1
|
Lepesheva A, Grobarcikova M, Osickova A, Jurnecka D, Knoblochova S, Cizkova M, Osicka R, Sebo P, Masin J. Modification of the RTX domain cap by acyl chains of adapted length rules the formation of functional hemolysin pores. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184311. [PMID: 38570122 DOI: 10.1016/j.bbamem.2024.184311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/14/2024] [Accepted: 03/25/2024] [Indexed: 04/05/2024]
Abstract
The acylated pore-forming Repeats in ToXin (RTX) cytolysins α-hemolysin (HlyA) and adenylate cyclase toxin (CyaA) preferentially bind to β2 integrins of myeloid leukocytes but can also promiscuously bind and permeabilize cells lacking the β2 integrins. We constructed a HlyA1-563/CyaA860-1706 chimera that was acylated either by the toxin-activating acyltransferase CyaC, using sixteen carbon-long (C16) acyls, or by the HlyC acyltransferase using fourteen carbon-long (C14) acyls. Cytolysin assays with the C16- or C14-acylated HlyA/CyaA chimeric toxin revealed that the RTX domain of CyaA can functionally replace the RTX domain of HlyA only if it is modified by C16-acyls on the Lys983 residue of CyaA. The C16-monoacylated HlyA/CyaA chimera was as pore-forming and cytolytic as native HlyA, whereas the C14-acylated chimera exhibited very low pore-forming activity. Hence, the capacity of the RTX domain of CyaA to support the insertion of the N-terminal pore-forming domain into the target cell membrane, and promote formation of toxin pores, strictly depends on the modification of the Lys983 residue by an acyl chain of adapted length.
Collapse
Affiliation(s)
- Anna Lepesheva
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Michaela Grobarcikova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Adriana Osickova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Sarka Knoblochova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Monika Cizkova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Jiri Masin
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.
| |
Collapse
|
2
|
Abettan A, Nguyen MH, Ladant D, Monticelli L, Chenal A. CyaA translocation across eukaryotic cell membranes. Front Mol Biosci 2024; 11:1359408. [PMID: 38584704 PMCID: PMC10995232 DOI: 10.3389/fmolb.2024.1359408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 01/23/2024] [Indexed: 04/09/2024] Open
Affiliation(s)
- Amiel Abettan
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
- Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, Lyon, France
| | - Minh-Ha Nguyen
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
- Université de Paris Cité, Paris, France
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, Paris, France
| | - Daniel Ladant
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
- Université de Paris Cité, Paris, France
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, Lyon, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France
| | - Alexandre Chenal
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
- Université de Paris Cité, Paris, France
| |
Collapse
|
3
|
Sadi M, Carvalho N, Léger C, Vitorge B, Ladant D, Guijarro JI, Chenal A. B2LiVe, a label-free 1D-NMR method to quantify the binding of amphitropic peptides or proteins to membrane vesicles. CELL REPORTS METHODS 2023; 3:100624. [PMID: 37909050 PMCID: PMC10694493 DOI: 10.1016/j.crmeth.2023.100624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 08/03/2023] [Accepted: 10/04/2023] [Indexed: 11/02/2023]
Abstract
Amphitropic proteins and peptides reversibly partition from solution to membrane, a key process that regulates their functions. Experimental approaches classically used to measure protein partitioning into lipid bilayers, such as fluorescence and circular dichroism, are hardly usable when the peptides or proteins do not exhibit significant polarity and/or conformational changes upon membrane binding. Here, we describe binding to lipid vesicles (B2LiVe), a simple, robust, and widely applicable nuclear magnetic resonance (NMR) method to determine the solution-to-membrane partitioning of unlabeled proteins or peptides. B2LiVe relies on previously described proton 1D-NMR fast-pulsing techniques. Membrane partitioning induces a large line broadening, leading to a loss of protein signals; therefore, the decrease of the NMR signal directly measures the fraction of membrane-bound protein. The method uses low polypeptide concentrations and has been validated on several membrane-interacting polypeptides, ranging from 3 to 54 kDa, with membrane vesicles of different sizes and various lipid compositions.
Collapse
Affiliation(s)
- Mirko Sadi
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France; Université de Paris Cité, 75005 Paris, France
| | - Nicolas Carvalho
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France; Université de Paris Cité, 75005 Paris, France
| | - Corentin Léger
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - Bruno Vitorge
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Daniel Ladant
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - J Iñaki Guijarro
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France.
| | - Alexandre Chenal
- Institut Pasteur, Université de Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France.
| |
Collapse
|
4
|
Osickova A, Knoblochova S, Bumba L, Man P, Kalaninova Z, Lepesheva A, Jurnecka D, Cizkova M, Biedermannova L, Goldsmith JA, Maynard JA, McLellan JS, Osicka R, Sebo P, Masin J. A conserved tryptophan in the acylated segment of RTX toxins controls their β 2 integrin-independent cell penetration. J Biol Chem 2023; 299:104978. [PMID: 37390987 PMCID: PMC10392135 DOI: 10.1016/j.jbc.2023.104978] [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: 04/19/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023] Open
Abstract
The acylated Repeats in ToXins (RTX) leukotoxins, the adenylate cyclase toxin (CyaA) or α-hemolysin (HlyA), bind β2 integrins of leukocytes but also penetrate cells lacking these receptors. We show that the indoles of conserved tryptophans in the acylated segments, W876 of CyaA and W579 of HlyA, are crucial for β2 integrin-independent membrane penetration. Substitutions of W876 by aliphatic or aromatic residues did not affect acylation, folding, or the activities of CyaA W876L/F/Y variants on cells expressing high amounts of the β2 integrin CR3. However, toxin activity of CyaA W876L/F/Y on cells lacking CR3 was strongly impaired. Similarly, a W579L substitution selectively reduced HlyA W579L cytotoxicity towards cells lacking β2 integrins. Intriguingly, the W876L/F/Y substitutions increased the thermal stability (Tm) of CyaA by 4 to 8 °C but locally enhanced the accessibility to deuteration of the hydrophobic segment and of the interface of the two acylated loops. W876Q substitution (showing no increase in Tm), or combination of W876F with a cavity-filling V822M substitution (this combination decreasing the Tm closer to that of CyaA), yielded a milder defect of toxin activity on erythrocytes lacking CR3. Furthermore, the activity of CyaA on erythrocytes was also selectively impaired when the interaction of the pyrrolidine of P848 with the indole of W876 was ablated. Hence, the bulky indoles of residues W876 of CyaA, or W579 of HlyA, rule the local positioning of the acylated loops and enable a membrane-penetrating conformation in the absence of RTX toxin docking onto the cell membrane by β2 integrins.
Collapse
Affiliation(s)
- Adriana Osickova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Sarka Knoblochova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ladislav Bumba
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Man
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Zuzana Kalaninova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic; Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Anna Lepesheva
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic; Faculty of Sciences, Charles University, Prague, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Monika Cizkova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lada Biedermannova
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Vestec, Czech Republic
| | - Jory A Goldsmith
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, USA
| | - Jennifer A Maynard
- Department of Chemical Engineering, The University of Texas at Austin, Austin, USA
| | - Jason S McLellan
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, USA
| | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Jiri Masin
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.
| |
Collapse
|
5
|
Fundamentals of HDX-MS. Essays Biochem 2022; 67:301-314. [PMID: 36251047 PMCID: PMC10070489 DOI: 10.1042/ebc20220111] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
Hydrogen deuterium exchange mass spectrometry (HDX-MS) is becoming part of the standard repertoire of techniques used by molecular biologists to investigate protein structure and dynamics. This is partly due to the increased use of automation in all stages of the technique and its versatility of application-many proteins that present challenges with techniques such as X-ray crystallography and cryoelectron microscopy are amenable to investigation with HDX-MS. The present review is aimed at scientists who are curious about the technique, and how it may aid their research. It describes the fundamental basis of solvent exchange, the basics of a standard HDX-MS experiment, as well as highlighting emerging novel experimental advances, which point to where the field is heading.
Collapse
|
6
|
Léger C, Pitard I, Sadi M, Carvalho N, Brier S, Mechaly A, Raoux-Barbot D, Davi M, Hoos S, Weber P, Vachette P, Durand D, Haouz A, Guijarro JI, Ladant D, Chenal A. Dynamics and structural changes of calmodulin upon interaction with the antagonist calmidazolium. BMC Biol 2022; 20:176. [PMID: 35945584 PMCID: PMC9361521 DOI: 10.1186/s12915-022-01381-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/29/2022] [Indexed: 11/11/2022] Open
Abstract
Background Calmodulin (CaM) is an evolutionarily conserved eukaryotic multifunctional protein that functions as the major sensor of intracellular calcium signaling. Its calcium-modulated function regulates the activity of numerous effector proteins involved in a variety of physiological processes in diverse organs, from proliferation and apoptosis, to memory and immune responses. Due to the pleiotropic roles of CaM in normal and pathological cell functions, CaM antagonists are needed for fundamental studies as well as for potential therapeutic applications. Calmidazolium (CDZ) is a potent small molecule antagonist of CaM and one the most widely used inhibitors of CaM in cell biology. Yet, CDZ, as all other CaM antagonists described thus far, also affects additional cellular targets and its lack of selectivity hinders its application for dissecting calcium/CaM signaling. A better understanding of CaM:CDZ interaction is key to design analogs with improved selectivity. Here, we report a molecular characterization of CaM:CDZ complexes using an integrative structural biology approach combining SEC-SAXS, X-ray crystallography, HDX-MS, and NMR. Results We provide evidence that binding of a single molecule of CDZ induces an open-to-closed conformational reorientation of the two domains of CaM and results in a strong stabilization of its structural elements associated with a reduction of protein dynamics over a large time range. These CDZ-triggered CaM changes mimic those induced by CaM-binding peptides derived from physiological protein targets, despite their distinct chemical natures. CaM residues in close contact with CDZ and involved in the stabilization of the CaM:CDZ complex have been identified. Conclusion Our results provide molecular insights into CDZ-induced dynamics and structural changes of CaM leading to its inhibition and open the way to the rational design of more selective CaM antagonists. Graphical abstract Calmidazolium is a potent and widely used inhibitor of calmodulin, a major mediator of calcium-signaling in eukaryotic cells. Structural characterization of calmidazolium-binding to calmodulin reveals that it triggers open-to-closed conformational changes similar to those induced by calmodulin-binding peptides derived from enzyme targets. These results provide molecular insights into CDZ-induced dynamics and structural changes of CaM leading to its inhibition and open the way to the rational design of more selective CaM antagonists.![]() Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01381-5.
Collapse
Affiliation(s)
- Corentin Léger
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Irène Pitard
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Mirko Sadi
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.,Université Paris Cité, Paris, France
| | - Nicolas Carvalho
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.,Université Paris Cité, Paris, France
| | - Sébastien Brier
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Ariel Mechaly
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Dorothée Raoux-Barbot
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Maryline Davi
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Sylviane Hoos
- Plateforme de Biophysique Moléculaire, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Patrick Weber
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Patrice Vachette
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Dominique Durand
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Ahmed Haouz
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - J Iñaki Guijarro
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Daniel Ladant
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.
| | - Alexandre Chenal
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.
| |
Collapse
|
7
|
Wang H, Chen G, Li H. Templated folding of the RTX domain of the bacterial toxin adenylate cyclase revealed by single molecule force spectroscopy. Nat Commun 2022; 13:2784. [PMID: 35589788 PMCID: PMC9120197 DOI: 10.1038/s41467-022-30448-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/26/2022] [Indexed: 11/18/2022] Open
Abstract
The RTX (repeats-in-toxin) domain of the bacterial toxin adenylate cyclase (CyaA) contains five RTX blocks (RTX-i to RTX-v) and its folding is essential for CyaA’s functions. It was shown that the C-terminal capping structure of RTX-v is critical for the whole RTX to fold. However, it is unknown how the folding signal transmits within the RTX domain. Here we use optical tweezers to investigate the interplay between the folding of RTX-iv and RTX-v. Our results show that RTX-iv alone is disordered, but folds into a Ca2+-loaded-β-roll structure in the presence of a folded RTX-v. Folding trajectories of RTX-iv-v reveal that the folding of RTX-iv is strictly conditional upon the folding of RTX-v, suggesting that the folding of RTX-iv is templated by RTX-v. This templating effect allows RTX-iv to fold rapidly, and provides significant mutual stabilization. Our study reveals a possible mechanism for transmitting the folding signal within the RTX domain. The authors use optical tweezers to show that the folding of repeats-in-toxin (RTX) block-iv in adenylate cyclase is templated by the folded RTX block-v. The findings suggest a possible mechanism for transmitting the folding signal in the RTX domain.
Collapse
Affiliation(s)
- Han Wang
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.,State Key Laboratory of Precision Measuring Technology and Instruments, School of Precision Instrument and Optoelectronics Engineering, Tianjin University, 300072, Tianjin, P. R. China
| | - Guojun Chen
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Hongbin Li
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
| |
Collapse
|
8
|
Filipi K, Rahman WU, Osickova A, Osicka R. Kingella kingae RtxA Cytotoxin in the Context of Other RTX Toxins. Microorganisms 2022; 10:microorganisms10030518. [PMID: 35336094 PMCID: PMC8953716 DOI: 10.3390/microorganisms10030518] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/04/2022] Open
Abstract
The Gram-negative bacterium Kingella kingae is part of the commensal oropharyngeal flora of young children. As detection methods have improved, K. kingae has been increasingly recognized as an emerging invasive pathogen that frequently causes skeletal system infections, bacteremia, and severe forms of infective endocarditis. K. kingae secretes an RtxA cytotoxin, which is involved in the development of clinical infection and belongs to an ever-growing family of cytolytic RTX (Repeats in ToXin) toxins secreted by Gram-negative pathogens. All RTX cytolysins share several characteristic structural features: (i) a hydrophobic pore-forming domain in the N-terminal part of the molecule; (ii) an acylated segment where the activation of the inactive protoxin to the toxin occurs by a co-expressed toxin-activating acyltransferase; (iii) a typical calcium-binding RTX domain in the C-terminal portion of the molecule with the characteristic glycine- and aspartate-rich nonapeptide repeats; and (iv) a C-proximal secretion signal recognized by the type I secretion system. RTX toxins, including RtxA from K. kingae, have been shown to act as highly efficient ‘contact weapons’ that penetrate and permeabilize host cell membranes and thus contribute to the pathogenesis of bacterial infections. RtxA was discovered relatively recently and the knowledge of its biological role remains limited. This review describes the structure and function of RtxA in the context of the most studied RTX toxins, the knowledge of which may contribute to a better understanding of the action of RtxA in the pathogenesis of K. kingae infections.
Collapse
|
9
|
Lepesheva A, Osickova A, Holubova J, Jurnecka D, Knoblochova S, Espinosa-Vinals C, Bumba L, Skopova K, Fiser R, Osicka R, Sebo P, Masin J. Different roles of conserved tyrosine residues of the acylated domains in folding and activity of RTX toxins. Sci Rep 2021; 11:19814. [PMID: 34615931 PMCID: PMC8494930 DOI: 10.1038/s41598-021-99112-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/17/2021] [Indexed: 12/31/2022] Open
Abstract
Pore-forming repeats in toxins (RTX) are key virulence factors of many Gram-negative pathogens. We have recently shown that the aromatic side chain of the conserved tyrosine residue 940 within the acylated segment of the RTX adenylate cyclase toxin-hemolysin (CyaA, ACT or AC-Hly) plays a key role in target cell membrane interaction of the toxin. Therefore, we used a truncated CyaA-derived RTX719 construct to analyze the impact of Y940 substitutions on functional folding of the acylated segment of CyaA. Size exclusion chromatography combined with CD spectroscopy revealed that replacement of the aromatic side chain of Y940 by the side chains of alanine or proline residues disrupted the calcium-dependent folding of RTX719 and led to self-aggregation of the otherwise soluble and monomeric protein. Intriguingly, corresponding alanine substitutions of the conserved Y642, Y643 and Y639 residues in the homologous RtxA, HlyA and ApxIA hemolysins from Kingella kingae, Escherichia coli and Actinobacillus pleuropneumoniae, affected the membrane insertion, pore-forming (hemolytic) and cytotoxic capacities of these toxins only marginally. Activities of these toxins were impaired only upon replacement of the conserved tyrosines by proline residues. It appears, hence, that the critical role of the aromatic side chain of the Y940 residue is highly specific for the functional folding of the acylated domain of CyaA and determines its capacity to penetrate target cell membrane.
Collapse
Affiliation(s)
- Anna Lepesheva
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Adriana Osickova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Holubova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Sarka Knoblochova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | | | - Ladislav Bumba
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Karolina Skopova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radovan Fiser
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Masin
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.
| |
Collapse
|
10
|
Voegele A, Sadi M, O'Brien DP, Gehan P, Raoux‐Barbot D, Davi M, Hoos S, Brûlé S, Raynal B, Weber P, Mechaly A, Haouz A, Rodriguez N, Vachette P, Durand D, Brier S, Ladant D, Chenal A. A High-Affinity Calmodulin-Binding Site in the CyaA Toxin Translocation Domain is Essential for Invasion of Eukaryotic Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003630. [PMID: 33977052 PMCID: PMC8097335 DOI: 10.1002/advs.202003630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/10/2020] [Indexed: 06/12/2023]
Abstract
The molecular mechanisms and forces involved in the translocation of bacterial toxins into host cells are still a matter of intense research. The adenylate cyclase (CyaA) toxin from Bordetella pertussis displays a unique intoxication pathway in which its catalytic domain is directly translocated across target cell membranes. The CyaA translocation region contains a segment, P454 (residues 454-484), which exhibits membrane-active properties related to antimicrobial peptides. Herein, the results show that this peptide is able to translocate across membranes and to interact with calmodulin (CaM). Structural and biophysical analyses reveal the key residues of P454 involved in membrane destabilization and calmodulin binding. Mutational analysis demonstrates that these residues play a crucial role in CyaA translocation into target cells. In addition, calmidazolium, a calmodulin inhibitor, efficiently blocks CyaA internalization. It is proposed that after CyaA binding to target cells, the P454 segment destabilizes the plasma membrane, translocates across the lipid bilayer and binds calmodulin. Trapping of CyaA by the CaM:P454 interaction in the cytosol may assist the entry of the N-terminal catalytic domain by converting the stochastic motion of the polypeptide chain through the membrane into an efficient vectorial chain translocation into host cells.
Collapse
Affiliation(s)
- Alexis Voegele
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Mirko Sadi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Darragh Patrick O'Brien
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Pauline Gehan
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Dorothée Raoux‐Barbot
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Maryline Davi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Sylviane Hoos
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Sébastien Brûlé
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Bertrand Raynal
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Patrick Weber
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ariel Mechaly
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ahmed Haouz
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Nicolas Rodriguez
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Patrice Vachette
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Dominique Durand
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Sébastien Brier
- Biological NMR Technological PlateformCenter for Technological Resources and ResearchDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Daniel Ladant
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Alexandre Chenal
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| |
Collapse
|
11
|
Zhang SP, Feng HZ, Wang Q, Kempher ML, Quan SW, Tao X, Niu S, Wang Y, Feng HY, He YX. Bacterial type II toxin-antitoxin systems acting through post-translational modifications. Comput Struct Biotechnol J 2020; 19:86-93. [PMID: 33384857 PMCID: PMC7758455 DOI: 10.1016/j.csbj.2020.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 11/17/2022] Open
Abstract
The post-translational modification (PTM) serves as an important molecular switch mechanism to modulate diverse biological functions in response to specific cues. Though more commonly found in eukaryotic cells, many PTMs have been identified and characterized in bacteria over the past decade, highlighting the importance of PTMs in regulating bacterial physiology. Several bacterial PTM enzymes have been characterized to function as the toxin component of type II TA systems, which consist of a toxin that inhibits cell growth and an antitoxin that protects the cell from poisoning by the toxin. While TA systems can be classified into seven types based on nature of the antitoxin and its activity, type II TA systems are perhaps the most studied among the different TA types and widely distributed in eubacteria and archaea. The type II toxins possessing PTM activities typically modify various cellular targets mostly associated with protein translation and DNA replication. This review mainly focuses on the enzymatic activities, target specificities, antitoxin neutralizing mechanisms of the different families of PTM toxins. We also proposed that TA systems can be conceptually viewed as molecular switches where the 'on' and 'off' state of the system is tightly controlled by antitoxins and discussed the perspective on toxins having other physiologically roles apart from growth inhibition by acting on the nonessential cellular targets.
Collapse
Affiliation(s)
- Si-Ping Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Han-Zhong Feng
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Qian Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Megan L Kempher
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Shuo-Wei Quan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Xuanyu Tao
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Shaomin Niu
- Institute of Urology, Lanzhou University Second Hospital, Key Laboratory of Urological Diseases in Gansu Province, Gansu Nephro-Urological Clinical Center, Lanzhou, PR China
| | - Yong Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Hu-Yuan Feng
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| |
Collapse
|
12
|
Isolation and genomic characterization of a pathogenic Providencia rettgeri strain G0519 in turtle Trachemys scripta. Antonie van Leeuwenhoek 2020; 113:1633-1662. [PMID: 32951105 DOI: 10.1007/s10482-020-01469-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 08/31/2020] [Indexed: 02/08/2023]
Abstract
Providencia rettgeri infection has occurred occasionally in aquaculture, but is rare in turtles. Here, a pathogenic P. rettgeri strain G0519 was isolated from a diseased slider turtle (Trachemys scripta) in China, and qPCR assay was established for the RTX toxin (rtxD) gene. Histopathological examination showed that many inflammatory cells were infiltrated into heart, liver and intestine, as well as the necrosis of liver, kidney and spleen. The genome consisted of one circular chromosome (4.493 Mb) and one plasmid (18.8 kb), and predicted to contain 4170 and 19 protein-coding genes, respectively. Multiple pathogenic and virulence factors (e.g., fimbria, adhesion, invasion, toxin, hemolysin, chemotaxis, secretion system), multidrug-resistant genes (e.g., ampC, per-1, oxa-1, sul1, tetR) and a novel genomic resistance island PRI519 were identified. Comparative genome analysis revealed the closest relationship was with P. rettgeri, and with P. heimbachae closer than with other Providencia spp. To our knowledge, this was first report on genomic characterization of multidrug-resistant pathogenic P. rettgeri in cultured turtles.
Collapse
|
13
|
Abstract
RTX-Toxins (Repeats in ToXin) are members of a rapidly expanding family of proteins [...].
Collapse
Affiliation(s)
- Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Campusring 1, 28759 Bremen, Germany;
- Rudolf-Virchow-Center for Experimental Biomedicine, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany
| |
Collapse
|
14
|
Osickova A, Khaliq H, Masin J, Jurnecka D, Sukova A, Fiser R, Holubova J, Stanek O, Sebo P, Osicka R. Acyltransferase-mediated selection of the length of the fatty acyl chain and of the acylation site governs activation of bacterial RTX toxins. J Biol Chem 2020; 295:9268-9280. [PMID: 32461253 DOI: 10.1074/jbc.ra120.014122] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/20/2020] [Indexed: 11/06/2022] Open
Abstract
In a wide range of organisms, from bacteria to humans, numerous proteins have to be posttranslationally acylated to become biologically active. Bacterial repeats in toxin (RTX) cytolysins form a prominent group of proteins that are synthesized as inactive protoxins and undergo posttranslational acylation on ε-amino groups of two internal conserved lysine residues by co-expressed toxin-activating acyltransferases. Here, we investigated how the chemical nature, position, and number of bound acyl chains govern the activities of Bordetella pertussis adenylate cyclase toxin (CyaA), Escherichia coli α-hemolysin (HlyA), and Kingella kingae cytotoxin (RtxA). We found that the three protoxins are acylated in the same E. coli cell background by each of the CyaC, HlyC, and RtxC acyltransferases. We also noted that the acyltransferase selects from the bacterial pool of acyl-acyl carrier proteins (ACPs) an acyl chain of a specific length for covalent linkage to the protoxin. The acyltransferase also selects whether both or only one of two conserved lysine residues of the protoxin will be posttranslationally acylated. Functional assays revealed that RtxA has to be modified by 14-carbon fatty acyl chains to be biologically active, that HlyA remains active also when modified by 16-carbon acyl chains, and that CyaA is activated exclusively by 16-carbon acyl chains. These results suggest that the RTX toxin molecules are structurally adapted to the length of the acyl chains used for modification of their acylated lysine residue in the second, more conserved acylation site.
Collapse
Affiliation(s)
- Adriana Osickova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Humaira Khaliq
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Masin
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Anna Sukova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radovan Fiser
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Jana Holubova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ondrej Stanek
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
15
|
Angely C, Ladant D, Planus E, Louis B, Filoche M, Chenal A, Isabey D. Functional and structural consequences of epithelial cell invasion by Bordetella pertussis adenylate cyclase toxin. PLoS One 2020; 15:e0228606. [PMID: 32392246 PMCID: PMC7213728 DOI: 10.1371/journal.pone.0228606] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 04/18/2020] [Indexed: 01/13/2023] Open
Abstract
Bordetella pertussis, the causative agent of whopping cough, produces an adenylate cyclase toxin (CyaA) that plays a key role in the host colonization by targeting innate immune cells which express CD11b/CD18, the cellular receptor of CyaA. CyaA is also able to invade non-phagocytic cells, via a unique entry pathway consisting in a direct translocation of its catalytic domain across the cytoplasmic membrane of the cells. Within the cells, CyaA is activated by calmodulin to produce high levels of cyclic adenosine monophosphate (cAMP) and alter cellular physiology. In this study, we explored the effects of CyaA toxin on the cellular and molecular structure remodeling of A549 alveolar epithelial cells. Using classical imaging techniques, biochemical and functional tests, as well as advanced cell mechanics method, we quantify the structural and functional consequences of the massive increase of intracellular cyclic AMP induced by the toxin: cell shape rounding associated to adhesion weakening process, actin structure remodeling for the cortical and dense components, increase in cytoskeleton stiffness, and inhibition of migration and repair. We also show that, at low concentrations (0.5 nM), CyaA could significantly impair the migration and wound healing capacities of the intoxicated alveolar epithelial cells. As such concentrations might be reached locally during B. pertussis infection, our results suggest that the CyaA, beyond its major role in disabling innate immune cells, might also contribute to the local alteration of the epithelial barrier of the respiratory tract, a hallmark of pertussis.
Collapse
Affiliation(s)
- Christelle Angely
- Equipe 13, Biomécanique & Appareil Respiratoire, Inserm U955, Créteil, France
- UMR 955, UPEC, Université Paris-Est, Créteil, France
- ERL 7000, CNRS, Créteil, France
| | - Daniel Ladant
- Unité de Biochimie des Interactions Macromoléculaires (CNRS UMR 3528), Département de Biologie Structurale et Chimie, Institut Pasteur, Paris, France
| | - Emmanuelle Planus
- Institut pour l’Avancée des Biosciences (IAB), Centre de Recherche UGA/ Inserm U1209 / CNRS UMR 5309, La Tronche, France
| | - Bruno Louis
- Equipe 13, Biomécanique & Appareil Respiratoire, Inserm U955, Créteil, France
- UMR 955, UPEC, Université Paris-Est, Créteil, France
- ERL 7000, CNRS, Créteil, France
| | - Marcel Filoche
- Equipe 13, Biomécanique & Appareil Respiratoire, Inserm U955, Créteil, France
- UMR 955, UPEC, Université Paris-Est, Créteil, France
- ERL 7000, CNRS, Créteil, France
- Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique, CNRS, IP Paris, Palaiseau, France
| | - Alexandre Chenal
- Unité de Biochimie des Interactions Macromoléculaires (CNRS UMR 3528), Département de Biologie Structurale et Chimie, Institut Pasteur, Paris, France
| | - Daniel Isabey
- Equipe 13, Biomécanique & Appareil Respiratoire, Inserm U955, Créteil, France
- UMR 955, UPEC, Université Paris-Est, Créteil, France
- ERL 7000, CNRS, Créteil, France
- * E-mail:
| |
Collapse
|
16
|
Masin J, Osickova A, Jurnecka D, Klimova N, Khaliq H, Sebo P, Osicka R. Retargeting from the CR3 to the LFA-1 receptor uncovers the adenylyl cyclase enzyme-translocating segment of Bordetella adenylate cyclase toxin. J Biol Chem 2020; 295:9349-9365. [PMID: 32393579 DOI: 10.1074/jbc.ra120.013630] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/07/2020] [Indexed: 12/11/2022] Open
Abstract
The Bordetella adenylate cyclase toxin-hemolysin (CyaA) and the α-hemolysin (HlyA) of Escherichia coli belong to the family of cytolytic pore-forming Repeats in ToXin (RTX) cytotoxins. HlyA preferentially binds the αLβ2 integrin LFA-1 (CD11a/CD18) of leukocytes and can promiscuously bind and also permeabilize many other cells. CyaA bears an N-terminal adenylyl cyclase (AC) domain linked to a pore-forming RTX cytolysin (Hly) moiety, binds the complement receptor 3 (CR3, αMβ2, CD11b/CD18, or Mac-1) of myeloid phagocytes, penetrates their plasma membrane, and delivers the AC enzyme into the cytosol. We constructed a set of CyaA/HlyA chimeras and show that the CyaC-acylated segment and the CR3-binding RTX domain of CyaA can be functionally replaced by the HlyC-acylated segment and the much shorter RTX domain of HlyA. Instead of binding CR3, a CyaA1-710/HlyA411-1024 chimera bound the LFA-1 receptor and effectively delivered AC into Jurkat T cells. At high chimera concentrations (25 nm), the interaction with LFA-1 was not required for CyaA1-710/HlyA411-1024 binding to CHO cells. However, interaction with the LFA-1 receptor strongly enhanced the specific capacity of the bound CyaA1-710/HlyA411-1024 chimera to penetrate cells and deliver the AC enzyme into their cytosol. Hence, interaction of the acylated segment and/or the RTX domain of HlyA with LFA-1 promoted a productive membrane interaction of the chimera. These results help delimit residues 400-710 of CyaA as an "AC translocon" sufficient for translocation of the AC polypeptide across the plasma membrane of target cells.
Collapse
Affiliation(s)
- Jiri Masin
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Adriana Osickova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Nela Klimova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic.,Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Humaira Khaliq
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
17
|
Negative charge of the AC-to-Hly linking segment modulates calcium-dependent membrane activities of Bordetella adenylate cyclase toxin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183310. [PMID: 32333856 DOI: 10.1016/j.bbamem.2020.183310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/31/2020] [Accepted: 04/13/2020] [Indexed: 02/08/2023]
Abstract
Two distinct conformers of the adenylate cyclase toxin (CyaA) appear to accomplish its two parallel activities within target cell membrane. The translocating conformer would deliver the N-terminal adenylyl cyclase (AC) enzyme domain across plasma membrane into cytosol of cells, while the pore precursor conformer would assemble into oligomeric cation-selective pores and permeabilize cellular membrane. Both toxin activities then involve a membrane-interacting 'AC-to-Hly-linking segment' (residues 400 to 500). Here, we report the NMR structure of the corresponding CyaA411-490 polypeptide in dodecylphosphocholine micelles and show that it consists of two α-helices linked by an unrestrained loop. The N-terminal α-helix (Gly418 to His439) remained solvent accessible, while the C-terminal α-helix (His457 to Phe485) was fully enclosed within detergent micelles. CyaA411-490 weakly bound Ca2+ ions (apparent KD 2.6 mM) and permeabilized negatively charged lipid vesicles. At high concentrations (10 μM) the CyaA411-490 polypeptide formed stable conductance units in artificial lipid bilayers with applied voltage, suggesting its possible transmembrane orientation in the membrane-inserted toxin. Mutagenesis revealed that two clusters of negatively charged residues within the 'AC-to-Hly-linking segment' (Glu419 to Glu432 and Asp445 to Glu448) regulate the balance between the AC domain translocating and pore-forming capacities of CyaA in function of calcium concentration.
Collapse
|
18
|
Knapp O, Benz R. Membrane Activity and Channel Formation of the Adenylate Cyclase Toxin (CyaA) of Bordetella pertussis in Lipid Bilayer Membranes. Toxins (Basel) 2020; 12:toxins12030169. [PMID: 32164365 PMCID: PMC7150934 DOI: 10.3390/toxins12030169] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/20/2020] [Accepted: 02/22/2020] [Indexed: 12/14/2022] Open
Abstract
The Gram-negative bacterium Bordetella pertussis is the cause of whooping cough. One of its pathogenicity factors is the adenylate cyclase toxin (CyaA) secreted by a Type I export system. The 1706 amino acid long CyaA (177 kDa) belongs to the continuously increasing family of repeat in toxin (RTX) toxins because it contains in its C-terminal half a high number of nine-residue tandem repeats. The protein exhibits cytotoxic and hemolytic activities that target primarily myeloid phagocytic cells expressing the αMβ2 integrin receptor (CD11b/CD18). CyaA represents an exception among RTX cytolysins because the first 400 amino acids from its N-terminal end possess a calmodulin-activated adenylate cyclase (AC) activity. The entry of the AC into target cells is not dependent on the receptor-mediated endocytosis pathway and penetrates directly across the cytoplasmic membrane of a variety of epithelial and immune effector cells. The hemolytic activity of CyaA is rather low, which may have to do with its rather low induced permeability change of target cells and its low conductance in lipid bilayer membranes. CyaA forms highly cation-selective channels in lipid bilayers that show a strong dependence on aqueous pH. The pore-forming activity of CyaA but not its single channel conductance is highly dependent on Ca2+ concentration with a half saturation constant of about 2 to 4 mM.
Collapse
Affiliation(s)
- Oliver Knapp
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759 Bremen, Germany
- Correspondence: (O.K.); (R.B.)
| | - Roland Benz
- Rudolf-Virchow-Center, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany
- Correspondence: (O.K.); (R.B.)
| |
Collapse
|
19
|
Krueger E, Brown AC. Aggregatibacter actinomycetemcomitans leukotoxin: From mechanism to targeted anti-toxin therapeutics. Mol Oral Microbiol 2020; 35:85-105. [PMID: 32061022 DOI: 10.1111/omi.12284] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 12/13/2022]
Abstract
Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium associated with localized aggressive periodontitis, as well as other systemic diseases. This organism produces a number of virulence factors, all of which provide some advantage to the bacterium. Several studies have demonstrated that clinical isolates from diseased patients, particularly those of African descent, frequently belong to specific clones of A. actinomycetemcomitans that produce significantly higher amounts of a protein exotoxin belonging to the repeats-in-toxin (RTX) family, leukotoxin (LtxA), whereas isolates from healthy patients harbor minimally leukotoxic strains. This finding suggests that LtxA might play a key role in A. actinomycetemcomitans pathogenicity. Because of this correlation, much work over the past 30 years has been focused on understanding the mechanisms by which LtxA interacts with and kills host cells. In this article, we review those findings, highlight the remaining open questions, and demonstrate how knowledge of these mechanisms, particularly the toxin's interactions with lymphocyte function-associated antigen-1 (LFA-1) and cholesterol, enables the design of targeted anti-LtxA strategies to prevent/treat disease.
Collapse
Affiliation(s)
- Eric Krueger
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| | - Angela C Brown
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| |
Collapse
|
20
|
Frey J. RTX Toxins of Animal Pathogens and Their Role as Antigens in Vaccines and Diagnostics. Toxins (Basel) 2019; 11:toxins11120719. [PMID: 31835534 PMCID: PMC6950323 DOI: 10.3390/toxins11120719] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 01/19/2023] Open
Abstract
Exotoxins play a central role in the pathologies caused by most major bacterial animal pathogens. The large variety of vertebrate and invertebrate hosts in the animal kingdom is reflected by a large variety of bacterial pathogens and toxins. The group of repeats in the structural toxin (RTX) toxins is particularly abundant among bacterial pathogens of animals. Many of these toxins are described as hemolysins due to their capacity to lyse erythrocytes in vitro. Hemolysis by RTX toxins is due to the formation of cation-selective pores in the cell membrane and serves as an important marker for virulence in bacterial diagnostics. However, their physiologic relevant targets are leukocytes expressing β2 integrins, which act as specific receptors for RTX toxins. For various RTX toxins, the binding to the CD18 moiety of β2 integrins has been shown to be host specific, reflecting the molecular basis of the host range of RTX toxins expressed by bacterial pathogens. Due to the key role of RTX toxins in the pathogenesis of many bacteria, antibodies directed against specific RTX toxins protect against disease, hence, making RTX toxins valuable targets in vaccine research and development. Due to their specificity, several structural genes encoding for RTX toxins have proven to be essential in modern diagnostic applications in veterinary medicine.
Collapse
Affiliation(s)
- Joachim Frey
- Vetsuisse Facutly, University of Bern, 3012 Bern, Switzerland
| |
Collapse
|