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Dougherty K, Hudak KA. Phylogeny and domain architecture of plant ribosome inactivating proteins. PHYTOCHEMISTRY 2022; 202:113337. [PMID: 35934106 DOI: 10.1016/j.phytochem.2022.113337] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/01/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Ribosome inactivating proteins (RIPs) are rRNA N-glycosylases (EC 3.2.2.22) best known for hydrolyzing an adenine base from the conserved sarcin/ricin loop of ribosomal RNA. Protein translation is inhibited by ribosome depurination; therefore, RIPs are generally considered toxic to cells. The expression of some RIPs is upregulated by biotic and abiotic stress, though the connection between RNA depurination and defense response is not well understood. Despite their prevalence in approximately one-third of flowering plant orders, our knowledge of RIPs stems primarily from biochemical analyses of individuals or genomics-scale analyses of small datasets from a limited number of species. Here, we performed an unbiased search for proteins with RIP domains and identified several-fold more RIPs than previously known - more than 800 from 120 species, many with novel associated domains and physicochemical characteristics. Based on protein domain configuration, we established 15 distinct groups, suggesting diverse functionality. Surprisingly, most of these RIPs lacked a signal peptide, indicating they may be localized to the nucleocytoplasm of cells, raising questions regarding their toxicity against conspecific ribosomes. Our phylogenetic analysis significantly extends previous models for RIP evolution in plants, predicting an original single-domain RIP that later evolved to acquire a signal peptide and different protein domains. We show that RIPs are distributed throughout 21 plant orders with many species maintaining genes for more than one RIP group. Our analyses provide the foundation for further characterization of these new RIP types, to understand how these enzymes function in plants.
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Affiliation(s)
- Kyra Dougherty
- Department of Biology, York University, Toronto, Canada.
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Lu JQ, Wong KB, Shaw PC. A Sixty-Year Research and Development of Trichosanthin, a Ribosome-Inactivating Protein. Toxins (Basel) 2022; 14:178. [PMID: 35324675 PMCID: PMC8950148 DOI: 10.3390/toxins14030178] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 02/04/2023] Open
Abstract
Tian Hua Fen, a herbal powder extract that contains trichosanthin (TCS), was used as an abortifacient in traditional Chinese medicine. In 1972, TCS was purified to alleviate the side effects. Because of its clinical applications, TCS became one of the most active research areas in the 1960s to the 1980s in China. These include obtaining the sequence information in the 1980s and the crystal structure in 1995. The replication block of TCS on human immunodeficiency virus in lymphocytes and macrophages was found in 1989 and started a new chapter of its development. Clinical studies were subsequently conducted. TCS was also found to have the potential for gastric and colorectal cancer treatment. Studies on its mechanism showed TCS acts as an rRNA N-glycosylase (EC 3.2.2.22) by hydrolyzing and depurinating A-4324 in α-sarcin/ricin loop on 28S rRNA of rat ribosome. Its interaction with acidic ribosomal stalk proteins was revealed in 2007, and its trafficking in mammalian cells was elucidated in the 2000s. The adverse drug reactions, such as inducing immune responses, short plasma half-life, and non-specificity, somehow became the obstacles to its usage. Immunotoxins, sequence modification, or coupling with polyethylene glycerol and dextran were developed to improve the pharmacological properties. TCS has nicely shown the scientific basis of traditional Chinese medicine and how its research and development have expanded the knowledge and applications of ribosome-inactivating proteins.
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Affiliation(s)
- Jia-Qi Lu
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
| | - Kam-Bo Wong
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
| | - Pang-Chui Shaw
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
- Li Dak Sum Yip Yio Chin R&D Centre for Chinese Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Bansia H, Bagaria S, Karande AA, Ramakumar S. Structural basis for neutralization of cytotoxic abrin by monoclonal antibody D6F10. FEBS J 2019; 286:1003-1029. [DOI: 10.1111/febs.14716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 11/02/2018] [Accepted: 11/30/2018] [Indexed: 11/26/2022]
Affiliation(s)
- Harsh Bansia
- Department of Physics Indian Institute of Science Bengaluru India
| | - Shradha Bagaria
- Department of Biochemistry Indian Institute of Science Bengaluru India
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Pandey SN, Iqbal N, Singh PK, Rastogi N, Kaur P, Sharma S, Singh TP. Binding and structural studies of the complexes of type 1 ribosome inactivating protein from Momordica balsamina
with uracil and uridine. Proteins 2018; 87:99-109. [DOI: 10.1002/prot.25584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/07/2018] [Accepted: 07/04/2018] [Indexed: 01/24/2023]
Affiliation(s)
- Sada Nand Pandey
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Naseer Iqbal
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Prashant K. Singh
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Nilisha Rastogi
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Punit Kaur
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Sujata Sharma
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
| | - Tej P. Singh
- Department of Biophysics; All India Institute of Medical Sciences; New Delhi India
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Akkouh O, Ng TB, Cheung RCF, Wong JH, Pan W, Ng CCW, Sha O, Shaw PC, Chan WY. Biological activities of ribosome-inactivating proteins and their possible applications as antimicrobial, anticancer, and anti-pest agents and in neuroscience research. Appl Microbiol Biotechnol 2015; 99:9847-63. [PMID: 26394859 DOI: 10.1007/s00253-015-6941-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/10/2015] [Accepted: 08/13/2015] [Indexed: 02/06/2023]
Abstract
Ribosome-inactivating proteins (RIPs) are enzymes which depurinate ribosomal RNA (rRNA), thus impeding the process of translation resulting in inhibition of protein synthesis. They are produced by various organisms including plants, fungi and bacteria. RIPs from plants are linked to plant defense due to their antiviral, antifungal, antibacterial, and insecticidal activities in which they can be applied in agriculture to combat microbial pathogens and pests. Their anticancer, antiviral, embryotoxic, and abortifacient properties may find medicinal applications. Besides, conjugation of RIPs with antibodies or other carriers to form immunotoxins has been found useful to research in neuroscience and anticancer therapy.
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Affiliation(s)
- Ouafae Akkouh
- Department of Biology and Medical Laboratory Research, Faculty of Technology, University of Applied Sciences Leiden, Zernikdreef 11, 2333 CK, Leiden, The Netherlands.
| | - Tzi Bun Ng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Randy Chi Fai Cheung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Jack Ho Wong
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Wenliang Pan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Charlene Cheuk Wing Ng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Ou Sha
- School of Medicine, Shenzhen University Health Science Centre, Shenzhen University, Shenzhen, China.
| | - Pang Chui Shaw
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Wai Yee Chan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
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6
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Wong KL, Wong RNS, Zhang L, Liu WK, Ng TB, Shaw PC, Kwok PCL, Lai YM, Zhang ZJ, Zhang Y, Tong Y, Cheung HP, Lu J, Sze SCW. Bioactive proteins and peptides isolated from Chinese medicines with pharmaceutical potential. Chin Med 2014; 9:19. [PMID: 25067942 PMCID: PMC4110622 DOI: 10.1186/1749-8546-9-19] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 07/04/2014] [Indexed: 02/07/2023] Open
Abstract
Some protein pharmaceuticals from Chinese medicine have been developed to treat cardiovascular diseases, genetic diseases, and cancer. Bioactive proteins with various pharmacological properties have been successfully isolated from animals such as Hirudo medicinalis (medicinal leech), Eisenia fetida (earthworm), and Mesobuthus martensii (Chinese scorpion), and from herbal medicines derived from species such as Cordyceps militaris, Ganoderma, Momordica cochinchinensis, Viscum album, Poria cocos, Senna obtusifolia, Panax notoginseng, Smilax glabra, Ginkgo biloba, Dioscorea batatas, and Trichosanthes kirilowii. This article reviews the isolation methods, molecular characteristics, bioactivities, pharmacological properties, and potential uses of bioactive proteins originating from these Chinese medicines.
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Affiliation(s)
- Kam Lok Wong
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Ricky Ngok Shun Wong
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Hong Kong Special Administrative Region, China
| | - Liang Zhang
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Wing Keung Liu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region, China
| | - Tzi Bun Ng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region, China
| | - Pang Chui Shaw
- School of Life Sciences and Centre for Protein Science and Crystallography, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region, China
| | - Philip Chi Lip Kwok
- Department of Pharmacology & Pharmacy, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Yau Ming Lai
- Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hung Hom, Hong Kong Special Administrative Region, China
| | - Zhang Jin Zhang
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Yanbo Zhang
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Yao Tong
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Ho-Pan Cheung
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Jia Lu
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
| | - Stephen Cho Wing Sze
- School of Chinese Medicine, LKS Faculty of Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
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Cai Y, Xiong S, Zheng Y, Luo F, Jiang P, Chu Y. Trichosanthin enhances anti-tumor immune response in a murine Lewis lung cancer model by boosting the interaction between TSLC1 and CRTAM. Cell Mol Immunol 2011; 8:359-67. [PMID: 21572449 DOI: 10.1038/cmi.2011.12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Trichosanthin (TCS), extracted from the Chinese medicinal herb Trichosanthes kirilowi, has shown promise for the inhibition of tumor growth. However, its immunomodulatory effect on tumor-host interaction remains unknown. In this study, we focused on the effect of TCS on murine anti-tumor immune response in the 3LL Lewis lung carcinoma tumor model and explored the possible molecular pathways involved. In addition to inhibiting cell proliferation and inducing apoptosis in the 3LL tumor, TCS retarded tumor growth and prolonged mouse survival more significantly in C57BL/6 immunocompetent mice than in nude mice. This reflected the fact that the host immune system was involved in tumor eradication. Using FACS analysis, we found that TCS increased the percentage of effector T cells, particularly Interferon-gamma (IFN-γ) producing CD4(+) and CD8(+) T cells from tumor-bearing mice. TCS also promoted the vigorous proliferation of antigen-specific effector T cells, markedly increased Th1 cytokine secretion and elicited more memory T cells in tumor-bearing mice, consequently enhancing the anti-tumor response and inducing immune protection. Furthermore, we found that TCS upregulated the expression of tumor suppressor in lung cancer 1 (TSLC1) in 3LL tumor cells and the expression of its ligand, class I-restricted T cell-associated molecule (CRTAM), in effector T cells. Blocking TSLC1 expression with small interfering RNA (siRNA) significantly eliminated the effects of TCS on the proliferation and cytokine secretion of effector T cells, suggesting that TCS enhances anti-tumor immune response at least partially by boosting the interaction between TSLC1 and CRTAM. Collectively, our data demonstrate that TCS not only affects tumor cells directly, but also enhances anti-tumor immunity via the interaction between TSLC1 and CRTAM. These findings may lead to the development of a novel approach for tumor regression.
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Affiliation(s)
- Yuchan Cai
- Department of Immunology, Shanghai Medical College, Key Laboratory of Molecular Medicine of Ministry of Education, Fudan University, China
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Shaw PC, Lee KM, Wong KB. Recent advances in trichosanthin, a ribosome-inactivating protein with multiple pharmacological properties. Toxicon 2005; 45:683-9. [PMID: 15804517 DOI: 10.1016/j.toxicon.2004.12.024] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Accepted: 12/24/2004] [Indexed: 11/22/2022]
Abstract
Trichosanthin (TCS), a ribosome-inactivating protein extracted from the root tuber of Chinese medicinal herb Trichosanthes kirilowii Maximowicz, has multiple pharmacological properties including abortifacient, anti-tumor and anti-HIV. It is traditionally used to induce abortion but its antigenicity and short plasma half-life have limited the repeated clinical administration. In this review, work to locating antigenic sites and prolonging plasma half-life are discussed. Studies on structure-function relationship and mechanism of cell entry are also covered. Recently, TCS has been found to induce apoptosis, enhance the action of chemokines and inhibit HIV-1 integrase. These findings give new insights on the pharmacological properties of TCS and other members of ribosome-inactivating proteins.
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Affiliation(s)
- Pang-Chui Shaw
- Department of Biochemistry, Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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Mishra V, Bilgrami S, Sharma RS, Kaur P, Yadav S, Krauspenhaar R, Betzel C, Voelter W, Babu CR, Singh TP. Crystal Structure of Himalayan Mistletoe Ribosome-inactivating Protein Reveals the Presence of a Natural Inhibitor and a New Functionally Active Sugar-binding Site. J Biol Chem 2005; 280:20712-21. [PMID: 15774467 DOI: 10.1074/jbc.m500735200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ribosome-inactivating proteins (RIPs) are toxins involved in plant defense. How the plant prevents autotoxicity is not yet fully understood. The present study is the first structural evidence of a naturally inhibited form of RIP from a plant. Himalayan mistletoe RIP (HmRIP) was purified from Viscum album leaves and crystallized with lactose. The structure was determined by the molecular replacement method and refined at 2.8-A resolution. The crystal structure revealed the presence of high quality non-protein electron density at the active site, into which a pteridine derivative (2-amino 4-isopropyl 6-carboxyl pteridine) was modeled. The carboxyl group of the ligand binds strongly with the key active site residue Arg(162), nullifies the positive charge required for catalysis, and thereby acts as a natural inhibitor. Lectin subunits of RIPs have two active sugar-binding sites present in 1alpha- and 2gamma-subdomains. A third functionally active site has been identified in the 1beta-subdomain of HmRIP. The 1beta-site is active despite the absence of conserved polar sugar-binding residues. Loss of these residues is compensated by the following: (i) the presence of an extended site where the penultimate sugar also interacts with the protein; (ii) the interactions of galactose with the protein main chain carbonyl and amide nitrogen atoms; (iii) the presence of a well defined pocket encircled by four walls; and (iv) a favorable stacking of the galactose ring with Tyr(66) besides the conserved Phe(75). The mode of sugar binding is also distinct at the 1alpha and 2gamma sugar-binding sites.
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Affiliation(s)
- Vandana Mishra
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
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Shaw PC, Wong KB, Chan DSB, Williams RL. Structural basis for the interaction of [E160A-E189A]-trichosanthin with adenine. Toxicon 2003; 41:575-81. [PMID: 12676436 DOI: 10.1016/s0041-0101(02)00387-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Trichosanthin is a ribosome-inactivating protein that cleaves specifically the N-glycosidic bond of A-4324 of 28S rRNA. Trichosanthin and its variant [E160A-E189A]-trichosanthin were found to bind an adenine base with a K(d) value of approximately 0.2mM. To determine how this doubly mutated variant of trichosanthin interacts with adenine, the co-crystal structure of [E160A-E189A]-trichosanthin and adenine was resolved to 0.193nm which revealed that the active site conformation of the doubly mutated variant is isomorphous to wild-type trichosanthin. Water molecules were found at locations corresponding to the eliminated side chain of Glu-160 and Glu-189. On the other hand, the adenine base interacted with [E160A-E189A]-trichosanthin in a manner similar to that in wild-type trichosanthin. Our structural analysis illustrates that Glu-160 and Glu-189 in trichosanthin do not play an important role in maintaining the active site conformation and binding adenine, an essential step for substrate-enzyme interaction. On the other hand, removal of two glutamate residues changed a large patch of negatively charged surface to a positive charge, which may account for the destabilization of the oxocarbenium-like transition-state and the significant decrease in ribosome-inactivating activity in [E160A-E189A]-trichosanthin.
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Affiliation(s)
- Pang-Chui Shaw
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, People's Republic of China.
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Rajamohan F, Mao C, Uckun FM. Binding interactions between the active center cleft of recombinant pokeweed antiviral protein and the alpha-sarcin/ricin stem loop of ribosomal RNA. J Biol Chem 2001; 276:24075-81. [PMID: 11313342 DOI: 10.1074/jbc.m011406200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pokeweed antiviral protein (PAP) is a ribosome-inactivating protein that catalytically cleaves a specific adenine base from the highly conserved alpha-sarcin/ricin loop of the large ribosomal RNA, thereby inhibiting protein synthesis at the elongation step. Recently, we discovered that alanine substitutions of the active center cleft residues significantly impair the depurinating and ribosome inhibitory activity of PAP. Here we employed site-directed mutagenesis combined with standard filter binding assays, equilibrium binding assays with Scatchard analyses, and surface plasmon resonance technology to elucidate the putative role of the PAP active center cleft in the binding of PAP to the alpha-sarcin/ricin stem loop of rRNA. Our findings presented herein provide experimental evidence that besides the catalytic site, the active center cleft also participates in the binding of PAP to the target tetraloop structure of rRNA. These results extend our recent modeling studies, which predicted that the residues of the active center cleft could, via electrostatic interactions, contribute to both the correct orientation and stable binding of the substrate RNA molecules in PAP active site pocket. The insights gained from this study also explain why and how the conserved charged and polar side chains located at the active center cleft of PAP and certain catalytic site residues, that do not directly participate in the catalytic deadenylation of ribosomal RNA, play a critical role in the catalytic removal of the adenine base from target rRNA substrates by affecting the binding interactions between PAP and rRNA.
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MESH Headings
- Animals
- Binding Sites
- Endoribonucleases/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Fungal Proteins
- Models, Molecular
- Mutagenesis, Site-Directed
- N-Glycosyl Hydrolases
- Plant Proteins/chemistry
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Protein Binding
- RNA, Bacterial/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 23S/metabolism
- RNA, Ribosomal, 28S/chemistry
- RNA, Ribosomal, 28S/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Ribosome Inactivating Proteins, Type 1
- Surface Plasmon Resonance
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Affiliation(s)
- F Rajamohan
- Biotherapy Program, Parker Hughes Cancer Center, and the Departments of Protein Engineering, Structural Biology, and Virology, Parker Hughes Institute, St. Paul, Minnesota 55113, USA.
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Zhu Z, Ming Y, Sun B. Identification of Epitopes of Trichosanthin by Phage Peptide Library. Biochem Biophys Res Commun 2001; 282:921-7. [PMID: 11352639 DOI: 10.1006/bbrc.2001.4643] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The phage displayed random peptide library has recently emerged as a powerful technique for analyzing Ab-Ag interactions. In this study, the method was employed to identify epitopes of trichosanthin. Two monoclonal Abs (4B5, 2E9) which recognized different epitopes of trichosanthin (TCS) were selected and a phage-peptide library with nine amino acids (9 aa) was used to screen the positive phage clones that have high affinity to the mAbs. Two groups of phage clones that carried peptide-specific binding to mAbs were identified by the screen. The identified phage clones carried peptide-specific binding to 4B5 and 2E9 mAbs were immunized in mice. To evaluate mimotope of selected phages, the specific binding activity to TCS was measured in the serum from phage-immunized mice. They all showed positive results. The conserved interaction motifs were deduced from the peptide sequences of each group of selected phage clones. When compared the motif sequence with the sequence of TCS, it was predicted that 4B5-corresponding epitope was located at 27-37 aa of TCS protein and 2E9-corresponding epitope was located at 41-48 aa of TCS. The predicted sequence of 4B5-corresponding epitope was further confirmed by site-directed mutation of TCS protein. The data showed that the expressed TCS protein mutated in 4B5-corresponding epitope was unable to bind 4B5 mAb. The results suggested that the phage display peptide library is useful to identify Ag epitopes and to raise Ab in disease diagnosis and treatment.
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Affiliation(s)
- Z Zhu
- Laboratory of Molecular Immunology, Chinese Academy of Sciences, Shanghai, 200031, People's Republic of China
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