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García-Montoya C, García-Linares S, Heras-Márquez D, Majnik M, Laxalde-Fernández D, Amigot-Sánchez R, Martínez-Del-Pozo Á, Palacios-Ortega J. The interaction of the ribotoxin α-sarcin with complex model lipid vesicles. Arch Biochem Biophys 2024; 751:109836. [PMID: 38000493 DOI: 10.1016/j.abb.2023.109836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/06/2023] [Accepted: 11/20/2023] [Indexed: 11/26/2023]
Abstract
Fungal ribotoxins are extracellular RNases that inactivate ribosomes by cleaving a single phosphodiester bond at the universally conserved sarcin-ricin loop of the large rRNA. However, to reach the ribosomes, they need to cross the plasma membrane. It is there where these toxins show their cellular specificity, being especially active against tumoral or virus-infected cells. Previous studies have shown that fungal ribotoxins interact with negatively charged membranes, typically containing phosphatidylserine or phosphatidylglycerol. This ability is rooted on their long, non-structured, positively charged loops, and its N-terminal β-hairpin. However, its effect on complex lipid mixtures, including sphingophospholipids or cholesterol, remains poorly studied. Here, wild-type α-sarcin was used to evaluate its interaction with a variety of membranes not assayed before, which resemble much more closely mammalian cell membranes. The results confirm that α-sarcin is particularly sensitive to charge density on the vesicle surface. Its ability to induce vesicle aggregation is strongly influenced by both the lipid headgroup and the degree of saturation of the fatty acid chains. Acyl chain length is indeed particularly important for lipid mixing. Finally, cholesterol plays an important role in diluting the concentration of available negative charges and modulates the ability of α-sarcin to cross the membrane.
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Affiliation(s)
- Carmen García-Montoya
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain
| | - Diego Heras-Márquez
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain
| | - Manca Majnik
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain
| | | | - Rafael Amigot-Sánchez
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain
| | | | - Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
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Narbona J, Hernández-Baraza L, Gordo RG, Sanz L, Lacadena J. Nanobody-Based EGFR-Targeting Immunotoxins for Colorectal Cancer Treatment. Biomolecules 2023; 13:1042. [PMID: 37509078 PMCID: PMC10377705 DOI: 10.3390/biom13071042] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/22/2023] [Accepted: 06/24/2023] [Indexed: 07/30/2023] Open
Abstract
Immunotoxins (ITXs) are chimeric molecules that combine the specificity of a targeting domain, usually derived from an antibody, and the cytotoxic potency of a toxin, leading to the selective death of tumor cells. However, several issues must be addressed and optimized in order to use ITXs as therapeutic tools, such as the selection of a suitable tumor-associated antigen (TAA), high tumor penetration and retention, low kidney elimination, or low immunogenicity of foreign proteins. To this end, we produced and characterized several ITX designs, using a nanobody against EGFR (VHH 7D12) as the targeting domain. First, we generated a nanoITX, combining VHH 7D12 and the fungal ribotoxin α-sarcin (αS) as the toxic moiety (VHHEGFRαS). Then, we incorporated a trimerization domain (TIEXVIII) into the construct, obtaining a trimeric nanoITX (TriVHHEGFRαS). Finally, we designed and characterized a bispecific ITX, combining the VHH 7D12 and the scFv against GPA33 as targeting domains, and a deimmunized (DI) variant of α-sarcin (BsITXαSDI). The results confirm the therapeutic potential of α-sarcin-based nanoITXs. The incorporation of nanobodies as target domains improves their therapeutic use due to their lower molecular size and binding features. The enhanced avidity and toxic load in the trimeric nanoITX and the combination of two different target domains in the bispecific nanoITX allow for increased antitumor effectiveness.
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Affiliation(s)
- Javier Narbona
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
| | - Luisa Hernández-Baraza
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
- University Institute of Biomedical and Health Research (IUIBS), Las Palmas University, 35016 Las Palmas de Gran Canaria, Spain
| | - Rubén G Gordo
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
| | - Laura Sanz
- Molecular Immunology Unit, Biomedical Research Institute, Hospital Universitario Puerta de Hierro, Majadahonda, 28222 Madrid, Spain
| | - Javier Lacadena
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
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Venugopalan LP, Aimanianda V, Namperumalsamy VP, Prajna L, Kuppamuthu D, Jayapal JM. Comparative proteome analysis identifies species-specific signature proteins in Aspergillus pathogens. Appl Microbiol Biotechnol 2023:10.1007/s00253-023-12559-4. [PMID: 37166481 DOI: 10.1007/s00253-023-12559-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 04/22/2023] [Accepted: 04/25/2023] [Indexed: 05/12/2023]
Abstract
Aspergillus flavus and Aspergillus fumigatus are important human pathogens that can infect the lung and cornea. During infection, Aspergillus dormant conidia are the primary morphotype that comes in contact with the host. As the conidial surface-associated proteins (CSPs) and the extracellular proteins during the early stages of growth play a crucial role in establishing infection, we profiled and compared these proteins between a clinical strain of A. flavus and a clinical strain of A. fumigatus. We identified nearly 100 CSPs in both Aspergillus, and these non-covalently associated surface proteins were able to stimulate the neutrophils to secrete interleukin IL-8. Mass spectrometry analysis identified more than 200 proteins in the extracellular space during the early stages of conidial growth and germination (early exoproteome). The conidial surface proteins and the early exoproteome of A. fumigatus were enriched with immunoreactive proteins and those with pathogenicity-related functions while that of the A. flavus were primarily enzymes involved in cell wall reorganization and binding. Comparative proteome analysis of the CSPs and the early exoproteome between A. flavus and A. fumigatus enabled the identification of a common core proteome and potential species-specific signature proteins. Transcript analysis of selected proteins indicate that the transcript-protein level correlation does not exist for all proteins and might depend on factors such as membrane-anchor signals and protein half-life. The probable signature proteins of A. flavus and A. fumigatus identified in this study can serve as potential candidates for developing species-specific diagnostic tests. KEY POINTS: • CSPs and exoproteins could differentiate A. flavus and A. fumigatus. • A. fumigatus conidial surface harbored more antigenic proteins than A. flavus. • Identified species-specific signature proteins of A. flavus and A. fumigatus.
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Affiliation(s)
- Lakshmi Prabha Venugopalan
- Department of Proteomics, Aravind Medical Research Foundation, Anna Nagar, Madurai, Tamil Nadu, India
- Present address: Centre for Biotechnology, Anna University, Chennai, India
| | - Vishukumar Aimanianda
- Unité des Aspergillus, Institut Pasteur, 75015, Paris, France
- Present address: Unité de recherche Mycologie Moléculaire, UMR2000, Institut Pasteur, 75015, Paris, France
| | | | - Lalitha Prajna
- Department of Ocular Microbiology, Aravind Medical Research Foundation, Anna Nagar, Madurai, Tamil Nadu, India
| | - Dharmalingam Kuppamuthu
- Department of Proteomics, Aravind Medical Research Foundation, Anna Nagar, Madurai, Tamil Nadu, India
| | - Jeya Maheshwari Jayapal
- Department of Proteomics, Aravind Medical Research Foundation, Anna Nagar, Madurai, Tamil Nadu, India.
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4
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Narbona J, Gordo RG, Tomé-Amat J, Lacadena J. A New Optimized Version of a Colorectal Cancer-Targeted Immunotoxin Based on a Non-Immunogenic Variant of the Ribotoxin α-Sarcin. Cancers (Basel) 2023; 15:cancers15041114. [PMID: 36831456 PMCID: PMC9954630 DOI: 10.3390/cancers15041114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023] Open
Abstract
Due to its incidence and mortality, cancer remains one of the main risks to human health and lifespans. In order to overcome this worldwide disease, immunotherapy and the therapeutic use of immunotoxins have arisen as promising approaches. However, the immunogenicity of foreign proteins limits the dose of immunotoxins administered, thereby leading to a decrease in its therapeutic benefit. In this study, we designed two different variants of non-immunogenic immunotoxins (IMTXA33αSDI and IMTXA33furαSDI) based on a deimmunized variant of the ribotoxin α-sarcin. The inclusion of a furin cleavage site in IMTXA33furαSDI would allow a more efficient release of the toxic domain to the cytosol. Both immunotoxins were produced and purified in the yeast Pichia pastoris and later functionally characterized (both in vitro and in vivo), and immunogenicity assays were carried out. The results showed that both immunotoxins were functionally active and less immunogenic than the wild-type immunotoxin. In addition, IMTXA33furαSDI showed a more efficient antitumor effect (both in vitro and in vivo) due to the inclusion of the furin linker. These results constituted a step forward in the optimization of immunotoxins with low immunogenicity and enhanced antitumor activity, which can lead to potential better outcomes in cancer treatment.
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Affiliation(s)
- Javier Narbona
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
| | - Rubén G. Gordo
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
| | - Jaime Tomé-Amat
- Centre for Plant Biotechnology and Genomics (UPM-INIA), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
| | - Javier Lacadena
- Department of Biochemistry and Molecular Biology, Faculty of Chemical Sciences, Complutense University, 28040 Madrid, Spain
- Correspondence:
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Beauveria bassiana Ribotoxin (BbRib) Induces Silkworm Cell Apoptosis via Activating Ros Stress Response. Processes (Basel) 2021. [DOI: 10.3390/pr9081470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The BbRib gene participates in the infection process of Beauveria bassiana (B. bassiana). It also helps pathogenic fungi to escape and defeat the insect host immune defense system by regulating the innate immune response. However, model insects are rarely used to study the mechanism of fungal ribosomal toxin protein. In this study, BbRib protein was produced by prokaryotic expression and injected into silkworm (Bombyx mori) larvae. The physiological and biochemical indexes of silkworm were monitored, and the pathological effects of BbRib protein on immune tissues of silkworm were examined by Hematoxylin and Eosin (HE) staining. BbRib protein can significantly affect the growth and development of the silkworm, causing poisoning, destroying the midgut and fat body and producing physiological changes. The ROS stress response in the adipose tissue and cells of the silkworm was activated to induce apoptosis. These results indicated that the BbRib gene not only participates in the infection process of B. bassiana, it also helps the pathogenic fungi escape the immune system by regulating the innate immune system of the silkworm, allowing it to break through the silkworm’s immune defense. This study reveals the potential molecular mechanism of BbRib protein to insect toxicity, and provides a theoretical basis and material basis for the development and use of novel insecticidal toxins.
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Bauer S, Yu D, Lawson AW, Saur IML, Frantzeskakis L, Kracher B, Logemann E, Chai J, Maekawa T, Schulze-Lefert P. The leucine-rich repeats in allelic barley MLA immune receptors define specificity towards sequence-unrelated powdery mildew avirulence effectors with a predicted common RNase-like fold. PLoS Pathog 2021; 17:e1009223. [PMID: 33534797 PMCID: PMC7857584 DOI: 10.1371/journal.ppat.1009223] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
Nucleotide-binding domain leucine-rich repeat-containing receptors (NLRs) in plants can detect avirulence (AVR) effectors of pathogenic microbes. The Mildew locus a (Mla) NLR gene has been shown to confer resistance against diverse fungal pathogens in cereal crops. In barley, Mla has undergone allelic diversification in the host population and confers isolate-specific immunity against the powdery mildew-causing fungal pathogen Blumeria graminis forma specialis hordei (Bgh). We previously isolated the Bgh effectors AVRA1, AVRA7, AVRA9, AVRA13, and allelic AVRA10/AVRA22, which are recognized by matching MLA1, MLA7, MLA9, MLA13, MLA10 and MLA22, respectively. Here, we extend our knowledge of the Bgh effector repertoire by isolating the AVRA6 effector, which belongs to the family of catalytically inactive RNase-Like Proteins expressed in Haustoria (RALPHs). Using structural prediction, we also identified RNase-like folds in AVRA1, AVRA7, AVRA10/AVRA22, and AVRA13, suggesting that allelic MLA recognition specificities could detect structurally related avirulence effectors. To better understand the mechanism underlying the recognition of effectors by MLAs, we deployed chimeric MLA1 and MLA6, as well as chimeric MLA10 and MLA22 receptors in plant co-expression assays, which showed that the recognition specificity for AVRA1 and AVRA6 as well as allelic AVRA10 and AVRA22 is largely determined by the receptors' C-terminal leucine-rich repeats (LRRs). The design of avirulence effector hybrids allowed us to identify four specific AVRA10 and five specific AVRA22 aa residues that are necessary to confer MLA10- and MLA22-specific recognition, respectively. This suggests that the MLA LRR mediates isolate-specific recognition of structurally related AVRA effectors. Thus, functional diversification of multi-allelic MLA receptors may be driven by a common structural effector scaffold, which could be facilitated by proliferation of the RALPH effector family in the pathogen genome.
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Affiliation(s)
- Saskia Bauer
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Dongli Yu
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Institute of Biochemistry, University of Cologne at Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Aaron W. Lawson
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Isabel M. L. Saur
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | | | - Barbara Kracher
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Elke Logemann
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Jijie Chai
- Institute of Biochemistry, University of Cologne at Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Takaki Maekawa
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
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Davies G, Singh O, Prattes J, Hoenigl M, Sheppard PW, Thornton CR. Aspergillus fumigatus and Its Allergenic Ribotoxin Asp f I: Old Enemies but New Opportunities for Urine-Based Detection of Invasive Pulmonary Aspergillosis Using Lateral-Flow Technology. J Fungi (Basel) 2020; 7:19. [PMID: 33396482 PMCID: PMC7823411 DOI: 10.3390/jof7010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/17/2020] [Accepted: 12/30/2020] [Indexed: 12/21/2022] Open
Abstract
Invasive pulmonary aspergillosis (IPA) caused by Aspergillus fumigatus is a life-threatening lung disease of immunocompromised patients. Diagnosis currently relies on non-specific chest CT, culture of the fungus from invasive lung biopsy, and detection of the cell wall carbohydrate galactomannan (GM) in serum or in BAL fluids recovered during invasive bronchoscopy. Urine provides an ideal bodily fluid for the non-invasive detection of pathogen biomarkers, with current urine-based immunodiagnostics for IPA focused on GM. Surrogate protein biomarkers might serve to improve disease detection. Here, we report the development of a monoclonal antibody (mAb), PD7, which is specific to A. fumigatus and related species in the section Fumigati, and which binds to its 18 kDa ribotoxin Asp f I. Using PD7, we show that the protein is secreted during hyphal development, and so represents an ideal candidate for detecting invasive growth. We have developed a lateral-flow device (Afu-LFD®) incorporating the mAb which has a limit of detection of ~15 ng Asp f I/mL urine. Preliminary evidence of the test's diagnostic potential is demonstrated with urine from a patient with acute lymphoid leukaemia with probable IPA. The Afu-LFD® therefore provides a potential novel opportunity for non-invasive urine-based detection of IPA caused by A. fumigatus.
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Affiliation(s)
- Genna Davies
- ISCA Diagnostics Ltd., Hatherly Laboratories, Prince of Wales Road, Exeter EX4 4PS, UK;
- Biosciences and MRC Centre for Medical Mycology, Hatherly Laboratories, University of Exeter, Prince of Wales Road, Exeter EX4 4PS, UK;
| | - Oski Singh
- Biosciences and MRC Centre for Medical Mycology, Hatherly Laboratories, University of Exeter, Prince of Wales Road, Exeter EX4 4PS, UK;
| | - Juergen Prattes
- Department of Internal Medicine, Section of Infectious Diseases and Tropical Medicine, Medical University of Graz, A-8036 Graz, Austria; (J.P.); (M.H.)
| | - Martin Hoenigl
- Department of Internal Medicine, Section of Infectious Diseases and Tropical Medicine, Medical University of Graz, A-8036 Graz, Austria; (J.P.); (M.H.)
- Division of Infectious Diseases and Global Public Health, University of California San Diego, San Diego, CA 92093, USA
| | - Paul W. Sheppard
- Vacye Associates, Lowerdown Cottage, Lowerdown, Bovey Tracey TQ13 9LF, UK;
| | - Christopher R. Thornton
- ISCA Diagnostics Ltd., Hatherly Laboratories, Prince of Wales Road, Exeter EX4 4PS, UK;
- Biosciences and MRC Centre for Medical Mycology, Hatherly Laboratories, University of Exeter, Prince of Wales Road, Exeter EX4 4PS, UK;
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Lázaro-Gorines R, López-Rodríguez JC, Benedé S, González M, Mayorga C, Vogel L, Martínez-Del-Pozo Á, Lacadena J, Villalba M. Der p 1-based immunotoxin as potential tool for the treatment of dust mite respiratory allergy. Sci Rep 2020; 10:12255. [PMID: 32703972 PMCID: PMC7378242 DOI: 10.1038/s41598-020-69166-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/04/2020] [Indexed: 11/25/2022] Open
Abstract
Immunotoxins appear as promising therapeutic molecules, alternative to allergen-specific-immunotherapy. In this work, we achieved the development of a protein chimera able to promote specific cell death on effector cells involved in the allergic reaction. Der p 1 allergen was chosen as cell-targeting domain and the powerful ribotoxin α-sarcin as the toxic moiety. The resultant construction, named proDerp1αS, was produced and purified from the yeast Pichia pastoris. Der p 1-protease activity and α-sarcin ribonucleolytic action were effectively conserved in proDerp1αS. Immunotoxin impact was assayed by using effector cells sensitized with house dust mite-allergic sera. Cell degranulation and death, triggered by proDerp1αS, was exclusively observed on Der p 1 sera sensitized-humRBL-2H3 cells, but not when treated with non-allergic sera. Most notably, equivalent IgE-binding and degranulation were observed with both proDerp1αS construct and native Der p 1 when using purified basophils from sensitized patients. However, proDerp1αS did not cause any cytotoxic effect on these cells, apparently due to its lack of internalization after their surface IgE-binding, showing the complex in vivo panorama governing allergic reactions. In conclusion, herein we present proDerp1αS as a proof of concept for a potential and alternative new designs of therapeutic tools for allergies. Development of new, and more specific, second-generation of immunotoxins following proDerp1αS, is further discussed.
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Affiliation(s)
- Rodrigo Lázaro-Gorines
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain
| | - Juan Carlos López-Rodríguez
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain
| | - Sara Benedé
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain
| | - Miguel González
- Allergy Research Laboratory, IBIMA, Hospital Regional Universitario de Málaga, UMA, Málaga, Spain
| | - Cristobalina Mayorga
- Allergy Research Laboratory, IBIMA, Hospital Regional Universitario de Málaga, UMA, Málaga, Spain.,U.G.C. Allergy, IBIMA, Hospital Regional Universitario de Málaga, UMA, Málaga, Spain
| | - Lothar Vogel
- Division of Allergology, Paul-Ehrlich-Institut, Langen, Germany
| | - Álvaro Martínez-Del-Pozo
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain
| | - Javier Lacadena
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain.
| | - Mayte Villalba
- Biochemistry and Molecular Biology Department, Chemical Sciences Faculty, Complutense University of Madrid, Av. Complutense w/n, 28040, Madrid, Spain.
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Heterologous Production and Functional Characterization of Ageritin, a Novel Type of Ribotoxin Highly Expressed during Fruiting of the Edible Mushroom Agrocybe aegerita. Appl Environ Microbiol 2019; 85:AEM.01549-19. [PMID: 31444206 DOI: 10.1128/aem.01549-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 08/21/2019] [Indexed: 12/11/2022] Open
Abstract
Fungi produce various defense proteins against antagonists, including ribotoxins. These toxins cleave a single phosphodiester bond within the universally conserved sarcin-ricin loop of ribosomes and inhibit protein biosynthesis. Here, we report on the structure and function of ageritin, a previously reported ribotoxin from the edible mushroom Agrocybe aegerita The amino acid sequence of ageritin was derived from cDNA isolated from the dikaryon A. aegerita AAE-3 and lacks, according to in silico prediction, a signal peptide for classical secretion, predicting a cytoplasmic localization of the protein. The calculated molecular weight of the protein is slightly higher than the one reported for native ageritin. The A. aegerita ageritin-encoding gene, AaeAGT1, is highly induced during fruiting, and toxicity assays with AaeAGT1 heterologously expressed in Escherichia coli showed a strong toxicity against Aedes aegypti larvae yet not against nematodes. The activity of recombinant A. aegerita ageritin toward rabbit ribosomes was confirmed in vitro Mutagenesis studies revealed a correlation between in vivo and in vitro activities, indicating that entomotoxicity is mediated by ribonucleolytic cleavage. The strong larvicidal activity of ageritin makes this protein a promising candidate for novel biopesticide development.IMPORTANCE Our results suggest a pronounced organismal specificity of a protein toxin with a very conserved intracellular molecular target. The molecular details of the toxin-target interaction will provide important insight into the mechanism of action of protein toxins and the ribosome. This insight might be exploited to develop novel bioinsecticides.
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10
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Ruiz-de-la-Herrán J, Tomé-Amat J, Lázaro-Gorines R, Gavilanes JG, Lacadena J. Inclusion of a Furin Cleavage Site Enhances Antitumor Efficacy against Colorectal Cancer Cells of Ribotoxin α-Sarcin- or RNase T1-Based Immunotoxins. Toxins (Basel) 2019; 11:E593. [PMID: 31614771 PMCID: PMC6832446 DOI: 10.3390/toxins11100593] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/08/2019] [Accepted: 10/10/2019] [Indexed: 02/07/2023] Open
Abstract
Immunotoxins are chimeric molecules that combine the specificity of an antibody to recognize and bind tumor antigens with the potency of the enzymatic activity of a toxin, thus, promoting the death of target cells. Among them, RNases-based immunotoxins have arisen as promising antitumor therapeutic agents. In this work, we describe the production and purification of two new immunoconjugates, based on RNase T1 and the fungal ribotoxin α-sarcin, with optimized properties for tumor treatment due to the inclusion of a furin cleavage site. Circular dichroism spectroscopy, ribonucleolytic activity studies, flow cytometry, fluorescence microscopy, and cell viability assays were carried out for structural and in vitro functional characterization. Our results confirm the enhanced antitumor efficiency showed by these furin-immunotoxin variants as a result of an improved release of their toxic domain to the cytosol, favoring the accessibility of both ribonucleases to their substrates. Overall, these results represent a step forward in the design of immunotoxins with optimized properties for potential therapeutic application in vivo.
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Affiliation(s)
- Javier Ruiz-de-la-Herrán
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
| | - Jaime Tomé-Amat
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
- Centre for Plant Biotechnology and Genomics (UPM-INIA), Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid 28223, Spain.
| | - Rodrigo Lázaro-Gorines
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
| | - Javier Lacadena
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
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11
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Ruggiero A, García-Ortega L, Ragucci S, Russo R, Landi N, Berisio R, Di Maro A. Structural and enzymatic properties of Ageritin, a novel metal-dependent ribotoxin-like protein with antitumor activity. Biochim Biophys Acta Gen Subj 2018; 1862:2888-2894. [DOI: 10.1016/j.bbagen.2018.09.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/07/2018] [Accepted: 09/15/2018] [Indexed: 12/15/2022]
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12
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Minimized natural versions of fungal ribotoxins show improved active site plasticity. Arch Biochem Biophys 2017; 619:45-53. [DOI: 10.1016/j.abb.2017.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/03/2017] [Accepted: 03/05/2017] [Indexed: 01/29/2023]
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13
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Frisvad JC, Larsen TO. Extrolites of Aspergillus fumigatus and Other Pathogenic Species in Aspergillus Section Fumigati. Front Microbiol 2016; 6:1485. [PMID: 26779142 PMCID: PMC4703822 DOI: 10.3389/fmicb.2015.01485] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 12/09/2015] [Indexed: 11/13/2022] Open
Abstract
Aspergillus fumigatus is an important opportunistic human pathogen known for its production of a large array of extrolites. Up to 63 species have been described in Aspergillus section Fumigati, some of which have also been reliably reported to be pathogenic, including A. felis, A. fischeri, A. fumigatiaffinis, A. fumisynnematus, A. hiratsukae, A. laciniosus, A. lentulus, A. novofumigatus, A. parafelis, A. pseudofelis, A. pseudoviridinutans, A. spinosus, A. thermomutatus, and A. udagawae. These species share the production of hydrophobins, melanins, and siderophores and ability to grow well at 37°C, but they only share some small molecule extrolites, that could be important factors in pathogenicity. According to the literature gliotoxin and other exometabolites can be contributing factors to pathogenicity, but these exometabolites are apparently not produced by all pathogenic species. It is our hypothesis that species unable to produce some of these metabolites can produce proxy-exometabolites that may serve the same function. We tabulate all exometabolites reported from species in Aspergillus section Fumigati and by comparing the profile of those extrolites, suggest that those producing many different kinds of exometabolites are potential opportunistic pathogens. The exometabolite data also suggest that the profile of exometabolites are highly specific and can be used for identification of these closely related species.
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Affiliation(s)
- Jens C. Frisvad
- Section of Eukaryotic Biotechnology, Department of Systems Biology, Technical University of DenmarkKongens Lyngby, Denmark
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14
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Agrawal Y, Khatri I, Subramanian S, Shenoy BD. Genome sequence, comparative analysis, and evolutionary insights into chitinases of entomopathogenic fungus Hirsutella thompsonii. Genome Biol Evol 2015; 7:916-30. [PMID: 25716828 PMCID: PMC5322555 DOI: 10.1093/gbe/evv037] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hirsutella thompsonii (Ht) is a fungal pathogen of acarines and the primary cause of epizootics among mites. The draft genomes of two isolates of Ht (MTCC 3556: Ht3, 34.6 Mb and MTCC 6686: Ht6, 34.7 Mb) are presented and compared with the genomes of Beauveria bassiana (Bb) ARSEF 2860 and Ophiocordyceps sinensis (Os) CO18. Comparative analysis of carbohydrate active enzymes, pathogen–host interaction genes, metabolism-associated genes, and genes involved in biosynthesis of secondary metabolites in the four genomes was carried out. Reduction in gene family sizes in Ht3 and Os as compared with Ht6 and Bb is observed. Analysis of the mating type genes in Ht reveals the presence of MAT idiomorphs which is suggestive of cryptic sexual traits in Ht. We further identify and classify putative chitinases that may function as virulence factors in fungal entomopathogens due to their role in degradation of arthropod cuticle.
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Affiliation(s)
- Yamini Agrawal
- CSIR-Institute of Microbial Technology, Chandigarh, India
| | - Indu Khatri
- CSIR-Institute of Microbial Technology, Chandigarh, India
| | | | - Belle Damodara Shenoy
- CSIR-Institute of Microbial Technology, Chandigarh, India Present address: CSIR-National Institute of Oceanography, Dona Paula, Goa, India
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15
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Castaño-Rodríguez C, Olombrada M, Partida-Hanon A, Lacadena J, Oñaderra M, Gavilanes JG, García-Ortega L, Martínez-Del-Pozo Á. Involvement of loops 2 and 3 of α-sarcin on its ribotoxic activity. Toxicon 2015; 96:1-9. [PMID: 25598497 DOI: 10.1016/j.toxicon.2015.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 12/21/2014] [Accepted: 01/14/2015] [Indexed: 01/07/2023]
Abstract
Ribotoxins are a family of fungal ribosome-inactivating proteins displaying highly specific ribonucleolytic activity against the sarcin/ricin loop (SRL) of the larger rRNA, with α-sarcin as its best-characterized member. Their toxicity arises from the combination of this activity with their ability to cross cell membranes. The involvement of α-sarcin's loops 2 and 3 in SRL and ribosomal proteins recognition, as well as in the ribotoxin-lipid interactions involving cell penetration, has been suggested some time ago. In the work presented now different mutants have been prepared in order to study the role of these loops in their ribonucleolytic and lipid-interacting properties. The results obtained confirm that loop 3 residues Lys 111, 112, and 114 are key actors of the specific recognition of the SRL. In addition, it is also shown that Lys 114 and Tyr 48 conform a network of interactions which is essential for the catalysis. Lipid-interaction studies show that this Lys-rich region is indeed involved in the phospholipids recognition needed to cross cell membranes. Loop 2 is shown to be responsible for the conformational change which exposes the region establishing hydrophobic interactions with the membrane inner leaflets and eases penetration of ribotoxins target cells.
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Affiliation(s)
- Carlos Castaño-Rodríguez
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Miriam Olombrada
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Angélica Partida-Hanon
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Javier Lacadena
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Mercedes Oñaderra
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain.
| | - Lucía García-Ortega
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain.
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16
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Crameri R. Structural aspects of fungal allergens. Semin Immunopathol 2014; 37:117-21. [PMID: 25413498 DOI: 10.1007/s00281-014-0458-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 11/04/2014] [Indexed: 11/26/2022]
Abstract
Despite the increasing number of solved crystal structures of allergens, the key question why some proteins are allergenic and the vast majority is not remains unanswered. The situation is not different for fungal allergens which cover a wide variety of proteins with different chemical properties and biological functions. They cover enzymes, cell wall, secreted, and intracellular proteins which, except cross-reactive allergens, does not show any evidence for structural similarities at least at the three-dimensional level. However, from a diagnostic point of view, pure allergens biotechnologically produced by recombinant technology can provide us, in contrast to fungal extracts which are hardly producible as standardized reagents, with highly pure perfectly standardized diagnostic reagents.
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Affiliation(s)
- Reto Crameri
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zürich, Davos, Switzerland,
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17
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Hussaarts L, Yazdanbakhsh M, Guigas B. Priming dendritic cells for th2 polarization: lessons learned from helminths and implications for metabolic disorders. Front Immunol 2014; 5:499. [PMID: 25368615 PMCID: PMC4202775 DOI: 10.3389/fimmu.2014.00499] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 09/25/2014] [Indexed: 12/20/2022] Open
Abstract
Nearly one quarter of the world's population is infected with helminth parasites. A common feature of helminth infections is the manifestation of a type 2 immune response, characterized by T helper 2 (Th2) cells that mediate anti-helminth immunity. In addition, recent literature describes a close association between type 2 immune responses and wound repair, suggesting that a Th2 response may concurrently mediate repair of parasite-induced damage. The molecular mechanisms that govern Th2 responses are poorly understood, although it is clear that dendritic cells (DCs), which are the most efficient antigen-presenting cells in the immune system, play a central role. Here, we review the molecular mechanisms by which DCs polarize Th2 cells, examining both helminth antigens and helminth-mediated tissue damage as Th2-inducing triggers. Finally, we discuss the implication of these findings in the context of metabolic disorders, as recent literature indicates that various aspects of the Th2-associated inflammatory response contribute to metabolic homeostasis.
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Affiliation(s)
- Leonie Hussaarts
- Department of Parasitology, Leiden University Medical Center , Leiden , Netherlands
| | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center , Leiden , Netherlands
| | - Bruno Guigas
- Department of Parasitology, Leiden University Medical Center , Leiden , Netherlands ; Department of Molecular Cell Biology, Leiden University Medical Center , Leiden , Netherlands
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18
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Crameri R, Garbani M, Rhyner C, Huitema C. Fungi: the neglected allergenic sources. Allergy 2014; 69:176-85. [PMID: 24286281 DOI: 10.1111/all.12325] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2013] [Indexed: 12/15/2022]
Abstract
Allergic diseases are considered the epidemics of the twentieth century estimated to affect more than 30% of the population in industrialized countries with a still increasing incidence. During the past two decades, the application of molecular biology allowed cloning, production and characterization of hundreds of recombinant allergens. In turn, knowledge about molecular, chemical and biologically relevant allergens contributed to increase our understanding of the mechanisms underlying IgE-mediated type I hypersensitivity reactions. It has been largely demonstrated that fungi are potent sources of allergenic molecules covering a vast variety of molecular structures including enzymes, toxins, cell wall components and phylogenetically highly conserved cross-reactive proteins. Despite the large knowledge accumulated and the compelling evidence for an involvement of fungal allergens in the pathophysiology of allergic diseases, fungi as a prominent source of allergens are still largely neglected in basic research as well as in clinical practice. This review aims to highlight the impact of fungal allergens with focus on asthma and atopic dermatitis.
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Affiliation(s)
- R. Crameri
- Swiss Institute of Allergy and Asthma Research (SIAF); University of Zürich; Davos Switzerland
| | - M. Garbani
- Swiss Institute of Allergy and Asthma Research (SIAF); University of Zürich; Davos Switzerland
| | - C. Rhyner
- Swiss Institute of Allergy and Asthma Research (SIAF); University of Zürich; Davos Switzerland
| | - C. Huitema
- Swiss Institute of Allergy and Asthma Research (SIAF); University of Zürich; Davos Switzerland
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19
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Olombrada M, Herrero-Galán E, Tello D, Oñaderra M, Gavilanes JG, Martínez-del-Pozo Á, García-Ortega L. Fungal extracellular ribotoxins as insecticidal agents. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:39-46. [PMID: 23153726 DOI: 10.1016/j.ibmb.2012.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/24/2012] [Accepted: 10/25/2012] [Indexed: 06/01/2023]
Abstract
Fungal ribotoxins were discovered almost 50 years ago as extracellular ribonucleases (RNases) with antitumoral properties. However, the biological function of these toxic proteins has remained elusive. The discovery of the ribotoxin HtA, produced by the invertebrates pathogen Hirsutella thompsonii, revived the old proposal that insecticidal activity would be their long searched function. Unfortunately, HtA is rather singular among all ribotoxins known in terms of sequence and structure similarities. Thus, it was intriguing to answer the question of whether HtA is just an exception or, on the contrary, the paradigmatic example of the ribotoxins function. The work presented uses HtA and α-sarcin, the most representative member of the ribotoxins family, to show their strong toxic action against insect larvae and cells.
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Affiliation(s)
- Miriam Olombrada
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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20
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Everts B, Hussaarts L, Driessen NN, Meevissen MHJ, Schramm G, van der Ham AJ, van der Hoeven B, Scholzen T, Burgdorf S, Mohrs M, Pearce EJ, Hokke CH, Haas H, Smits HH, Yazdanbakhsh M. Schistosome-derived omega-1 drives Th2 polarization by suppressing protein synthesis following internalization by the mannose receptor. ACTA ACUST UNITED AC 2012; 209:1753-67, S1. [PMID: 22966004 PMCID: PMC3457738 DOI: 10.1084/jem.20111381] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Schistosome ribonuclease Omega-1 primes DCs to generate Th2 responses by binding and internalization by the mannose receptor and by subsequently impairing protein synthesis. Omega-1, a glycosylated T2 ribonuclease (RNase) secreted by Schistosoma mansoni eggs and abundantly present in soluble egg antigen, has recently been shown to condition dendritic cells (DCs) to prime Th2 responses. However, the molecular mechanisms underlying this effect remain unknown. We show in this study by site-directed mutagenesis of omega-1 that both the glycosylation and the RNase activity are essential to condition DCs for Th2 polarization. Mechanistically, we demonstrate that omega-1 is bound and internalized via its glycans by the mannose receptor (MR) and subsequently impairs protein synthesis by degrading both ribosomal and messenger RNA. These experiments reveal an unrecognized pathway involving MR and interference with protein synthesis that conditions DCs for Th2 priming.
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Affiliation(s)
- Bart Everts
- Department of Parasitology, Leiden University Medical Center, 2333 ZA Leiden, Netherlands
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21
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Carreras-Sangrà N, Tomé-Amat J, García-Ortega L, Batt CA, Oñaderra M, Martínez-del-Pozo A, Gavilanes JG, Lacadena J. Production and characterization of a colon cancer-specific immunotoxin based on the fungal ribotoxin α-sarcin. Protein Eng Des Sel 2012; 25:425-35. [PMID: 22718791 DOI: 10.1093/protein/gzs032] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A single-chain fusion protein that directed the cytolytic activity of α-sarcin to A33 tumor antigen expressing cells was constructed and shown to effectively kill targeted cells. Glycoprotein A33 (GPA33) is a well-known colon cancer marker and a humanized antibody against it was used to target the α-sarcin. The fungal ribotoxin α-sarcin is one of the most potent and specific toxins known. It is small, protease resistant, thermostable and highly efficient towards the inactivation of ribosomes. This work describes the production and characterization of an immunotoxin resulting from fusing the single-chain variable fragment (scFv) of the monoclonal antibody that targets GPA33 to fungal α-sarcin. This chimeric protein (scFvA33αsarcin), produced in Pichia pastoris and purified in high yield was proven to be properly folded, active, specific and stable. It showed high specific toxicity against GPA33-positive tumoral cell lines providing scientific evidence to sustain that scFvA33αsarcin is a good immunotherapeutic candidate against GPA33-positive colon carcinomas.
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Affiliation(s)
- Nelson Carreras-Sangrà
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense, 28040 Madrid, Spain
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22
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Álvarez-García E, Diago-Navarro E, Herrero-Galán E, García-Ortega L, López-Villarejo J, Olmo N, Díaz-Orejas R, Gavilanes JG, Martínez-del-Pozo Á. The ribonucleolytic activity of the ribotoxin α-sarcin is not essential for in vitro protein biosynthesis inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1377-82. [DOI: 10.1016/j.bbapap.2011.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/21/2011] [Accepted: 06/29/2011] [Indexed: 11/16/2022]
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23
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Herrero-Galán E, García-Ortega L, Lacadena J, Martínez-Del-Pozo A, Olmo N, Gavilanes JG, Oñaderra M. Implication of an Asp residue in the ribonucleolytic activity of hirsutellin A reveals new electrostatic interactions at the active site of ribotoxins. Biochimie 2011; 94:427-33. [PMID: 21871524 DOI: 10.1016/j.biochi.2011.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 08/15/2011] [Indexed: 10/17/2022]
Abstract
Ribotoxins are fungal extracellular ribonucleases that specifically cleave ribosomes leading to cell-death via apoptosis. α-Sarcin is the ribotoxin studied in deepest detail, and therefore constitutes the referential protein for the whole family. It has been demonstrated that ribotoxin activity depends on a very precise structural microenvironment in which electrostatic interactions among residues in the active site are of the highest importance. Hirsutellin A (HtA) has been recently described as the smallest ribotoxin known to date, encompassing all the abilities of previously characterized members of this family into a shorter sequence. Comparison of HtA and α-sarcin three-dimensional structures suggested that residues presumably forming the catalytic triad of HtA would be His 42, Glu 66, and His 113. Within this same idea, the presence of an Asp residue (Asp 40) in a position equivalent to α-sarcin Tyr 48 is highlighted as a novelty in this field. In this work, substitution mutants H42Q, E66Q and H113Q, as well as double and triple mutants in all possible combinations, are studied regarding their ribonucleolytic activity and cytotoxicity. Implication of these three residues in the ribotoxin activity of HtA is confirmed, though none of them is strictly essential for ribosomal cleavage. Studies with mutants D40N and D40N/E66Q demonstrate an important role for Asp 40 in the activity of HtA and establish a new set of electrostatic interactions different from the one described for already known ribotoxins.
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Affiliation(s)
- Elías Herrero-Galán
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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24
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Álvarez-García E, Martínez-del-Pozo Á, Gavilanes JG. Role of the basic character of α-sarcin’s NH2-terminal β-hairpin in ribosome recognition and phospholipid interaction. Arch Biochem Biophys 2009; 481:37-44. [DOI: 10.1016/j.abb.2008.10.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/06/2008] [Accepted: 10/07/2008] [Indexed: 11/17/2022]
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25
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Herrero-Galán E, Lacadena J, Martínez del Pozo A, Boucias DG, Olmo N, Oñaderra M, Gavilanes JG. The insecticidal protein hirsutellin A from the mite fungal pathogen Hirsutella thompsonii is a ribotoxin. Proteins 2008; 72:217-28. [PMID: 18214983 DOI: 10.1002/prot.21910] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mite fungal pathogen Hirsutella thompsonii produces a single polypeptide chain, insecticidal protein named hirsutellin A (HtA) that is composed of 130 amino acid residues. This protein has been purified from its natural source and produced as a recombinant protein in Escherichia coli. Spectroscopic analysis has determined that the two protein forms are indistinguishable. HtA specifically inactivates ribosomes and produces the alpha-fragment characteristic of ribotoxin activity on rRNA. Behaving as a cyclizing ribonuclease, HtA specifically cleaves oligonucleotides that mimick the sarcin/ricin loop of the ribosome, as well as selected polynucleotides and dinucleosides. HtA interacts with phospholipid membranes as do other ribotoxins. As a consequence of its ribonuclease activity and its ability to interact with cell membranes, HtA exhibits cytotoxic activity on human tumor cells. On the basis of these results, HtA is considered to be a member of the ribotoxin group of proteins, although it is significantly smaller (130 aa) than all known ribotoxins that are composed of 149/150 amino acids. Ribotoxins are members of a larger family of fungal ribonucleases whose members of smaller size (100/110 aa) are not cytotoxic. Thus, the characterization of the fungal ribotoxin HtA represents an important milestone in the study of the diversity and the function of fungal ribonucleases.
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Affiliation(s)
- Elías Herrero-Galán
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense, 28040 Madrid, Spain
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26
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Varga J, Samson RA. Ribotoxin genes in isolates of Aspergillus section Clavati. Antonie van Leeuwenhoek 2008; 94:481-5. [PMID: 18600469 PMCID: PMC2519116 DOI: 10.1007/s10482-008-9266-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 06/20/2008] [Indexed: 11/27/2022]
Abstract
Ribotoxins are ribosome inactivator proteins with high specificity against the sarcin/ricin domain of the 28S ribosomal RNA. We examined the presence of ribotoxin genes in isolates of species recently assigned to Aspergillus section Clavati using specific primer pairs. All species assigned to this section have been found to carry ribotoxin genes. Phylogenetic analysis of the sequences of the amplified gene fragments allowed us to classify the genes to different groups including the α-sarcin, gigantin, c-sarcin and mitogillin/restrictocin families. Two species, A. longivesica and N. acanthosporus produced ribotoxins which were only distantly related to gigantins and c-sarcins, respectively. Comparison of the protein sequences of the genes to known ribotoxin sequences revealed that all of them carry the presumed catalytic residues of ribotoxins, the cystein residues, and also the two Trp residues of α-sarcin conserved in all ribotoxins known so far. These data indicate that these genes probably encode active ribotoxins. Further studies are in progress to examine the secretion and activities of these new ribotoxins.
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Affiliation(s)
- János Varga
- CBS Fungal Biodiversity Centre, Uppsalalaan 8, Utrecht, The Netherlands.
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27
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Álvarez-García E, Alegre-Cebollada J, Batanero E, Monedero V, Pérez-Martínez G, García-Fernández R, Gavilanes JG, Martínez del Pozo Á. Lactococcus lactis as a vehicle for the heterologous expression of fungal ribotoxin variants with reduced IgE-binding affinity. J Biotechnol 2008; 134:1-8. [DOI: 10.1016/j.jbiotec.2007.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 09/29/2007] [Accepted: 12/13/2007] [Indexed: 02/03/2023]
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28
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Lacadena J, Alvarez-García E, Carreras-Sangrà N, Herrero-Galán E, Alegre-Cebollada J, García-Ortega L, Oñaderra M, Gavilanes JG, Martínez del Pozo A. Fungal ribotoxins: molecular dissection of a family of natural killers. FEMS Microbiol Rev 2007; 31:212-37. [PMID: 17253975 DOI: 10.1111/j.1574-6976.2006.00063.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
RNase T1 is the best known representative of a large family of ribonucleolytic proteins secreted by fungi, mostly Aspergillus and Penicillium species. Ribotoxins stand out among them by their cytotoxic character. They exert their toxic action by first entering the cells and then cleaving a single phosphodiester bond located within a universally conserved sequence of the large rRNA gene, known as the sarcin-ricin loop. This cleavage leads to inhibition of protein biosynthesis, followed by cellular death by apoptosis. Although no protein receptor has been found for ribotoxins, they preferentially kill cells showing altered membrane permeability, such as those that are infected with virus or transformed. Many steps of the cytotoxic process have been elucidated at the molecular level by means of a variety of methodological approaches and the construction and purification of different mutant versions of these ribotoxins. Ribotoxins have been used for the construction of immunotoxins, because of their cytotoxicity. Besides this activity, Aspf1, a ribotoxin produced by Aspergillus fumigatus, has been shown to be one of the major allergens involved in allergic aspergillosis-related pathologies. Protein engineering and peptide synthesis have been used in order to understand the basis of these pathogenic mechanisms as well as to produce hypoallergenic proteins with potential diagnostic and immunotherapeutic applications.
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Affiliation(s)
- Javier Lacadena
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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29
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Crameri R, Limacher A, Weichel M, Glaser AG, Zeller S, Rhyner C. Structural aspects and clinical relevance of Aspergillus fumigatus antigens/allergens. Med Mycol 2006; 44:S261-S267. [PMID: 30408912 DOI: 10.1080/13693780600789160] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Robotics-based high throughput screening of Aspergillus fumigatus cDNA libraries displayed on phage surfaces revealed at last 81 different structures able to bind IgE from serum of patients sensitized to this fungus. Among these, species-specific as well as phylogenetically highly conserved structures and such with unknown function have been detected. A subset of cDNAs have been used to produce and characterize the corresponding recombinant allergens which have proven to be useful diagnostic reagents allowing specific detection of A. fumigatus sensitization and differential diagnosis of allergic bronchopulmonary aspergillosis. Phylogenetically highly conserved structures like manganese-dependent superoxide dismutase, P2 acidic ribosomal protein, cyclophilins and thioredoxins induce, beyond sensitization, IgE antibodies able to cross-react with the corresponding homologous self antigens. These reactions, likely to contribute to the exacerbation and perpetuation of allergic bronchopulmonary aspergillosis, can be traced back to shared conformational B-cell epitopes build up from conserved amino acid residues scattered over the surface of the molecules as shown by detailed analyses of the crystal structures.
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Affiliation(s)
- R Crameri
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
| | - A Limacher
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
| | - M Weichel
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
| | - A G Glaser
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
| | - S Zeller
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
| | - C Rhyner
- Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland
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30
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Alvarez-García E, García-Ortega L, Verdún Y, Bruix M, Martínez del Pozo A, Gavilanes JG. Tyr-48, a conserved residue in ribotoxins, is involved in the RNA-degrading activity of α-sarcin. Biol Chem 2006; 387:535-41. [PMID: 16740124 DOI: 10.1515/bc.2006.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Residue Tyr-48 in alpha-sarcin is conserved not only within the ribotoxin family, but also within the larger group of extracellular fungal ribonucleases, best represented by RNase T1. A mutant protein in which this Tyr residue was substituted by Phe has been produced and isolated to homogeneity. It was spectroscopically analyzed by means of circular dichroism, fluorescence emission and NMR. Taken together, these results and those from enzyme characterization have revealed the essential role of the -OH group from the Tyr-48 phenolic ring in the cleavage of polymeric RNA substrates, including the ribosome-embedded 28S rRNA, the natural substrate of ribotoxins. Thus, the mutant protein does not degrade its natural ribosomal RNA substrate. However, it has been shown that this Y48F mutant still retains its ability to cleave a phosphodiester bond in a minimal substrate such as the dinucleoside phosphate ApA. The role of different alpha-sarcin residues within the enzyme reaction catalyzed by this protein is discussed.
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Affiliation(s)
- Elisa Alvarez-García
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, E-28040 Madrid, Spain
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31
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García-Mayoral F, García-Ortega L, Alvarez-García E, Bruix M, Gavilanes JG, del Pozo AM. Modeling the highly specific ribotoxin recognition of ribosomes. FEBS Lett 2005; 579:6859-64. [PMID: 16337202 DOI: 10.1016/j.febslet.2005.11.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 10/27/2005] [Accepted: 11/01/2005] [Indexed: 11/16/2022]
Abstract
The three-dimensional structures of the alpha-sarcin ribotoxin and its delta(7-22) deletion mutant, both complexed with a 20-mer oligonucleotide mimicking the sarcin/ricin loop (SRL) of the ribosome, have been docked into the structure of the Halobacterium marismortui ribosome by fitting the nucleotide atomic coordinates into those of the ribosomal SRL. This study has revealed that two regions of the ribotoxin, residues 11-16 and 84-85, contact the ribosomal proteins L14 (residues 99-105) and L6 (residues 88-92), respectively. The first of these two ribotoxin regions appears to be crucial for its specific ribosome recognition.
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Affiliation(s)
- Flor García-Mayoral
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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32
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Garciá-Ortega L, Lacadena J, Villalba M, Rodríguez R, Crespo JF, Rodríguez J, Pascual C, Olmo N, Oñaderra M, del Pozo AM, Gavilanes JG. Production and characterization of a noncytotoxic deletion variant of the Aspergillus fumigatus allergen Aspf1 displaying reduced IgE binding. FEBS J 2005; 272:2536-44. [PMID: 15885102 DOI: 10.1111/j.1742-4658.2005.04674.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aspergillus fumigatus is responsible for many allergic respiratory diseases, the most notable of which - due to its severity - is allergic bronchopulmonary aspergillosis. Aspf1 is a major allergen of this fungus: this 149-amino acid protein belongs to the ribotoxin family, whose best characterized member is alpha-sarcin (EC 3.1.27.10). The proteins of this group are cytotoxic ribonucleases that degrade a unique bond in ribosomal RNA impairing protein biosynthesis. Aspf1 and its deletion mutant Aspf1Delta(7-22) have been produced as recombinant proteins; the deleted region corresponds to an exposed beta-hairpin. The conformation of these two proteins has been studied by CD and fluorescence spectroscopy. Their enzymatic activity and cytotoxicity against human rhabdomyosarcoma cells was also measured and their allergenic properties have been studied by using 58 individual sera of patients sensitized to Aspergillus. Aspf1Delta(7-22) lacks cytotoxicity and shows a remarkably reduced IgE reactivity. From these studies it can be concluded that the deleted beta-hairpin is involved in ribosome recognition and is a significant allergenic region.
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Affiliation(s)
- Lucía Garciá-Ortega
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, Madrid, Spain
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33
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Siemer A, Masip M, Carreras N, García-Ortega L, Oñaderra M, Bruix M, Del Pozo AM, Gavilanes JG. Conserved asparagine residue 54 of alpha-sarcin plays a role in protein stability and enzyme activity. Biol Chem 2005; 385:1165-70. [PMID: 15653429 DOI: 10.1515/bc.2004.150] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Asparagine 54 of alpha-sarcin is a conserved residue within the proteins of the ribotoxin family of microbial ribonucleases. It is located in loop 2 of the protein, which lacks repetitive secondary structure elements but exhibits a well-defined conformation. Five mutant variants at this residue have been produced and characterized. The spectroscopic characterization of these proteins indicates that the overall conformation is not changed upon mutation. Activity and denaturation assays show that Asn-54 largely contributes to protein stability, and its presence is a requirement for the highly specific inhibitory activity of these ribotoxins on ribosomes.
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Affiliation(s)
- Ansgar Siemer
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, E-28040 Madrid, Spain
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34
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Pérez-Cañadilllas JM, García-Mayoral MF, Laurents DV, Martínez del Pozo A, Gavilanes JG, Rico M, Bruix M. Tautomeric state of alpha-sarcin histidines. Ndelta tautomers are a common feature in the active site of extracellular microbial ribonucleases. FEBS Lett 2003; 534:197-201. [PMID: 12527386 DOI: 10.1016/s0014-5793(02)03844-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Extracellular fungal RNases, including ribotoxins such as alpha-sarcin, constitute a family of structurally related proteins represented by RNase T1. The tautomeric preferences of the alpha-sarcin imidazole side chains have been determined by nuclear magnetic resonance and electrostatic calculations. Histidine residues at the active site, H50 and H137, adopt the Ndelta tautomer, which is less common in short peptides, as has been found for RNase T1. Comparison with tautomers predicted from crystal structures of other ribonucleases suggests that two active site histidine residues with the Ndelta tautomer are a conserved feature of microbial ribonucleases and that this is related to their ribonucleolytic function.
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Affiliation(s)
- José Manuel Pérez-Cañadilllas
- Departamento de Espectroscopía y Estructura Molecular, Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
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35
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Masip M, García-Ortega L, Olmo N, García-Mayoral MF, Pérez-Cañadillas JM, Bruix M, Oñaderra M, Martínez del Pozo A, Gavilanes JG. Leucine 145 of the ribotoxin alpha-sarcin plays a key role for determining the specificity of the ribosome-inactivating activity of the protein. Protein Sci 2003; 12:161-9. [PMID: 12493839 PMCID: PMC2312396 DOI: 10.1110/ps.0225903] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Revised: 10/04/2002] [Accepted: 10/04/2002] [Indexed: 10/27/2022]
Abstract
Secreted fungal RNases, represented by RNase T1, constitute a family of structurally related proteins that includes ribotoxins such as alpha-sarcin. The active site residues of RNase T1 are conserved in all fungal RNases, except for Phe 100 that is not present in the ribotoxins, in which Leu 145 occupies the equivalent position. The mutant Leu145Phe of alpha-sarcin has been recombinantly produced and characterized by spectroscopic methods (circular dichroism, fluorescence spectroscopy, and NMR). These analyses have revealed that the mutant protein retained the overall conformation of the wild-type alpha-sarcin. According to the analyses performed, Leu 145 was shown to be essential to preserve the electrostatic environment of the active site that is required to maintain the anomalous low pKa value reported for the catalytic His 137 of alpha-sarcin. Enzymatic characterization of the mutant protein has revealed that Leu 145 is crucial for the specific activity of alpha-sarcin on ribosomes.
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Affiliation(s)
- Manuel Masip
- Departamento de Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, 28040-Madrid, Spain
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36
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Garcia-Ortega L, Masip M, Mancheño JM, Oñaderra M, Lizarbe MA, García-Mayoral MF, Bruix M, Martínez del Pozo A, Gavilanes JG. Deletion of the NH2-terminal beta-hairpin of the ribotoxin alpha-sarcin produces a nontoxic but active ribonuclease. J Biol Chem 2002; 277:18632-9. [PMID: 11897788 DOI: 10.1074/jbc.m200922200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ribotoxins are a family of highly specific fungal ribonucleases that inactivate the ribosomes by hydrolysis of a single phosphodiester bond of the 28 S rRNA. alpha-Sarcin, the best characterized member of this family, is a potent cytotoxin that promotes apoptosis of human tumor cells after internalization via endocytosis. This latter ability is related to its interaction with phospholipid bilayers. These proteins share a common structural core with nontoxic ribonucleases of the RNase T1 family. However, significant structural differences between these two groups of proteins are related to the presence of a long amino-terminal beta-hairpin in ribotoxins and to the different length of their unstructured loops. The amino-terminal deletion mutant Delta(7-22) of alpha-sarcin has been produced in Escherichia coli and purified to homogeneity. It retains the same conformation as the wild-type protein as ascertained by complete spectroscopic characterization based on circular dichroism, fluorescence, and NMR techniques. This mutant exhibits ribonuclease activity against naked rRNA and synthetic substrates but lacks the specific ability of the wild-type protein to degrade rRNA in intact ribosomes. The results indicate that alpha-sarcin interacts with the ribosome at two regions, i.e. the well known sarcin-ricin loop of the rRNA and a different region recognized by the beta-hairpin of the protein. In addition, this latter protein portion is involved in interaction with cell membranes. The mutant displays decreased interaction with lipid vesicles and shows behavior compatible with the absence of one vesicle-interacting region. In agreement with this conclusion, the deletion mutant exhibits a very low cytotoxicity on human rhabdomyosarcoma cells.
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Affiliation(s)
- Lucia Garcia-Ortega
- Departamento de Bioquimica y Biologia Molecular I, Universidad Complutense, Madrid 28040, Spain
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