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Perbandt M, Eberle R, Fischer-Riepe L, Cang H, Liebau E, Betzel C. High resolution structures of Plasmodium falciparum GST complexes provide novel insights into the dimer-tetramer transition and a novel ligand-binding site. J Struct Biol 2015; 191:365-75. [PMID: 26072058 DOI: 10.1016/j.jsb.2015.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
Protection from oxidative stress and efficient redox regulation are essential for malarial parasites which have to grow and multiply rapidly in pro-oxidant rich environments. Therefore, redox active proteins currently belong to the most attractive antimalarial drug targets. The glutathione S-transferase from Plasmodium falciparum (PfGST) is a redox active protein displaying a peculiar dimer-tetramer transition that causes full enzyme-inactivation. This distinct structural feature is absent in mammalian GST isoenzyme counterparts. A flexible loop between residues 113-119 has been reported to be necessary for this tetramerization process. However, here we present structural data of a modified PfGST lacking loop 113-119 at 1.9 Å resolution. Our results clearly show that this loop is not essential for the formation of stable tetramers. Moreover we present for the first time the structures of both, the inactive and tetrameric state at 1.7 Å and the active dimeric state in complex with reduced glutathione at 2.4 Å resolution. Surprisingly, the structure of the inactive tetrameric state reveals a novel non-substrate binding-site occupied by a 2-(N-morpholino) ethane sulfonic acid (MES) molecule in each monomer. Although it is known that the PfGST has the ability to bind lipophilic anionic ligands, the location of the PfGST ligand-binding site remained unclear up to now.
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Affiliation(s)
- Markus Perbandt
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany; Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf (UKE), D-20246 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.
| | - Raphael Eberle
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany
| | - Lena Fischer-Riepe
- Department of Molecular Physiology, University of Münster, Schlossplatz 8, D-48143 Münster, Germany
| | - Huaixing Cang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Eva Liebau
- Department of Molecular Physiology, University of Münster, Schlossplatz 8, D-48143 Münster, Germany
| | - Christian Betzel
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
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Plancarte A, Romero JR, Nava G, Reyes H, Hernández M. Evaluation of the non-catalytic binding function of Ts26GST a glutathione transferase isoform of Taenia solium. Exp Parasitol 2014; 138:63-70. [PMID: 24560769 DOI: 10.1016/j.exppara.2014.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 02/07/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022]
Abstract
Taenia solium glutathione transferase isoform of 26.5 kDa (Ts26GST) was observed to bind non-catalytically to porphyrins, trans-trans-dienals, bile acids and fatty acids, as assessed by inhibition kinetics, fluorescence spectroscopy and competitive fluorescence assays with 8-anilino-1-naphthalene sulfonate (ANS). The quenching of Ts26GST intrinsic fluorescence allowed for the determination of the dissociation constants (KD) for all ligands. Obtained data indicate that Ts26GST binds to all ligands but with different affinity. Porphyrins and lipid peroxide products inhibited Ts26GST catalytic activity up to 100% in contrast with only 20-30% inhibition observed for bile acids and two saturated fatty acids. Non-competitive type inhibition was observed for all enzyme inhibitor ligands except for trans-trans-2,4-decadienal, which exhibited uncompetitive type inhibition. The dissociation constant value KD = 0.7 μM for the hematin ligand, determined by competitive fluorescence assays with ANS, was in good agreement with its inhibition kinetic value Ki = 0.3 μM and its intrinsic fluorescence quenching KD = 0.7 μM. The remaining ligands did not displace ANS from the enzyme suggesting the existence of different binding sites. In addition to the catalytic activity of Ts26GST the results obtained suggest that the enzyme exhibits a ligandin function with broad specificity towards nonsubstrate ligands.
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Affiliation(s)
- A Plancarte
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico.
| | - J R Romero
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
| | - G Nava
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
| | - H Reyes
- Laboratorio de Bioquímica-Genética y División de Investigación, Instituto Nacional de Pediatría, D.F., Mexico
| | - M Hernández
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, México, D.F. 04510, Mexico
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