1
|
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
|
2
|
Gupta T, Mondal AK, Pani I, Chattopadhyay K, Pal SK. Elucidating liquid crystal-aqueous interface for the study of cholesterol-mediated action of a β-barrel pore forming toxin. SOFT MATTER 2022; 18:5293-5301. [PMID: 35790122 DOI: 10.1039/d2sm00447j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Pore-forming toxins (PFTs) produced by pathogenic bacteria serve as prominent virulence factors with potent cell-killing activity. Most of the β-barrel PFTs form transmembrane oligomeric pores in the membrane lipid bilayer in the presence of cholesterol. The pore-formation mechanisms of the PFTs highlight well-orchestrated regulated events in the membrane environment, which involve dramatic changes in the protein structure and organization. Also, concerted crosstalk between protein and membrane lipid components appears to play crucial roles in the process. Membrane-damaging lesions formed by the pore assembly of the PFTs would also be expected to impose drastic alterations in the membrane organization, details of which remain obscure in most of the cases. Prior reports have established that aqueous interfaces of liquid crystals (LCs) offer promise as responsive interfaces for biomolecular events (at physiologically relevant concentrations), which can be visualized as optical signals. Inspired by this, herein, we sought to understand the lipid membrane interactions of a β-barrel PFT i.e., Vibrio cholerae cytolysin (VCC), using LC-aqueous interfaces. Our results show the formation of dendritic patterns upon the addition of VCC to the lipid embedded with cholesterol over the LC film. In contrast, we did not observe any LC reorientation upon the addition of VCC to the lipid-laden LC-aqueous interface in the absence of cholesterol. An array of techniques such as polarizing optical microscopy (POM), atomic force microscopy (AFM), and fluorescence measurements were utilized to decipher the LC response to the lipid interactions of VCC occurring at these interfaces. Altogether, the results obtained from our study provide a novel platform to explore the mechanistic aspects of the protein-membrane interactions, in the process of membrane pore-formation by the membrane-damaging PFTs.
Collapse
Affiliation(s)
- Tarang Gupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Mohali 140306, India.
| | - Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Mohali 140306, India.
| | - Ipsita Pani
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Mohali 140306, India.
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Mohali 140306, India.
| | - Santanu Kumar Pal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Mohali 140306, India.
| |
Collapse
|
3
|
Sengupta N, Mondal AK, Mishra S, Chattopadhyay K, Dutta S. Single-particle cryo-EM reveals conformational variability of the oligomeric VCC β-barrel pore in a lipid bilayer. J Cell Biol 2021; 220:212683. [PMID: 34617964 PMCID: PMC8504180 DOI: 10.1083/jcb.202102035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/25/2021] [Accepted: 09/19/2021] [Indexed: 11/22/2022] Open
Abstract
Vibrio cholerae cytolysin (VCC) is a water-soluble, membrane-damaging, pore-forming toxin (PFT) secreted by pathogenic V. cholerae, which causes eukaryotic cell death by altering the plasma membrane permeability. VCC self-assembles on the cell surface and undergoes a dramatic conformational change from prepore to heptameric pore structure. Over the past few years, several high-resolution structures of detergent-solubilized PFTs have been characterized. However, high-resolution structural characterization of small β-PFTs in a lipid environment is still rare. Therefore, we used single-particle cryo-EM to characterize the structure of the VCC oligomer in large unilamellar vesicles, which is the first atomic-resolution cryo-EM structure of VCC. From our study, we were able to provide the first documented visualization of the rim domain amino acid residues of VCC interacting with lipid membrane. Furthermore, cryo-EM characterization of lipid bilayer–embedded VCC suggests interesting conformational variabilities, especially in the transmembrane channel, which could have a potential impact on the pore architecture and assist us in understanding the pore formation mechanism.
Collapse
Affiliation(s)
- Nayanika Sengupta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Suman Mishra
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Somnath Dutta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| |
Collapse
|
4
|
Revisiting the role of cholesterol in regulating the pore-formation mechanism of Vibrio cholerae cytolysin, a membrane-damaging β-barrel pore-forming toxin. Biochem J 2018; 475:3039-3055. [DOI: 10.1042/bcj20180387] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/03/2018] [Accepted: 09/10/2018] [Indexed: 11/17/2022]
Abstract
Vibrio cholerae cytolysin (VCC) is a β-barrel pore-forming toxin with potent membrane-damaging cell-killing activity. Previous studies employing the model membranes of lipid vesicles (liposomes) have shown that pore formation by VCC requires the presence of cholesterol in the liposome membranes. However, the exact role of cholesterol in the mode of action of VCC still remains unclear. Most importantly, implication of cholesterol, if any, in regulating the pore-formation mechanism of VCC in the biomembranes of eukaryotic cells remains unexplored. Here, we show that the presence of cholesterol promotes the interaction of VCC with the membrane lipid bilayer, when non-lipid-dependent interactions are absent. However, in the case of biomembranes of human erythrocytes, where accessory interactions are available, cholesterol appears to play a less critical role in the binding step. Nevertheless, in the absence of an optimal level of membrane cholesterol in the human erythrocytes, membrane-bound fraction of the toxin remains trapped in the form of abortive oligomeric assembly, devoid of functional pore-forming activity. Our study also shows that VCC exhibits a prominent propensity to associate with the cholesterol-rich membrane micro-domains of human erythrocytes. Interestingly, mutation of the cholesterol-binding ability of VCC does not block association with the cholesterol-rich membrane micro-domains on human erythrocytes. Based on these results, we propose that the specific cholesterol-binding ability of VCC does not appear to dictate its association with the cholesterol-rich micro-domains on human erythrocytes. Rather, targeting of VCC toward the membrane micro-domains of human erythrocytes possibly acts to facilitate the cholesterol-dependent pore-formation mechanism of the toxin.
Collapse
|
5
|
Kathuria R, Chattopadhyay K. Vibrio choleraecytolysin: Multiple facets of the membrane interaction mechanism of aβ-barrel pore-forming toxin. IUBMB Life 2018; 70:260-266. [DOI: 10.1002/iub.1725] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 02/05/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Reema Kathuria
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences; Indian Institute of Science Education and Research Mohali; Manauli, Mohali Punjab India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences; Indian Institute of Science Education and Research Mohali; Manauli, Mohali Punjab India
| |
Collapse
|
6
|
Vibrio cholerae Cytolysin: Structure–Function Mechanism of an Atypical β-Barrel Pore-Forming Toxin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 842:109-25. [DOI: 10.1007/978-3-319-11280-0_7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
7
|
Rai AK, Chattopadhyay K. Trapping of Vibrio cholerae cytolysin in the membrane-bound monomeric state blocks membrane insertion and functional pore formation by the toxin. J Biol Chem 2014; 289:16978-87. [PMID: 24794872 DOI: 10.1074/jbc.m114.567099] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Vibrio cholerae cytolysin (VCC) is a potent membrane-damaging cytolytic toxin that belongs to the family of β barrel pore-forming protein toxins. VCC induces lysis of its target eukaryotic cells by forming transmembrane oligomeric β barrel pores. The mechanism of membrane pore formation by VCC follows the overall scheme of the archetypical β barrel pore-forming protein toxin mode of action, in which the water-soluble monomeric form of the toxin first binds to the target cell membrane, then assembles into a prepore oligomeric intermediate, and finally converts into the functional transmembrane oligomeric β barrel pore. However, there exists a vast knowledge gap in our understanding regarding the intricate details of the membrane pore formation process employed by VCC. In particular, the membrane oligomerization and membrane insertion steps of the process have only been described to a limited extent. In this study, we determined the key residues in VCC that are critical to trigger membrane oligomerization of the toxin. Alteration of such key residues traps the toxin in its membrane-bound monomeric state and abrogates subsequent oligomerization, membrane insertion, and functional transmembrane pore-formation events. The results obtained from our study also suggest that the membrane insertion of VCC depends critically on the oligomerization process and that it cannot be initiated in the membrane-bound monomeric form of the toxin. In sum, our study, for the first time, dissects membrane binding from the subsequent oligomerization and membrane insertion steps and, thus, defines the exact sequence of events in the membrane pore formation process by VCC.
Collapse
Affiliation(s)
- Anand Kumar Rai
- From the Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Manauli, Mohali, 140306 Punjab, India
| | - Kausik Chattopadhyay
- From the Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Manauli, Mohali, 140306 Punjab, India
| |
Collapse
|
8
|
Paul K, Chattopadhyay K. Single point mutation inVibrio choleraecytolysin compromises the membrane pore-formation mechanism of the toxin. FEBS J 2012; 279:4039-51. [DOI: 10.1111/j.1742-4658.2012.08809.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/08/2012] [Accepted: 08/24/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Karan Paul
- Department of Biological Sciences; Indian Institute of Science Education and Research (IISER) Mohali; SAS Nagar; Manauli; 140306; Punjab; India
| | - Kausik Chattopadhyay
- Department of Biological Sciences; Indian Institute of Science Education and Research (IISER) Mohali; SAS Nagar; Manauli; 140306; Punjab; India
| |
Collapse
|
9
|
Harris JR, Palmer M. Cholesterol specificity of some heptameric beta-barrel pore-forming bacterial toxins: structural and functional aspects. Subcell Biochem 2010; 51:579-596. [PMID: 20213559 DOI: 10.1007/978-90-481-8622-8_21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Apart from the thiol-specific/cholesterol-dependent cytolysin family of toxins (see Chapter 20) there are a number of other unrelated bacterial toxins that also have an affinity for plasma membrane cholesterol. Emphasis is given here on the Vibrio cholerae cytolysin (VCC) and the cytolysins from related Vibrio species. The inhibition of the cytolytic activity of these toxins by prior incubation with extracellular cholesterol or low density lipoprotein emerges as a unifying feature, as does plasma membrane cholesterol depletion. Incubation of VCC with cholesterol produces a heptameric oligomer, which is not equivalent to the pre-pore since it is unable to penetrate the plasma membrane. In structural terms, the precise sequence of VCC monomer binding to membrane, oligomer formation and pore insertion through the bilayer has yet to be fully defined. Several other bacterial toxins have a dependency for cholesterol, although the available data is limited in most cases.
Collapse
Affiliation(s)
- J Robin Harris
- Institute of Zoology, University of Mainz, Mainz, D-55099, Germany.
| | | |
Collapse
|
10
|
Tagami Y, Narita T, Ikigai H, Oishi Y. Penetration behavior of Vibrio cholerae hemolysin into (DMPC/cholesterol) mixed monolayer. Colloids Surf A Physicochem Eng Asp 2009. [DOI: 10.1016/j.colsurfa.2009.04.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
11
|
Anai S, Tagami Y, Narita T, Ikigai H, Oishi Y. Morphological and mechanical studies of cholesterol monolayer on aqueous solution of Vibrio cholerae hemolysin. Colloids Surf A Physicochem Eng Asp 2008. [DOI: 10.1016/j.colsurfa.2008.01.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|