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Naidu AS, Wang CK, Rao P, Mancini F, Clemens RA, Wirakartakusumah A, Chiu HF, Yen CH, Porretta S, Mathai I, Naidu SAG. Precision nutrition to reset virus-induced human metabolic reprogramming and dysregulation (HMRD) in long-COVID. NPJ Sci Food 2024; 8:19. [PMID: 38555403 PMCID: PMC10981760 DOI: 10.1038/s41538-024-00261-2] [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: 10/12/2023] [Accepted: 03/15/2024] [Indexed: 04/02/2024] Open
Abstract
SARS-CoV-2, the etiological agent of COVID-19, is devoid of any metabolic capacity; therefore, it is critical for the viral pathogen to hijack host cellular metabolic machinery for its replication and propagation. This single-stranded RNA virus with a 29.9 kb genome encodes 14 open reading frames (ORFs) and initiates a plethora of virus-host protein-protein interactions in the human body. These extensive viral protein interactions with host-specific cellular targets could trigger severe human metabolic reprogramming/dysregulation (HMRD), a rewiring of sugar-, amino acid-, lipid-, and nucleotide-metabolism(s), as well as altered or impaired bioenergetics, immune dysfunction, and redox imbalance in the body. In the infectious process, the viral pathogen hijacks two major human receptors, angiotensin-converting enzyme (ACE)-2 and/or neuropilin (NRP)-1, for initial adhesion to cell surface; then utilizes two major host proteases, TMPRSS2 and/or furin, to gain cellular entry; and finally employs an endosomal enzyme, cathepsin L (CTSL) for fusogenic release of its viral genome. The virus-induced HMRD results in 5 possible infectious outcomes: asymptomatic, mild, moderate, severe to fatal episodes; while the symptomatic acute COVID-19 condition could manifest into 3 clinical phases: (i) hypoxia and hypoxemia (Warburg effect), (ii) hyperferritinemia ('cytokine storm'), and (iii) thrombocytosis (coagulopathy). The mean incubation period for COVID-19 onset was estimated to be 5.1 days, and most cases develop symptoms after 14 days. The mean viral clearance times were 24, 30, and 39 days for acute, severe, and ICU-admitted COVID-19 patients, respectively. However, about 25-70% of virus-free COVID-19 survivors continue to sustain virus-induced HMRD and exhibit a wide range of symptoms that are persistent, exacerbated, or new 'onset' clinical incidents, collectively termed as post-acute sequelae of COVID-19 (PASC) or long COVID. PASC patients experience several debilitating clinical condition(s) with >200 different and overlapping symptoms that may last for weeks to months. Chronic PASC is a cumulative outcome of at least 10 different HMRD-related pathophysiological mechanisms involving both virus-derived virulence factors and a multitude of innate host responses. Based on HMRD and virus-free clinical impairments of different human organs/systems, PASC patients can be categorized into 4 different clusters or sub-phenotypes: sub-phenotype-1 (33.8%) with cardiac and renal manifestations; sub-phenotype-2 (32.8%) with respiratory, sleep and anxiety disorders; sub-phenotype-3 (23.4%) with skeleto-muscular and nervous disorders; and sub-phenotype-4 (10.1%) with digestive and pulmonary dysfunctions. This narrative review elucidates the effects of viral hijack on host cellular machinery during SARS-CoV-2 infection, ensuing detrimental effect(s) of virus-induced HMRD on human metabolism, consequential symptomatic clinical implications, and damage to multiple organ systems; as well as chronic pathophysiological sequelae in virus-free PASC patients. We have also provided a few evidence-based, human randomized controlled trial (RCT)-tested, precision nutrients to reset HMRD for health recovery of PASC patients.
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Affiliation(s)
- A Satyanarayan Naidu
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA.
- N-terminus Research Laboratory, 232659 Via del Rio, Yorba Linda, CA, 92887, USA.
| | - Chin-Kun Wang
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- School of Nutrition, Chung Shan Medical University, 110, Section 1, Jianguo North Road, Taichung, 40201, Taiwan
| | - Pingfan Rao
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- College of Food and Bioengineering, Fujian Polytechnic Normal University, No.1, Campus New Village, Longjiang Street, Fuqing City, Fujian, China
| | - Fabrizio Mancini
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- President-Emeritus, Parker University, 2540 Walnut Hill Lane, Dallas, TX, 75229, USA
| | - Roger A Clemens
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- University of Southern California, Alfred E. Mann School of Pharmacy/D. K. Kim International Center for Regulatory & Quality Sciences, 1540 Alcazar St., CHP 140, Los Angeles, CA, 90089, USA
| | - Aman Wirakartakusumah
- International Union of Food Science and Technology (IUFoST), Guelph, ON, Canada
- IPMI International Business School Jakarta; South East Asian Food and Agriculture Science and Technology, IPB University, Bogor, Indonesia
| | - Hui-Fang Chiu
- Department of Chinese Medicine, Taichung Hospital, Ministry of Health & Well-being, Taichung, Taiwan
| | - Chi-Hua Yen
- Department of Family and Community Medicine, Chung Shan Medical University Hospital; School of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Sebastiano Porretta
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- President, Italian Association of Food Technology (AITA), Milan, Italy
- Experimental Station for the Food Preserving Industry, Department of Consumer Science, Viale Tanara 31/a, I-43121, Parma, Italy
| | - Issac Mathai
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- Soukya International Holistic Health Center, Whitefield, Bengaluru, India
| | - Sreus A G Naidu
- Global Nutrition Healthcare Council (GNHC) Mission-COVID, Yorba Linda, CA, USA
- N-terminus Research Laboratory, 232659 Via del Rio, Yorba Linda, CA, 92887, USA
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Hiller M, Diwo M, Wamp S, Gutsmann T, Lang C, Blankenfeldt W, Flieger A. Structure-function relationships underpin disulfide loop cleavage-dependent activation of Legionella pneumophila lysophospholipase A PlaA. Mol Microbiol 2024; 121:497-512. [PMID: 38130174 DOI: 10.1111/mmi.15201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 11/03/2023] [Indexed: 12/23/2023]
Abstract
Legionella pneumophila, the causative agent of a life-threatening pneumonia, intracellularly replicates in a specialized compartment in lung macrophages, the Legionella-containing vacuole (LCV). Secreted proteins of the pathogen govern important steps in the intracellular life cycle including bacterial egress. Among these is the type II secreted PlaA which, together with PlaC and PlaD, belongs to the GDSL phospholipase family found in L. pneumophila. PlaA shows lysophospholipase A (LPLA) activity which increases after secretion and subsequent processing by the zinc metalloproteinase ProA within a disulfide loop. Activity of PlaA contributes to the destabilization of the LCV in the absence of the type IVB-secreted effector SdhA. We here present the 3D structure of PlaA which shows a typical α/β-hydrolase fold and reveals that the uncleaved disulfide loop forms a lid structure covering the catalytic triad S30/D278/H282. This leads to reduction of substrate access before activation; however, the catalytic site gets more accessible when the disulfide loop is processed. After structural modeling, a similar activation process is suggested for the GDSL hydrolase PlaC, but not for PlaD. Furthermore, the size of the PlaA substrate-binding site indicated preference toward phospholipids comprising ~16 carbon fatty acid residues which was verified by lipid hydrolysis, suggesting a molecular ruler mechanism. Indeed, mutational analysis changed the substrate profile with respect to fatty acid chain length. In conclusion, our analysis revealed the structural basis for the regulated activation and substrate preference of PlaA.
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Affiliation(s)
- Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Maurice Diwo
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sabrina Wamp
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Thomas Gutsmann
- Research Center Borstel, Leibniz Lung Center, Division of Biophysics, Borstel, Germany
- CSSB-Centre for Structural Systems Biology, Hamburg, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch Institute, Wernigerode, Germany
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A proteolytically activated antimicrobial toxin encoded on a mobile plasmid of Bacteroidales induces a protective response. Nat Commun 2022; 13:4258. [PMID: 35871068 PMCID: PMC9308784 DOI: 10.1038/s41467-022-31925-w] [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: 09/01/2021] [Accepted: 07/11/2022] [Indexed: 01/19/2023] Open
Abstract
Phocaeicola vulgatus is one of the most abundant and ubiquitous bacterial species of the human gut microbiota, yet a comprehensive analysis of antibacterial toxin production by members of this species has not been reported. Here, we identify and characterize a previously undescribed antibacterial protein. This toxin, designated BcpT, is encoded on a small mobile plasmid that is largely confined to strains of the closely related species Phocaeicola vulgatus and Phocaeicola dorei. BcpT is unusual in that it requires cleavage at two distinct sites for activation, and we identify bacterial proteases that perform this activation. We further identify BcpT's receptor as the Lipid A-core glycan, allowing BcpT to target species of other Bacteroidales families. Exposure of cells to BcpT induces a response involving an unusual sigma/anti-sigma factor pair that is likely triggered by cell envelope stress, resulting in the expression of genes that partially protect cells from multiple antimicrobial toxins.
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Identification of Kukoamine A, Zeaxanthin, and Clexane as New Furin Inhibitors. Int J Mol Sci 2022; 23:ijms23052796. [PMID: 35269938 PMCID: PMC8911046 DOI: 10.3390/ijms23052796] [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] [Received: 01/24/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 02/01/2023] Open
Abstract
The endogenous protease furin is a key protein in many different diseases, such as cancer and infections. For this reason, a wide range of studies has focused on targeting furin from a therapeutic point of view. Our main objective consisted of identifying new compounds that could enlarge the furin inhibitor arsenal; secondarily, we assayed their adjuvant effect in combination with a known furin inhibitor, CMK, which avoids the SARS-CoV-2 S protein cleavage by means of that inhibition. Virtual screening was carried out to identify potential furin inhibitors. The inhibition of physiological and purified recombinant furin by screening selected compounds, Clexane, and these drugs in combination with CMK was assayed in fluorogenic tests by using a specific furin substrate. The effects of the selected inhibitors from virtual screening on cell viability (293T HEK cell line) were assayed by means of flow cytometry. Through virtual screening, Zeaxanthin and Kukoamine A were selected as the main potential furin inhibitors. In fluorogenic assays, these two compounds and Clexane inhibited both physiological and recombinant furin in a dose-dependent way. In addition, these compounds increased physiological furin inhibition by CMK, showing an adjuvant effect. In conclusion, we identified Kukoamine A, Zeaxanthin, and Clexane as new furin inhibitors. In addition, these drugs were able to increase furin inhibition by CMK, so they could also increase its efficiency when avoiding S protein proteolysis, which is essential for SARS-CoV-2 cell infection.
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Dynamic, but Not Necessarily Disordered, Human-Virus Interactions Mediated through SLiMs in Viral Proteins. Viruses 2021; 13:v13122369. [PMID: 34960638 PMCID: PMC8703344 DOI: 10.3390/v13122369] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/13/2022] Open
Abstract
Most viruses have small genomes that encode proteins needed to perform essential enzymatic functions. Across virus families, primary enzyme functions are under functional constraint; however, secondary functions mediated by exposed protein surfaces that promote interactions with the host proteins may be less constrained. Viruses often form transient interactions with host proteins through conformationally flexible interfaces. Exposed flexible amino acid residues are known to evolve rapidly suggesting that secondary functions may generate diverse interaction potentials between viruses within the same viral family. One mechanism of interaction is viral mimicry through short linear motifs (SLiMs) that act as functional signatures in host proteins. Viral SLiMs display specific patterns of adjacent amino acids that resemble their host SLiMs and may occur by chance numerous times in viral proteins due to mutational and selective processes. Through mimicry of SLiMs in the host cell proteome, viruses can interfere with the protein interaction network of the host and utilize the host-cell machinery to their benefit. The overlap between rapidly evolving protein regions and the location of functionally critical SLiMs suggest that these motifs and their functional potential may be rapidly rewired causing variation in pathogenicity, infectivity, and virulence of related viruses. The following review provides an overview of known viral SLiMs with select examples of their role in the life cycle of a virus, and a discussion of the structural properties of experimentally validated SLiMs highlighting that a large portion of known viral SLiMs are devoid of predicted intrinsic disorder based on the viral SLiMs from the ELM database.
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Ramasamy K, Balasubramanian S, Kirkpatrick A, Szabo D, Pandranki L, Baseman JB, Kannan TR. Mycoplasma pneumoniae CARDS toxin exploits host cell endosomal acidic pH and vacuolar ATPase proton pump to execute its biological activities. Sci Rep 2021; 11:11571. [PMID: 34078958 PMCID: PMC8172646 DOI: 10.1038/s41598-021-90948-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 05/19/2021] [Indexed: 11/09/2022] Open
Abstract
Mycoplasma pneumoniae is the leading cause of bacterial community-acquired pneumonia among hospitalized children in the United States. It is also responsible for a spectrum of other respiratory tract disorders and extrapulmonary manifestations in children and adults. The main virulence factor of M. pneumoniae is a 591 amino acid multifunctional protein called Community Acquired Respiratory Distress Syndrome (CARDS) toxin. The amino terminal region of CARDS toxin (N-CARDS) retains ADP-ribosylating activity and the carboxy region (C-CARDS) contains the receptor binding and vacuolating activities. After internalization, CARDS toxin is transported in a retrograde manner from endosome through the Golgi complex into the endoplasmic reticulum. However, the mechanisms and criteria by which internalized CARDS toxin is transported and activated to execute its cytotoxic effects remain unknown. In this study, we used full-length CARDS toxin and its mutant and truncated derivatives to analyze how pharmacological drugs that alter pH of intracellular vesicles and electrical potential across vesicular membranes affect translocation of CARDS toxin in mammalian cells. Our results indicate that an acidic environment is essential for CARDS toxin retrograde transport to endoplasmic reticulum. Moreover, retrograde transport facilitates toxin clipping and is required to induce vacuole formation. Additionally, toxin-mediated cell vacuolation is strictly dependent on the function of vacuolar type-ATPase.
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Affiliation(s)
- Kumaraguruparan Ramasamy
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Sowmya Balasubramanian
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Alejandra Kirkpatrick
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Daniel Szabo
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Lavanya Pandranki
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Joel B Baseman
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - T R Kannan
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, 78229, USA.
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Ghaderi S, Bozorgmehr MR, Ahmadi M, Tarahomjoo S. Identification of Conformational B-cell Epitopes in Diphtheria Toxin at Varying Temperatures Using Molecular Dynamics Simulations. ARCHIVES OF RAZI INSTITUTE 2021; 75:427-437. [PMID: 33403838 PMCID: PMC8410147 DOI: 10.22092/ari.2019.127251.1377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/15/2019] [Indexed: 09/30/2022]
Abstract
The changes in temperature levels can potentially affect the toxins in terms of stability and immunological properties via alteration of their structures. Diphtheria Toxin (DT) is highly considered by scientists since its mechanism of action is similar to those of most bacterial toxins, such as botulinum, tetanus, and anthrax. The protection of conformational B-cell epitopes is critically important in the process of diphtheria vaccine production. This study aimed to evaluate the conformational changes of the DT structure at three different temperature levels (27˚C, 37˚C, and 47˚C) using molecular dynamic simulations. Secondary structures were analyzed in YASARA software. According to the results, significant decreases were observed in percentages of the β-sheets, turns, and the helices of the DT structure at 47˚C in comparison with those at 27˚C and 37˚C. Furthermore, the tertiary structure of the DT was compared at different temperatures using the contact map. Accordingly, the results showed that the root-mean-square deviation of the DT structure increased upon temperature rising. In addition, amino acids D68, G128, G171, C186, and K534-S535 at 27˚C and 37˚C, as well as amino acids G26, P38, S291, T267, H384, A356, and V518 at 47˚C showed higher root mean square fluctuation values. The finding demonstrated that the stability of the DT structure decreased at high temperature (47˚C). The solvent-accessible surface area diagram showed that the hydrophobicity of the DT structure increased via temperature rising, and the amino acid residues belonging to B-cell epitopes extended through increasing temperature. However, B-cell epitopes belonging to the junction region of chains A and B were only present at 37˚C. The results of this study are expected to be applicable for determining a suitable temperature level for the production process of the diphtheria vaccine.
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Affiliation(s)
- S Ghaderi
- Division of Central Laboratory, Department of Biotechnology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - M R Bozorgmehr
- Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
| | - M Ahmadi
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Sh Tarahomjoo
- Division of Genomics and Genetic Engineering, Department of Biotechnology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
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König A, Hube B, Kasper L. The Dual Function of the Fungal Toxin Candidalysin during Candida albicans-Macrophage Interaction and Virulence. Toxins (Basel) 2020; 12:toxins12080469. [PMID: 32722029 PMCID: PMC7471981 DOI: 10.3390/toxins12080469] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/16/2020] [Accepted: 07/19/2020] [Indexed: 12/12/2022] Open
Abstract
The dimorphic fungus Candida albicans is both a harmless commensal organism on mucosal surfaces and an opportunistic pathogen. Under certain predisposing conditions, the fungus can overgrow the mucosal microbiome and cause both superficial and life-threatening systemic infections after gaining access to the bloodstream. As the first line of defense of the innate immune response, infecting C. albicans cells face macrophages, which mediate the clearance of invading fungi by intracellular killing. However, the fungus has evolved sophisticated strategies to counteract macrophage antimicrobial activities and thus evade immune surveillance. The cytolytic peptide toxin, candidalysin, contributes to this fungal defense machinery by damaging immune cell membranes, providing an escape route from the hostile phagosome environment. Nevertheless, candidalysin also induces NLRP3 inflammasome activation, leading to an increased host-protective pro-inflammatory response in mononuclear phagocytes. Therefore, candidalysin facilitates immune evasion by acting as a classical virulence factor but also contributes to an antifungal immune response, serving as an avirulence factor. In this review, we discuss the role of candidalysin during C. albicans infections, focusing on its implications during C. albicans-macrophage interactions.
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Affiliation(s)
- Annika König
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology–Hans Knoell Institute, 07745 Jena, Germany;
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology–Hans Knoell Institute, 07745 Jena, Germany;
- Center for Sepsis Control and Care, University Hospital Jena, 07747 Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, 07743 Jena, Germany
- Correspondence: (B.H.); (L.K.)
| | - Lydia Kasper
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology–Hans Knoell Institute, 07745 Jena, Germany;
- Correspondence: (B.H.); (L.K.)
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Abstract
How protein toxins translocate their catalytic domain across a cell membrane is the least understood step in toxin action. This study utilized a reporter, β-lactamase, that was genetically fused to full-length, nontoxic tetanus toxin (βlac-TT) in discovery-based live-cell assays to study LC translocation. Directed mutagenesis identified a role for K768 in LC translocation. K768 was located between α15 and α16 (termed the cis-loop). Cellular assays showed that K768 did not interfere with other toxin functions, including cell binding, intracellular trafficking, and pore formation. The equivalent K768 is conserved among the clostridial neurotoxin family of proteins as a conserved structural motif. The cis-loop appears to contribute to LC translocation. The clostridial neurotoxins (CNTs) comprise tetanus toxin (TT) and botulinum neurotoxin (BoNT [BT]) serotypes (A to G and X) and several recently identified CNT-like proteins, including BT/En and the mosquito BoNT-like toxin Pmp1. CNTs are produced as single proteins cleaved to a light chain (LC) and a heavy chain (HC) connected by an interchain disulfide bond. LC is a zinc metalloprotease (cleaving soluble N-ethylmaleimide-sensitive factor attachment protein receptors [SNAREs]), while HC contains an N-terminal translocation domain (HCN) and a C-terminal receptor binding domain (HCC). HCN-mediated LC translocation is the least understood function of CNT action. Here, β-lactamase (βlac) was used as a reporter in discovery-based live-cell assays to characterize TT-mediated LC translocation. Directed mutagenesis identified a role for a charged loop (767DKE769) connecting α15 and α16 (cis-loop) within HCN in LC translocation; aliphatic substitution inhibited LC translocation but not other toxin functions such as cell binding, intracellular trafficking, or HCN-mediated pore formation. K768 was conserved among the CNTs. In molecular simulations of the HCN with a membrane, the cis-loop did not bind with the cell membrane. Taken together, the results of these studies implicate the cis-loop in LC translocation, independently of pore formation. IMPORTANCE How protein toxins translocate their catalytic domain across a cell membrane is the least understood step in toxin action. This study utilized a reporter, β-lactamase, that was genetically fused to full-length, nontoxic tetanus toxin (βlac-TT) in discovery-based live-cell assays to study LC translocation. Directed mutagenesis identified a role for K768 in LC translocation. K768 was located between α15 and α16 (termed the cis-loop). Cellular assays showed that K768 did not interfere with other toxin functions, including cell binding, intracellular trafficking, and pore formation. The equivalent K768 is conserved among the clostridial neurotoxin family of proteins as a conserved structural motif. The cis-loop appears to contribute to LC translocation.
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Braun E, Sauter D. Furin-mediated protein processing in infectious diseases and cancer. Clin Transl Immunology 2019; 8:e1073. [PMID: 31406574 PMCID: PMC6682551 DOI: 10.1002/cti2.1073] [Citation(s) in RCA: 197] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 07/10/2019] [Accepted: 07/13/2019] [Indexed: 12/17/2022] Open
Abstract
Proteolytic cleavage regulates numerous processes in health and disease. One key player is the ubiquitously expressed serine protease furin, which cleaves a plethora of proteins at polybasic recognition motifs. Mammalian substrates of furin include cytokines, hormones, growth factors and receptors. Thus, it is not surprising that aberrant furin activity is associated with a variety of disorders including cancer. Furthermore, the enzymatic activity of furin is exploited by numerous viral and bacterial pathogens, thereby enhancing their virulence and spread. In this review, we describe the physiological and pathophysiological substrates of furin and discuss how dysregulation of a simple proteolytic cleavage event may promote infectious diseases and cancer. One major focus is the role of furin in viral glycoprotein maturation and pathogenicity. We also outline cellular mechanisms regulating the expression and activation of furin and summarise current approaches that target this protease for therapeutic intervention.
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Affiliation(s)
- Elisabeth Braun
- Institute of Molecular VirologyUlm University Medical CenterUlmGermany
| | - Daniel Sauter
- Institute of Molecular VirologyUlm University Medical CenterUlmGermany
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Mamedov T, Musayeva I, Acsora R, Gun N, Gulec B, Mammadova G, Cicek K, Hasanova G. Engineering, and production of functionally active human Furin in N. benthamiana plant: In vivo post-translational processing of target proteins by Furin in plants. PLoS One 2019; 14:e0213438. [PMID: 30861020 PMCID: PMC6413912 DOI: 10.1371/journal.pone.0213438] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 02/21/2019] [Indexed: 11/19/2022] Open
Abstract
A plant expression platform with eukaryotic post-translational modification (PTM) machinery has many advantages compared to other protein expression systems. This promising technology is useful for the production of a variety of recombinant proteins including, therapeutic proteins, vaccine antigens, native additives, and industrial enzymes. However, plants lack some of the important PTMs, including furin processing, which limits this system for the production of certain mammalian complex proteins of therapeutic value. Furin is a ubiquitous proprotein convertase that is involved in the processing (activation) of a wide variety of precursor proteins, including blood coagulation factors, cell surface receptors, hormones and growth factors, viral envelope glycoproteins, etc. and plays a critical regulatory role in a wide variety of cellular events. In this study, we engineered the human furin gene for expression in plants and demonstrated the production of a functional active recombinant truncated human furin in N. benthamiana plant. We demonstrate that plant produced human furin is highly active both in vivo and in vitro and specifically cleaved the tested target proteins, Factor IX (FIX) and Protective Antigen (PA83). We also demonstrate that both, enzymatic deglycosylation and proteolytic processing of target proteins can be achieved in vivo by co-expression of deglycosylating and furin cleavage enzymes in a single cell to produce deglycosylated and furin processed target proteins. It is highly expected that this strategy will have many potential applications in pharmaceutical industry and can be used to produce safe and affordable therapeutic proteins, antibodies, and vaccines using a plant expression system.
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Affiliation(s)
- Tarlan Mamedov
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
- Azerbaijan National Academy of Science, Department of Biology and Medical Science, Baku, Azerbaijan
| | - Ilaha Musayeva
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Rabia Acsora
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Nilufer Gun
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Burcu Gulec
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Gulshan Mammadova
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Kader Cicek
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
| | - Gulnara Hasanova
- Akdeniz University, Department of Agricultural Biotechnology, Antalya, Turkey
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Hoffmann HH, Schneider WM, Blomen VA, Scull MA, Hovnanian A, Brummelkamp TR, Rice CM. Diverse Viruses Require the Calcium Transporter SPCA1 for Maturation and Spread. Cell Host Microbe 2018; 22:460-470.e5. [PMID: 29024641 DOI: 10.1016/j.chom.2017.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/05/2017] [Accepted: 09/06/2017] [Indexed: 10/18/2022]
Abstract
Respiratory and arthropod-borne viral infections are a global threat due to the lack of effective antivirals and vaccines. A potential strategy is to target host proteins required for viruses but non-essential for the host. To identify such proteins, we performed a genome-wide knockout screen in human haploid cells and identified the calcium pump SPCA1. SPCA1 is required by viruses from the Paramyxoviridae, Flaviviridae, and Togaviridae families, including measles, dengue, West Nile, Zika, and chikungunya viruses. Calcium transport activity is required for SPCA1 to promote virus spread. SPCA1 regulates proteases within the trans-Golgi network that require calcium for their activity and are critical for virus glycoprotein maturation. Consistent with these findings, viral glycoproteins fail to mature in SPCA1-deficient cells preventing viral spread, which is evident even in cells with partial loss of SPCA1. Thus, SPCA1 is an attractive antiviral host target for a broad spectrum of established and emerging viral infections.
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Affiliation(s)
- H-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - William M Schneider
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Vincent A Blomen
- Biochemistry Division, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Margaret A Scull
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Alain Hovnanian
- INSERM UMR 1163 and Imagine Institute, 75015 Paris, France; Université Paris V Descartes - Sorbonne Paris Cité, 75006 Paris, France; Department of Genetics, Necker Hospital, 75015 Paris, France
| | - Thijn R Brummelkamp
- Biochemistry Division, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands; Cancer Genomics Centre, 3584 CG Utrecht, The Netherlands
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA.
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Zuverink M, Barbieri JT. Protein Toxins That Utilize Gangliosides as Host Receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 156:325-354. [PMID: 29747819 DOI: 10.1016/bs.pmbts.2017.11.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Subsets of protein toxins utilize gangliosides as host receptors. Gangliosides are preferred receptors due to their extracellular localization on the eukaryotic cell and due to their essential nature in host physiology. Glycosphingolipids, including gangliosides, are mediators of signal transduction within and between eukaryotic cells. Protein toxins possess AB structure-function organization, where the A domain encodes a catalytic function for the posttranslational modification of a host macromolecule, including proteins and nucleic acids, and a B domain, which encodes host receptor recognition, including proteins and glycosphingolipids, alone or in combination. Protein toxins use similar strategies to bind glycans by pockets and loops, generally employing hydrogen bonding and aromatic stacking to stabilize interactions with sugars. In some cases, glycan binding facilitates uptake, while in other cases, cross-linking or a second receptor is necessary to stimulate entry. The affinity that protein toxins have for host glycans is necessary for tissue targeting, but not always sufficient to cause disease. In addition to affinity for binding the glycan, the lipid moiety also plays an important role in productive uptake and tissue tropism. Upon endocytosis, the protein toxin must escape to another intracellular compartment or into cytosol to modify a host substrate, modulating host signaling, often resulting in cytotoxic or apoptotic events in the cell, and a unique morbidity for the organism. The study of protein toxins that utilize gangliosides as host receptors has illuminated numerous eukaryotic cellular processes, identified the basis for developing interventions to prevent disease through vaccines and control bacterial diseases through therapies. In addition, subsets of these protein toxins have been utilized as therapeutic agents to treat numerous human inflictions.
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Böttcher-Friebertshäuser E, Garten W, Klenk HD. Characterization of Proprotein Convertases and Their Involvement in Virus Propagation. ACTIVATION OF VIRUSES BY HOST PROTEASES 2018. [PMCID: PMC7122180 DOI: 10.1007/978-3-319-75474-1_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Wolfgang Garten
- Institut für Virologie, Philipps Universität, Marburg, Germany
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15
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Belousov MV, Bondarev SA, Kosolapova AO, Antonets KS, Sulatskaya AI, Sulatsky MI, Zhouravleva GA, Kuznetsova IM, Turoverov KK, Nizhnikov AA. M60-like metalloprotease domain of the Escherichia coli YghJ protein forms amyloid fibrils. PLoS One 2018; 13:e0191317. [PMID: 29381728 PMCID: PMC5790219 DOI: 10.1371/journal.pone.0191317] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 01/03/2018] [Indexed: 12/31/2022] Open
Abstract
Amyloids are protein fibrils with a characteristic spatial structure. Amyloids were long perceived as the pathogens involved in a set of lethal diseases in humans and animals. In recent decades, it has become clear that amyloids represent a quaternary protein structure that is not only pathological but also functionally important and is widely used by different organisms, ranging from archaea to animals, to implement diverse biological functions. The greatest biological variety of amyloids is found in prokaryotes, where they control the formation of biofilms and cell wall sheaths, facilitate the overcoming of surface tension, and regulate the metabolism of toxins. Several amyloid proteins were identified in the important model, biotechnological and pathogenic bacterium Escherichia coli. In previous studies, using a method for the proteomic screening and identification of amyloids, we identified 61 potentially amyloidogenic proteins in the proteome of E. coli. Among these proteins, YghJ was the most enriched with bioinformatically predicted amyloidogenic regions. YghJ is a lipoprotein with a zinc metalloprotease M60-like domain that is involved in mucin degradation in the intestine as well as in proinflammatory responses. In this study, we analyzed the amyloid properties of the YghJ M60-like domain and demonstrated that it forms amyloid-like fibrils in vitro and in vivo.
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Affiliation(s)
- Mikhail V. Belousov
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
| | - Stanislav A. Bondarev
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
- Laboratory of Amyloid Biology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
| | - Anastasiia O. Kosolapova
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), Podbelskogo sh., Pushkin, St. Petersburg, Russian Federation
| | - Kirill S. Antonets
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), Podbelskogo sh., Pushkin, St. Petersburg, Russian Federation
| | - Anna I. Sulatskaya
- Institute of Cytology, Russian Academy of Science, St. Petersburg, Russian Federation
| | - Maksim I. Sulatsky
- Institute of Cytology, Russian Academy of Science, St. Petersburg, Russian Federation
| | - Galina A. Zhouravleva
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
- Laboratory of Amyloid Biology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
| | - Irina M. Kuznetsova
- Institute of Cytology, Russian Academy of Science, St. Petersburg, Russian Federation
| | - Konstantin K. Turoverov
- Institute of Cytology, Russian Academy of Science, St. Petersburg, Russian Federation
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, St. Petersburg, Russian Federation
| | - Anton A. Nizhnikov
- Department of Genetics and Biotechnology, St. Petersburg State University, Universitetskaya nab., St. Petersburg, Russian Federation
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), Podbelskogo sh., Pushkin, St. Petersburg, Russian Federation
- Vavilov Institute of General Genetics, Russian Academy of Sciences, St Petersburg Branch, Universitetskaya nab., St. Petersburg, Russian Federation
- * E-mail:
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16
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Lang C, Hiller M, Flieger A. Disulfide loop cleavage of Legionella pneumophila PlaA boosts lysophospholipase A activity. Sci Rep 2017; 7:16313. [PMID: 29176577 PMCID: PMC5701174 DOI: 10.1038/s41598-017-12796-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 09/14/2017] [Indexed: 02/07/2023] Open
Abstract
L. pneumophila, an important facultative intracellular bacterium, infects the human lung and environmental protozoa. At least fifteen phospholipases A (PLA) are encoded in its genome. Three of which, namely PlaA, PlaC, and PlaD, belong to the GDSL lipase family abundant in bacteria and higher plants. PlaA is a lysophospholipase A (LPLA) that destabilizes the phagosomal membrane in absence of a protective factor. PlaC shows PLA and glycerophospholipid: cholesterol acyltransferase (GCAT) activities which are activated by zinc metalloproteinase ProA via cleavage of a disulphide loop. In this work, we compared GDSL enzyme activities, their secretion, and activation of PlaA. We found that PlaA majorly contributed to LPLA, PlaC to PLA, and both substrate-dependently to GCAT activity. Western blotting revealed that PlaA and PlaC are type II-secreted and both processed by ProA. Interestingly, ProA steeply increased LPLA but diminished GCAT activity of PlaA. Deletion of 20 amino acids within a predicted disulfide loop of PlaA had the same effect. In summary, we propose a model by which ProA processes PlaA via disulfide loop cleavage leading to a steep increase in LPLA activity. Our results help to further characterize the L. pneumophila GDSL hydrolases, particularly PlaA, an enzyme acting in the Legionella-containing phagosome.
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Affiliation(s)
- Christina Lang
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany
| | - Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Burgstr. 37, D-38855, Wernigerode, Germany.
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17
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The human cancer cell active toxin Cry41Aa from Bacillus thuringiensis acts like its insecticidal counterparts. Biochem J 2017; 474:1591-1602. [PMID: 28341807 DOI: 10.1042/bcj20170122] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/20/2017] [Accepted: 03/24/2017] [Indexed: 12/15/2022]
Abstract
Understanding how certain protein toxins from the normally insecticidal bacterium Bacillus thuringiensis (Bt) target human cell lines has implications for both the risk assessment of products containing these toxins and potentially for cancer therapy. This understanding requires knowledge of whether the human cell active toxins work by the same mechanism as their insecticidal counterparts or by alternative ones. The Bt Cry41Aa (also known as Parasporin3) toxin is structurally related to the toxins synthesised by commercially produced transgenic insect-resistant plants, with the notable exception of an additional C-terminal β-trefoil ricin domain. To better understand its mechanism of action, we developed an efficient expression system for the toxin and created mutations in regions potentially involved in the toxic mechanism. Deletion of the ricin domain did not significantly affect the activity of the toxin against the human HepG2 cell line, suggesting that this region was not responsible for the mammalian specificity of Cry41Aa. Various biochemical assays suggested that unlike some other human cell active toxins from Bt Cry41Aa did not induce apoptosis, but that its mechanism of action was consistent with that of a pore-forming toxin. The toxin induced a rapid and significant decrease in metabolic activity. Adenosine triphosphate depletion, cell swelling and membrane damage were also observed. An exposed loop region believed to be involved in receptor binding of insecticidal Cry toxins was shown to be important for the activity of Cry41Aa against HepG2 cells.
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Furin Cleavage of L2 during Papillomavirus Infection: Minimal Dependence on Cyclophilins. J Virol 2016; 90:6224-6234. [PMID: 27122588 DOI: 10.1128/jvi.00038-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/21/2016] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Despite an abundance of evidence supporting an important role for the cleavage of minor capsid protein L2 by cellular furin, direct cleavage of capsid-associated L2 during human papillomavirus 16 (HPV16) infection remains poorly characterized. The conserved cleavage site, close to the L2 N terminus, confounds observation and quantification of the small cleavage product by SDS-PAGE. To overcome this difficulty, we increased the size shift by fusing a compact protein domain, the Propionibacterium shermanii transcarboxylase domain (PSTCD), to the N terminus of L2. The infectious PSTCD-L2 virus displayed an appreciable L2 size shift during infection of HaCaT keratinocytes. Cleavage under standard cell culture conditions rarely exceeded 35% of total L2. Cleavage levels were enhanced by the addition of exogenous furin, and the absolute levels of infection correlated to the level of L2 cleavage. Cleavage occurred on both the HaCaT cell surface and extracellular matrix (ECM). Contrary to current models, experiments on the involvement of cyclophilins revealed little, if any, role for these cellular enzymes in the modulation of furin cleavage. HPV16 L2 contains two consensus cleavage sites, Arg5 (2RHKR5) and Arg12 (9RTKR12). Mutant PSTCD-L2 viruses demonstrated that although furin can cleave either site, cleavage must occur at Arg12, as cleavage at Arg5 alone is insufficient for successful infection. Mutation of the conserved cysteine residues revealed that the Cys22-Cys28 disulfide bridge is not required for cleavage. The PSTCD-L2 virus or similar N-terminal fusions will be valuable tools to study additional cellular and viral determinants of furin cleavage. IMPORTANCE Furin cleavage of minor capsid protein L2 during papillomavirus infection has been difficult to directly visualize and quantify, confounding efforts to study this important step of HPV infection. Fusion of a small protein domain to the N terminus greatly facilitates direct visualization of the cleavage product, revealing important characteristics of this critical process. Contrary to the current model, we found that cleavage is largely independent of cyclophilins, suggesting that cyclophilins act either in parallel to or downstream of furin to trigger exposure of a conserved N-terminal L2 epitope (RG-1) during infection. Based on this finding, we strongly caution against using L2 RG-1 epitope exposure as a convenient but indirect proxy of furin cleavage.
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Michalska M, Wolf P. Pseudomonas Exotoxin A: optimized by evolution for effective killing. Front Microbiol 2015; 6:963. [PMID: 26441897 PMCID: PMC4584936 DOI: 10.3389/fmicb.2015.00963] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/31/2015] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas Exotoxin A (PE) is the most toxic virulence factor of the pathogenic bacterium Pseudomonas aeruginosa. This review describes current knowledge about the intoxication pathways of PE. Moreover, PE represents a remarkable example for pathoadaptive evolution, how bacterial molecules have been structurally and functionally optimized under evolutionary pressure to effectively impair and kill their host cells.
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Affiliation(s)
- Marta Michalska
- Department of Urology, Medical Center, University of Freiburg Freiburg, Germany
| | - Philipp Wolf
- Department of Urology, Medical Center, University of Freiburg Freiburg, Germany
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20
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Noskov AN. [Molecular model of anthrax toxin translocation into target-cells]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2015; 40:399-404. [PMID: 25898749 DOI: 10.1134/s1068162014040098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anthrax toxin is formed from three components: protective antigen (PA), lethal (LF) and edema (EF) factors. PA83 is cleaved by cell surface protease furin to produce a 63-kDa fragment (PA63). PA63 and LF/EF molecules are assembled to anthrax toxin complexes: oligomer PA63 x 7 + LF/EF x 3. Assembly is occurred during of binding with cellular receptor or near surface of target-cell. This toxin complex forms pore and induces receptor-mediated endocytosis. Formed endosome consists extracellular liquid with LF/EF and membrane-associated ferments (H+ and K+/Na+-ATPases) and proteins (receptors and others). H+ concentration is increased into endosome as result of K/Na-ATPase-dependent- activity of H+-ATPase. Difference of potentials (between endosome and intracellular liquid) is increased and LF/EF molecules are moved to pore and bound with PA63-oligomer to PA63 x 7 + LF/EF x 7 and full block pore (ion-selective channel). Endosome is increased in volume and induces increasing of PA63-oligomer pore to.size of effector complex: LF/EF x 7 + PAl7 x 7 = 750 kDa. Effector complex is translocated from endosome to cytosol by means high difference of potentials (H+) and dissociates from PA47 x 7 complex after cleavage of FFD315-sait by intracellular chymotrypsin-like proteases in all 7 molecules PA63. PA47 x 7 complex (strongly fixed in membrane with debris of hydrophobic loops) return into endosome and pore is destroyed. Endosome pH is decreased rapidly and PA47 x 7 complex is destroyed by endosomal/lysosomal proteases. Receptor-mediated endocytosis is ended by endosome recycling in cell-membrane.
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21
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Labyntsev AJ, Kolybo DV, Yurchenko ES, Kaberniuk AA, Korotkevych NV, Komisarenko SV. Effect of the T-domain on intracellular transport of diphtheria toxin. UKRAINIAN BIOCHEMICAL JOURNAL 2014; 86:77-87. [PMID: 25033557 DOI: 10.15407/ubj86.03.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Subunit B of diphtheria toxin (DT), which consists of two domains: R (receptor-binding) and T (transmembrane), plays an important role in toxin-receptor binding on the cell-targets and in transportation of catalytic subunit A to the cell cytosol. Recombinant analogues of the subunit B are promising representatives in the unique class of transporting proteins, able to deliver different types of biologically active molecules to cell cytosol. In the development of these protein constructs understanding of the role of each of the DT fragments in determination of transporting pathways of endocytosed complex toxin-receptor is urgently required. We have studied in this work the T-domain effect on intracellular transport of recombinant fragments of DT. We have compared intracellular transport of the R-domain and the subunit B, the last one consisted of both R-domain and T-domain. Recombinant fragments of DT used in this work were labeled with fluorescent proteins, which allowed applying colocalization technique for our study. Application of confocal microscopy technique revealed differences in transportation of recombinant derivates of DT in Vero cells: R-domain moved faster than subunit B to tubular compartments. Analysis of R-domain and subunit B transportation confirmed almost linear increase of their colocalization with the time regarding to Pearsons correlation coefficient (PCC). However, amount of colocalized with R-domain subunit B were not linearly increased with time according to Manders coefficient (M1), this could indicate the ability of subunit B to transport to such compartments that R-domain do not reach. Possible role of the T-domain in intracellular transportation and compartmentalization of the toxin may be associated with the ability of the T-domain to form a proton channels and its ability to interact with COPI complex.
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Gadwal S, Korotkov KV, Delarosa JR, Hol WGJ, Sandkvist M. Functional and structural characterization of Vibrio cholerae extracellular serine protease B, VesB. J Biol Chem 2014; 289:8288-98. [PMID: 24459146 PMCID: PMC3961656 DOI: 10.1074/jbc.m113.525261] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/22/2014] [Indexed: 11/06/2022] Open
Abstract
The chymotrypsin subfamily A of serine proteases consists primarily of eukaryotic proteases, including only a few proteases of bacterial origin. VesB, a newly identified serine protease that is secreted by the type II secretion system in Vibrio cholerae, belongs to this subfamily. VesB is likely produced as a zymogen because sequence alignment with trypsinogen identified a putative cleavage site for activation and a catalytic triad, His-Asp-Ser. Using synthetic peptides, VesB efficiently cleaved a trypsin substrate, but not chymotrypsin and elastase substrates. The reversible serine protease inhibitor, benzamidine, inhibited VesB and served as an immobilized ligand for VesB affinity purification, further indicating its relationship with trypsin-like enzymes. Consistent with this family of serine proteases, N-terminal sequencing implied that the propeptide is removed in the secreted form of VesB. Separate mutagenesis of the activation site and catalytic serine rendered VesB inactive, confirming the importance of these features for activity, but not for secretion. Similar to trypsin but, in contrast to thrombin and other coagulation factors, Na(+) did not stimulate the activity of VesB, despite containing the Tyr(250) signature. The crystal structure of catalytically inactive pro-VesB revealed that the protease domain is structurally similar to trypsinogen. The C-terminal domain of VesB was found to adopt an immunoglobulin (Ig)-fold that is structurally homologous to Ig-folds of other extracellular Vibrio proteins. Possible roles of the Ig-fold domain in stability, substrate specificity, cell surface association, and type II secretion of VesB, the first bacterial multidomain trypsin-like protease with known structure, are discussed.
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Affiliation(s)
- Shilpa Gadwal
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
| | - Konstantin V. Korotkov
- the Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, Washington 98195
| | - Jaclyn R. Delarosa
- the Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, Washington 98195
| | - Wim G. J. Hol
- the Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, Washington 98195
| | - Maria Sandkvist
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
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Zhang D, de Souza RF, Anantharaman V, Iyer LM, Aravind L. Polymorphic toxin systems: Comprehensive characterization of trafficking modes, processing, mechanisms of action, immunity and ecology using comparative genomics. Biol Direct 2012; 7:18. [PMID: 22731697 PMCID: PMC3482391 DOI: 10.1186/1745-6150-7-18] [Citation(s) in RCA: 360] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 05/31/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Proteinaceous toxins are observed across all levels of inter-organismal and intra-genomic conflicts. These include recently discovered prokaryotic polymorphic toxin systems implicated in intra-specific conflicts. They are characterized by a remarkable diversity of C-terminal toxin domains generated by recombination with standalone toxin-coding cassettes. Prior analysis revealed a striking diversity of nuclease and deaminase domains among the toxin modules. We systematically investigated polymorphic toxin systems using comparative genomics, sequence and structure analysis. RESULTS Polymorphic toxin systems are distributed across all major bacterial lineages and are delivered by at least eight distinct secretory systems. In addition to type-II, these include type-V, VI, VII (ESX), and the poorly characterized "Photorhabdus virulence cassettes (PVC)", PrsW-dependent and MuF phage-capsid-like systems. We present evidence that trafficking of these toxins is often accompanied by autoproteolytic processing catalyzed by HINT, ZU5, PrsW, caspase-like, papain-like, and a novel metallopeptidase associated with the PVC system. We identified over 150 distinct toxin domains in these systems. These span an extraordinary catalytic spectrum to include 23 distinct clades of peptidases, numerous previously unrecognized versions of nucleases and deaminases, ADP-ribosyltransferases, ADP ribosyl cyclases, RelA/SpoT-like nucleotidyltransferases, glycosyltranferases and other enzymes predicted to modify lipids and carbohydrates, and a pore-forming toxin domain. Several of these toxin domains are shared with host-directed effectors of pathogenic bacteria. Over 90 families of immunity proteins might neutralize anywhere between a single to at least 27 distinct types of toxin domains. In some organisms multiple tandem immunity genes or immunity protein domains are organized into polyimmunity loci or polyimmunity proteins. Gene-neighborhood-analysis of polymorphic toxin systems predicts the presence of novel trafficking-related components, and also the organizational logic that allows toxin diversification through recombination. Domain architecture and protein-length analysis revealed that these toxins might be deployed as secreted factors, through directed injection, or via inter-cellular contact facilitated by filamentous structures formed by RHS/YD, filamentous hemagglutinin and other repeats. Phyletic pattern and life-style analysis indicate that polymorphic toxins and polyimmunity loci participate in cooperative behavior and facultative 'cheating' in several ecosystems such as the human oral cavity and soil. Multiple domains from these systems have also been repeatedly transferred to eukaryotes and their viruses, such as the nucleo-cytoplasmic large DNA viruses. CONCLUSIONS Along with a comprehensive inventory of toxins and immunity proteins, we present several testable predictions regarding active sites and catalytic mechanisms of toxins, their processing and trafficking and their role in intra-specific and inter-specific interactions between bacteria. These systems provide insights regarding the emergence of key systems at different points in eukaryotic evolution, such as ADP ribosylation, interaction of myosin VI with cargo proteins, mediation of apoptosis, hyphal heteroincompatibility, hedgehog signaling, arthropod toxins, cell-cell interaction molecules like teneurins and different signaling messengers.
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Affiliation(s)
- Dapeng Zhang
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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24
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Lang C, Rastew E, Hermes B, Siegbrecht E, Ahrends R, Banerji S, Flieger A. Zinc metalloproteinase ProA directly activates Legionella pneumophila PlaC glycerophospholipid:cholesterol acyltransferase. J Biol Chem 2012; 287:23464-78. [PMID: 22582391 DOI: 10.1074/jbc.m112.346387] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzymes secreted by Legionella pneumophila, such as phospholipases A (PLAs) and glycerophospholipid:cholesterol acyltransferases (GCATs), may target host cell lipids and therefore contribute to the establishment of Legionnaires disease. L. pneumophila possesses three proteins, PlaA, PlaC, and PlaD, belonging to the GDSL family of lipases/acyltransferases. We have shown previously that PlaC is the major GCAT secreted by L. pneumophila and that the zinc metalloproteinase ProA is essential for GCAT activity. Here we characterized the mode of PlaC GCAT activation and determined that ProA directly processes PlaC. We further found that not only cholesterol but also ergosterol present in protozoa was palmitoylated by PlaC. Such ester formations were not induced by either PlaA or PlaD. PlaD was shown here to possess lysophospholipase A activity, and interestingly, all three GDSL enzymes transferred short chain fatty acids to sterols. The three single putative catalytic amino acids (Ser-37, Asp-398, and His-401) proved essential for all PlaC-associated PLA, lysophospholipase A, and GCAT activities. A further four cysteine residues are important for the PLA/GCAT activities as well as their oxidized state, and we therefore conclude that PlaC likely forms at least one disulfide loop. Analysis of cleavage site and loop deletion mutants suggested that for GCAT activation deletion of several amino acids within the loop is necessary rather than cleavage at a single site. Our data therefore suggest a novel enzyme inhibition/activation mechanism where a disulfide loop inhibits PlaC GCAT activity until the protein is exported to the external space where it is ProA-activated.
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Affiliation(s)
- Christina Lang
- Division of Bacterial Infections, Robert Koch-Institut, Burgstrasse 37, 38855 Wernigerode, Germany
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25
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Feld GK, Kintzer AF, Tang II, Thoren KL, Krantz BA. Domain flexibility modulates the heterogeneous assembly mechanism of anthrax toxin protective antigen. J Mol Biol 2012; 415:159-74. [PMID: 22063095 PMCID: PMC3249527 DOI: 10.1016/j.jmb.2011.10.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/01/2011] [Accepted: 10/18/2011] [Indexed: 01/07/2023]
Abstract
The three protein components of anthrax toxin are nontoxic individually, but they form active holotoxin complexes upon assembly. The role of the protective antigen (PA) component of the toxin is to deliver two other enzyme components, lethal factor and edema factor, across the plasma membrane and into the cytoplasm of target cells. PA is produced as a proprotein, which must be proteolytically activated; generally, cell surface activation is mediated by a furin family protease. Activated PA can then assemble into one of two noninterconverting oligomers, a homoheptamer and a homooctamer, which have unique properties. Herein we describe molecular determinants that influence the stoichiometry of PA in toxin complexes. By tethering PA domain 4 (D4) to domain 2 with two different-length cross-links, we can control the relative proportions of PA heptamers and octamers. The longer cross-link favors octamer formation, whereas the shorter one favors formation of the heptamer. X-ray crystal structures of PA (up to 1.45 Å resolution), including these cross-linked PA constructs, reveal that a hinge-like movement of D4 correlates with the relative preference for each oligomeric architecture. Furthermore, we report the conformation of the flexible loop containing the furin cleavage site and show that, for efficient processing, the furin site cannot be moved ~5 or 6 residues within the loop. We propose that there are different orientations of D4 relative to the main body of PA that favor the formation of either the heptamer or the octamer.
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Affiliation(s)
- Geoffrey K. Feld
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.
| | | | - Iok I Tang
- California Institute for Quantitative Biomedical Research, University of California, Berkeley, CA, 94720, U.S.A.
| | - Katie L. Thoren
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.
| | - Bryan A. Krantz
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.
,California Institute for Quantitative Biomedical Research, University of California, Berkeley, CA, 94720, U.S.A.
,Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A.
,Address correspondence to: Bryan Krantz, Ph.D., University of California, Berkeley 492 Stanley Hall, #3220 Berkeley, CA 94720-3220. Phone: 510-666-2788, (B.A.K.)
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Sikora AE, Zielke RA, Lawrence DA, Andrews PC, Sandkvist M. Proteomic analysis of the Vibrio cholerae type II secretome reveals new proteins, including three related serine proteases. J Biol Chem 2011; 286:16555-66. [PMID: 21385872 DOI: 10.1074/jbc.m110.211078] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The type II secretion (T2S) system is responsible for extracellular secretion of a broad range of proteins, including toxins and degradative enzymes that play important roles in the pathogenesis and life cycle of many gram-negative bacteria. In Vibrio cholerae, the etiological agent of cholera, the T2S machinery transports cholera toxin, which induces profuse watery diarrhea, a hallmark of this life-threatening disease. Besides cholera toxin, four other proteins have been shown to be transported by the T2S machinery, including hemagglutinin protease, chitinase, GbpA, and lipase. Here, for the first time, we have applied proteomic approaches, including isotope tagging for relative and absolute quantification coupled with multidimensional liquid chromatography and tandem mass spectrometry, to perform an unbiased and comprehensive analysis of proteins secreted by the T2S apparatus of the V. cholerae El Tor strain N16961 under standard laboratory growth conditions. This analysis identified 16 new putative T2S substrates, including sialidase, several proteins participating in chitin utilization, two aminopeptidases, TagA-related protein, cytolysin, RbmC, three hypothetical proteins encoded by VCA0583, VCA0738, and VC2298, and three serine proteases VesA, VesB, and VesC. Focusing on the initial characterization of VesA, VesB, and VesC, we have confirmed enzymatic activities and T2S-dependent transport for each of these proteases. In addition, analysis of single, double, and triple protease knock-out strains indicated that VesA is the primary protease responsible for processing the A subunit of cholera toxin during in vitro growth of the V. cholerae strain N16961.
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Affiliation(s)
- Aleksandra E Sikora
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA
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In vitro assay for protease activity of proprotein convertase subtilisin kexins (PCSKs): an overall review of existing and new methodologies. Methods Mol Biol 2011; 768:127-53. [PMID: 21805240 DOI: 10.1007/978-1-61779-204-5_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian proprotein convertase subtilisin kexins (PCSKs) previously called proprotein or prohormone convertases (PCs) are a family of Ca(+2)-dependent endoproteases in the subtilisin family. These proteolytic enzymes exert their many crucial physiological and biological functions in vivo via their ability to cleave larger inactive precursor proteins into their biologically active mature forms. This event takes place in a highly efficient and selective manner. Such actions of PCSKs either alone or in combination to cleave specific protein bonds are the hallmark events that not only define the normal functions and metabolism of the body but also may lead to a variety of diseases or disorders with associated conditions. These include among others, diabetes, obesity, cancer, cardiovascular diseases, reproduction abnormalities as well as viral bacterial infections. These conditions were the direct consequences of an enhanced level of enzymatic activity of one or more PCSKs except only PCSK9, whose protease activity in relation to its physiological substrate has yet to be characterized. Owing to this finding, a large number of research studies have been exclusively devoted to develop rapid, efficient and reliable in vitro methods for examining the protease activity of these enzymes. Several assays have been developed to monitor PCSK activity and these are widely used in chemical, biochemical, cellular and animal studies. This review will cover various methodologies and protocols that are currently available in the literature for PCSK activity assays. These include liquid phase methods using fluorogenic, chromogenic and intramolecularly quenched fluorescent substrates as well as a newly developed novel solid phase fluorescence method. This review will also highlight the usefulness of these methodologies and finally a comparative analysis has been made to examine their merits and demerits with some key examples.
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28
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Endocytosis and retrograde transport of Shiga toxin. Toxicon 2010; 56:1181-5. [DOI: 10.1016/j.toxicon.2009.11.021] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 11/17/2009] [Indexed: 01/22/2023]
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Toxin-based therapeutic approaches. Toxins (Basel) 2010; 2:2519-83. [PMID: 22069564 PMCID: PMC3153180 DOI: 10.3390/toxins2112519] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 10/25/2010] [Accepted: 10/26/2010] [Indexed: 01/08/2023] Open
Abstract
Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin.
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Abstract
Large bacterial protein toxins autotranslocate functional effector domains to the eukaryotic cell cytosol, resulting in alterations to cellular functions that ultimately benefit the infecting pathogen. Among these toxins, the clostridial glucosylating toxins (CGTs) produced by Gram-positive bacteria and the multifunctional-autoprocessing RTX (MARTX) toxins of Gram-negative bacteria have distinct mechanisms for effector translocation, but a shared mechanism of post-translocation autoprocessing that releases these functional domains from the large holotoxins. These toxins carry an embedded cysteine protease domain (CPD) that is activated for autoprocessing by binding inositol hexakisphosphate (InsP6), a molecule found exclusively in eukaryotic cells. Thus, InsP6-induced autoprocessing represents a unique mechanism for toxin effector delivery specifically within the target cell. This review summarizes recent studies of the structural and molecular events for activation of autoprocessing for both CGT and MARTX toxins, demonstrating both similar and potentially distinct aspects of autoprocessing among the toxins that utilize this method of activation and effector delivery.
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Shen A. Autoproteolytic activation of bacterial toxins. Toxins (Basel) 2010; 2:963-77. [PMID: 22069620 PMCID: PMC3153235 DOI: 10.3390/toxins2050963] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 04/28/2010] [Accepted: 05/05/2010] [Indexed: 01/05/2023] Open
Abstract
Protease domains within toxins typically act as the primary effector domain within target cells. By contrast, the primary function of the cysteine protease domain (CPD) in Multifunctional Autoprocessing RTX-like (MARTX) and Clostridium sp. glucosylating toxin families is to proteolytically cleave the toxin and release its cognate effector domains. The CPD becomes activated upon binding to the eukaryotic-specific small molecule, inositol hexakisphosphate (InsP6), which is found abundantly in the eukaryotic cytosol. This property allows the CPD to spatially and temporally regulate toxin activation, making it a prime candidate for developing anti-toxin therapeutics. In this review, we summarize recent findings related to defining the regulation of toxin function by the CPD and the development of inhibitors to prevent CPD-mediated activation of bacterial toxins.
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Affiliation(s)
- Aimee Shen
- Department of Pathology, Stanford School of Medicine, 300 Pasteur Drive, Stanford, California, USA.
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32
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Protein toxins from plants and bacteria: Probes for intracellular transport and tools in medicine. FEBS Lett 2010; 584:2626-34. [DOI: 10.1016/j.febslet.2010.04.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Accepted: 04/07/2010] [Indexed: 01/07/2023]
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Remacle AG, Gawlik K, Golubkov VS, Cadwell GW, Liddington RC, Cieplak P, Millis SZ, Desjardins R, Routhier S, Yuan XW, Neugebauer WA, Day R, Strongin AY. Selective and potent furin inhibitors protect cells from anthrax without significant toxicity. Int J Biochem Cell Biol 2010; 42:987-95. [PMID: 20197107 DOI: 10.1016/j.biocel.2010.02.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 02/22/2010] [Indexed: 01/08/2023]
Abstract
Furin and related proprotein convertases cleave the multibasic motifs R-X-R/K/X-R in the precursor proteins and, as a result, transform the latent proproteins into biologically active proteins and peptides. Furin is present both in the intracellular secretory pathway and at the cell surface. Intracellular furin processes its multiple normal cellular targets in the Golgi and secretory vesicle compartments while cell-surface furin appears to be essential only for the processing of certain pathogenic proteins and, importantly, anthrax. To design potent, safe and selective inhibitors of furin, we evaluated the potency and selectivity of the derivatized peptidic inhibitors modeled from the extended furin cleavage sequence of avian influenza A H5N1. We determined that the N- and C-terminal modifications of the original RARRRKKRT inhibitory scaffold produced selective and potent, nanomolar range, inhibitors of furin. These inhibitors did not interfere with the normal cellular function of furin because of the likely functional redundancy existing between furin and other proprotein convertases. These furin inhibitors, however, were highly potent in blocking the furin-dependent cell-surface processing of anthrax protective antigen-83 both in vitro and cell-based assays and in vivo. We conclude that the inhibitors we have designed have a promising potential as selective anthrax inhibitors, without affecting major cell functions.
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Affiliation(s)
- Albert G Remacle
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, United States
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Mechanistic and structural insights into the proteolytic activation of Vibrio cholerae MARTX toxin. Nat Chem Biol 2009; 5:469-78. [PMID: 19465933 PMCID: PMC2783333 DOI: 10.1038/nchembio.178] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 03/25/2009] [Indexed: 12/11/2022]
Abstract
MARTX toxins modulate the virulence of a number of Gram-negative Vibrio species. This family of toxins is defined by the presence of a cysteine protease domain (CPD), which proteolytically activates the Vibrio cholerae MARTX toxin. Although recent structural studies of the CPD have uncovered a novel allosteric activation mechanism, the mechanism of CPD substrate recognition or toxin processing is unknown. Here, we show that interdomain cleavage of MARTXVc enhances effector domain function. We also identify the first small molecule inhibitors of this protease domain and present the 2.35 Å structure of the CPD bound to one of these inhibitors. This structure, coupled with biochemical and mutational studies of the toxin, reveals the molecular basis of CPD substrate specificity and underscores the evolutionary relationship between the CPD and the clan CD caspase proteases. These studies are likely to prove valuable for devising novel anti-toxin strategies for a number of bacterial pathogens.
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35
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Venkatraman P, Balakrishnan S, Rao S, Hooda Y, Pol S. A sequence and structure based method to predict putative substrates, functions and regulatory networks of endo proteases. PLoS One 2009; 4:e5700. [PMID: 19492082 PMCID: PMC2683571 DOI: 10.1371/journal.pone.0005700] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2009] [Accepted: 04/28/2009] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Proteases play a central role in cellular homeostasis and are responsible for the spatio-temporal regulation of function. Many putative proteases have been recently identified through genomic approaches, leading to a surge in global profiling attempts to characterize their function. Through such efforts and others it has become evident that many proteases play non-traditional roles. Accordingly, the number and the variety of the substrate repertoire of proteases are expected to be much larger than previously assumed. In line with such global profiling attempts, we present here a method for the prediction of natural substrates of endo proteases (human proteases used as an example) by employing short peptide sequences as specificity determinants. METHODOLOGY/PRINCIPAL FINDINGS Our method incorporates specificity determinants unique to individual enzymes and physiologically relevant dual filters namely, solvent accessible surface area--a parameter dependent on protein three-dimensional structure and subcellular localization. By incorporating such hitherto unused principles in prediction methods, a novel ligand docking strategy to mimic substrate binding at the active site of the enzyme, and GO functions, we identify and perform subjective validation on putative substrates of matriptase and highlight new functions of the enzyme. Using relative solvent accessibility to rank order we show how new protease regulatory networks and enzyme cascades can be created. CONCLUSION We believe that our physiologically relevant computational approach would be a very useful complementary method in the current day attempts to profile proteases (endo proteases in particular) and their substrates. In addition, by using functional annotations, we have demonstrated how normal and unknown functions of a protease can be envisaged. We have developed a network which can be integrated to create a proteolytic world. This network can in turn be extended to integrate other regulatory networks to build a system wide knowledge of the proteome.
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Affiliation(s)
- Prasanna Venkatraman
- Advanced Centre for Treatment, Research and Education in Cancer, Navi Mumbai, Maharashtra, India.
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36
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Wolf P, Elsässer-Beile U. Pseudomonas exotoxin A: from virulence factor to anti-cancer agent. Int J Med Microbiol 2009; 299:161-76. [PMID: 18948059 DOI: 10.1016/j.ijmm.2008.08.003] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 07/07/2008] [Accepted: 08/13/2008] [Indexed: 11/24/2022] Open
Abstract
The pathogenic bacterium Pseudomonas aeruginosa has the ability to cause severe acute and chronic infections in humans. Pseudomonas exotoxin A (PE) is the most toxic virulence factor of this bacterium. It has ADP-ribosylation activity and decisively affects the protein synthesis of the host cells. The cytotoxic pathways of PE have been elucidated, and it could be shown that PE uses several molecular strategies developed under evolutionary pressure for effective killing. Interestingly, a medical benefit from this molecule has also been ascertained in recent years and several PE-based immunotoxins have been constructed and tested in preclinical and clinical trials against different cancers. In these molecules, the enzymatic active domain of PE is specifically targeted to tumor-related antigens. This review describes the current knowledge about the cytotoxic pathways of PE. Additionally, it summarizes preclinical and clinical trials of PE-based immunotoxins and furthermore discusses current problems and answers with these agents.
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Affiliation(s)
- Philipp Wolf
- Department of Urology, University of Freiburg, Germany.
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37
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Lupardus PJ, Shen A, Bogyo M, Garcia KC. Small molecule-induced allosteric activation of the Vibrio cholerae RTX cysteine protease domain. Science 2008; 322:265-8. [PMID: 18845756 DOI: 10.1126/science.1162403] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vibrio cholerae RTX (repeats in toxin) is an actin-disrupting toxin that is autoprocessed by an internal cysteine protease domain (CPD). The RTX CPD is efficiently activated by the eukaryote-specific small molecule inositol hexakisphosphate (InsP6), and we present the 2.1 angstrom structure of the RTX CPD in complex with InsP6. InsP6 binds to a conserved basic cleft that is distant from the protease active site. Biochemical and kinetic analyses of CPD mutants indicate that InsP6 binding induces an allosteric switch that leads to the autoprocessing and intracellular release of toxin-effector domains.
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Affiliation(s)
- Patrick J Lupardus
- Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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38
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Remacle AG, Shiryaev SA, Oh ES, Cieplak P, Srinivasan A, Wei G, Liddington RC, Ratnikov BI, Parent A, Desjardins R, Day R, Smith JW, Lebl M, Strongin AY. Substrate cleavage analysis of furin and related proprotein convertases. A comparative study. J Biol Chem 2008; 283:20897-906. [PMID: 18505722 DOI: 10.1074/jbc.m803762200] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We present the data and the technology, a combination of which allows us to determine the identity of proprotein convertases (PCs) related to the processing of specific protein targets including viral and bacterial pathogens. Our results, which support and extend the data of other laboratories, are required for the design of effective inhibitors of PCs because, in general, an inhibitor design starts with a specific substrate. Seven proteinases of the human PC family cleave the multibasic motifs R-X-(R/K/X)-R downward arrow and, as a result, transform proproteins, including those from pathogens, into biologically active proteins and peptides. The precise cleavage preferences of PCs have not been known in sufficient detail; hence we were unable to determine the relative importance of the individual PCs in infectious diseases, thus making the design of specific inhibitors exceedingly difficult. To determine the cleavage preferences of PCs in more detail, we evaluated the relative efficiency of furin, PC2, PC4, PC5/6, PC7, and PACE4 in cleaving over 100 decapeptide sequences representing the R-X-(R/K/X)-R downward arrow motifs of human, bacterial, and viral proteins. Our computer analysis of the data and the follow-on cleavage analysis of the selected full-length proteins corroborated our initial results thus allowing us to determine the cleavage preferences of the PCs and to suggest which PCs are promising drug targets in infectious diseases. Our results also suggest that pathogens, including anthrax PA83 and the avian influenza A H5N1 (bird flu) hemagglutinin precursor, evolved to be as sensitive to PC proteolysis as the most sensitive normal human proteins.
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Affiliation(s)
- Albert G Remacle
- Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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Coppola JM, Bhojani MS, Ross BD, Rehemtulla A. A small-molecule furin inhibitor inhibits cancer cell motility and invasiveness. Neoplasia 2008; 10:363-70. [PMID: 18392131 PMCID: PMC2288536 DOI: 10.1593/neo.08166] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 01/15/2008] [Accepted: 01/16/2008] [Indexed: 11/18/2022]
Abstract
Furin, a member the proprotein convertase (PC) family, processes inactive precursor proteins to functional proteins within the Golgi/trans-Golgi network secretory pathway. Furin and other PC family members (furin/PCs) activate proteins vital to proper physiological functioning, including growth factors and hormones, receptors, plasma proteins, and matrix metalloproteases (MMPs). Additionally, the expression and activity of furin/PC are necessary for processing substrates important for cell transformation and tumor progression, metastasis, and angiogenesis. Furin processing of the remodeling protease membrane type-1 matrix metalloproteinase (MT1-MMP) enhances cellular motility and invasiveness, contributing to aggression and metastatic potential cancer cells. Whereas overexpression and activity of furin/PC exacerbate the cancer phenotype, inhibition of its activity decreases or nullifies furin/PC-mediated effects, and thus, inhibition of furin may be a viable route to cancer therapy. Recently, we identified a small-molecule inhibitor of furin, named B3, by high-throughput screening with a K(i) and IC(50) of 12 microM. Here, we show that this cell-permeable, small-molecule compound inhibits furin-mediated cleavage of proMT1-MMP, resulting in decreased MMP-2 activation and cell motility in CHO cells expressing proMT1-MMP. Additionally, this molecule inhibited proMT1-MMP processing, complete MMP-2 maturation, and invasiveness of human fibrosarcoma cells (HT1080).
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Affiliation(s)
- Julia M Coppola
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109 USA
| | - Mahaveer S Bhojani
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI 48109 USA
| | - Brian D Ross
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109 USA
| | - Alnawaz Rehemtulla
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI 48109 USA
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El Hage T, Decottignies P, Authier F. Endosomal proteolysis of diphtheria toxin without toxin translocation into the cytosol of rat liver in vivo. FEBS J 2008; 275:1708-22. [DOI: 10.1111/j.1742-4658.2008.06326.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Alam M, Miyoshi SI, Ahmed KU, Hasan NA, Tomochika KI, Shinoda S. Proteolytic activation of Vibrio mimicus (Vm) major outer membrane protein haemagglutinin (HA) with Vm-HA/protease: Implication for understanding bacterial adherence. Microbiol Immunol 2007; 50:845-50. [PMID: 17116978 DOI: 10.1111/j.1348-0421.2006.tb03859.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrio mimicus (Vm) haemagglutinins (HAs), such as an extracellular HA/protease (Vm-HA/protease) and a major outer membrane protein-HA (Vm-OMPHA), have been recognized as the putative adherence factors for the bacterium. However, the mechanism by which HAs coordinate the adherence function of the bacterium remains as yet unknown. We report herein the positive interaction between Vm-HA/protease and Vm-OMPHA resulting in significant enhancement of the haemagglutinating ability. In this interaction, no cleaved polypeptide was detected; however, limited proteolysis of Vm-OMPHA was confirmed by SDS-PAGE. The proteolytic activation of the native cell-associated Vm-OMPHA by limited proteolysis was also demonstrated in several V. mimicus strains. Proteolytic activation of OMPHA was also achieved with various proteases from bacterial and eukaryotic sources. These findings may indicate a novel coordination of V. mimicus HAs in the adherence of the bacterium.
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Affiliation(s)
- Munirul Alam
- Laboratory of Enteric Microbiology, International Center for Diarrhoeal Disease Research, Dhaka, Bangladesh.
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Salles II, Voth DE, Ward SC, Averette KM, Tweten RK, Bradley KA, Ballard JD. Cytotoxic activity of Bacillus anthracis protective antigen observed in a macrophage cell line overexpressing ANTXR1. Cell Microbiol 2006; 8:1272-81. [PMID: 16882031 DOI: 10.1111/j.1462-5822.2006.00708.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Anthrax toxin protective antigen (PA) binds cell surface receptors (e.g. ANTXR1,2), forms heptameric pores, and translocates lethal factor (LF) or oedema factor (OF) into the cytoplasm of mammalian cells. In the current study, we sought to determine how receptor levels influence these events, by examining PA heptamer stability and related processes in macrophages that overexpress ANTXR1 (RAW 264.7ANTXR1). In these experiments, PA-oligomers demonstrated an extended half-life in RAW 264.7ANTXR1 macrophages, with SDS-resistant heptamers detected up to 10 h following treatment, while levels of PA-oligomers declined within 3 h in control cells. RAW 264.7ANTXR1 macrophages were also more sensitive to lethal toxin, a combination of PA and LF. Surprisingly, we found that PA alone was cytotoxic to RAW 264.7ANTXR1 cells. Further analysis found that PA cytotoxicity required direct interaction with ANTXR1, oligomerization, channel formation, endosomal acidification, and was independent of the ANTXR1 cytoplasmic tail. PA intoxication of RAW 264.7ANTXR1 macrophages resulted in caspase-3 activation, with corresponding DNA fragmentation and proteolytic cleavage of poly-ADP-ribose polymerase, as well as activation of Bid, suggesting cell death occurred via apoptosis. Overall, results from the current study suggest that receptor levels dictate the extent of PA oligomer stability, and shifts in this normal process can lead to cell death via apoptosis in the absence of toxin catalytic subunits.
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Affiliation(s)
- Isabelle I Salles
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Lord JM, Roberts LM, Lencer WI. Entry of protein toxins into mammalian cells by crossing the endoplasmic reticulum membrane: co-opting basic mechanisms of endoplasmic reticulum-associated degradation. Curr Top Microbiol Immunol 2006; 300:149-68. [PMID: 16573240 DOI: 10.1007/3-540-28007-3_7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The catalytic polypeptides of certain bacterial and plant protein toxins reach their substrates in the cytosol of mammalian cells by retro-translocation from the endoplasmic reticulum (ER). Emerging evidence indicates that these proteins subvert the ER-associated protein degradation (ERAD) pathway that normally removes misfolded or unassembled proteins from the ER, to achieve retrotranslocation. Upon entering the ER lumen, the toxins are unfolded to be perceived as ERAD substrates. Toxins that retro-translocate from the ER have an unusually low lysine content to avoid ubiquitin-mediated proteasomal degradation. This allows the exported toxins to refold into the proteasome-resistant, biologically active conformation, and leads to cellular intoxication.
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Affiliation(s)
- J M Lord
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
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Richards RM, Lowy DR, Schiller JT, Day PM. Cleavage of the papillomavirus minor capsid protein, L2, at a furin consensus site is necessary for infection. Proc Natl Acad Sci U S A 2006; 103:1522-7. [PMID: 16432208 PMCID: PMC1360554 DOI: 10.1073/pnas.0508815103] [Citation(s) in RCA: 250] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Papillomaviruses (PV) comprise a large family of nonenveloped DNA viruses that include the oncogenic PV types that are the causative agents of human cervical cancer. As is true of many animal DNA viruses, PV are taken into the cell by endocytosis and must escape from the endosomal compartment to the cytoplasm to initiate infection. Here we show that this step depends on the site-specific enzymatic cleavage of the PV minor virion protein L2 at a consensus furin recognition site. Cleavage by furin, a cell-encoded proprotein convertase, is known to be required for endosome escape by many bacterial toxins. However, to our knowledge, furin has not been previously implicated in the viral entry process. This step is potentially a target for PV inhibition.
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Affiliation(s)
- Rebecca M Richards
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Rupnik M, Pabst S, Rupnik M, von Eichel-Streiber C, Urlaub H, Söling HD. Characterization of the cleavage site and function of resulting cleavage fragments after limited proteolysis of Clostridium difficile toxin B (TcdB) by host cells. MICROBIOLOGY-SGM 2005; 151:199-208. [PMID: 15632438 DOI: 10.1099/mic.0.27474-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Clostridium difficile toxin B (TcdB) is a single-stranded protein consisting of a C-terminal domain responsible for binding to the host cell membrane, a middle part involved in internalization, and the N-terminal catalytic (toxic) part. This study shows that TcdB is processed by a single proteolytic step which cleaves TcdB(10463) between Leu(543) and Gly(544) and the naturally occurring variant TcdB(8864) between Leu(544) and Gly(545). The cleavage occurs at neutral pH and is catalysed by a pepstatin-sensitive protease localized in the cytoplasm and on the cytoplasmic face of intracellular membranes. The smaller N-terminal cleavage products [63 121 Da (TcdB(10463)) and 62 761 Da (TcdB(8864))] harbour the cytotoxic and glucosyltransferase activities of the toxins. When microinjected into cultured Chinese hamster lung fibroblasts, the N-terminal cleavage fragment shows full cytotoxic activity shortly after injection whereas the holotoxin initially exhibits a very low activity which, however, increases with time. Twenty minutes after the start of internalization of TcdB, the larger cleavage products [206 609 Da (TcdB(10463)) and 206 245 Da (TcdB(8864))] are found exclusively in a membrane fraction, whereas the N-terminal cleavage products appear mainly in the cytosol and associated with the membrane. This is in line with a proposed model according to which the longer, C-terminal, part of these toxins forms a channel allowing for the translocation of the toxic N-terminal part, which is subsequently cleaved off at the cytoplasmic face of an intracellular compartment, most likely endosomes.
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Affiliation(s)
- Maja Rupnik
- Max-Planck-Institute of Biophysical Chemistry, Department of Neurobiology, Göttingen, Germany
- Department of Biology, University of Ljubljana, Ljubljana, Slovenia
| | - Stefan Pabst
- Max-Planck-Institute of Biophysical Chemistry, Department of Neurobiology, Göttingen, Germany
| | | | | | - Henning Urlaub
- Max-Planck-Institute of Biophysical Chemistry, Department of Cellular Biochemistry, Göttingen, Germany
| | - Hans-Dieter Söling
- Max-Planck-Institute of Biophysical Chemistry, Department of Neurobiology, Göttingen, Germany
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Carbonetti NH, Mays RM, Artamonova GV, Plaut RD, Worthington ZEV. Proteolytic cleavage of pertussis toxin S1 subunit is not essential for its activity in mammalian cells. BMC Microbiol 2005; 5:7. [PMID: 15691377 PMCID: PMC550662 DOI: 10.1186/1471-2180-5-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 02/03/2005] [Indexed: 11/13/2022] Open
Abstract
Background Pertussis toxin (PT) is an exotoxin virulence factor produced by Bordetella pertussis, the causative agent of whooping cough. PT consists of an active subunit (S1) that ADP-ribosylates the alpha subunit of several mammalian G proteins, and a B oligomer (S2–S5) that binds glycoconjugate receptors on cells. PT appears to enter cells by endocytosis, and retrograde transport through the Golgi apparatus may be important for its cytotoxicity. A previous study demonstrated that proteolytic processing of S1 occurs after PT enters mammalian cells. We sought to determine whether this proteolytic processing of S1 is necessary for PT cytotoxicity. Results Protease inhibitor studies suggested that S1 processing may involve a metalloprotease, and processing does not involve furin, a mammalian cell protease that cleaves several other bacterial toxins. However, inhibitor studies showed a general lack of correlation of S1 processing with PT cellular activity. A combination of replacement, insertion and deletion mutations in the C-terminal region of S1, as well as mass spectrometry data, suggested that the cleavage site is located around residue 203–204, but that cleavage is not strongly sequence-dependent. Processing of S1 was abolished by each of 3 overlapping 8 residue deletions just downstream of the putative cleavage site, but not by smaller deletions in the same region. Processing of the various mutant forms of PT did not correlate with cellular activity of the toxin, nor with the ability of the bacteria producing them to infect the mouse respiratory tract. In addition, S1 processing was not detected in transfected cells expressing S1, even though S1 was fully active in these cells. Conclusions S1 processing is not essential for the cellular activity of PT. This distinguishes it from the processing of various other bacterial toxins, which has been shown to be important for their cytotoxicity. S1 processing may be mediated primarily by a metalloprotease, but the cleavage site on S1 is not sequence-dependent and processing appears to depend on the general topology of the protein in that region, indicating that multiple proteases may contribute to this cleavage.
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Affiliation(s)
- Nicholas H Carbonetti
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - R Michael Mays
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Galina V Artamonova
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Roger D Plaut
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Zoë EV Worthington
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Barth H, Aktories K, Popoff MR, Stiles BG. Binary bacterial toxins: biochemistry, biology, and applications of common Clostridium and Bacillus proteins. Microbiol Mol Biol Rev 2004; 68:373-402, table of contents. [PMID: 15353562 PMCID: PMC515256 DOI: 10.1128/mmbr.68.3.373-402.2004] [Citation(s) in RCA: 285] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic "A-B" paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The "B" components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated "B" components form homoheptameric rings that subsequently dock with an "A" component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, "A" molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria.
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Affiliation(s)
- Holger Barth
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Otto-Krayer-Haus, Albertstrasse 25, D-79104 Freiburg, Germany.
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49
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Silva TA, Noronha FSM, de Macêdo Farias L, Carvalho MAR. In vitro activation of the hemolysin in Prevotella nigrescens ATCC 33563 and Prevotella intermedia ATCC 25611. Res Microbiol 2004; 155:31-8. [PMID: 14759706 DOI: 10.1016/j.resmic.2003.09.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2003] [Accepted: 09/12/2003] [Indexed: 11/16/2022]
Abstract
Hemolytic activity was evaluated in the putative periodontopathogens Prevotella intermedia and Prevotella nigrescens. Whole cells of both species present weak hemolytic activity evidenced only by solid media assays after 48 h of bacterial growth or after 5 h of interaction with erythrocytes at 37 degrees C in liquid assays. In this work we show that the use of crude extract allowed the detection of a higher hemolytic activity for P. intermedia, but surprisingly not for P. nigrescens. Incubation at 37 degrees C for 9 h, or treatment with trypsin or proteinase K, increased or exposed the hemolytic activity of P. intermedia and P. nigrescens crude extract, respectively. The activation process was inhibited by TLCK and PMSF but not by EDTA, E-64 or pepstatin A, indicating the serino-protease nature of the factor involved in activation of P. intermedia and P. nigrescens hemolysins. Both the buffer and the pH employed for cell fractionation influenced the activation of hemolysin, and the best results were obtained with Universal buffer at pH 8.0. The activated hemolysins acted optimally at pH 6.5 at 37 degrees C and the maximum hemolytic activity was detected at the early log phase of growth. The results of this study show for the first time a strong hemolytic activity for P. nigrescens and evidence of proteolytic activation of hemolysins produced by periodontopathogens.
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Affiliation(s)
- Tarcília Aparecida Silva
- Laboratório de Microbiologia Oral e Anaeróbios, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 Pampulha, CEP 31 270-901, Belo Horizonte, MG, Brazil
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Matsuzawa T, Fukui A, Kashimoto T, Nagao K, Oka K, Miyake M, Horiguchi Y. Bordetella dermonecrotic toxin undergoes proteolytic processing to be translocated from a dynamin-related endosome into the cytoplasm in an acidification-independent manner. J Biol Chem 2003; 279:2866-72. [PMID: 14597616 DOI: 10.1074/jbc.m310340200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bordetella pertussis dermonecrotic toxin (DNT), which activates intracellular Rho GTPases, is a single chain polypeptide composed of an N-terminal receptor-binding domain and a C-terminal enzymatic domain. We found that DNT was cleaved by furin, a mammalian endoprotease, on the C-terminal side of Arg(44), which generates an N-terminal fragment almost corresponding to the receptor-binding domain and a C-terminal remainder (deltaB) containing the enzymatic domain. These two fragments remained associated even after the cleavage and made a nicked form. DNT mutants insensitive to furin had no cellular effect, whereas the nicked toxin was much more potent than the intact form, indicating that the nicking by furin was a prerequisite for action. DeltaB, but not the nicked toxin, associated with artificial liposomes and activated Rho in cells resistant to DNT because of a lack of surface receptor. These results imply that deltaB, dissociated from the binding domain, fully possesses the ability to enter the cytoplasm across the lipid bilayer membrane. The translocation ability of deltaB was found to be attributable to the N-terminal region encompassing amino acids 45-166, including a putative transmembrane domain. Pharmacological analyses with various reagents disturbing vesicular trafficking revealed that the translocation requires neither the acidification of the endosomes nor retrograde vesicular transport to deeper organelles, although DNT appeared to be internalized via a dynamin-dependent endocytosis. We conclude that DNT binds to its receptor and is internalized into endosomes where the proteolytic processing occurs. DeltaB, liberated from the binding domain after the processing, begins to translocate the enzymatic domain into the cytoplasm.
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Affiliation(s)
- Takeshi Matsuzawa
- Department of Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
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