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Kumari P, Agrawal P, Umarao P, Ramachandran V, Gourinath S. Identification of Small Molecule Inhibitors Targeting Phosphoserine Phosphatase: A Novel Target for the Development of Antiamoebic Drugs. ACS OMEGA 2024; 9:27906-27918. [PMID: 38973836 PMCID: PMC11223228 DOI: 10.1021/acsomega.3c09439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 07/09/2024]
Abstract
Amoebiasis, a widespread disease caused by the protozoan parasite Entamoeba histolytica, poses challenges due to the adverse effects of existing antiamoebic drugs and rising drug resistance. Novel targeted drugs are in need of the hour to combat the prevalence of this disease. Given the significance of cysteine for Entamoeba survival, the rate-determining step in the serine (the sole substrate of cysteine synthesis) biosynthetic pathway, i.e., the conversion of 3-phosphoserine to l-serine catalyzed by phosphoserine phosphatase (PSP), emerges as a promising drug target. Our previous study unveils the essential role of EhPSP in amoebas' survival, particularly under oxidative stress, by increasing cysteine production. The study also revealed that EhPSP differs significantly from its human counterpart, both structurally and biochemically, highlighting its potential as a viable target for developing new antiamoebic drugs. In the present study, employing in silico screening of vast natural and synthetic small chemical compound libraries, we identified 21 potential EhPSP inhibitor molecules. Out of the 21 compounds examined, only five could inhibit the catalytic activity of EhPSP. The inhibition capability of these five compounds was subsequently validated by in silico binding free energy calculations, SPR-based real-time binding studies, and molecular simulations to assess the stability of the EhPSP-inhibitor complexes. By identifying the five potential inhibitors that can target cysteine synthesis via EhPSP, our findings establish EhPSP as a drug candidate that can serve as a foundation for antiamoebic drug research.
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Affiliation(s)
- Poonam Kumari
- International
Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
- Structural
Biology Lab, School of Life Sciences, Jawaharlal
Nehru University, New Delhi 110067, India
| | - Prakhar Agrawal
- International
Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Preeti Umarao
- Structural
Biology Lab, School of Life Sciences, Jawaharlal
Nehru University, New Delhi 110067, India
| | - Vijayan Ramachandran
- The
Centre for Innovation in Brain Sciences, University of Arizona, Tucson 85721, Arizona, United States
| | - Samudrala Gourinath
- Structural
Biology Lab, School of Life Sciences, Jawaharlal
Nehru University, New Delhi 110067, India
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Jang J, Chang JH. Molecular Structure of Phosphoserine Aminotransferase from Saccharomyces cerevisiae. Int J Mol Sci 2023; 24:ijms24065139. [PMID: 36982214 PMCID: PMC10049462 DOI: 10.3390/ijms24065139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
Phosphoserine aminotransferase (PSAT) is a pyridoxal 5′-phosphate-dependent enzyme involved in the second step of the phosphorylated pathway of serine biosynthesis. PSAT catalyzes the transamination of 3-phosphohydroxypyruvate to 3-phosphoserine using L-glutamate as the amino donor. Although structural studies of PSAT have been performed from archaea and humans, no structural information is available from fungi. Therefore, to elucidate the structural features of fungal PSAT, we determined the crystal structure of Saccharomyces cerevisiae PSAT (ScPSAT) at a resolution of 2.8 Å. The results demonstrated that the ScPSAT protein was dimeric in its crystal structure. Moreover, the gate-keeping loop of ScPSAT exhibited a conformation similar to that of other species. Several distinct structural features in the halide-binding and active sites of ScPSAT were compared with its homologs. Overall, this study contributes to our current understanding of PSAT by identifying the structural features of fungal PSAT for the first time.
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Affiliation(s)
- Jiyeon Jang
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Department of Biomedical Convergence Science and Technology, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
- Correspondence: ; Tel.: +82-53-950-5913; Fax: +82-53-950-6809
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Marchesani F, Zangelmi E, Murtas G, Costanzi E, Ullah R, Peracchi A, Bruno S, Pollegioni L, Mozzarelli A, Storici P, Campanini B. L-Serine Biosynthesis in The Human Central Nervous System: Structure and Function of Phosphoserine Aminotransferase. Protein Sci 2023; 32:e4609. [PMID: 36851825 PMCID: PMC10031235 DOI: 10.1002/pro.4609] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 01/12/2023] [Accepted: 02/23/2023] [Indexed: 03/01/2023]
Abstract
Organisms from all kingdoms of life synthesize L-serine from 3-phosphoglycerate through the phosphorylated pathway, a three-step diversion of glycolysis. Phosphoserine aminotransferase (PSAT) catalyzes the intermediate step, the pyridoxal 5'-phosphate-dependent transamination of 3-phosphohydroxypyruvate and L-glutamate to O-phosphoserine and α-ketoglutarate. PSAT is particularly relevant in the central nervous system of mammals because L-serine is the metabolic precursor of D-serine, cysteine, phospholipids, and nucleotides. Several mutations in the human psat gene have been linked to serine deficiency disorders, characterized by severe neurological symptoms. Furthermore, PSAT is overexpressed in many tumors and this overexpression has been associated with poor clinical outcomes. Here, we report the detailed functional and structural characterization of the recombinant human PSAT. The reaction catalyzed by PSAT is reversible, with an equilibrium constant of about 10, and the enzyme is very efficient, with a kcat /Km of 5.9 × 106 M-1 s-1 , thus contributing in driving the pathway towards the products despite the extremely unfavorable first step catalyzed by 3-phosphoglycerate dehydrogenase. The three-dimensional X-ray crystal structure of PSAT was solved in the substrate-free as well as in the O-phosphoserine-bound forms. Both structures contain eight protein molecules in the asymmetric unit, arranged in four dimers, with a bound cofactor in each subunit. In the substrate-free form, the active site of PSAT contains a sulfate ion that, in the substrate-bound form, is replaced by the phosphate group of O-phosphoserine. Interestingly, fast crystal soaking used to produce the substrate-bound form allowed the trapping of different intermediates along the catalytic cycle. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Erika Zangelmi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Giulia Murtas
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Elisa Costanzi
- Protein Facility, Elettra Sincrotrone Trieste S.C.p.A., Trieste, Italy
| | - Raheem Ullah
- Protein Facility, Elettra Sincrotrone Trieste S.C.p.A., Trieste, Italy
- Present address: Structural Biology Lab, NIBGE, Faisalabad, Pakistan
| | - Alessio Peracchi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Stefano Bruno
- Department of Food and Drug, University of Parma, Parma, Italy
| | - Loredano Pollegioni
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | | | - Paola Storici
- Protein Facility, Elettra Sincrotrone Trieste S.C.p.A., Trieste, Italy
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Mishra V. Affinity Tags for Protein Purification. Curr Protein Pept Sci 2021; 21:821-830. [PMID: 32504500 DOI: 10.2174/1389203721666200606220109] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 04/09/2020] [Accepted: 05/06/2020] [Indexed: 11/22/2022]
Abstract
The affinity tags are unique proteins/peptides that are attached at the N- or C-terminus of the recombinant proteins. These tags help in protein purification. Additionally, some affinity tags also serve a dual purpose as solubility enhancers for challenging protein targets. By applying a combinatorial approach, carefully chosen affinity tags designed in tandem have proven to be very successful in the purification of single proteins or multi-protein complexes. In this mini-review, the key features of the most commonly used affinity tags are discussed. The affinity tags have been classified into two significant categories, epitope tags, and protein/domain tags. The epitope tags are generally small peptides with high affinity towards a chromatography resin. The protein/domain tags often perform double duty as solubility enhancers as well as aid in affinity purification. Finally, protease-based affinity tag removal strategies after purification are discussed.
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Affiliation(s)
- Vibhor Mishra
- Department of Biology, Indiana University, Bloomington, IN 47405, USA,Howard Hughes Medical Institute, Indiana University, Bloomington, IN 47405, USA
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5
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Singh RK, Kumar D, Gourinath S. Phosphoserine aminotransferase has conserved active site from microbes to higher eukaryotes with minor deviations. Protein Pept Lett 2021; 28:996-1008. [PMID: 33588715 DOI: 10.2174/0929866528666210215140231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 11/22/2022]
Abstract
Serine is ubiquitously synthesized in all living organisms from the glycolysis intermediate 3-phosphoglycerate (PGA) by phosphoserine biosynthetic pathway, consisting of three different enzymes, namely: 3-phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Any functional defect or mutation in these enzymes may cause deliberating conditions, such as colon cancer progression and chemoresistance in humans. Phosphoserine aminotransferase (PSAT) is the second enzyme in this pathway that converts phosphohydroxypyruvate (PHP) to O-phospho-L-serine (OPLS). Humans encode two isoforms of this enzyme: PSAT1 and PSAT2. PSAT1 exists as a functional dimer, where each protomer has a large and a small domain; each large domain contains a Lys residue that covalently binds PLP. The PLP-binding site of human PSAT1 and most of its active site residues are highly conserved in all known PSAT structures except for Cys-80. Interestingly, Two PSAT structures from different organisms show halide binding near their active site. While the human PSAT1 shows a water molecule at this site with different interacting residues, suggesting the inability of halide binding in the human enzyme. Analysis of the human PSAT1 structure showed a big patch of positive charge around the active site, in contrast to the bacterial PSATs. Compared to human PSAT1, the PSAT2 isoform lacks 46 residues at its C-terminal tail. This tail region is present at the opening of the active site as observed in the other PSAT structures. Further structural work on human PSAT2 may reveal the functional importance of these 46 residues.
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Affiliation(s)
- Rohit Kumar Singh
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi - 110067. India
| | - Devbrat Kumar
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi - 110067. India
| | - Samudrala Gourinath
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi - 110067. India
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Tarique KF, Devi S, Tomar P, Ali MF, Rehman SAA, Gourinath S. Characterization and functional insights into the Entamoeba histolytica pyridoxal kinase, an enzyme essential for its survival. J Struct Biol 2020; 212:107645. [PMID: 33045383 DOI: 10.1016/j.jsb.2020.107645] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/29/2020] [Accepted: 10/06/2020] [Indexed: 01/18/2023]
Abstract
Pyridoxal 5'-phosphate (PLP) is the active form of vitamin B6 and a cofactor for more than 140 enzymes. This coenzyme plays a pivotal role in catalysis of various enzymatic reactions that are critical for the survival of organisms. Entamoeba histolytica depends on the uptake of pyridoxal (PL), a B6 vitamer from the external environment which is then phosphorylated by pyridoxal kinase (EhPLK) to form PLP via the salvage pathway. E. histolytica cannot synthesise vitamin B6de-novo, and also lacks pyridoxine 5'-phosphate oxidase, a salvage pathway enzyme required to produce PLP from pyridoxine phosphate (PNP) and pyridoxamine phosphate (PMP). Analysing the importance of PLK in E. histolytica, we have determined the high-resolution crystal structures of the dimeric pyridoxal kinase in apo, ADP-bound, and PLP-bound states. These structures provided a snapshot of the transition state and help in understanding the reaction mechanism in greater detail. The EhPLK structure significantly differed from the human homologue at its PLP binding site, and the phylogenetic study also revealed its divergence from human PLK. Further, gene regulation of EhPLK using sense and antisense RNA showed that any change in optimal level is harmful to the pathogen. Biochemical and in vivo studies unveiled EhPLK to be essential for this pathogen, while the molecular differences with human PLK structure can be exploited for the structure-guided design of EhPLK inhibitors.
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Affiliation(s)
- Khaja Faisal Tarique
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India; Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Suneeta Devi
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Priya Tomar
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mohammad Farhan Ali
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Syed Arif Abdul Rehman
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India; MRC Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Samudrala Gourinath
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
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Abdelfattah F, Kariminejad A, Kahlert AK, Morrison PJ, Gumus E, Mathews KD, Darbro BW, Amor DJ, Walsh M, Sznajer Y, Weiß L, Weidensee S, Chitayat D, Shannon P, Bermejo-Sánchez E, Riaño-Galán I, Hayes I, Poke G, Rooryck C, Pennamen P, Khung-Savatovsky S, Toutain A, Vuillaume ML, Ghaderi-Sohi S, Kariminejad MH, Weinert S, Sticht H, Zenker M, Schanze D. Expanding the genotypic and phenotypic spectrum of severe serine biosynthesis disorders. Hum Mutat 2020; 41:1615-1628. [PMID: 32579715 DOI: 10.1002/humu.24067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/31/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022]
Abstract
Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.
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Affiliation(s)
- Fatima Abdelfattah
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | | | - Anne-Karin Kahlert
- Institut für Klinische Genetik, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Department of Congenital Heart Disease and Pediatric Cardiology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Patrick J Morrison
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, UK
| | - Evren Gumus
- Division of Medical Genetics, School of Medicine, Harran University, Sanliurfa, Turkey
| | | | | | - David J Amor
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia.,Royal Children's Hospital, Parkville, Victoria, Australia
| | - Maie Walsh
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Yves Sznajer
- Centre de Génétique Humaine, Cliniques Universitaires Saint Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Luisa Weiß
- Institut für Klinische Genetik, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | | | - David Chitayat
- Department of Obstetrics and Gynecology, The Prenatal Diagnosis and Medical Genetics Program, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.,Division of Clinical and Metabolic Genetics, The Hospital for SickKids, University of Toronto, Toronto, Ontario, Canada
| | - Patrick Shannon
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Eva Bermejo-Sánchez
- ECEMC (Spanish Collaborative Study of Congenital Malformations), Research Unit on Congenital Anomalies (UIAC), Institute of Rare Diseases Research (IIER), Institute of Health Carlos III, Ministry of Science and Innovation, Madrid, Spain
| | - Isolina Riaño-Galán
- AGC de Pediatría, Hospital Universitario Central de Asturias, Oviedo, Spain.,IUOPA-Departamento de Medicina-ISPA, Universidad de Oviedo, Oviedo, Spain.,CIBER de Epidemiologia y Salud Pública, Madrid, Spain
| | - Ian Hayes
- Genetic Health Service New Zealand, Auckland Hospital, Auckland, New Zealand
| | - Gemma Poke
- Genetic Health Service New Zealand, Wellington Regional Hospital, Wellington, New Zealand
| | - Caroline Rooryck
- MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, University of Bordeaux, Bordeaux, France
| | - Perrine Pennamen
- MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, University of Bordeaux, Bordeaux, France
| | | | - Annick Toutain
- Service de Génétique, CHU de Tours, UMR 1253, iBrain, Université de Tours, INSERM, Tours, France
| | - Marie-Laure Vuillaume
- Service de Génétique, CHU de Tours, UMR 1253, iBrain, Université de Tours, INSERM, Tours, France
| | | | | | - Sönke Weinert
- Department of Cardiology and Angiology, Internal Medicine, University Hospital Magdeburg, Magdeburg, Germany
| | - Heinrich Sticht
- Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martin Zenker
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | - Denny Schanze
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
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N-terminal residues are crucial for quaternary structure and active site conformation for the phosphoserine aminotransferase from enteric human parasite E. histolytica. Int J Biol Macromol 2019; 132:1012-1023. [PMID: 30959130 DOI: 10.1016/j.ijbiomac.2019.04.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 11/24/2022]
Abstract
Phosphoserine aminotransferase (PSAT) is a pyridoxal-5'phosphate (PLP)-dependent enzyme that catalyzes the second reversible step in the phosphoserine biosynthetic pathway producing serine. The crystal structure of E. histolytica PSAT (EhPSAT) complexed with PLP was elucidated at 3.0 Å resolution and the structures of its mutants, EhPSAT_Δ45 and EhPSAT_Δ4, at 1.8 and 2.4 Å resolution respectively. Deletion of 45 N-terminal residues (EhPSAT_Δ45) resulted in an inactive protein, the structure showed a dimeric arrangement drastically different from that of the wild-type protein, with the two monomers translated and rotated by almost 180° with respect to each other; causing a rearrangement of the active site to which PLP was unable to bind. Deletion of first N-terminal 15 (EhPSAT_Δ15) and four 11th to 14th residues (EhPSAT_Δ4) yielded up to 98% and 90% decrease in the activity respectively. Absence of aldimine linkage between PLP-Lys in the crystal structure of EhPSAT_Δ4 mutant explains for such decrease in activity and describes the importance of these N-terminal residues. Furthermore, a halide-binding site was found in close proximity to the active site. A stretch of six amino acids (146-NNTIYG-151) only conserved in the Entamoeba genus, contributes to halide binding may explain that the halide inhibition could be specific to Entamoeba.
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Structural investigation and inhibitory response of halide on phosphoserine aminotransferase from Trichomonas vaginalis. Biochim Biophys Acta Gen Subj 2016; 1860:1508-18. [PMID: 27102280 DOI: 10.1016/j.bbagen.2016.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 04/04/2016] [Accepted: 04/17/2016] [Indexed: 11/20/2022]
Abstract
BACKGROUND Phosphoserine aminotransferase (PSAT) catalyses the second reversible step of the phosphoserine biosynthetic pathway in Trichomonas vaginalis, which is crucial for the synthesis of serine and cysteine. METHODS PSAT from T. vaginalis (TvPSAT) was analysed using X-ray crystallography, enzyme kinetics, and molecular dynamics simulations. RESULTS The crystal structure of TvPSAT was determined to 2.15Å resolution, and is the first protozoan PSAT structure to be reported. The active site of TvPSAT structure was found to be in a closed conformation, and at the active site PLP formed an internal aldimine linkage to Lys 202. In TvPSAT, Val 340 near the active site while it is Arg in most other members of the PSAT family, might be responsible in closing the active site. Kinetic studies yielded Km values of 54 μM and 202 μM for TvPSAT with OPLS and AKG, respectively. Only iodine inhibited the TvPSAT activity while smaller halides could not inhibit. CONCLUSION Results from the structure, comparative molecular dynamics simulations, and the inhibition studies suggest that iodine is the only halide that can bind TvPSAT strongly and may thus inhibit the activity of TvPSAT. The long loop between β8 and α8 at the opening of the TvPSAT active site cleft compared to other PSATs, suggests that this loop may help control the access of substrates to the TvPSAT active site and thus influences the enzyme kinetics. GENERAL SIGNIFICANCE Our structural and functional studies have improved our understanding of how PSAT helps this organism persists in the environment.
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Penuliar GM, Nakada-Tsukui K, Nozaki T. Phenotypic and transcriptional profiling in Entamoeba histolytica reveal costs to fitness and adaptive responses associated with metronidazole resistance. Front Microbiol 2015; 6:354. [PMID: 25999919 PMCID: PMC4419850 DOI: 10.3389/fmicb.2015.00354] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/08/2015] [Indexed: 12/11/2022] Open
Abstract
Antimicrobial chemotherapy is critical in the fight against infectious diseases caused by Entamoeba histolytica. Among the drugs available for the treatment of amebiasis, metronidazole (MTZ) is considered the drug of choice. Recently, in vitro studies have described MTZ resistance and the potential mechanisms involved. Costs to fitness and adaptive responses associated with resistance, however, have not been investigated. In this study we generated an HM-1 derived strain resistant to 12 μM MTZ (MTZR). We examined its phenotypic and transcriptional profile to determine the consequences and mRNA level changes associated with MTZ resistance. Our results indicated increased cell size and granularity, and decreased rates in cell division, adhesion, phagocytosis, cytopathogenicity, and glucose consumption. Transcriptome analysis revealed 142 differentially expressed genes in MTZR. In contrast to other MTZ resistant parasites, MTZR did not down-regulate pyruvate:ferredoxin oxidoreductase, but showed increased expression of genes for a hypothetical protein (HP1) and several iron-sulfur flavoproteins, and downregulation of genes for leucine-rich proteins. Fisher's exact test showed 24 significantly enriched GO terms in MTZR, and a 3-way comparison of modulated genes in MTZR against those of MTZR cultured without MTZ and HM-1 cultured with MTZ, showed that 88 genes were specific to MTZR. Overall, our findings suggested that MTZ resistance is associated with specific transcriptional changes and decreased parasite virulence.
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Affiliation(s)
- Gil M Penuliar
- Department of Parasitology, National Institute of Infectious Diseases Tokyo, Japan ; Department of Parasitology, Gunma University Graduate School of Medicine Maebashi, Japan
| | - Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases Tokyo, Japan
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases Tokyo, Japan ; Graduate School of Life and Environmental Sciences, University of Tsukuba Tsukuba, Japan
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Wang ZD, Jiang YR, Sun Y, Li Q, Li YP, Du ZJ, Liu YQ, Qin L. Molecular characterization of a phosphoserine aminotransferase gene in Antheraea pernyi and assessment of its value for phylogenetic inference. BIOCHEM SYST ECOL 2013. [DOI: 10.1016/j.bse.2013.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Mishra V, Kumar A, Ali V, Nozaki T, Zhang KY, Bhakuni V. Novel protein–protein interactions between Entamoeba histolytica d-phosphoglycerate dehydrogenase and phosphoserine aminotransferase. Biochimie 2012; 94:1676-86. [DOI: 10.1016/j.biochi.2012.02.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 02/18/2012] [Indexed: 11/26/2022]
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13
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Mishra V, Kumar A, Ali V, Nozaki T, Zhang KYJ, Bhakuni V. Role of conserved active site tryptophan-101 in functional activity and stability of phosphoserine aminotransferase from an enteric human parasite. Amino Acids 2011; 43:483-91. [PMID: 22038178 DOI: 10.1007/s00726-011-1105-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/23/2011] [Indexed: 10/15/2022]
Abstract
Site-directed mutagenesis study was performed to elucidate the role of conserved tryptophan-101 present at the active site of phosphoserine aminotransferase from an enteric human parasite Entamoeba histolytica. Fluorescence resonance energy transfer and molecular dynamic simulation show that the indole ring of Trp101 stacks with the cofactor PLP. Loss of enzymatic activity and PLP polarization values suggest that Trp101 plays a major role in maintaining a defined PLP microenvironment essentially required for optimal enzymatic activity. Studies on W101F, W101H and W101A mutants show that only the indole ring of the conserved Trp101 forms most favorable stacking interaction with the pyridine ring of the cofactor PLP. Protein stability was compromised on substitution of Trp101 with Phe/His/Ala amino acids. A difference in conformational free energy of 1.65 kcal mol(-1) was observed between WT-protein and W101A mutant.
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Affiliation(s)
- Vibhor Mishra
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, 226001, India.
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Biophysical characterization of Entamoeba histolytica phosphoserine aminotransferase (EhPSAT): role of cofactor and domains in stability and subunit assembly. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 40:599-610. [DOI: 10.1007/s00249-010-0654-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 11/21/2010] [Accepted: 11/25/2010] [Indexed: 10/18/2022]
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