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Hooda P, Ishtikhar M, Saraswat S, Bhatia P, Mishra D, Trivedi A, Kulandaisamy R, Aggarwal S, Munde M, Ali N, AlAsmari AF, Rauf MA, Inampudi KK, Sehgal D. Biochemical and Biophysical Characterisation of the Hepatitis E Virus Guanine-7-Methyltransferase. Molecules 2022; 27:1505. [PMID: 35268608 PMCID: PMC8911963 DOI: 10.3390/molecules27051505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 02/09/2022] [Accepted: 02/18/2022] [Indexed: 11/21/2022] Open
Abstract
Hepatitis E virus (HEV) is an understudied pathogen that causes infection through fecal contaminated drinking water and is prominently found in South Asian countries. The virus affects ~20 million people annually, leading to ~60,000 infections per year. The positive-stranded RNA genome of the HEV genotype 1 has four conserved open reading frames (ORFs), of which ORF1 encodes a polyprotein of 180 kDa in size, which is processed into four non-structural enzymes: methyltransferase (MTase), papain-like cysteine protease, RNA-dependent RNA polymerase, and RNA helicase. MTase is known to methylate guanosine triphosphate at the 5'-end of viral RNA, thereby preventing its degradation by host nucleases. In the present study, we cloned, expressed, and purified MTase spanning 33-353 amino acids of HEV genotype 1. The activity of the purified enzyme and the conformational changes were established through biochemical and biophysical studies. The binding affinity of MTase with magnesium ions (Mg2+) was studied by isothermal calorimetry (ITC), microscale thermophoresis (MST), far-UV CD analysis and, fluorescence quenching. In summary, a short stretch of nucleotides has been cloned, coding for the HEV MTase of 37 kDa, which binds Mg2+ and modulate its activity. The chelation of magnesium reversed the changes, confirming its role in enzyme activity.
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Affiliation(s)
- Preeti Hooda
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Mohd Ishtikhar
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Shweta Saraswat
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Pooja Bhatia
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Deepali Mishra
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Aditya Trivedi
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
| | - Rajkumar Kulandaisamy
- Department of Biophysics, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India;
| | - Soumya Aggarwal
- School of Physical Sciences, Jawaharlal Nehru University (JNU), New Delhi 110067, India; (S.A.); (M.M.)
| | - Manoj Munde
- School of Physical Sciences, Jawaharlal Nehru University (JNU), New Delhi 110067, India; (S.A.); (M.M.)
| | - Nemat Ali
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia; (N.A.); (A.F.A.)
| | - Abdullah F. AlAsmari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia; (N.A.); (A.F.A.)
| | - Mohd A. Rauf
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA;
| | - Krishna K. Inampudi
- Department of Biophysics, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India;
| | - Deepak Sehgal
- Virology Lab, Department of Life Sciences, Shiv Nadar University, Greater Noida 201314, India; (P.H.); (M.I.); (S.S.); (P.B.); (D.M.); (A.T.)
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Cifuente JO, Comino N, D'Angelo C, Marina A, Gil-Carton D, Albesa-Jové D, Guerin ME. The allosteric control mechanism of bacterial glycogen biosynthesis disclosed by cryoEM. Curr Res Struct Biol 2020; 2:89-103. [PMID: 34235472 PMCID: PMC8244506 DOI: 10.1016/j.crstbi.2020.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/12/2020] [Accepted: 04/20/2020] [Indexed: 11/10/2022] Open
Abstract
Glycogen and starch are the major carbon and energy reserve polysaccharides in nature, providing living organisms with a survival advantage. The evolution of the enzymatic machinery responsible for the biosynthesis and degradation of such polysaccharides, led the development of mechanisms to control the assembly and disassembly rate, to store and recover glucose according to cell energy demands. The tetrameric enzyme ADP-glucose pyrophosphorylase (AGPase) catalyzes and regulates the initial step in the biosynthesis of both α-polyglucans. AGPase displays cooperativity and allosteric regulation by sensing metabolites from the cell energy flux. The understanding of the allosteric signal transduction mechanisms in AGPase arises as a long-standing challenge. In this work, we disclose the cryoEM structures of the paradigmatic homotetrameric AGPase from Escherichia coli (EcAGPase), in complex with either positive or negative physiological allosteric regulators, fructose-1,6-bisphosphate (FBP) and AMP respectively, both at 3.0 Å resolution. Strikingly, the structures reveal that FBP binds deeply into the allosteric cleft and overlaps the AMP site. As a consequence, FBP promotes a concerted conformational switch of a regulatory loop, RL2, from a "locked" to a "free" state, modulating ATP binding and activating the enzyme. This notion is strongly supported by our complementary biophysical and bioinformatics evidence, and a careful analysis of vast enzyme kinetics data on single-point mutants of EcAGPase. The cryoEM structures uncover the residue interaction networks (RIN) between the allosteric and the catalytic components of the enzyme, providing unique details on how the signaling information is transmitted across the tetramer, from which cooperativity emerges. Altogether, the conformational states visualized by cryoEM reveal the regulatory mechanism of EcAGPase, laying the foundations to understand the allosteric control of bacterial glycogen biosynthesis at the molecular level of detail.
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Key Words
- AGPase, ADP-glucose pyrophosphorylase
- AMP, adenosine 5′-monophosphate
- ATP, adenosine 5′-triphosphate
- EcAGPase, AGPase from E. coli
- Enzyme allosterism
- FBP, fructose 1,6-bisphosphate
- G1P, α-d-glucose-1-phosphate
- GBE, glycogen branching enzyme
- GDE, glycogen debranching enzyme
- GP, glycogen phosphorylase
- GS, glycogen synthase
- GTA-like, glycosyltransferase-A like domain
- Glycogen biosynthesis
- Glycogen regulation
- LβH, left-handed β-helix domain
- Nucleotide sugar biosynthesis
- PPi, pyrophosphate
- RIN, residue interaction network
- SM, sensory motif
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Affiliation(s)
- Javier O. Cifuente
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - Natalia Comino
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - Cecilia D'Angelo
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - Alberto Marina
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - David Gil-Carton
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - David Albesa-Jové
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
| | - Marcelo E. Guerin
- Structural Biology Unit, CIC BioGUNE, Bizkaia Technology Park, 48160, Derio, Spain
- IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain
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Structural basis of glycogen metabolism in bacteria. Biochem J 2019; 476:2059-2092. [PMID: 31366571 DOI: 10.1042/bcj20170558] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/11/2019] [Accepted: 07/15/2019] [Indexed: 01/25/2023]
Abstract
The evolution of metabolic pathways is a major force behind natural selection. In the spotlight of such process lies the structural evolution of the enzymatic machinery responsible for the central energy metabolism. Specifically, glycogen metabolism has emerged to allow organisms to save available environmental surplus of carbon and energy, using dedicated glucose polymers as a storage compartment that can be mobilized at future demand. The origins of such adaptive advantage rely on the acquisition of an enzymatic system for the biosynthesis and degradation of glycogen, along with mechanisms to balance the assembly and disassembly rate of this polysaccharide, in order to store and recover glucose according to cell energy needs. The first step in the classical bacterial glycogen biosynthetic pathway is carried out by the adenosine 5'-diphosphate (ADP)-glucose pyrophosphorylase. This allosteric enzyme synthesizes ADP-glucose and acts as a point of regulation. The second step is carried out by the glycogen synthase, an enzyme that generates linear α-(1→4)-linked glucose chains, whereas the third step catalyzed by the branching enzyme produces α-(1→6)-linked glucan branches in the polymer. Two enzymes facilitate glycogen degradation: glycogen phosphorylase, which functions as an α-(1→4)-depolymerizing enzyme, and the debranching enzyme that catalyzes the removal of α-(1→6)-linked ramifications. In this work, we rationalize the structural basis of glycogen metabolism in bacteria to the light of the current knowledge. We describe and discuss the remarkable progress made in the understanding of the molecular mechanisms of substrate recognition and product release, allosteric regulation and catalysis of all those enzymes.
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Chen H, Giese TJ, Golden BL, York DM. Divalent Metal Ion Activation of a Guanine General Base in the Hammerhead Ribozyme: Insights from Molecular Simulations. Biochemistry 2017; 56:2985-2994. [PMID: 28530384 DOI: 10.1021/acs.biochem.6b01192] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hammerhead ribozyme is a well-studied nucleolytic ribozyme that catalyzes the self-cleavage of the RNA phosphodiester backbone. Despite experimental and theoretical efforts, key questions remain about details of the mechanism with regard to the activation of the nucleophile by the putative general base guanine (G12). Straightforward interpretation of the measured activity-pH data implies the pKa value of the N1 position in the G12 nucleobase is significantly shifted by the ribozyme environment. Recent crystallographic and biochemical work has identified pH-dependent divalent metal ion binding at the N7/O6 position of G12, leading to the hypothesis that this binding mode could induce a pKa shift of G12 toward neutrality. We present computational results that support this hypothesis and provide a model that unifies the interpretation of available structural and biochemical data and paints a detailed mechanistic picture of the general base step of the reaction. Experimentally testable predictions are made for mutational and rescue effects on G12, which will give further insights into the catalytic mechanism. These results contribute to our growing knowledge of the potential roles of divalent metal ions in RNA catalysis.
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Affiliation(s)
- Haoyuan Chen
- Laboratory for Biomolecular Simulation Research, Center for Integrative Proteomics Research, and Department of Chemistry & Chemical Biology, Rutgers University , 174 Frelinghuysen Road, Piscataway, New Jersey 08854-8076, United States
| | - Timothy J Giese
- Laboratory for Biomolecular Simulation Research, Center for Integrative Proteomics Research, and Department of Chemistry & Chemical Biology, Rutgers University , 174 Frelinghuysen Road, Piscataway, New Jersey 08854-8076, United States
| | - Barbara L Golden
- Department of Biochemistry, Purdue University , West Lafayette, Indiana 47907, United States
| | - Darrin M York
- Laboratory for Biomolecular Simulation Research, Center for Integrative Proteomics Research, and Department of Chemistry & Chemical Biology, Rutgers University , 174 Frelinghuysen Road, Piscataway, New Jersey 08854-8076, United States
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Comino N, Cifuente JO, Marina A, Orrantia A, Eguskiza A, Guerin ME. Mechanistic insights into the allosteric regulation of bacterial ADP-glucose pyrophosphorylases. J Biol Chem 2017; 292:6255-6268. [PMID: 28223362 DOI: 10.1074/jbc.m116.773408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/17/2017] [Indexed: 11/06/2022] Open
Abstract
ADP-glucose pyrophosphorylase (AGPase) controls bacterial glycogen and plant starch biosynthetic pathways, the most common carbon storage polysaccharides in nature. AGPase activity is allosterically regulated by a series of metabolites in the energetic flux within the cell. Very recently, we reported the first crystal structures of the paradigmatic AGPase from Escherichia coli (EcAGPase) in complex with its preferred physiological negative and positive allosteric regulators, adenosine 5'-monophosphate (AMP) and fructose 1,6-bisphosphate (FBP), respectively. However, understanding the molecular mechanism by which AMP and FBP allosterically modulates EcAGPase enzymatic activity still remains enigmatic. Here we found that single point mutations of key residues in the AMP-binding site decrease its inhibitory effect but also clearly abolish the overall AMP-mediated stabilization effect in wild-type EcAGPase. Single point mutations of key residues for FBP binding did not revert the AMP-mediated stabilization. Strikingly, an EcAGPase-R130A mutant displayed a dramatic increase in activity when compared with wild-type EcAGPase, and this increase correlated with a significant increment of glycogen content in vivo The crystal structure of EcAGPase-R130A revealed unprecedented conformational changes in structural elements involved in the allosteric signal transmission. Altogether, we propose a model in which the positive and negative energy reporters regulate AGPase catalytic activity via intra- and interprotomer cross-talk, with a "sensory motif" and two loops, RL1 and RL2, flanking the ATP-binding site playing a significant role. The information reported herein provides exciting possibilities for industrial/biotechnological applications.
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Affiliation(s)
- Natalia Comino
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Javier O Cifuente
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Alberto Marina
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Ane Orrantia
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Ander Eguskiza
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Marcelo E Guerin
- From the Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain, .,Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibertsitatea (CSIC,UPV/EHU), Barrio Sarriena s/n, Leioa, 48940 Bizkaia, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, 48940 Bizkaia, Spain, and.,IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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Xu XF, Wang B, Lou Y, Han WJ, Lu JY, Li DD, Li LG, Zhu J, Yang ZN. Magnesium Transporter 5 plays an important role in Mg transport for male gametophyte development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:925-36. [PMID: 26478267 DOI: 10.1111/tpj.13054] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/22/2015] [Accepted: 10/01/2015] [Indexed: 05/27/2023]
Abstract
During anther development the male gametophyte develops inside the locule and the tapetal cells provide all nutrients for its development. Magnesium Transporter 5 (MGT5) is a member of the MGT family and has dual functions of Mg export and import. Here, we show that male gametophyte mitosis and intine formation are defective in a mgt5 mutant. The transient expression of GFP-MGT5 revealed that MGT5 is localized in the plasma membrane. These findings suggest that in the male gametophyte MGT5 plays a role in importing Mg from the locule and that Mg is essential for male gametophyte development. The expression of MGT5 in the knockout ABORTED MICROSPORES (AMS) mutant (AMS being an essential regulator of tapetum) is tremendously reduced. Chromatin immunoprecipitation and mobility shift assay experiments demonstrated that AMS can directly bind the promoter of MGT5. An immunoelectron microscopy assay revealed that MGT5-His is localized to the plasma membrane of the tapetum. These findings suggest that AMS directly regulates MGT5 in the tapetum and thus induces export of Mg into the locule. The mgt5 plant exhibits severe male sterility while the expression of MGT5 under the tapetum-specific promoter A9 partly rescued mgt5 fertility. mgt5 fertility was restored under high-Mg conditions. These findings suggest that the mgt5 tapetum still has the ability to export Mg and that a sufficient supply of Mg from the tapetum can improve the importation of Mg in the mgt5 male gametophyte. Therefore, MGT5 plays an important role in Mg transport from the tapetum to the microspore.
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Affiliation(s)
- Xiao-Feng Xu
- Department of Molecular and Cell Biology, School of Life Science and Technology, Tongji University, Shanghai, 200092, China
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Bo Wang
- Department of Molecular and Cell Biology, School of Life Science and Technology, Tongji University, Shanghai, 200092, China
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Yue Lou
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Wen-Jian Han
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Jie-Yang Lu
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Dan-Dan Li
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Le-Gong Li
- College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Jian Zhu
- Department of Molecular and Cell Biology, School of Life Science and Technology, Tongji University, Shanghai, 200092, China
| | - Zhong-Nan Yang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
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Biswas P, Kundu A, Ghosh AK. Genome segment 5 of Antheraea mylitta cytoplasmic polyhedrosis virus encodes a bona fide guanylyltransferase. Virol J 2014; 11:53. [PMID: 24649879 PMCID: PMC4000049 DOI: 10.1186/1743-422x-11-53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 03/10/2014] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Antheraea mylitta cytoplasmic polyhedrosis virus (AmCPV), a cypovirus of Reoviridae family, infects non mulberry Indian silk worm, Antheraea mylitta, and contains eleven segmented double stranded RNA in its genome (S1-S11). Some of its genome segments (S1-S3, and S6-S11) have been previously characterized but genome segment encoding the viral guanylyltransferase which helps in RNA capping has not been characterized. RESULTS In this study genome segment 5 (S5) of AmCPV was converted to cDNA, cloned and sequenced. S5 consisted of 2180 nucleotides, with one long ORF of 1818 nucleotides and could encode a protein of 606 amino acids with molecular mass of ~65 kDa (p65). Bioinformatics analysis showed presence of KLRS and HxnH motifs as observed in some other reoviral guanylyltransferase and suggests that S5 may encodes viral guanylyltransferase. The ORF of S5 was expressed in E. coli as 65 kDa his tagged fusion protein, purified through Ni-NTA chromatography and polyclonal antibody was raised. Immunoblot analysis of virion particles with the purified antibody showed specific immunoreactive band and suggests p65 as a viral structural protein. Functional analysis showed that recombinant p65 possesses guanylyltransferase activity, and transfers GMP moiety to the 5' diphosphate (A/G) ended viral RNA after the formation of p65-GMP complex for capping. Kinetic analysis showed K(m) of this enzyme for GTP and RNA was 34.24 uM and 98.35 nM, respectively. Site directed mutagenesis at K21A in KLRS motif, and H93A or H105A in HxnH motif completely abolished the autoguanylylation activity and indicates importance of these residues at these sites. Thermodynamic analysis showed p65-GTP interaction was primarily driven by enthalpy (ΔH = -399.1 ± 4.1 kJ/mol) whereas the p65-RNA interaction by favorable entropy (0.043 ± 0.0049 kJ/ mol). CONCLUSION Viral capping enzymes play a critical role in the post transcriptional or post replication modification in case of RNA virus. Our results of cloning, sequencing and functional analysis of AmCPV S5 indicates that S5 encoded p65 through its guanylyltransferase activity can transfer guanine residue to the 5' end of viral RNA for capping. Further studies will help to understand complete capping process of cypoviral RNA during viral replication within the viral capsid.
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Affiliation(s)
- Poulomi Biswas
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Anirban Kundu
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ananta Kumar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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