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Molina-Vera C, Morales-Tlalpan V, Chavez-Vega A, Uribe-López J, Trujillo-Barrientos J, Campos-Guillén J, Chávez-Servín JL, García-Gasca T, Saldaña C. The Killer Saccharomyces cerevisiae Toxin: From Origin to Biomedical Research. Microorganisms 2024; 12:2481. [PMID: 39770684 PMCID: PMC11727844 DOI: 10.3390/microorganisms12122481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2024] [Revised: 11/13/2024] [Accepted: 11/24/2024] [Indexed: 01/16/2025] Open
Abstract
The killer systems of S. cerevisiae are defined by the co-infection of two viral agents, an M virus and a helper virus. Each killer toxin is determined by the type of M virus (ScV-M1, ScV-M2, ScV-M28, and ScV-Mlus), which encodes a specific toxin (K1, K2, K28, and Klus). Since their discovery, interest in their potential use as antimicrobial agents has driven research into the mechanisms of action of these toxins on susceptible cells. This review provides an overview of the key aspects of killer toxins, including their origin and the evolutionary implications surrounding the viruses involved in the killer system, as well as their potential applications in the biomedical field and as a biological control strategy. Special attention is given to the mechanisms of action described to date for the various S. cerevisiae killer toxins.
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Affiliation(s)
- Carlos Molina-Vera
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
| | - Verónica Morales-Tlalpan
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
- National Laboratory for Advanced Scientific Visualization (LAVIS-FCN-UAQ), Querétaro 76230, Mexico
| | - Amairani Chavez-Vega
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
| | - Jennifer Uribe-López
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
| | - Jessica Trujillo-Barrientos
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
| | - Juan Campos-Guillén
- Faculty of Chemistry, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76320, Mexico; (J.C.-G.); (J.L.C.-S.)
| | - Jorge Luis Chávez-Servín
- Faculty of Chemistry, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76320, Mexico; (J.C.-G.); (J.L.C.-S.)
| | - Teresa García-Gasca
- Molecular Biology Laboratory, Facultad de Ciencias Naturales, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76230, Mexico;
| | - Carlos Saldaña
- Membrane Biophysics and Nanotechnology Laboratory, Natural Sciences Faculty, Autonomous University of Quéretaro, Av. De las Ciencias S/N, Juriquilla, Querétaro 76220, Mexico; (C.M.-V.); (V.M.-T.); (A.C.-V.); (J.U.-L.); (J.T.-B.)
- National Laboratory for Advanced Scientific Visualization (LAVIS-FCN-UAQ), Querétaro 76230, Mexico
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2
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Carratalá JV, Ferrer‐Miralles N, Garcia‐Fruitós E, Arís A. LysJEP8: A promising novel endolysin for combating multidrug-resistant Gram-negative bacteria. Microb Biotechnol 2024; 17:e14483. [PMID: 38864495 PMCID: PMC11167605 DOI: 10.1111/1751-7915.14483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 05/03/2024] [Accepted: 05/08/2024] [Indexed: 06/13/2024] Open
Abstract
Antimicrobial resistance (AMR) is an escalating global health crisis, driven by the overuse and misuse of antibiotics. Multidrug-resistant Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, are particularly concerning due to their high morbidity and mortality rates. In this context, endolysins, derived from bacteriophages, offer a promising alternative to traditional antibiotics. This study introduces LysJEP8, a novel endolysin derived from Escherichia phage JEP8, which exhibits remarkable antimicrobial activity against key Gram-negative members of the ESKAPE group. Comparative assessments highlight LysJEP8's superior performance in reducing bacterial survival rates compared to previously described endolysins, with the most significant impact observed against P. aeruginosa, and notable effects on A. baumannii and K. pneumoniae. The study found that LysJEP8, as predicted by in silico analysis, worked best at lower pH values but lost its effectiveness at salt concentrations close to physiological levels. Importantly, LysJEP8 exhibited remarkable efficacy in the disruption of P. aeruginosa biofilms. This research underscores the potential of LysJEP8 as a valuable candidate for the development of innovative antibacterial agents, particularly against Gram-negative pathogens, and highlights opportunities for further engineering and optimization to address AMR effectively.
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Affiliation(s)
- Jose Vicente Carratalá
- Institute of Biotechnology and BiomedicineAutonomous University of BarcelonaBarcelonaSpain
- Department of Genetics and MicrobiologyAutonomous University of BarcelonaBarcelonaSpain
- Department of Ruminant ProductionInstitute of Agriculture and Agrifood Research and Technology (IRTA)BarcelonaSpain
- Bioengineering, Biomaterials and Nanomedicine Networking Biomedical Research Centre (CIBER‐BBN)MadridSpain
| | - Neus Ferrer‐Miralles
- Institute of Biotechnology and BiomedicineAutonomous University of BarcelonaBarcelonaSpain
- Department of Genetics and MicrobiologyAutonomous University of BarcelonaBarcelonaSpain
- Bioengineering, Biomaterials and Nanomedicine Networking Biomedical Research Centre (CIBER‐BBN)MadridSpain
| | - Elena Garcia‐Fruitós
- Department of Ruminant ProductionInstitute of Agriculture and Agrifood Research and Technology (IRTA)BarcelonaSpain
| | - Anna Arís
- Department of Ruminant ProductionInstitute of Agriculture and Agrifood Research and Technology (IRTA)BarcelonaSpain
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Jia J, Zhu L, Yue X, Tang S, Jing S, Tan C, Du Y, Gao J, Lee I, Qian Y. Crosstalk between KDEL receptor and EGF receptor mediates cell proliferation and migration via STAT3 signaling. Cell Commun Signal 2024; 22:140. [PMID: 38378560 PMCID: PMC10880305 DOI: 10.1186/s12964-024-01517-w] [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: 09/05/2023] [Accepted: 02/07/2024] [Indexed: 02/22/2024] Open
Abstract
Hostile microenvironment of cancer cells provoke a stressful condition for endoplasmic reticulum (ER) and stimulate the expression and secretion of ER chaperones, leading to tumorigenic effects. However, the molecular mechanism underlying these effects is largely unknown. In this study, we reveal that the last four residues of ER chaperones, which are recognized by KDEL receptor (KDELR), is required for cell proliferation and migration induced by secreted chaperones. By combining proximity-based mass spectrometry analysis, split venus imaging and membrane yeast two hybrid assay, we present that EGF receptor (EGFR) may be a co-receptor for KDELR on the surface. Prior to ligand addition, KDELR spontaneously oligomerizes and constantly undergoes recycling near the plasma membrane. Upon KDEL ligand binding, the interactions of KDELR with itself and with EGFR increase rapidly, leading to augmented internalization of KDELR and tyrosine phosphorylation in the C-terminus of EGFR. STAT3, which binds the phosphorylated tyrosine motif on EGFR, is subsequently activated by EGFR and mediates cell growth and migration. Taken together, our results suggest that KDELR serves as a bona fide cell surface receptor for secreted ER chaperones and transactivates EGFR-STAT3 signaling pathway.
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Affiliation(s)
- Jie Jia
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Lianhui Zhu
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Xihua Yue
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Shuocheng Tang
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Shuaiyang Jing
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
- Present address: Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Chuanting Tan
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Yulei Du
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Jingkai Gao
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China
| | - Intaek Lee
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China.
| | - Yi Qian
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai, China.
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KDEL Receptors: Pathophysiological Functions, Therapeutic Options, and Biotechnological Opportunities. Biomedicines 2022; 10:biomedicines10061234. [PMID: 35740256 PMCID: PMC9220330 DOI: 10.3390/biomedicines10061234] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 02/07/2023] Open
Abstract
KDEL receptors (KDELRs) are ubiquitous seven-transmembrane domain proteins encoded by three mammalian genes. They bind to and retro-transport endoplasmic reticulum (ER)-resident proteins with a C-terminal Lys-Asp-Glu-Leu (KDEL) sequence or variants thereof. In doing this, KDELR participates in the ER quality control of newly synthesized proteins and the unfolded protein response. The binding of KDEL proteins to KDELR initiates signaling cascades involving three alpha subunits of heterotrimeric G proteins, Src family kinases, protein kinases A (PKAs), and mitogen-activated protein kinases (MAPKs). These signaling pathways coordinate membrane trafficking flows between secretory compartments and control the degradation of the extracellular matrix (ECM), an important step in cancer progression. Considering the basic cellular functions performed by KDELRs, their association with various diseases is not surprising. KDELR mutants unable to bind the collagen-specific chaperon heat-shock protein 47 (HSP47) cause the osteogenesis imperfecta. Moreover, the overexpression of KDELRs appears to be linked to neurodegenerative diseases that share pathological ER-stress and activation of the unfolded protein response (UPR). Even immune function requires a functional KDELR1, as its mutants reduce the number of T lymphocytes and impair antiviral immunity. Several studies have also brought to light the exploitation of the shuttle activity of KDELR during the intoxication and maturation/exit of viral particles. Based on the above, KDELRs can be considered potential targets for the development of novel therapeutic strategies for a variety of diseases involving proteostasis disruption, cancer progression, and infectious disease. However, no drugs targeting KDELR functions are available to date; rather, KDELR has been leveraged to deliver drugs efficiently into cells or improve antigen presentation.
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Expression of the K74 Killer Toxin from Saccharomyces paradoxus Is Modulated by the Toxin-Encoding M74 Double-Stranded RNA 5' Untranslated Terminal Region. Appl Environ Microbiol 2022; 88:e0203021. [PMID: 35389250 DOI: 10.1128/aem.02030-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Yeast killer toxins are widely distributed in nature, conferring a competitive advantage to the producer yeasts over nonkiller ones when nutrients are scarce. Most of these toxins are encoded on double-stranded RNAs (dsRNAs) generically called M. L-A members of the viral family Totiviridae act as helper viruses to maintain M, providing the virion proteins that separately encapsidate and replicate L-A and M genomes. M genomes are organized in three regions, a 5' region coding the preprotoxin, followed by an internal poly(A) stretch and a 3' noncoding region. In this work, we report the characterization of K74 toxin encoded on M74 dsRNA from Saccharomyces paradoxus Q74.4. In M74, there is a 5' upstream sequence of 141 nucleotides (nt), which contains regulatory signals for internal translation of the preprotoxin open reading frame (ORF) at the second AUG codon. The first AUG close to the 5' end is not functional. For K74 analysis, M74 viruses were first introduced into laboratory strains of Saccharomyces cerevisiae. We show here that the mature toxin is an α/β heterodimer linked by disulfide bonds. Though the toxin (or preprotoxin) confers immunity to the carrier, cells with increased K74 loads have a sick phenotype that may lead to cell death. Thus, a fine-tuning of K74 production by the upstream regulatory sequence is essential for the host cell to benefit from the toxin it produces and, at the same time, to safely avoid damage by an excess of toxin. IMPORTANCE Killer yeasts produce toxins to which they are immune by mechanisms not well understood. This self-immunity, however, is compromised in certain strains, which secrete an excess of toxin, leading to sick cells or suicidal phenotypes. Thus, a fine-tuning of toxin production has to be achieved to reach a balance between the beneficial effect of toxin production and the stress imposed on the host metabolism. K74 toxin from S. paradoxus is very active against Saccharomyces uvarum, among other yeasts, but an excess of toxin production is deleterious for the host. Here, we report that the presence of a 5' 141-nt upstream sequence downregulates K74 toxin precursor translation, decreasing toxin levels 3- to 5-fold. Thus, this is a special case of translation regulation performed by sequences on the M74 genome itself, which have been presumably incorporated into the viral RNA during evolution for that purpose.
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Li X, Cordat E, Schmitt MJ, Becker B. Boosting endoplasmic reticulum folding capacity reduces unfolded protein response activation and intracellular accumulation of human kidney anion exchanger 1 in Saccharomyces cerevisiae. Yeast 2021; 38:521-534. [PMID: 34033682 DOI: 10.1002/yea.3652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/20/2021] [Accepted: 05/21/2021] [Indexed: 11/09/2022] Open
Abstract
Human kidney anion exchanger 1 (kAE1) facilitates simultaneous efflux of bicarbonate and absorption of chloride at the basolateral membrane of α-intercalated cells. In these cells, kAE1 contributes to systemic acid-base balance along with the proton pump v-H+ -ATPase and the cytosolic carbonic anhydrase II. Recent electron microscopy analyses in yeast demonstrate that heterologous expression of several kAE1 variants causes a massive accumulation of the anion transporter in intracellular membrane structures. Here, we examined the origin of these kAE1 aggregations in more detail. Using various biochemical techniques and advanced light and electron microscopy, we showed that accumulation of kAE1 mainly occurs in endoplasmic reticulum (ER) membranes which eventually leads to strong unfolded protein response (UPR) activation and severe growth defect in kAE1 expressing yeast cells. Furthermore, our data indicate that UPR activation is dose dependent and uncoupled from the bicarbonate transport activity. By using truncated kAE1 variants, we identified the C-terminal region of kAE1 as crucial factor for the increased ER stress level. Finally, a redistribution of ER-localized kAE1 to the cell periphery was achieved by boosting the ER folding capacity. Our findings not only demonstrate a promising strategy for preventing intracellular kAE1 accumulation and improving kAE1 plasma membrane targeting but also highlight the versatility of yeast as model to investigate kAE1-related research questions including the analysis of structural features, protein degradation and trafficking. Furthermore, our approach might be a promising strategy for future analyses to further optimize the cell surface targeting of other disease-related PM proteins, not only in yeast but also in mammalian cells.
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Affiliation(s)
- Xiaobing Li
- Molecular and Cell Biology, Department of Biosciences and Centre of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Manfred J Schmitt
- Molecular and Cell Biology, Department of Biosciences and Centre of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Björn Becker
- Molecular and Cell Biology, Department of Biosciences and Centre of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
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Cell-type-specific differences in KDEL receptor clustering in mammalian cells. PLoS One 2020; 15:e0235864. [PMID: 32645101 PMCID: PMC7347126 DOI: 10.1371/journal.pone.0235864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/23/2020] [Indexed: 12/16/2022] Open
Abstract
In eukaryotic cells, KDEL receptors (KDELRs) facilitate the retrieval of endoplasmic reticulum (ER) luminal proteins from the Golgi compartment back to the ER. Apart from the well-documented retention function, recent findings reveal that the cellular KDELRs have more complex roles, e.g. in cell signalling, protein secretion, cell adhesion and tumorigenesis. Furthermore, several studies suggest that a sub-population of KDELRs is located at the cell surface, where they could form and internalize KDELR/cargo clusters after K/HDEL-ligand binding. However, so far it has been unclear whether there are species- or cell-type-specific differences in KDELR clustering. By comparing ligand-induced KDELR clustering in different mouse and human cell lines via live cell imaging, we show that macrophage cell lines from both species do not develop any clusters. Using RT-qPCR experiments and numerical analysis, we address the role of KDELR expression as well as endocytosis and exocytosis rates on the receptor clustering at the plasma membrane and discuss how the efficiency of directed transport to preferred docking sites on the membrane influences the exponent of the power-law distribution of the cluster size.
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8
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Sheppard S, Dikicioglu D. Dynamic modelling of the killing mechanism of action by virus-infected yeasts. J R Soc Interface 2020; 16:20190064. [PMID: 30890050 DOI: 10.1098/rsif.2019.0064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Killer yeasts are microorganisms, which can produce and secrete proteinaceous toxins, a characteristic gained via infection by a virus. These toxins are able to kill sensitive cells of the same or a related species. From a biotechnological perspective, killer yeasts are beneficial due to their antifungal/antimicrobial activity, but also regarded as problematic for large-scale fermentation processes, whereby those yeasts would kill starter cultures species and lead to stuck fermentations. Here, we propose a mechanistic model of the toxin-binding kinetics pertaining to the killer population coupled with the toxin-induced death kinetics of the sensitive population to study toxic action. The dynamic model captured the transient toxic activity starting from the introduction of killer cells into the culture at the time of inoculation through to induced cell death. The kinetics of K1/K2 activity via its primary pathway of toxicity was 5.5 times faster than its activity at low concentration inducing the apoptotic pathway in sensitive cells. Conversely, we showed that the primary pathway for K28 was approximately three times slower than its equivalent apoptotic pathway, indicating the particular relevance of K28 in biotechnological applications where the toxin concentration is rarely above those limits to trigger the primary pathway of killer activity.
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Affiliation(s)
- Sean Sheppard
- 1 St John's College , St John's Street, Cambridge , UK
| | - Duygu Dikicioglu
- 2 Department of Chemical Engineering and Biotechnology, University of Cambridge , Cambridge , UK
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Gier S, Schmitt MJ, Breinig F. Analysis of Yeast Killer Toxin K1 Precursor Processing via Site-Directed Mutagenesis: Implications for Toxicity and Immunity. mSphere 2020; 5:e00979-19. [PMID: 32051241 PMCID: PMC7021474 DOI: 10.1128/msphere.00979-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 01/29/2020] [Indexed: 11/21/2022] Open
Abstract
K1 represents a heterodimeric A/B toxin secreted by virus-infected Saccharomyces cerevisiae strains. In a two-staged receptor-mediated process, the ionophoric activity of K1 leads to an uncontrolled influx of protons, culminating in the breakdown of the cellular transmembrane potential of sensitive cells. K1 killer yeast necessitate not only an immunity mechanism saving the toxin-producing cell from its own toxin but, additionally, a molecular system inactivating the toxic α subunit within the secretory pathway. In this study, different derivatives of the K1 precursor were constructed to analyze the biological function of particular structural components and their influence on toxin activity as well as the formation of protective immunity. Our data implicate an inactivation of the α subunit during toxin maturation and provide the basis for an updated model of K1 maturation within the host cell's secretory pathway.IMPORTANCE The killer phenotype in the baker's yeast Saccharomyces cerevisiae relies on two double-stranded RNA viruses that are persistently present in the cytoplasm. As they carry the same receptor populations as sensitive cells, killer yeast cells need-in contrast to various bacterial toxin producers-a specialized immunity mechanism. The ionophoric killer toxin K1 leads to the formation of cation-specific pores in the plasma membrane of sensitive yeast cells. Based on the data generated in this study, we were able to update the current model of toxin processing, validating the temporary inactivation of the toxic α subunit during maturation in the secretory pathway of the killer yeast.
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Affiliation(s)
- Stefanie Gier
- Molecular and Cell Biology, Saarland University, Saarbrücken, Germany
- Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Manfred J Schmitt
- Molecular and Cell Biology, Saarland University, Saarbrücken, Germany
- Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Frank Breinig
- Molecular and Cell Biology, Saarland University, Saarbrücken, Germany
- Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
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Saccharomyces cerevisiae: First Steps to a Suitable Model System To Study the Function and Intracellular Transport of Human Kidney Anion Exchanger 1. mSphere 2020; 5:5/1/e00802-19. [PMID: 31996424 PMCID: PMC6992373 DOI: 10.1128/msphere.00802-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Distal renal tubular acidosis (dRTA) is a common kidney dysfunction characterized by impaired acid secretion via urine. Previous studies revealed that α-intercalated cells of dRTA patients express mutated forms of human kidney anion exchanger 1 (kAE1) which result in inefficient plasma membrane targeting or diminished expression levels of kAE1. However, the precise dRTA-causing processes are inadequately understood, and alternative model systems are helpful tools to address kAE1-related questions in a fast and inexpensive way. In contrast to a previous study, we successfully expressed full-length kAE1 in Saccharomyces cerevisiae. Using advanced microscopy techniques as well as different biochemical and functionality assays, plasma membrane localization and biological activity were confirmed for the heterologously expressed anion transporter. These findings represent first important steps to use the potential of yeast as a model organism for studying trafficking, activity, and degradation of kAE1 and its mutant variants in the future. Saccharomyces cerevisiae has been frequently used to study biogenesis, functionality, and intracellular transport of various renal proteins, including ion channels, solute transporters, and aquaporins. Specific mutations in genes encoding most of these renal proteins affect kidney function in such a way that various disease phenotypes ultimately occur. In this context, human kidney anion exchanger 1 (kAE1) represents an important bicarbonate/chloride exchanger which maintains the acid-base homeostasis in the human body. Malfunctions in kAE1 lead to a pathological phenotype known as distal renal tubular acidosis (dRTA). Here, we evaluated the potential of baker's yeast as a model system to investigate different cellular aspects of kAE1 physiology. For the first time, we successfully expressed yeast codon-optimized full-length versions of tagged and untagged wild-type kAE1 and demonstrated their partial localization at the yeast plasma membrane (PM). Finally, pH and chloride measurements further suggest biological activity of full-length kAE1, emphasizing the potential of S. cerevisiae as a model system for studying trafficking, activity, and/or degradation of mammalian ion channels and transporters such as kAE1 in the future. IMPORTANCE Distal renal tubular acidosis (dRTA) is a common kidney dysfunction characterized by impaired acid secretion via urine. Previous studies revealed that α-intercalated cells of dRTA patients express mutated forms of human kidney anion exchanger 1 (kAE1) which result in inefficient plasma membrane targeting or diminished expression levels of kAE1. However, the precise dRTA-causing processes are inadequately understood, and alternative model systems are helpful tools to address kAE1-related questions in a fast and inexpensive way. In contrast to a previous study, we successfully expressed full-length kAE1 in Saccharomyces cerevisiae. Using advanced microscopy techniques as well as different biochemical and functionality assays, plasma membrane localization and biological activity were confirmed for the heterologously expressed anion transporter. These findings represent first important steps to use the potential of yeast as a model organism for studying trafficking, activity, and degradation of kAE1 and its mutant variants in the future.
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Substitution of cysteines in the yeast viral killer toxin K1 precursor reveals novel insights in heterodimer formation and immunity. Sci Rep 2019; 9:13127. [PMID: 31511600 PMCID: PMC6739482 DOI: 10.1038/s41598-019-49621-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 08/28/2019] [Indexed: 02/07/2023] Open
Abstract
The killer toxin K1 is a virally encoded fungal A/B toxin acting by disrupting plasma membrane integrity. The connection of α and β constitutes a critical feature for toxin biology and for decades the formation of three disulphide bonds linking the major toxin subunits was accepted as status quo. Due to the absence of experimental evidence, the involvement of each cysteine in heterodimer formation, K1 lethality and immunity was systematically analysed. Substitution of any cysteine in α led to a complete loss of toxin dimer secretion and toxicity, whereas K1 toxin derivatives carrying mutations of C248, C312 or the double mutation C248-312 were active against spheroplasted cells. Importantly, substitution of the C95 and C107 in the toxin precursor completely abolished the mediation of functional immunity. In contrast, K1 toxicity, i.e. its ionophoric effect, does not depend on the cysteine residues at all. In contrast to the literature, our data imply the formation of a single disulphide bond involving C92 in α and C239 in β. This finding not only refines the current model stated for decades but also provides new opportunities to elucidate the mechanisms underlying K1 toxicity and immunity at the molecular level.
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Blum A, Khalifa S, Nordström K, Simon M, Schulz MH, Schmitt MJ. Transcriptomics of a KDELR1 knockout cell line reveals modulated cell adhesion properties. Sci Rep 2019; 9:10611. [PMID: 31337861 PMCID: PMC6650600 DOI: 10.1038/s41598-019-47027-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/05/2019] [Indexed: 11/10/2022] Open
Abstract
KDEL receptors (KDELRs) represent transmembrane proteins of the secretory pathway which regulate the retention of soluble ER-residents as well as retrograde and anterograde vesicle trafficking. In addition, KDELRs are involved in the regulation of cellular stress response and ECM degradation. For a deeper insight into KDELR1 specific functions, we characterised a KDELR1-KO cell line (HAP1) through whole transcriptome analysis by comparing KDELR1-KO cells with its respective HAP1 wild-type. Our data indicate more than 300 significantly and differentially expressed genes whose gene products are mainly involved in developmental processes such as cell adhesion and ECM composition, pointing out to severe cellular disorders due to a loss of KDELR1. Impaired adhesion capacity of KDELR1-KO cells was further demonstrated through in vitro adhesion assays, while collagen- and/or laminin-coating nearly doubled the adhesion property of KDELR1-KO cells compared to wild-type, confirming a transcriptional adaptation to improve or restore the cellular adhesion capability. Perturbations within the secretory pathway were verified by an increased secretion of ER-resident PDI and decreased cell viability under ER stress conditions, suggesting KDELR1-KO cells to be severely impaired in maintaining cellular homeostasis.
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Affiliation(s)
- Andrea Blum
- Molecular and Cell Biology, Department of Biosciences (FR 8.3) and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123, Saarbrücken, Germany.
| | - Saleem Khalifa
- Cluster of Excellence, Multimodal Computing and Interaction, Saarland University and Department for Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, Saarbrücken, Germany
| | - Karl Nordström
- Genetics/Epigenetics, Center for Human and Molecular Biology, Saarland University, Saarbrücken, Germany
| | - Martin Simon
- Molecular Cell Biology and Microbiology, Wuppertal University, D-42097, Wuppertal, Germany
| | - Marcel H Schulz
- Cluster of Excellence, Multimodal Computing and Interaction, Saarland University and Department for Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, Saarbrücken, Germany.,Institute for Cardiovascular Regeneration, Goethe University Frankfurt, 60590 Frankfurt am Main, Frankfurt, Germany
| | - Manfred J Schmitt
- Molecular and Cell Biology, Department of Biosciences (FR 8.3) and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123, Saarbrücken, Germany.
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13
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Gier S, Simon M, Nordström K, Khalifa S, Schulz MH, Schmitt MJ, Breinig F. Transcriptome Kinetics of Saccharomyces cerevisiae in Response to Viral Killer Toxin K1. Front Microbiol 2019; 10:1102. [PMID: 31156606 PMCID: PMC6531845 DOI: 10.3389/fmicb.2019.01102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/30/2019] [Indexed: 11/29/2022] Open
Abstract
The K1 A/B toxin secreted by virus-infected Saccharomyces cerevisiae strains kills sensitive cells via disturbance of cytoplasmic membrane functions. Despite decades of research, the mechanisms underlying K1 toxicity and immunity have not been elucidated yet. In a novel approach, this study aimed to characterize transcriptome changes in K1-treated sensitive yeast cells in a time-dependent manner. Global transcriptional profiling revealed substantial cellular adaptations in target cells resulting in 1,189 differentially expressed genes in total. Killer toxin K1 induced oxidative, cell wall and hyperosmotic stress responses as well as rapid down-regulation of transcription and translation. Essential pathways regulating energy metabolism were also significantly affected by the toxin. Remarkably, a futile cycle of the osmolytes trehalose and glycogen was identified probably representing a critical feature of K1 intoxication. In silico analysis suggested several transcription factors involved in toxin-triggered signal transduction. The identified transcriptome changes provide valuable hints to illuminate the still unknown molecular events leading to K1 toxicity and immunity implicating an evolutionarily conserved response at least initially counteracting ionophoric toxin action.
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Affiliation(s)
- Stefanie Gier
- Department of Molecular and Cell Biology, Saarland University, Saarbrücken, Germany.,Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Martin Simon
- Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany.,Molecular Cell Biology and Microbiology, University of Wuppertal, Wuppertal, Germany.,Molecular Cell Dynamics, Saarland University, Saarbrücken, Germany
| | - Karl Nordström
- Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany.,Department of Genetics/Epigenetics, Saarland University, Saarbrücken, Germany
| | - Salem Khalifa
- Cluster of Excellence "Multimodal Computing and Interaction", Max Planck Institute for Informatics, Saarland University, Saarbrücken, Germany
| | - Marcel H Schulz
- Cluster of Excellence "Multimodal Computing and Interaction", Max Planck Institute for Informatics, Saarland University, Saarbrücken, Germany
| | - Manfred J Schmitt
- Department of Molecular and Cell Biology, Saarland University, Saarbrücken, Germany.,Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Frank Breinig
- Department of Molecular and Cell Biology, Saarland University, Saarbrücken, Germany.,Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
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14
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Khan ES, Sankaran S, Paez JI, Muth C, Han MKL, del Campo A. Photoactivatable Hsp47: A Tool to Regulate Collagen Secretion and Assembly. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801982. [PMID: 31065523 PMCID: PMC6498102 DOI: 10.1002/advs.201801982] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 02/13/2019] [Indexed: 06/09/2023]
Abstract
Collagen is the most abundant structural protein in mammals and is crucial for the mechanical integrity of tissues. Hsp47, an endoplasmic reticulum resident collagen-specific chaperone, is involved in collagen biosynthesis and plays a fundamental role in the folding, stability, and intracellular transport of procollagen triple helices. This work reports on a photoactivatable derivative of Hsp47 that allows regulation of collagen biosynthesis within mammalian cells using light. Photoactivatable Hsp47 contains a non-natural light-responsive tyrosine (o-nitro benzyl tyrosine (ONBY)) at Tyr383 position of the protein sequence. This mutation renders Hsp47 inactive toward collagen binding. The inactive, photoactivatable protein is easily uptaken by cells within a few minutes of incubation, and accumulated at the endoplasmic reticulum via retrograde KDEL receptor-mediated uptake. Upon light exposure, the photoactivatable Hsp47 turns into functional Hsp47 in situ. The increased intracellular concentration of Hsp47 results in stimulated secretion of collagen. The ability to promote collagen synthesis on demand, with spatiotemporal resolution, and in diseased state cells is demonstrated in vitro. It is envisioned that photoactivatable Hsp47 allows unprecedented fundamental studies of collagen biosynthesis, matrix biology, and inspires new therapeutic concepts in biomedicine and tissue regeneration.
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Affiliation(s)
- Essak S. Khan
- INM‐Leibniz Institute for New MaterialsCampus D2 2,66123SaarbrückenGermany
- Chemistry DepartmentSaarland University66123SaarbrückenGermany
| | | | - Julieta I. Paez
- INM‐Leibniz Institute for New MaterialsCampus D2 2,66123SaarbrückenGermany
| | - Christina Muth
- INM‐Leibniz Institute for New MaterialsCampus D2 2,66123SaarbrückenGermany
| | - Mitchell K. L. Han
- INM‐Leibniz Institute for New MaterialsCampus D2 2,66123SaarbrückenGermany
| | - Aránzazu del Campo
- INM‐Leibniz Institute for New MaterialsCampus D2 2,66123SaarbrückenGermany
- Chemistry DepartmentSaarland University66123SaarbrückenGermany
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15
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Giesselmann E, Becker B, Schmitt MJ. Production of fluorescent and cytotoxic K28 killer toxin variants through high cell density fermentation of recombinant Pichia pastoris. Microb Cell Fact 2017; 16:228. [PMID: 29258515 PMCID: PMC5735513 DOI: 10.1186/s12934-017-0844-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/13/2017] [Indexed: 01/29/2023] Open
Abstract
Background Virus infected killer strains of the baker’s yeast Saccharomyces cerevisiae secrete protein toxins such as K28, K1, K2 and Klus which are lethal to sensitive yeast strains of the same or related species. K28 is somewhat unique as it represents an α/β heterodimeric protein of the A/B toxin family which, after having bound to the surface of sensitive target cells, is taken up by receptor-mediated endocytosis and transported through the secretory pathway in a retrograde manner. While the current knowledge on yeast killer toxins is largely based on genetic screens for yeast mutants with altered toxin sensitivity, in vivo imaging of cell surface binding and intracellular toxin transport is still largely hampered by a lack of fluorescently labelled and biologically active killer toxin variants. Results In this study, we succeeded for the first time in the heterologous K28 preprotoxin expression and production of fluorescent K28 variants in Pichia pastoris. Recombinant P. pastoris GS115 cells were shown to successfully process and secrete K28 variants fused to mCherry or mTFP by high cell density fermentation. The fluorescent K28 derivatives were obtained in high yield and possessed in vivo toxicity and specificity against sensitive yeast cells. In cell binding studies the resulting K28 variants caused strong fluorescence signals at the cell periphery due to toxin binding to primary K28 receptors within the yeast cell wall. Thereby, the β-subunit of K28 was confirmed to be the sole component required and sufficient for K28 cell wall binding. Conclusion Successful production of fluorescent killer toxin variants of S. cerevisiae by high cell density fermentation of recombinant, K28 expressing strains of P. pastoris now opens the possibility to study and monitor killer toxin cell surface binding, in particular in toxin resistant yeast mutants in which toxin resistance is caused by defects in toxin binding due to alterations in cell wall structure and composition. This novel approach might be easily transferable to other killer toxins from different yeast species and genera. Furthermore, the fluorescent toxin variants described here might likewise represent a powerful tool in future studies to visualize intracellular A/B toxin trafficking with the help of high resolution single molecule imaging techniques.
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Affiliation(s)
- Esther Giesselmann
- Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, 66123, Saarbrücken, Germany
| | - Björn Becker
- Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, 66123, Saarbrücken, Germany
| | - Manfred J Schmitt
- Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, 66123, Saarbrücken, Germany.
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16
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Royal JM, Matoba N. Therapeutic Potential of Cholera Toxin B Subunit for the Treatment of Inflammatory Diseases of the Mucosa. Toxins (Basel) 2017; 9:toxins9120379. [PMID: 29168738 PMCID: PMC5744099 DOI: 10.3390/toxins9120379] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/14/2017] [Accepted: 11/21/2017] [Indexed: 01/03/2023] Open
Abstract
Cholera toxin B subunit (CTB) is a mucosal immunomodulatory protein that induces robust mucosal and systemic antibody responses. This well-known biological activity has been exploited in cholera prevention (as a component of Dukoral® vaccine) and vaccine development for decades. On the other hand, several studies have investigated CTB's immunotherapeutic potential in the treatment of inflammatory diseases such as Crohn's disease and asthma. Furthermore, we recently found that a variant of CTB could induce colon epithelial wound healing in mouse colitis models. This review summarizes the possible mechanisms behind CTB's anti-inflammatory activity and discuss how the protein could impact mucosal inflammatory disease treatment.
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Affiliation(s)
- Joshua M Royal
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
- Center for Predictive Medicine, University of Louisville, Louisville, KY 40202, USA.
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA.
| | - Nobuyuki Matoba
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
- Center for Predictive Medicine, University of Louisville, Louisville, KY 40202, USA.
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA.
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17
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Becker B, Schmitt MJ. Yeast Killer Toxin K28: Biology and Unique Strategy of Host Cell Intoxication and Killing. Toxins (Basel) 2017; 9:toxins9100333. [PMID: 29053588 PMCID: PMC5666379 DOI: 10.3390/toxins9100333] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/12/2017] [Accepted: 10/17/2017] [Indexed: 01/18/2023] Open
Abstract
The initial discovery of killer toxin-secreting brewery strains of Saccharomyces cerevisiae (S. cerevisiae) in the mid-sixties of the last century marked the beginning of intensive research in the yeast virology field. So far, four different S. cerevisiae killer toxins (K28, K1, K2, and Klus), encoded by cytoplasmic inherited double-stranded RNA viruses (dsRNA) of the Totiviridae family, have been identified. Among these, K28 represents the unique example of a yeast viral killer toxin that enters a sensitive cell by receptor-mediated endocytosis to reach its intracellular target(s). This review summarizes and discusses the most recent advances and current knowledge on yeast killer toxin K28, with special emphasis on its endocytosis and intracellular trafficking, pointing towards future directions and open questions in this still timely and fascinating field of killer yeast research.
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Affiliation(s)
- Björn Becker
- Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbrücken, Germany.
| | - Manfred J Schmitt
- Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbrücken, Germany.
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18
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Suzuki Y, Schwartz SL, Mueller NC, Schmitt MJ. Cysteine residues in a yeast viral A/B toxin crucially control host cell killing via pH-triggered disulfide rearrangements. Mol Biol Cell 2017; 28:1123-1131. [PMID: 28228551 PMCID: PMC5391188 DOI: 10.1091/mbc.e16-12-0842] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 11/24/2022] Open
Abstract
K28 is a viral A/B protein toxin that intoxicates yeast and fungal cells by endocytosis and retrograde transport to the endoplasmic reticulum (ER). Although toxin translocation into the cytosol occurs on the oxidized α/β heterodimer, the precise mechanism of how the toxin crosses the ER membrane is unknown. Here we identify pH-triggered, toxin-intrinsic thiol rearrangements that crucially control toxin conformation and host cell killing. In the natural habitat and low-pH environment of toxin-secreting killer yeasts, K28 is structurally stable and biologically active as a disulfide-bonded heterodimer, whereas it forms inactive disulfide-bonded oligomers at neutral pH that are caused by activation and thiol deprotonation of β-subunit cysteines. Because such pH increase reflects the pH gradient during compartmental transport within target cells, potential K28 oligomerization in the ER lumen is prevented by protein disulfide isomerase. In addition, we show that pH-triggered thiol rearrangements in K28 can cause the release of cytotoxic α monomers, suggesting a toxin-intrinsic mechanism of disulfide bond reduction and α/β heterodimer dissociation in the cytosol.
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Affiliation(s)
- Yutaka Suzuki
- Molecular and Cell Biology, Department of Biosciences, and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbruecken, Germany
| | - Sara L Schwartz
- Molecular and Cell Biology, Department of Biosciences, and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbruecken, Germany
| | - Nina C Mueller
- Molecular and Cell Biology, Department of Biosciences, and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbruecken, Germany
| | - Manfred J Schmitt
- Molecular and Cell Biology, Department of Biosciences, and Center of Human and Molecular Biology (ZHMB), Saarland University, D-66123 Saarbruecken, Germany
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19
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Belda I, Ruiz J, Alonso A, Marquina D, Santos A. The Biology of Pichia membranifaciens Killer Toxins. Toxins (Basel) 2017; 9:toxins9040112. [PMID: 28333108 PMCID: PMC5408186 DOI: 10.3390/toxins9040112] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/07/2017] [Accepted: 03/20/2017] [Indexed: 02/07/2023] Open
Abstract
The killer phenomenon is defined as the ability of some yeast to secrete toxins that are lethal to other sensitive yeasts and filamentous fungi. Since the discovery of strains of Saccharomyces cerevisiae capable of secreting killer toxins, much information has been gained regarding killer toxins and this fact has substantially contributed knowledge on fundamental aspects of cell biology and yeast genetics. The killer phenomenon has been studied in Pichia membranifaciens for several years, during which two toxins have been described. PMKT and PMKT2 are proteins of low molecular mass that bind to primary receptors located in the cell wall structure of sensitive yeast cells, linear (1→6)-β-d-glucans and mannoproteins for PMKT and PMKT2, respectively. Cwp2p also acts as a secondary receptor for PMKT. Killing of sensitive cells by PMKT is characterized by ionic movements across plasma membrane and an acidification of the intracellular pH triggering an activation of the High Osmolarity Glycerol (HOG) pathway. On the contrary, our investigations showed a mechanism of killing in which cells are arrested at an early S-phase by high concentrations of PMKT2. However, we concluded that induced mortality at low PMKT2 doses and also PMKT is indeed of an apoptotic nature. Killer yeasts and their toxins have found potential applications in several fields: in food and beverage production, as biocontrol agents, in yeast bio-typing, and as novel antimycotic agents. Accordingly, several applications have been found for P. membranifaciens killer toxins, ranging from pre- and post-harvest biocontrol of plant pathogens to applications during wine fermentation and ageing (inhibition of Botrytis cinerea, Brettanomyces bruxellensis, etc.).
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Affiliation(s)
- Ignacio Belda
- Department of Microbiology, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Javier Ruiz
- Department of Microbiology, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Alejandro Alonso
- Department of Microbiology, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Domingo Marquina
- Department of Microbiology, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Antonio Santos
- Department of Microbiology, Biology Faculty, Complutense University of Madrid, 28040 Madrid, Spain.
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