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Alonazi M, Krayem N, Alharbi MG, Khayyat AIA, Alanazi H, Horchani H, Ben Bacha A. Functional Characterization and Anti-Tumor Effect of a Novel Group II Secreted Phospholipase A 2 from Snake Venom of Saudi Cerastes cerates gasperetti. Molecules 2023; 28:6517. [PMID: 37764293 PMCID: PMC10536776 DOI: 10.3390/molecules28186517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/31/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
Secreted phospholipases A2 are snake-venom proteins with many biological activities, notably anti-tumor activity. Phospholipases from the same snake type but different geographical locations have shown similar biochemical and biological activities with minor differences in protein sequences. Thus, the discovery of a new phospholipase A2 with unique characteristics identified in a previously studied venom could suggest the origins of these differences. Here, a new Group II secreted phospholipase A2 (Cc-PLA2-II) from the snake venom of Saudi Cerastes cerastes gasperetti was isolated and characterized. The purified enzyme had a molecular weight of 13.945 kDa and showed high specific activity on emulsified phosphatidylcholine of 1560 U/mg at pH 9.5 and 50 °C with strict calcium dependence. Interestingly, stability in extreme pH and high temperatures was observed after enzyme incubation at several pH levels and temperatures. Moreover, a significant dose-dependent cytotoxic anti-tumor effect against six human cancer cell lines was observed with concentrations of Cc-PLA2 ranging from 2.5 to 8 µM. No cytotoxic effect on normal human umbilical-vein endothelial cells was noted. These results suggest that Cc-PLA2-II potentially has angiogenic activity of besides cytotoxicity as part of its anti-tumor mechanism. This study justifies the inclusion of this enzyme in many applications for anticancer drug development.
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Affiliation(s)
- Mona Alonazi
- Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; (M.A.); (M.G.A.); (A.I.A.K.); (H.A.)
| | - Najeh Krayem
- Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS, Université de Sfax, Route de Soukra 3038, Sfax BP 1173, Tunisia;
| | - Mona G. Alharbi
- Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; (M.A.); (M.G.A.); (A.I.A.K.); (H.A.)
| | - Arwa Ishaq A. Khayyat
- Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; (M.A.); (M.G.A.); (A.I.A.K.); (H.A.)
| | - Humidah Alanazi
- Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; (M.A.); (M.G.A.); (A.I.A.K.); (H.A.)
| | - Habib Horchani
- Science Department, College of Rivière-Du-Loup, Rivière-Du-Loup, QC G5R 1R1, Canada;
| | - Abir Ben Bacha
- Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; (M.A.); (M.G.A.); (A.I.A.K.); (H.A.)
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Devi A, Doley R. Neutralization of Daboxin P activities by rationally designed aptamers. Toxicon 2021; 203:93-103. [PMID: 34619285 DOI: 10.1016/j.toxicon.2021.09.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022]
Abstract
Inefficacy and associated risks of current antivenom has raised the need for alternative approaches of snakebite management. Aptamers are one such alternative which is being pursued for therapeutic interventions as well as for design of diagnostic kits due to its high specificity. Present study focussed on designing and validating nucleic acid aptamers against snake venom PLA2, a hydrolytic enzyme present in all venomous snakes. The aptamers were designed by adding nucleic acid chain on the surface of Daboxin P, a major PLA2 enzyme of Daboia russelii venom. Binding characteristics of the aptamers were confirmed by docking to Daboxin P as well as acidic and basic PLA2s from different snake species using in silico docking. The aptamers folded into different tertiary structures and bound to the active and Ca2+ binding site of PLA2 enzymes. Molecular dynamics simulation analysis of Daboxin P-aptamer complexes showed that the complexes were stable in an aqueous environment. The electrophoretic mobility shift assay further confirmed the binding of the synthetic aptamers to Daboxin P and other snake venom PLA2 enzymes. The aptamers inhibited the sPLA2 activity with an IC50 value ranging between 0.52 μM and 0.77 μM as well as the anticoagulant activity of Daboxin P. The aptamers could also inhibit the PLA2 activity of Echis carinatus crude venom and anti-coagulant activity of Bungarus caeruleus crude venom, members of big four snakes. However, the aptamers didn't inhibit fibrinogenolytic or proteolytic activity of big four venom as well as the coagulation and hemolytic activities. Thus, aptamers can be rationally designed to inhibit the biochemical and biological activities of snake venom proteins.
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Affiliation(s)
- Arpita Devi
- Molecular Toxinology Laboratory, Department of Molecular Biology and Biotechnology, Tezpur University, Napaam, Tezpur, Assam, India
| | - Robin Doley
- Molecular Toxinology Laboratory, Department of Molecular Biology and Biotechnology, Tezpur University, Napaam, Tezpur, Assam, India.
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Khan MI, Hariprasad G. Human Secretary Phospholipase A2 Mutations and Their Clinical Implications. J Inflamm Res 2020; 13:551-561. [PMID: 32982370 PMCID: PMC7502393 DOI: 10.2147/jir.s269557] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/13/2020] [Indexed: 01/05/2023] Open
Abstract
Phospholipases A2 (PLA2s) belong to a superfamily of enzymes responsible for hydrolysis of the sn-2 fatty acids of membrane phospholipids to release arachidonic acid. PLA2s are the rate limiting enzyme for the downstream synthesis of prostaglandins and leukotrienes that are the main mediators of inflammation. The extracellular forms of this enzyme are also called the secretary phospholipase A2 (sPLA2) and are distributed extensively in most of the tissues in the human body. Their integral role in inflammatory pathways has been the primary reason for the extensive research on this molecule. The catalytic mechanism of sPLA2 is initiated by a histidine/aspartic acid/calcium complex within the active site. Though they are known to have certain housekeeping functions, certain mutations of sPLA2 are known to be implicated in causation of certain pathologies leading to diseases such as atherosclerosis, cardiovascular diseases, benign fleck retina, neurodegeneration, and asthma. We present an overview of human sPLA2 and a comprehensive compilation of the mutations that result in various disease phenotypes. The study not only helps to have a holistic understanding of human sPLA2 mutations and their clinical implications, but is also a useful platform to initiate research pertaining to structure–function relationship of the mutations to develop effective therapies for management of these diseases.
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Affiliation(s)
- Mohd Imran Khan
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Gururao Hariprasad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
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4
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Trento MVC, Sales TA, de Abreu TS, Braga MA, Cesar PHS, Marques TR, Marcussi S. Exploring the structural and functional aspects of the phospholipase A 2 from Naja spp. Int J Biol Macromol 2019; 140:49-58. [PMID: 31421173 DOI: 10.1016/j.ijbiomac.2019.08.125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 01/22/2023]
Abstract
Naja spp. venom is a natural source of active compounds with therapeutic application potential. Phospholipase A2 (PLA2) is abundant in the venom of Naja spp. and can perform neurotoxicity, cytotoxicity, cardiotoxicity, and hematological disorders. The PLA2s from Naja spp. venoms are Asp 49 isoenzymes with the exception of PLA2 Cys 49 from Naja sagittifera. When looking at the functional aspects, the neurotoxicity occurs by PLA2 called β-toxins that have affinity for phosphatidylcholine in nerve endings and synaptosomes membranes, and by α-toxins that block the nicotinic acetylcholine receptors in the neuromuscular junctions. In addition, these neurotoxins may inhibit K+ and Ca++ channels or even interfere with the Na+/K+/ATPase enzyme. The disturbance in the membrane fluidity also results in inhibition of the release of acetylcholine. The PLA2 can act as anticoagulants or procoagulant. The cytotoxicity exerted by PLA2s result from changes in the cardiomyocyte membranes, triggering cardiac failure and hemolysis. The antibacterial activity, however, is the result of alterations that decrease the stability of the lipid bilayer. Thus, the understanding of the structural and functional aspects of PLA2s can contribute to studies on the toxic and therapeutic mechanisms involved in the envenomation by Naja spp. and in the treatment of pathologies.
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Affiliation(s)
- Marcus Vinícius Cardoso Trento
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil.
| | - Thais Aparecida Sales
- Computational Chemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Tatiane Silva de Abreu
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Mariana Aparecida Braga
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Pedro Henrique Souza Cesar
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Tamara Rezende Marques
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Silvana Marcussi
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
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5
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Mariani ME, Fidelio GD. Secretory Phospholipases A 2 in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:861. [PMID: 31354755 PMCID: PMC6635587 DOI: 10.3389/fpls.2019.00861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/14/2019] [Indexed: 05/17/2023]
Abstract
Secreted phospholipases (sPLA2s) in plants are a growing group of enzymes that catalyze the hydrolysis of sn-2 glycerophospholipids to lysophospholipids and free fatty acids. Until today, around only 20 sPLA2s were reported from plants. This review discusses the newly acquired information on plant sPLA2s including molecular, biochemical, catalytic, and functional aspects. The comparative analysis also includes phylogenetic, evolutionary, and tridimensional structure. The observations with emphasis in Glycine max sPLA2 are compared with the available data reported for all plants sPLA2s and with those described for animals (mainly from pancreatic juice and venoms sources).
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Affiliation(s)
- María Elisa Mariani
- Departamento de Química Biológica, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
- Instituto de Investigaciones Biológicas y Tecnológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Fundamentación Biológica, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gerardo Daniel Fidelio
- Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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6
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Du QS, Trabi M, Richards RS, Mirtschin P, Madaras F, Nouwens A, Zhao KN, de Jersey J, Lavin MF, Guddat LW, Masci PP. Characterization and structural analysis of a potent anticoagulant phospholipase A2 from Pseudechis australis snake venom. Toxicon 2016; 111:37-49. [DOI: 10.1016/j.toxicon.2015.12.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 12/22/2015] [Accepted: 12/28/2015] [Indexed: 11/24/2022]
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Hariprasad G, Kota D, Baskar Singh S, Srinivasan A, Adhikary S. Delineation of the Structural Elements of Oriental Liver Fluke PLA2 Isoforms for Potent Drug Designing. Indian J Clin Biochem 2013; 29:430-41. [PMID: 25298624 DOI: 10.1007/s12291-013-0377-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/24/2013] [Indexed: 01/25/2023]
Abstract
Clonorchis sinensis or the Chinese liver fluke is one of the most prevalent parasites affecting a major population in the oriental countries. The parasite lacks lipid generating mechanisms but is exposed to fatty acid rich bile in the liver. A secretory phospholipase A2, an enzyme that breaks down complex lipids, is important for the growth of the parasite. The enzyme is also implicated in the pathogenesis leading up to the hepatic fibrosis and its complications including cancer. The five isoforms of this particular enzyme from the parasite therefore qualify as potential drug targets. In this study, a detailed structural and ligand binding analysis of the isoforms has been done by modeling. The overall three dimensional structures of the isoforms are well conserved with three helices and a β-wing stabilized by four disulfide bonds. There are characteristic differences at the calcium binding loop, hydrophobic channel and the C-terminal domain that can potentially be exploited for drug binding. But the most significant feature pertains to the catalytic site where the isoforms exhibit three variations of either a histidine-aspartate-tyrosine or histidine-glutamate-tyrosine or histidine-aspartate-phenylalanine. Molecular docking studies show that isoform specific residues and their conformations in the substrate binding hydrophobic channel make unique interactions with certain inhibitor molecules resulting in a perfect tight fit. The proposed ligand molecules have a predicted affinity in micro-molar to nano-molar range. Interestingly, few of the ligand binding interaction patterns is in accordance to the phylogenetic studies to thereby establish the usefulness of evolutionary mechanisms in aiding ligand design. The molecular diversity of the parasitic PLA2 described in this study provides a platform for personalized medicine in the therapeutics of clonorchiasis.
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Affiliation(s)
- Gururao Hariprasad
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029 India
| | - Divya Kota
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029 India
| | - Sundararajan Baskar Singh
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029 India
| | - Alagiri Srinivasan
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029 India
| | - Souparno Adhikary
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029 India
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8
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Structural and phylogenetic basis for the classification of group III phospholipase A2. J Mol Model 2013; 19:3779-91. [DOI: 10.1007/s00894-013-1913-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 06/06/2013] [Indexed: 10/26/2022]
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9
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Hariprasad G, Kaur P, Srinivasan A, Singh TP, Kumar M. Structural analysis of secretory phospholipase A2 from Clonorchis sinensis: therapeutic implications for hepatic fibrosis. J Mol Model 2012; 18:3139-45. [PMID: 22215060 DOI: 10.1007/s00894-011-1333-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 12/12/2011] [Indexed: 11/25/2022]
Abstract
Hepatic fibrosis is a common complication of the infection by the parasite, Clonorchis sinensis. There is a high incidence of this disease in the Asian countries with an increased risk of conversion to cancer. A secretory phospholipase A(2) (PLA(2)) enzyme from the parasite is implicated in the pathology. This is an attractive drug target in the light of extensive structural characterization of this class of enzyme. In this study, the structure of the enzyme was modeled based on its sequence homology to the group III bee venom PLA(2). On analysis, the overall structure essentially is comprised of three helices, two sets of β-wings and an elongated C-terminal extension. The structure is stabilized by four disulfide bonds. The structure is comprised of a calcium binding loop, active site and a substrate binding hydrophobic channel. The active site of the enzyme shows the classical features of PLA(2) with the participation of the three residues: histidine-aspartic acid-tyrosine in hydrogen bond formation. This is an interesting variation from the house keeping group III PLA(2) enzyme of human which has a histidine-aspartic acid and phenylalanine arrangement at the active site. This difference is therefore an important structural parameter that can be exploited to design specific inhibitor molecules against the pathogen PLA(2). Likewise, there are certain unique structural features in the hydrophobic channel and the putative membrane binding surface of the PLA(2) from Clonorchis sinensis that not only help understand the mechanism of action but also provide knowledge for a targeted therapy of liver fibrosis caused by the parasite.
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Affiliation(s)
- Gururao Hariprasad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India.
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Kang TS, Georgieva D, Genov N, Murakami MT, Sinha M, Kumar RP, Kaur P, Kumar S, Dey S, Sharma S, Vrielink A, Betzel C, Takeda S, Arni RK, Singh TP, Kini RM. Enzymatic toxins from snake venom: structural characterization and mechanism of catalysis. FEBS J 2011; 278:4544-76. [PMID: 21470368 DOI: 10.1111/j.1742-4658.2011.08115.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Snake venoms are cocktails of enzymes and non-enzymatic proteins used for both the immobilization and digestion of prey. The most common snake venom enzymes include acetylcholinesterases, l-amino acid oxidases, serine proteinases, metalloproteinases and phospholipases A(2) . Higher catalytic efficiency, thermal stability and resistance to proteolysis make these enzymes attractive models for biochemists, enzymologists and structural biologists. Here, we review the structures of these enzymes and describe their structure-based mechanisms of catalysis and inhibition. Some of the enzymes exist as protein complexes in the venom. Thus we also discuss the functional role of non-enzymatic subunits and the pharmacological effects of such protein complexes. The structures of inhibitor-enzyme complexes provide ideal platforms for the design of potent inhibitors which are useful in the development of prototypes and lead compounds with potential therapeutic applications.
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Affiliation(s)
- Tse Siang Kang
- Department of Pharmacy, National University of Singapore, Singapore
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Discrimination between the regioisomeric 1,2- and 1,3-diacylglycerophosphocholines by phospholipases. Chem Phys Lipids 2011; 164:196-204. [DOI: 10.1016/j.chemphyslip.2010.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 12/18/2010] [Accepted: 12/22/2010] [Indexed: 11/15/2022]
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12
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Structural analysis of a group III Glu62-phospholipase A2 from the scorpion, Mesobuthus tamulus: Targeting and reversible inhibition by native peptides. Int J Biol Macromol 2011; 48:423-31. [PMID: 21238479 DOI: 10.1016/j.ijbiomac.2011.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 12/22/2010] [Accepted: 01/04/2011] [Indexed: 11/22/2022]
Abstract
Group III phospholipase A(2) enzyme transcript from the Mesobuthus tamulus (Indian red scorpion) codes for three distinct products that include a large enzymatic subunit, a pentameric peptide and a small non-enzymatic subunit. The structures of these two subunits were modeled based on their sequence identity to bee venom PLA(2) and the partial sequence of MU2 adaptin subunit of AP2 clathrin adaptor, respectively. The enzymatic subunit comprises of three helices, the calcium binding loop and a substrate binding hydrophobic channel where the structure is stabilized by four disulfide bonds. The active site of the enzyme shows a catalytic histidine residue. Interestingly, there is a conservative mutation of the conserved aspartic acid, a classical participant of catalysis in this enzyme family, to glutamic acid. However, the side chain oxygen atoms of this glutamate are oriented away from the catalytic histidine implicating the non-participation of this residue in stabilizing the tautomeric conformation of the histidine. The acidic non-enzymatic subunit comprises of extensive hydrophobic residues with a conformation of an anti-parallel β-sheets making it ideal for tissue specific targeting. The native pentapeptide with the sequence Alanine-Arginine-Serine-Alanine-Arginine was docked to the enzymatic subunit. The peptide ligand occupies the hydrophobic cavity and makes a plethora of interactions with the residues in the channel, including a hydrogen bond with the crucial catalytic histidine and coordinate bond with the calcium ion. This ligand has a binding constant (K(D)) of 1.5μM. This makes the ligand a potential reversible inhibitor, ideal to prevent the enzyme from interacting with non-specific molecules enroute to the target. The enzyme-ligand complex also provides a model to understand the stereochemistry required for the design of more potent drug molecules against such enzyme drug targets.
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Hariprasad G, Kumar M, Kaur P, Singh TP, Kumar RP. Human group III PLA2 as a drug target: structural analysis and inhibitor binding studies. Int J Biol Macromol 2010; 47:496-501. [PMID: 20654644 DOI: 10.1016/j.ijbiomac.2010.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 07/13/2010] [Accepted: 07/13/2010] [Indexed: 11/24/2022]
Abstract
Group III phospholipase A(2) is a known mediator of inflammation, atherosclerosis and cancer in mammals. This enzyme, therefore, is a potential drug target. The availability of the human group III phospholipase A(2) (hIIIPLA(2)) amino acid sequence offers an opportunity to study its structural features by modeling. The monomeric hIII PLA(2) model is based on the 44% identity it has with the bee venom PLA(2), the only known representative structure of this group. The overall structure comprises of three α-helices, a β-wing and the calcium binding loop which is present at the N-terminus of the enzyme. However, the unique structural features of hIIIPLA(2) in comparison to the other well known group I/II PLA(2)s are: (1) the replacement of the 'conserved' tyrosine residue by phenylalanine at position 87 in the active site; (2) a decrease in the volume of the substrate binding hydrophobic channel and (3) presence of a C-terminal extension which has a close proximity to the third helix. Docking studies of the enzyme with small molecules gives a detailed insight into the participating residues of the enzyme and also the possible type of interactions with the drug molecules. The ligand molecules have binding affinities predicted to range from micromolar to nanomolar range, thereby making them either potential lead molecules or potent drugs. This analysis paves the way for possible therapeutic applications in pathological states caused by this enzyme.
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Affiliation(s)
- Gururao Hariprasad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India.
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Baek JH, Lee SH. Differential gene expression profiles in the venom gland/sac of Eumenes pomiformis (Hymenoptera: Eumenidae). Toxicon 2010; 55:1147-56. [PMID: 20096300 DOI: 10.1016/j.toxicon.2010.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 12/07/2009] [Accepted: 01/02/2010] [Indexed: 10/19/2022]
Abstract
To search for novel transcripts encoding biologically active venom components, a subtractive cDNA library specific to the venom gland and sac (gland/sac) of a solitary hunting wasp species, Eumenes pomiformis Fabricius (1781), was constructed by suppression subtractive hybridization. A total of 541 expressed sequence tags (ESTs) were clustered and assembled into 102 contigs (31 multiple sequences and 71 singletons). In total, 37 cDNAs were found in the library via BLASTx searching and manual annotation. Eight contigs (337 ESTs) encoding short venom peptides (10 to 16 amino acids) occupied 62% of the library. The deduced amino acid sequence (78 amino acids) of a novel venom peptide transcript shared sequence similarity with trypsin inhibitors and dendrotoxin-like venom peptides known to be K(+) channel blockers, implying that this novel peptide may play a role in the paralysis of prey. In addition to phospholipase A2 and hyaluronidase, which are known to be the main components of wasp venoms, several transcripts encoding enzymes, including three metallopeptidases and a decarboxylase likely involved in the processing and activation of venomous proteins, peptides, amines, and neurotransmitters, were also isolated from the library. The presence of a transcript encoding a putative insulin/insulin-like peptide binding protein suggests that solitary hunting wasps use their venom to control their prey, leading to larval growth cessation. The abundance of these venom components in the venom gland/sac and in the alimentary canal was confirmed by quantitative real-time PCR. Discovery of venom gland/sac-specific transcripts should promote further studies on biologically active components in the venom of solitary hunting wasps.
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Affiliation(s)
- Ji Hyeong Baek
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
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Baek JH, Woo TH, Kim CB, Park JH, Kim H, Lee S, Lee SH. Differential gene expression profiles in the venom gland/sac of Orancistrocerus drewseni (Hymenoptera: Eumenidae). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2009; 71:205-222. [PMID: 19479740 DOI: 10.1002/arch.20316] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
To determine differential gene expression profiles in the venom gland and sac (gland/sac) of a solitary hunting wasp species, Orancistrocerus drewseni Saussure (1857), a subtractive cDNA library was constructed by suppression subtractive hybridization. A total of 498 expressed sequence tags (EST) were clustered and assembled into 205 contigs (94 multiple sequences and 111 singletons). About 65% (134) of the contigs had matched BLASTx hits (E< or =10(-4)). Among these, 115 contigs had similarity to proteins with assigned molecular function in the Gene Ontology database, and most of them (112 contigs, 83%) were homologous to genes from Hymenoptera, particularly to Apis mellifera (98 contigs). The contigs encoding hyaluronidase and phospholipase A2, known to be main components of wasp venoms, were found in high frequencies (27 and 4%, respectively, as judged by the number of ESTs) in the gene ontology category of catalytic activity. Full-length open reading frames of hyaluronidase and phospholipase A2 were characterized and their abundance in the venom gland/sac was confirmed by quantitative real-time PCR. Several contigs encoding enzymes, including zinc-metallopeptidases that are likely involved in the processing and activation of venomous proteins or peptides, were also identified from the library. Discovery of venom gland/sac-specific genes should promote further studies on biologically active components in the venom of O. drewseni.
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Affiliation(s)
- Ji Hyeong Baek
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
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Sharma M, Ethayathulla AS, Jabeen T, Singh N, Sarvanan K, Yadav S, Sharma S, Srinivasan A, Singh TP. Crystal structure of a highly acidic neurotoxin from scorpion Buthus tamulus at 2.2Ǻ resolution reveals novel structural features. J Struct Biol 2006; 155:52-62. [PMID: 16677826 DOI: 10.1016/j.jsb.2005.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 12/02/2005] [Accepted: 12/06/2005] [Indexed: 10/25/2022]
Abstract
The crystal structure of a highly acidic neurotoxin from the scorpion Buthus tamulus has been determined at 2.2A resolution. The amino acid sequence determination shows that the polypeptide chain has 64 amino acid residues. The pI measurement gave a value of 4.3 which is one of the lowest pI values reported so far for a scorpion toxin. As observed in other alpha-toxins, it contains four disulphide bridges, Cys12-Cys63, Cys16-Cys36, Cys22-Cys46, and Cys26-Cys48. The crystal structure reveals the presence of two crystallographically independent molecules in the asymmetric unit. The conformations of two molecules are identical with an r.m.s. value of 0.3A for their C(alpha) tracings. The overall fold of the toxin is very similar to other scorpion alpha-toxins. It is a betaalphabetabeta protein. The beta-sheet involves residues Glu2-Ile6 (strand beta1), Asp32-Trp39 (strand beta3) and Val45-Val55 (strand beta4). The single alpha-helix formed is by residues Asn19-Asp28 (alpha2). The structure shows a trans peptide bond between residues 9 and 10 in the five-membered reverse turn Asp8-Cys12. This suggests that this toxin belongs to classical alpha-toxin subfamily. The surface features of the present toxin are highly characteristic, the first (A-site) has residues, Phe18, Trp38 and Trp39 that protrude outwardly presumably to interact with its receptor. There is another novel face (N-site) of this neurotoxin that contains several negatively charged residues such as, Glu2, Asp3, Asp32, Glu49 and Asp50 which are clustered in a small region of the toxin structure. On yet another face (P-site) in a triangular arrangement, with respect to the above two faces there are several positively charged residues, Arg58, Lys62 and Arg64 that also protrude outwardly for a potentially potent interaction with other molecules. This toxin with three strong features appears to be one of the most toxic molecules reported so far. In this sense, it may be a new subclass of neurotoxins with the largest number of hot spots.
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Affiliation(s)
- Madhu Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
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