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Gupta LK, Molla J, Prabhu AA. Story of Pore-Forming Proteins from Deadly Disease-Causing Agents to Modern Applications with Evolutionary Significance. Mol Biotechnol 2023:10.1007/s12033-023-00776-1. [PMID: 37294530 DOI: 10.1007/s12033-023-00776-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 05/21/2023] [Indexed: 06/10/2023]
Abstract
Animal venoms are a complex mixture of highly specialized toxic molecules. Among them, pore-forming proteins (PFPs) or toxins (PFTs) are one of the major disease-causing toxic elements. The ability of the PFPs in defense and toxicity through pore formation on the host cell surface makes them unique among the toxin proteins. These features made them attractive for academic and research purposes for years in the areas of microbiology as well as structural biology. All the PFPs share a common mechanism of action for the attack of host cells and pore formation in which the selected pore-forming motifs of the host cell membrane-bound protein molecules drive to the lipid bilayer of the cell membrane and eventually produces water-filled pores. But surprisingly their sequence similarity is very poor. Their existence can be seen both in a soluble state and also in transmembrane complexes in the cell membrane. PFPs are prevalent toxic factors that are predominately produced by all kingdoms of life such as virulence bacteria, nematodes, fungi, protozoan parasites, frogs, plants, and also from higher organisms. Nowadays, multiple approaches to applications of PFPs have been conducted by researchers both in basic as well as applied biological research. Although PFPs are very devastating for human health nowadays researchers have been successful in making these toxic proteins into therapeutics through the preparation of immunotoxins. We have discussed the structural, and functional mechanism of action, evolutionary significance through dendrogram, domain organization, and practical applications for various approaches. This review aims to emphasize the PFTs to summarize toxic proteins together for basic knowledge as well as to highlight the current challenges, and literature gap along with the perspective of promising biotechnological applications for their future research.
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Affiliation(s)
- Laxmi Kumari Gupta
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Johiruddin Molla
- Ghatal Rabindra Satabarsiki Mahavidyalaya Ghatal, Paschim Medinipur, Ghatal, West Bengal, 721212, India
| | - Ashish A Prabhu
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
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2
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Bian X, Si Z, Wang Q, Liu L, Shi Z, Tian C, Lee W, Zhang Y. IgG Fc-binding protein positively regulates the assembly of pore-forming protein complex βγ-CAT evolved to drive cell vesicular delivery and transport. J Biol Chem 2023; 299:104717. [PMID: 37068610 DOI: 10.1016/j.jbc.2023.104717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 04/19/2023] Open
Abstract
Cell membranes form barriers for molecule exchange between the cytosol and the extracellular environments. βγ-CAT, a complex of pore-forming protein (PFP) BmALP1 (two βγ-crystallin domains with an aerolysin pore-forming domain) and the trefoil factor BmTFF3, has been identified in toad Bombina maxima. It plays pivotal roles, via inducing channel formation in various intra- or extra- cellular vesicles, as well as in nutrient acquisition, maintaining water balance, and antigen presentation. Thus, such a protein machine should be tightly regulated. Indeed, BmALP3 (a paralog of BmALP1) oxidizes BmALP1 to form a water-soluble polymer, leading to dissociation of the βγ-CAT complex and loss of biological activity. Here, we found that the B. maxima IgG Fc-binding protein (FCGBP), a well-conserved vertebrate mucin-like protein with unknown functions, acted as a positive regulator for βγ-CAT complex assembly. The interactions among FCGBP, BmALP1, and BmTFF3 were revealed by co-immunoprecipitation assays. Interestingly, FCGBP reversed the inhibitory effect of BmALP3 on the βγ-CAT complex. Furthermore, FCGBP reduced BmALP1 polymers and facilitated the assembly of βγ-CAT with the biological pore-forming activity in the presence of BmTFF3. Our findings define the role of FCGBP in mediating the assembly of a PFP machine evolved to drive cell vesicular delivery and transport.
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Affiliation(s)
- Xianling Bian
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, China; Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Ziru Si
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, China; Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Qiquan Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China; Human Aging Research Institute (HARI) and School of Life Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
| | - Lingzhen Liu
- Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Zhihong Shi
- Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Changlin Tian
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, China.
| | - Wenhui Lee
- Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
| | - Yun Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of The Chinese Academy of Sciences/Engineering Laboratory of Peptides of the Chinese Academy of Sciences, Institute of Zoology, the Chinese Academy of Sciences, Kunming, Yunnan 650201, China; Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
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3
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Morris AK, Perera RS, Sahu ID, Lorigan GA. Topological examination of the bacteriophage lambda S holin by EPR spectroscopy. Biochim Biophys Acta Biomembr 2023; 1865:184083. [PMID: 36370910 PMCID: PMC9771973 DOI: 10.1016/j.bbamem.2022.184083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/26/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022]
Abstract
The S protein from bacteriophage lambda is a three-helix transmembrane protein produced by the prophage which accumulates in the host membrane during late gene expression. It is responsible for the first step in lysing the host cell at the end of the viral life cycle by multimerizing together to form large pores which permeabilize the host membrane to allow the escape of virions. Several previous studies have established a model for the assembly of holin into functional holes and the manner in which they pack together, but it is still not fully understood how the very rapid transition from monomer or dimer to multimeric pore occurs with such precise timing once the requisite threshold is reached. Here, site-directed spin labeling with a nitroxide label at introduced cysteine residues is used to corroborate existing topological data from a crosslinking study of the multimerized holin by EPR spectroscopy. CW-EPR spectral lineshape analysis and power saturation data are consistent with a three-helix topology with an unstructured C-terminal domain, as well as at least one interface on transmembrane domain 1 which is exposed to the lumen of the hole, and a highly constrained steric environment suggestive of a tight helical packing interface at transmembrane domain 2.
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Affiliation(s)
- Andrew K Morris
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
| | - Rehani S Perera
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA.
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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Hervis YP, Valle A, Canet L, Rodríguez A, Lanio ME, Alvarez C, Steinhoff HJ, Pazos IF. Cys mutants as tools to study the oligomerization of the pore-forming toxin sticholysin I. Toxicon 2023; 222:106994. [PMID: 36529153 DOI: 10.1016/j.toxicon.2022.106994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022]
Abstract
Sticholysin I (StI) is a water-soluble protein with the ability to bind membranes where it oligomerizes and forms pores leading to cell death. Understanding the assembly property of this protein may be valuable for designing potential biotechnological tools, such as stable or structurally defined nanopores. In order to get insights into the stabilization of StI oligomers by disulfide bonds, we designed and characterized single and double cysteine mutants at the oligomerization interface. The oligomer formation was induced in the presence of lipid membranes and visualized by SDS-PAGE. The contribution of the oligomeric structures to the membrane binding and pore-forming capacities of StI was assessed. Single and double cysteine introduction at the protein-protein oligomerization interface does not considerably affect the conformation and function of the monomeric protein. In the presence of membranes, a cysteine double mutation at positions 15 and 59 favored formation of different size oligomers stabilized by disulfide bonds. The results of this work highlight the relevance of these positions (15 and 59) to be considered for developing biosensors based on nanopores from StI.
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Affiliation(s)
- Yadira P Hervis
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
| | - Aisel Valle
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
| | - Liem Canet
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
| | | | - Maria E Lanio
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
| | - Carlos Alvarez
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
| | - Heinz J Steinhoff
- Department of Physics, University of Osnabrueck, Osnabrueck, 49069, Germany.
| | - Isabel F Pazos
- Center for Protein Studies/Department of Biochemistry, Faculty of Biology, University of Havana, Havana, ZIP 10400, Cuba.
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5
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Wang K, Ding J, Shao F. Determination of Gasdermin Pores. Methods Mol Biol 2023; 2696:149-167. [PMID: 37578722 DOI: 10.1007/978-1-0716-3350-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The gasdermin family represents a type of membrane pore-forming proteins. The gasdermin family is extensively characterized as the executioner of pyroptotic cell death in mammals; recent studies suggest that gasdermin-like pore-forming proteins are also present in bacteria and fungi. In humans, gasdermin D (GSDMD) is activated through inter-domain cleavage by caspase-1 in the canonical inflammasome pathway and cytosolic LPS-activated caspase-4 or caspase-5. The cleavage disrupts the autoinhibition of GSDMD and liberates the N-terminal gasdermin-N domain that binds to membrane lipids and forms pores of an inner diameter of ~18 nm on the membrane, responsible for cell pyroptosis. Here, we describe the methods of determining the phospholipid-binding and pore-forming activity of gasdermins in a robust in vitro system. We also introduce a method of specifically detecting the caspase-cleaved form of GSDMD in pyroptotic cells.
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Affiliation(s)
- Kun Wang
- National Institute of Biological Sciences, Beijing, China
| | - Jingjin Ding
- National Institute of Biological Sciences, Beijing, China
| | - Feng Shao
- National Institute of Biological Sciences, Beijing, China.
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6
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Heuck AP, Brovedan MA. Evolutionary Conservation, Variability, and Adaptation of Type III Secretion Systems. J Membr Biol 2022. [PMID: 35695900 DOI: 10.1007/s00232-022-00247-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 05/20/2022] [Indexed: 10/18/2022]
Abstract
Type III secretion (T3S) systems are complex bacterial structures used by many pathogens to inject proteins directly into the cytosol of the host cell. These secretion machines evolved from the bacterial flagella and they have been grouped into families by phylogenetic analysis. The T3S system is composed of more than 20 proteins grouped into five complexes: the cytosolic platform, the export apparatus, the basal body, the needle, and the translocon complex. While the proteins located inside the bacterium are conserved, those exposed to the external media present high variability among families. This suggests that the T3S systems have adapted to interact with different cells or tissues in the host, and/or have been subjected to the evolutionary pressure of the host immune defenses. Such adaptation led to changes in the sequence of the T3S needle tip and translocon suggesting differences in the mechanism of assembly and structure of this complex.
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Mu M, Yu Q, Zhang Q, Guo J, Wang X, Sun X, Yu J. A pan-cancer analysis of molecular characteristics and oncogenic role of gasdermins. Cancer Cell Int 2022; 22:80. [PMID: 35164740 PMCID: PMC8842873 DOI: 10.1186/s12935-022-02483-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/22/2022] [Indexed: 12/16/2022] Open
Abstract
Background The gasdermins (GSDMs) family is proposed to be pore-forming effector proteins that cause cell membrane permeabilization and pyroptosis. Despite our increasing knowledge of GSDMD, GSDME and GSDMB, the biological functions and the regulation of GSDM expression and activation remain elusive for most GSDMs. In this study, we analyzed the molecular characteristics and oncogenic role of GSDM family genes systematically. Methods TCGA, CCLE, cBioPortal, GEPIA, CellMiner and BioGRID databases were utilized in this study. Immunohistochemical analysis and a series of in vitro experiments were conducted. Results We found that, in cancer, GSDM genes and their expressions extensively changed, which were associated with patient survival. The expression of GSDMs was widely associated with cancer-related pathways, drug resistance, immune subtypes, tumor microenvironment and cancer cell stemness. However, an intra- and inter-cancer heterogeneity was discovered regarding the corresponding GSDM gene. We found that GSDMA and GSDMB regulated drug resistance to the opposite direction of GSDME. In colorectal cancer, GSDME might be a positive regulator in cell invasion and metastasis through cell migration and angiogenesis, while GSDMA, GSDMB and GSDMD might be a negatively regulator of cell migration. Conclusions GSDM family genes might play important roles in cancer other than pyroptosis. We suggest more efforts be made to investigate the GSDM family and each GSDM gene be studied as an entity in each type of cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s12935-022-02483-4.
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Affiliation(s)
- Mingchao Mu
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Qiaoling Yu
- Department of Pathology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710004, Shaanxi, China
| | - Qin Zhang
- Department of Dermatology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710004, Shaanxi, China
| | - Jing Guo
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Xingjie Wang
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Xuejun Sun
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
| | - Junhui Yu
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
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8
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Hatakeyama T, Kishigawa A, Unno H. Molecular cloning and characterization of the two putative toxins expressed in the venom of the devil stinger Inimicus japonicus. Toxicon 2021; 201:9-20. [PMID: 34391787 DOI: 10.1016/j.toxicon.2021.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 07/10/2021] [Accepted: 08/09/2021] [Indexed: 11/16/2022]
Abstract
Various proteins are involved in fish venom toxicity, but limited information is available regarding their structure and mode of action. Here, we analyzed RNA transcripts in the dorsal spine of the devil stinger Inimicus japonicus using next-generation sequencing (NGS), and identified two putative protein toxins, a natterin-like protein (Ij-natterin) and a phospholipase A2 (Ij-PLA2), as well as a previously reported stonustoxin-like protein. The deduced amino acid sequence of Ij-natterin suggested that it acts as a pore-forming toxin through the cooperation of the N-terminal lectin-like domain and the C-terminal pore-forming domain. Ij-PLA2 showed significant homology with secreted Ca2+-dependent PLA2s from snake venom and mammals (sPLA2-I/II). The recombinant Ij-PLA2 protein exhibited PLA2 activity in the absence of Ca2+, in contrast to canonical sPLA2-I/II. Comparison of the amino acid sequences of Ij-PLA2 with the other sPLA2-I/II suggests that the C-terminal extended peptide region of Ij-PLA2 is involved in its Ca2+-independent activity.
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Affiliation(s)
- Tomomitsu Hatakeyama
- Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki, 852-8521, Japan.
| | - Akihiro Kishigawa
- Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki, 852-8521, Japan
| | - Hideaki Unno
- Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki, 852-8521, Japan; Organization for Marine Science and Technology, Nagasaki University, Bunkyo-machi 1-14, Nagasaki, 852-8521, Japan
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9
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Abstract
Pore-forming proteins (PFPs) of the diverse life forms have emerged as the potent cell-killing entities owing to their specialized membrane-damaging properties. PFPs have the unique ability to perforate the plasma membranes of their target cells, and they exert this functionality by creating oligomeric pores in the membrane lipid bilayer. Pathogenic bacteria employ PFPs as toxins to execute their virulence mechanisms, whereas in the higher vertebrates PFPs are deployed as the part of the immune system and to generate inflammatory responses. PFPs are the unique dimorphic proteins that are generally synthesized as water-soluble molecules, and transform into membrane-inserted oligomeric pore assemblies upon interacting with the target membranes. In spite of sharing very little sequence similarity, PFPs from diverse organisms display incredible structural similarity. Yet, at the same time, structure-function mechanisms of the PFPs document remarkable versatility. Such notions establish PFPs as the fascinating model system to explore variety of unsolved issues pertaining to the structure-function paradigm of the proteins that interact and act in the membrane environment. In this article, we discuss our current understanding regarding the structural basis of the pore-forming functions of the diverse class of PFPs. We attempt to highlight the similarities and differences in their structures, membrane pore-formation mechanisms, and their implications for the various biological processes, ranging from the bacterial virulence mechanisms to the inflammatory immune response generation in the higher animals.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
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Kessenich C, Silvanovich A. Challenges of automation and scale: Bioinformatics and the evaluation of proteins to support genetically modified product safety assessments. J Invertebr Pathol 2021;:107587. [PMID: 33838205 DOI: 10.1016/j.jip.2021.107587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 11/24/2022]
Abstract
Bioinformatic analyses of protein sequences play an important role in the discovery and subsequent safety assessment of insect control proteins in Genetically Modified (GM) crops. Due to the rapid adoption of high-throughput sequencing methods over the last decade, the number of protein sequences in GenBank and other public databases has increased dramatically. Many of these protein sequences are the product of whole genome sequencing efforts, coupled with automated protein sequence prediction and annotation pipelines. Published genome sequencing studies provide a rich and expanding foundation of new source organisms and proteins for insect control or other desirable traits in GM products. However, data generated by automated pipelines can also confound regulatory safety assessments that employ bioinformatics. Largely this issue does not arise due to underlying sequence, but rather its annotation or associated metadata, and the downstream integration of that data into existing repositories. Observations made during bioinformatic safety assessments are described.
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Abstract
Secretory pore-forming proteins (PFPs) have been identified in organisms from all kingdoms of life. Our studies with the toad species Bombina maxima found an interaction network among aerolysin family PFPs (af-PFPs) and trefoil factors (TFFs). As a toad af-PFP, BmALP1 can be reversibly regulated between active and inactive forms, with its paralog BmALP3 acting as a negative regulator. BmALP1 interacts with BmTFF3 to form a cellular active complex called βγ-CAT. This PFP complex is characterized by acting on endocytic pathways and forming pores on endolysosomes, including stimulating cell macropinocytosis. In addition, cell exocytosis can be induced and/or modulated in the presence of βγ-CAT. Depending on cell contexts and surroundings, these effects can facilitate the toad in material uptake and vesicular transport, while maintaining mucosal barrier function as well as immune defense. Based on experimental evidence, we hereby propose a secretory endolysosome channel (SELC) pathway conducted by a secreted PFP in cell endocytic and exocytic systems, with βγ-CAT being the first example of a SELC protein. With essential roles in cell interactions and environmental adaptations, the proposed SELC protein pathway should be conserved in other living organisms.
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Affiliation(s)
- Yun Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, Yunnan 650223, China. E-mail:
| | - Qi-Quan Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Zhong Zhao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Cheng-Jie Deng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
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12
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Abstract
Pore-forming proteins (PFPs) include virulence factors that are produced by many pathogenic bacteria. However, PFPs also comprise non-virulence factors, such as apoptotic Bcl2-like proteins, and also occur in non-pathogenic bacteria and indeed in all kingdoms of life. Pore-forming proteins are an ancient class of proteins, which are tremendously powerful in damaging cell membranes. In general, upon binding to lipid membranes, they convert from the soluble monomeric form into an oligomeric state, and then undergo a dramatic conformational change to form transmembrane pores. Thus, PFPs render the plasma membrane of their target cells permeable to solutes, potentially leading to cell death, or to more subtle manipulations of cellular functions. Recent cryo-EM and X-ray crystallography studies revealed high-resolution structures of several PFPs in their pre-pore and pore states, however many aspects regarding the cues that induce pore formation, the pre-pore to pore conformational transition, the mechanism of membrane permeation and associated dynamics are still less well understood, and direct visualization of the dynamics of these transitions are missing. Using high-speed atomic force microscopy (HS-AFM), the kinetics of oligomerization and the pre-pore to pore transition dynamics of various PFPs, such as Listeriolysin O (LLO), lysenin, and Perforin-2 (PFN2), could be studied. These studies revealed that LLO does not form pores of regular shape or size, but rather forms membrane inserted arcs that propagate and damage lipid membranes as lineactants. In contrast, lysenin forms stable pre-pore and pore nonameric rings and HS-AFM allowed to study their diffusion on and the pH-dependent insertion into the membrane. Similarly, PFN2 underwent pre-pore to pore transition upon acidification. The openness of the HS-AFM system allowed the transition to be imaged in real time and revealed that all observed molecules transitioned into the pore state within 3s. In this chapter, we detail protocols to prepare lipids, form supported lipid bilayers, and provide guidelines for real-time, real-space HS-AFM observations of PFPs in action.
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Zhang Z, Huang B, Zhang XC, Lin J. Cysteine-based crosslinking approach for characterization of oligomeric pore-forming proteins in the mitochondrial membranes. Methods Enzymol 2021; 649:371-396. [PMID: 33712193 DOI: 10.1016/bs.mie.2021.01.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mitochondria are important not only to healthy but also dying cells. In particular, apoptotic cell death initiates when the mitochondrial outer membrane is permeabilized by Bax, a protein of the Bcl-2 family. Bax shares a structural fold with some α-helical bacterial pore-forming toxins before these proteins actively engage membranes. Despite decades of intensive research, the structures of the pores formed by these proteins are mostly unknown, mainly because the pores are assembled by different numbers of the proteins whose conformation and interaction are highly dynamic. Site-specific crosslinking of the pore-forming proteins in cellular membranes where the pores are assembled is a powerful approach to assess the biological pore structure, dynamics and function. In this chapter, we describe a cysteine-based site-specific crosslinking protocol for the Bax protein in the mitochondrial membrane. We discuss the expected results and the resulting structural-functional models for the pore-forming Bax oligomer, in comparison with other crosslinking approaches that have been used to study other mitochondrial protein complexes. At the end, we highlight the advantages of the crosslinking approaches as well as the limitations and alternative approaches.
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Affiliation(s)
- Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Bo Huang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xuejun C Zhang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jialing Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
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14
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Mondal AK, Verma P, Lata K, Singh M, Chatterjee S, Chattopadhyay K. Sequence Diversity in the Pore-Forming Motifs of the Membrane-Damaging Protein Toxins. J Membr Biol 2020; 253:469-478. [PMID: 32955633 DOI: 10.1007/s00232-020-00141-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 09/08/2020] [Indexed: 12/21/2022]
Abstract
Pore-forming proteins/toxins (PFPs/PFTs) are the distinct class of membrane-damaging proteins. They act by forming oligomeric pores in the plasma membranes. PFTs and PFPs from diverse organisms share a common mechanism of action, in which the designated pore-forming motifs of the membrane-bound protein molecules insert into the membrane lipid bilayer to create the water-filled pores. One common characteristic of these pore-forming motifs is that they are amphipathic in nature. In general, the hydrophobic sidechains of the pore-forming motifs face toward the hydrophobic core of the membranes, while the hydrophilic residues create the lining of the water-filled pore lumen. Interestingly, pore-forming motifs of the distinct subclass of PFPs/PFTs share very little sequence similarity with each other. Therefore, the common guiding principle that governs the sequence-to-structure paradigm in the mechanism of action of these PFPs/PFTs still remains an enigma. In this article, we discuss this notion using the examples of diverse groups of membrane-damaging PFPs/PFTs.
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Affiliation(s)
- Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Pratima Verma
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kusum Lata
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Mahendra Singh
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Shamaita Chatterjee
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India.
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15
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Xia S. Biological mechanisms and therapeutic relevance of the gasdermin family. Mol Aspects Med 2020; 76:100890. [PMID: 32800355 DOI: 10.1016/j.mam.2020.100890] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/14/2020] [Accepted: 07/29/2020] [Indexed: 12/18/2022]
Abstract
Innate immunity enables host defense against pathogens and endogenous danger through inflammasomes, which are supramolecular complexes that recognize the threats and activate the immune response. Inflammasome activation often leads to pyroptosis, a highly inflammatory and lytic form of cell death, as a means of killing infected cells and releasing IL-1 family cytokines that communicate with other cells. Dysregulated inflammasome signaling results in a wide range of immune disorders including gout, sepsis, and hepatitis. Discovered as a direct killer molecule in pyroptosis, gasdermin D (GSDMD) is a pore-forming protein that represents a novel family with diverse cellular functions and pathological roles. This review summarizes current opinions in the biological mechanisms and therapeutic values of the GSDM family, particularly of GSDMD. Detailed mechanisms of auto-inhibition and pore formation by the GSDM family are presented, followed by a brief summary of the progress in the development of GSDM-targeting therapeutics.
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Affiliation(s)
- Shiyu Xia
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
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16
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Abstract
The gasdermin (GSDM) family consists of gasdermin A (GSDMA), B (GSDMB), C (GSDMC), D (GSDMD), E or DNFA5 (GSDME), and DFNB59 in human. Expressed in the skin, gastrointestinal tract, and various immune cells, GSDMs mediate homeostasis and inflammation upon activation by caspases and unknown proteases. In particular, GSDMD is activated by inflammasome-activated caspases-1/-4/-5/-11 as well as a caspase-8-mediated pathway during Yersinia infection. These caspases cleave GSDMD to release its functional N-terminal fragment (GSDMD-NT) from its auto-inhibitory C-terminal fragment (GSDMD-CT). GSDMD-NTs bind to acid lipids in mammalian cell membranes and bacterial membranes, oligomerize, and insert into the membranes to form large transmembrane pores. Consequently, cellular contents including inflammatory cytokines are released and cells can undergo pyroptosis, a highly inflammatory form of cell death. In this chapter, we summarize recent research findings and present experimental procedures to obtain pure recombinant GSDMs for biochemical studies. We highlight a liposome-based assay that yields robust fluorescence signals for characterizing GSDM activities in vitro and may be applicable to other pore-forming proteins and ion channels in general.
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Affiliation(s)
- Shiyu Xia
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, United States; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Jianbin Ruan
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, United States; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States.
| | - Hao Wu
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, United States; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States.
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17
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Abstract
Atomic force microscopy (AFM) is a form of contact microscopy that uses a very sharp tip to scan the surface of a sample. It provides a 3D image of the surface structure and in the force mode it can also be used to test the mechanical properties of the sample. AFM has been successfully applied to study the molecular mechanism of pore-forming proteins on model membranes. It gives information about both the structural reorganization of the membrane surface and the changes in the force required for membrane piercing upon incubation with this special type of proteins. Here we describe robust protocols to investigate the effect of pore-forming proteins in supported lipid bilayers .
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Affiliation(s)
- Joseph D Unsay
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
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18
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Tsutsui K, Sato T. Identification of the two new, functional actinoporins, CJTOX I and CJTOX II, from the deep-sea anemone Cribrinopsis japonica. Toxicon 2018; 148:40-49. [PMID: 29649486 DOI: 10.1016/j.toxicon.2018.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/23/2018] [Accepted: 04/05/2018] [Indexed: 11/30/2022]
Abstract
Actinoporins are pore-forming proteins found in sea anemones. Although we now have a large collection of data on actinoporins, our knowledge is based heavily on those identified in shallow-water anemones. Because the deep sea differs considerably from shallow waters in hydrostatic pressures, temperatures, and the prey composition, the deep-sea actinoporin may have evolved in unique ways. This study, therefore, aimed to obtain new actinoporins in the deep-sea anemone Cribrinopis japonica (Actiniaria, Actiniidae). An actinoporin-like sequence was identified from the previously established C. japonica RNA-Seq database, and the complete length (663 bp) of the deep-sea actinoporin gene, Cjtox I, was obtained. In addition, a similar gene, Cjtox II (666 bp), was also identified from RNA of actinopharynx. CJTOX I and CJTOX II were similar in their primary structures, but CJTOX I lacked one residue in the middle of the protein. There was also a difference in the gene expression in live animals, where only Cjtox I was expressed in tentacles of C. japonica. In the heterologous expression where BL21 (DE3) strain was retransformed with the plasmid containing either Cjtox I or Cjtox II gene, the supernatants of both cell lysates showed hemolytic activity on the equine erythrocytes. Preincubation of the supernatants with sphingomyelin caused reduced activity, implying that the CJTOX I and II would target sphingomyelin as with other actinoporins. Because of the structures similarity to the known actinoporins and the sphingomyelin-inhibitable hemolytic activity, both CJTOX I and II were concluded to be new actinoporins, which were identified for the first time from a deep-sea anemone.
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Affiliation(s)
- Kenta Tsutsui
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027, Japan
| | - Tomomi Sato
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027, Japan.
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19
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Butala M, Novak M, Kraševec N, Skočaj M, Veranič P, Maček P, Sepčić K. Aegerolysins: Lipid-binding proteins with versatile functions. Semin Cell Dev Biol 2017; 72:142-151. [PMID: 28506897 DOI: 10.1016/j.semcdb.2017.05.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/13/2017] [Accepted: 05/11/2017] [Indexed: 01/21/2023]
Abstract
Proteins of the aegerolysin family span many kingdoms of life. They are relatively widely distributed in bacteria and fungi, but also appear in plants, protozoa and insects. Despite being produced in abundance in cells at specific developmental stages and present in secretomes, only a few aegerolysins have been studied in detail. In particular, their organism-specific physiological roles are intriguing. Here, we review published findings to date on the distribution, molecular interactions and biological activities of this family of structurally and functionally versatile proteins, the aegerolysins.
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Affiliation(s)
- Matej Butala
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Maruša Novak
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Nada Kraševec
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Matej Skočaj
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Peter Veranič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Peter Maček
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia.
| | - Kristina Sepčić
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia.
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20
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Sha HX, Hwang JS. Identification of a target protein of Hydra actinoporin-like toxin-1 (HALT-1) using GST affinity purification and SILAC-based quantitative proteomics. Toxicon 2017; 133:153-161. [PMID: 28478056 DOI: 10.1016/j.toxicon.2017.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 04/29/2017] [Accepted: 05/02/2017] [Indexed: 11/20/2022]
Abstract
Hydra actinoporin-like toxin-1 (HALT-1) is a 20.8 kDa pore-forming toxin isolated from Hydra magnipapillata. HALT-1 shares structural similarity with actinoporins, a family that is well known for its haemolytic and cytolytic activity. However, the precise pore-forming mechanism of HALT-1 remains an open question since little is known about the specific target binding for HALT-1. For this reason, a comprehensive proteomic analysis was performed using affinity purification and SILAC-based mass spectrometry to identify potential protein-protein interactions between mammalian HeLa cell surface proteins and HALT-1. A total of 4 mammalian proteins was identified, of which only folate receptor alpha was further verified by ELISA. Our preliminary results highlight an alternative-binding mode of HALT-1 to the human plasma membrane. This is the first evidence showing that HALT-1, an actinoporin-like protein, binds to a membrane protein, the folate receptor alpha. This study would advance our understanding of the molecular basis of toxicity of pore-forming toxins and provide new insights in the production of more potent inhibitors for the toxin-membrane receptor interactions.
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Affiliation(s)
- Hong Xi Sha
- Faculty of Applied Sciences, UCSI University, No. 1, Jalan Menara Gading, UCSI Heights Cheras, 56000, Kuala Lumpur, Malaysia.
| | - Jung Shan Hwang
- Sunway Institute for Healthcare Development, Sunway University, No. 5 Jalan Universiti, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia.
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21
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Abstract
Immune cells and skin and mucosal epithelial cells recognize invasive microbes and other signs of danger to sound alarms that recruit responder cells and initiate an immediate "innate" immune response. An especially powerful alarm is triggered by cytosolic sensors of invasive infection that assemble into multimolecular complexes, called inflammasomes, that activate the inflammatory caspases, leading to maturation and secretion of proinflammatory cytokines and pyroptosis, an inflammatory death of the infected cell. Work in the past year has defined the molecular basis of pyroptosis. Activated inflammatory caspases cleave Gasdermin D (GSDMD), a cytosolic protein in immune antigen-presenting cells and epithelia. Cleavage separates the autoinhibitory C-terminal fragment from the active N-terminal fragment, which moves to the cell membrane, binds to lipids on the inside of the cell membrane, and oligomerizes to form membrane pores that disrupt cell membrane integrity, causing death and leakage of small molecules, including the proinflammatory cytokines and GSDMD itself. GSDMD also binds to cardiolipin on bacterial membranes and kills the very bacteria that activate the inflammasome. GSDMD belongs to a family of poorly studied gasdermins, expressed in the skin and mucosa, which can also form membrane pores. Spontaneous mutations that disrupt the binding of the N- and C-terminal domains of other gasdermins are associated with alopecia and asthma. Here, we review recent studies that identified the roles of the inflammasome, inflammatory caspases, and GSDMD in pyroptosis and highlight some of the outstanding questions about their roles in innate immunity, control of infection, and sepsis.
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Affiliation(s)
- Xing Liu
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Judy Lieberman
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.
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22
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Abstract
In the study of regulated cell death, the rapidly expanding field of regulated necrosis, in particular necroptosis, has been drawing much attention. The signaling of necroptosis represents a sophisticated form of a death pathway. Anti-caspase mechanisms (e.g., using inhibitors of caspases, or genetic ablation of caspase-8) switch cell fate from apoptosis to necroptosis. The initial extracellular death signals regulate RIP1 and RIP3 kinase activation. The RIP3-associated death complex assembly is necessary and sufficient to initiate necroptosis. MLKL was initially identified as an essential mediator of RIP1/RIP3 kinase-initiated necroptosis. Recent studies on the signal transduction using chemical tools and biomarkers support the idea that MLKL is able to make more functional sense for the core machinery of the necroptosis death complex, called the necrosome, to connect to the necroptosis execution. The experimental data available now have pointed that the activated MLKL forms membrane-disrupting pores causing membrane leakage, which extends the prototypical concept of morphological and biochemical events following necroptosis happening in vivo. The key role of MLKL in necroptosis signaling thus sheds light on the logic underlying this unique "membrane-explosive" cell death pathway. In this review, we provide the general concepts and strategies that underlie signal transduction of this form of cell death, and then focus specifically on the role of MLKL in necroptosis.
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Affiliation(s)
- Jing Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Rd, Shanghai, 200031, China
| | - Yu Yang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Rd, Shanghai, 200031, China
| | - Wenyan He
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Rd, Shanghai, 200031, China
| | - Liming Sun
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Rd, Shanghai, 200031, China.
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23
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Jerga A, Chen D, Zhang C, Fu J, Kouadio JLK, Wang Y, Duff SMG, Howard JE, Rydel TJ, Evdokimov AG, Ramaseshadri P, Evans A, Bolognesi R, Park Y, Haas JA. Mechanistic insights into the first Lygus-active β-pore forming protein. Arch Biochem Biophys 2016; 600:1-11. [PMID: 27001423 DOI: 10.1016/j.abb.2016.03.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 11/26/2022]
Abstract
The cotton pests Lygus hesperus and Lygus lineolaris can be controlled by expressing Cry51Aa2.834_16 in cotton. Insecticidal activity of pore-forming proteins is generally associated with damage to the midgut epithelium due to pores, and their biological specificity results from a set of key determinants including proteolytic activation and receptor binding. We conducted mechanistic studies to gain insight into how the first Lygus-active β-pore forming protein variant functions. Biophysical characterization revealed that the full-length Cry51Aa2.834_16 was a stable dimer in solution, and when exposed to Lygus saliva or to trypsin, the protein underwent proteolytic cleavage at the C-terminus of each of the subunits, resulting in dissociation of the dimer to two separate monomers. The monomer showed tight binding to a specific protein in Lygus brush border membranes, and also formed a membrane-associated oligomeric complex both in vitro and in vivo. Chemically cross-linking the β-hairpin to the Cry51Aa2.834_16 body rendered the protein inactive, but still competent to compete for binding sites with the native protein in vivo. Our study suggests that disassociation of the Cry51Aa2.834_16 dimer into monomeric units with unoccupied head-region and sterically unhindered β-hairpin is required for brush border membrane binding, oligomerization, and the subsequent steps leading to insect mortality.
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Affiliation(s)
| | | | | | - Jinping Fu
- Department of Entomology, Kansas State University, Manhattan, KS, USA
| | | | | | | | | | | | | | | | | | | | - Yoonseong Park
- Department of Entomology, Kansas State University, Manhattan, KS, USA
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24
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Largo E, Gladue DP, Huarte N, Borca MV, Nieva JL. Pore-forming activity of pestivirus p7 in a minimal model system supports genus-specific viroporin function. Antiviral Res 2013; 101:30-6. [PMID: 24189547 DOI: 10.1016/j.antiviral.2013.10.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/03/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
Viroporins are small integral membrane proteins functional in viral assembly and egress by promoting permeabilization. Blocking of viroporin function therefore constitutes a target for antiviral development. Classical swine fever virus (CSFV) protein p7 has been recently regarded as a class II viroporin. Here, we sought to establish the determinants of the CSFV p7 permeabilizing activity in a minimal model system. Assessment of an overlapping peptide library mapped the porating domain to the C-terminal hydrophobic stretch (residues 39-67). Pore-opening dependence on pH or sensitivity to channel blockers observed for the full protein required the inclusion of a preceding polar sequence (residues 33-38). Effects of lipid composition and structural data further support that the resulting peptide (residues 33-67), may comprise a bona fide surrogate to assay p7 activity in model membranes. Our observations imply that CSFV p7 relies on genus-specific structures-mechanisms to perform its viroporin function.
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Affiliation(s)
- Eneko Largo
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Douglas P Gladue
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA
| | - Nerea Huarte
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Manuel V Borca
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944, USA
| | - José L Nieva
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain.
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