.
Collapse
Affiliation(s)
- Poyin Chen
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Marcia B Goldberg
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Microbiology, Harvard Medical School, Boston, MA, USA; Broad Institute, Cambridge, MA, USA.
| |
Collapse
|
6
|
Godlee C, Holden DW. Transmembrane substrates of type three secretion system injectisomes. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001292. [PMID: 36748571 PMCID: PMC9993115 DOI: 10.1099/mic.0.001292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The type three secretion system injectisome of Gram-negative bacterial pathogens injects virulence proteins, called effectors, into host cells. Effectors of mammalian pathogens carry out a range of functions enabling bacterial invasion, replication, immune suppression and transmission. The injectisome secretes two translocon proteins that insert into host cell membranes to form a translocon pore, through which effectors are delivered. A subset of effectors also integrate into infected cell membranes, enabling a unique range of biochemical functions. Both translocon proteins and transmembrane effectors avoid cytoplasmic aggregation and integration into the bacterial inner membrane. Translocated transmembrane effectors locate and integrate into the appropriate host membrane. In this review, we focus on transmembrane translocon proteins and effectors of bacterial pathogens of mammals. We discuss what is known about the mechanisms underlying their membrane integration, as well as the functions conferred by the position of injectisome effectors within membranes.
Collapse
Affiliation(s)
- Camilla Godlee
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
- Present address: Department of Infectious Diseases, School of Immunology and Microbial Sciences, King's College London, London, UK
- *Correspondence: Camilla Godlee, ;
| | - David W. Holden
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
- *Correspondence: David W. Holden,
| |
Collapse
|
7
|
PopB-PcrV Interactions Are Essential for Pore Formation in the Pseudomonas aeruginosa Type III Secretion System Translocon. mBio 2022; 13:e0238122. [PMID: 36154276 PMCID: PMC9600203 DOI: 10.1128/mbio.02381-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type III secretion system (T3SS) is a syringe-like virulence factor that delivers bacterial proteins directly into the cytoplasm of host cells. An essential component of the system is the translocon, which creates a pore in the host cell membrane through which proteins are injected. In Pseudomonas aeruginosa, the translocation pore is formed by proteins PopB and PopD and attaches to the T3SS needle via the needle tip protein PcrV. The structure and stoichiometry of the multimeric pore are unknown. We took a genetic approach to map contact points within the system by taking advantage of the fact that the translocator proteins of P. aeruginosa and the related Aeromonas hydrophila T3SS are incompatible and cannot be freely exchanged. We created chimeric versions of P. aeruginosa PopB and A. hydrophila AopB to intentionally disrupt and restore protein-protein interactions. We identified a chimeric B-translocator that specifically disrupts an interaction with the needle tip protein. This disruption did not affect membrane insertion of the B-translocator but did prevent formation of the translocation pore, arguing that the needle tip protein drives the formation of the translocation pore. IMPORTANCE Type III secretion systems are integral to the pathogenesis of many Gram-negative bacterial pathogens. A hallmark of these secretion systems is that they deliver effector proteins vectorially into the targeted host cell via a translocation pore. The translocon is crucial for T3SS function, but it has proven difficult to study biochemically and structurally. Here, we used a genetic approach to identify protein-protein contacts among translocator proteins that are important for function. This genetic approach allowed us to specifically break a contact between the translocator PopB and the T3SS needle tip protein PcrV. Breaking this contact allowed us to determine, for the first time, that the needle tip actively participates in the assembly of the translocation pore by the membrane-bound pore-forming translocator proteins. Our study therefore both expands our knowledge of the network of functionally important interactions among translocator proteins and illuminates a new step in the assembly of this critical host cell interface.
Collapse
|
8
|
Evolutionary Conservation, Variability, and Adaptation of Type III Secretion Systems. J Membr Biol 2022; 255:599-612. [PMID: 35695900 DOI: 10.1007/s00232-022-00247-9] [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: 04/03/2022] [Accepted: 05/20/2022] [Indexed: 10/18/2022]
Abstract
Type III secretion (T3S) systems are complex bacterial structures used by many pathogens to inject proteins directly into the cytosol of the host cell. These secretion machines evolved from the bacterial flagella and they have been grouped into families by phylogenetic analysis. The T3S system is composed of more than 20 proteins grouped into five complexes: the cytosolic platform, the export apparatus, the basal body, the needle, and the translocon complex. While the proteins located inside the bacterium are conserved, those exposed to the external media present high variability among families. This suggests that the T3S systems have adapted to interact with different cells or tissues in the host, and/or have been subjected to the evolutionary pressure of the host immune defenses. Such adaptation led to changes in the sequence of the T3S needle tip and translocon suggesting differences in the mechanism of assembly and structure of this complex.
Collapse
|
9
|
Brahma R, Raghuraman H. Measuring Membrane Penetration Depths and Conformational Changes in Membrane Peptides and Proteins. J Membr Biol 2022; 255:469-483. [PMID: 35274157 DOI: 10.1007/s00232-022-00224-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/23/2022] [Indexed: 10/18/2022]
Abstract
The structural organization and dynamic nature of the biomembrane components are important determinants for numerous cellular functions. Particularly, membrane proteins are critically important for various physiological functions and are important drug targets. The mechanistic insights on the complex functionality of membrane lipids and proteins can be elucidated by understanding the interplay between structure and dynamics. In this regard, membrane penetration depth represents an important parameter to obtain the precise depth of membrane-embedded molecules that often define the conformation and topology of membrane probes and proteins. In this review, we discuss about the widely used fluorescence quenching-based methods (parallax method, distribution analysis, and dual-quencher analysis) to accurately determine the membrane penetration depths of fluorescent probes that are either membrane-embedded or attached to lipids and proteins. Further, we also discuss a relatively novel fluorescence quenching method that utilizes tryptophan residue as the quencher, namely the tryptophan-induced quenching, which is sensitive to monitor small-scale conformational changes (short distances of < 15 Å) and useful in mapping distances in proteins. We have provided numerous examples for the benefit of readers to appreciate the importance and applicability of these simple yet powerful methods to study membrane proteins.
Collapse
Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India.
| |
Collapse
|
10
|
Sabzehali F, Goudarzi H, Goudarzi M, Salimi Chirani A, Yoosefi Izad MH. Immunopotentiating properties of chimeric OprF-OprI-PopB protein against Pseudomonas aeruginosa PAO1 in the infected burned rat model. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2022; 25:276-285. [PMID: 35656187 PMCID: PMC9148398 DOI: 10.22038/ijbms.2022.61448.13595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 03/06/2022] [Indexed: 11/06/2022]
Abstract
Objectives Pseudomonas aeruginosa, as an opportunistic pathogen, is known to cause nosocomial infections among patients suffering from burn injuries and also cystic fibrosis patients. The objective of our research was to develop a novel vaccine against P. aeruginosa. Materials and Methods A recombinant P. aeruginosa subunit vaccine based on the outer membrane proteins, including the OprF-OprI region and its major protein in the type III secretion system, PopB (called FIB protein) was formulated. To induce a robust immune response, our preferred regions were conjugated to a carrier protein, GMCSF (Granulocyte-macrophage colony-stimulating factor). FIB protein's immunogenicity with and without adjuvant was evaluated in vaccinated rats and also burned rat models, which were subcutaneously challenged by the PAO1 strain of P. aeruginosa. Results Antibody levels were increased in sera of rats in this study. Assessment of the resident memory CD4+ T cells in splenocytes from vaccinated rats demonstrated that the FIB conjugated with GMCSF could cause higher responses in comparison with other groups. Moreover, immunization with the FIB plus adjuvant protein could improve interferon-gamma (IFN-γ) production, interleukin 17A (IL-17A), and IL-4, contributing to elicit humoral and cellular immune responses and decreased post-infection bacterial loads after PA challenge, pathology, and inflammatory cell infiltration. Conclusion These observations demonstrated that FIB conjugated with GMCSF can be a putative vaccine candidate against P. aeruginosa in burnt rat models.
Collapse
Affiliation(s)
- Fattaneh Sabzehali
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Alireza Salimi Chirani
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | |
Collapse
|
11
|
Gershberg J, Braverman D, Sal-Man N. Transmembrane domains of type III-secreted proteins affect bacterial-host interactions in enteropathogenic E. coli. Virulence 2021; 12:902-917. [PMID: 33729090 PMCID: PMC7993127 DOI: 10.1080/21505594.2021.1898777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many bacterial pathogens utilize a specialized secretion system, termed type III secretion system (T3SS), to translocate effector proteins into host cells and establish bacterial infection. The T3SS is anchored within the bacterial membranes and contains a long needle/filament that extends toward the host-cell and forms, at its distal end, a pore complex within the host membrane. The T3SS pore complex consists of two bacterial proteins, termed SctB and SctE, which have conflicting targeting indications; a signal sequence that targets to secretion to the extracellular environment via the T3SS, and transmembrane domains (TMDs) that target to membrane localization. In this study, we investigate whether the TMD sequences of SctB and SctE have special features that differentiate them from classical TMDs and allow them to escape bacterial membrane integration. For this purpose, we exchanged the SctB and SctE native TMDs for alternative hydrophobic sequences and found that the TMD sequences of SctB and SctE dictate membrane destination (bacterial versus host membrane). Moreover, we examined the role of the SctB TMD sequence in the activity of the full-length protein, post secretion, and found that the TMD does not serve only as a hydrophobic segment, but is also involved in the ability of the protein to translocate itself and other proteins into and across the host cell membrane.
Collapse
Affiliation(s)
- Jenia Gershberg
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dor Braverman
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Neta Sal-Man
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
12
|
Tang Y, Guo H, Vermeulen AJ, Heuck AP. Topological analysis of type 3 secretion translocons in native membranes. Methods Enzymol 2021; 649:397-429. [PMID: 33712194 DOI: 10.1016/bs.mie.2021.01.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PFPs (Pore-forming proteins) perforate cellular membranes to create an aqueous pore and allow the passage of ions and polar molecules. The molecular mechanisms for many of these PFPs have been elucidated by combining high resolution structural information of these proteins with biochemical and biophysical approaches. However, some PFPs do not adopt stable conformations and are difficult to study in vitro. An example of these proteins are the bacterial Type 3 Secretion (T3S) translocators. The translocators are secreted by the bacterium and insert into the target cell membrane to form a translocon pore providing a portal for the passage of T3S toxins into eukaryotic cells. Given the important role that the T3S systems play in pathogenesis, methods to study these translocon pores in cellular membranes are needed. Using a combination of protein modifications and methods to selectively permeate and solubilized eukaryotic membranes, we have established an experimental procedure to analyze the topology of the Pseudomonas aeruginosa T3S translocon using P. aeruginosa strain variants and HeLa cell lines.
Collapse
Affiliation(s)
- Yuzhou Tang
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, United States
| | - Hanling Guo
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, United States
| | - Arjan J Vermeulen
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, United States
| | - Alejandro P Heuck
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, United States.
| |
Collapse
|
13
|
Sawa T, Kinoshita M, Inoue K, Ohara J, Moriyama K. Immunoglobulin for Treating Bacterial Infections: One More Mechanism of Action. Antibodies (Basel) 2019; 8:antib8040052. [PMID: 31684203 PMCID: PMC6963986 DOI: 10.3390/antib8040052] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/17/2019] [Accepted: 10/28/2019] [Indexed: 02/08/2023] Open
Abstract
The mechanisms underlying the effects of immunoglobulins on bacterial infections are thought to involve bacterial cell lysis via complement activation, phagocytosis via bacterial opsonization, toxin neutralization, and antibody-dependent cell-mediated cytotoxicity. Nevertheless, recent advances in the study of the pathogenicity of Gram-negative bacteria have raised the possibility of an association between immunoglobulin and bacterial toxin secretion. Over time, new toxin secretion systems like the type III secretion system have been discovered in many pathogenic Gram-negative bacteria. With this system, the bacterial toxins are directly injected into the cytoplasm of the target cell through a special secretory apparatus without any exposure to the extracellular environment, and therefore with no opportunity for antibodies to neutralize the toxin. However, antibodies against the V-antigen, which is located on the needle-shaped tip of the bacterial secretion apparatus, can inhibit toxin translocation, thus raising the hope that the toxin may be susceptible to antibody targeting. Because multi-drug resistant bacteria are now prevalent, inhibiting this secretion mechanism is an attractive alternative or adjunctive therapy against lethal bacterial infections. Thus, it is not unreasonable to define the blocking effect of anti-V-antigen antibodies as the fifth mechanism for immunoglobulin action against bacterial infections.
Collapse
Affiliation(s)
- Teiji Sawa
- Department of Anesthesiology, School of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
| | - Mao Kinoshita
- Department of Anesthesiology, School of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
| | - Keita Inoue
- Department of Anesthesiology, School of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
| | - Junya Ohara
- Department of Anesthesiology, School of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
| | - Kiyoshi Moriyama
- Department of Anesthesiology, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
| |
Collapse
|
14
|
Dey S, Chakravarty A, Guha Biswas P, De Guzman RN. The type III secretion system needle, tip, and translocon. Protein Sci 2019; 28:1582-1593. [PMID: 31301256 DOI: 10.1002/pro.3682] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/05/2019] [Accepted: 07/08/2019] [Indexed: 11/06/2022]
Abstract
Many Gram-negative bacteria pathogenic to plants and animals deploy the type III secretion system (T3SS) to inject virulence factors into their hosts. All bacteria that rely on the T3SS to cause infectious diseases in humans have developed antibiotic resistance. The T3SS is an attractive target for developing new antibiotics because it is essential in virulence, and part of its structural component is exposed on the bacterial surface. The structural component of the T3SS is the needle apparatus, which is assembled from over 20 different proteins and consists of a base, an extracellular needle, a tip, and a translocon. This review summarizes the current knowledge on the structure and assembly of the needle, tip, and translocon.
Collapse
Affiliation(s)
- Supratim Dey
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
| | | | | | | |
Collapse
|