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Takahashi K, Sato K. The Conventional and Breakthrough Tool for the Study of L-Glutamate Transporters. MEMBRANES 2024; 14:77. [PMID: 38668105 PMCID: PMC11052088 DOI: 10.3390/membranes14040077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/26/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024]
Abstract
In our recent report, we clarified the direct interaction between the excitatory amino acid transporter (EAAT) 1/2 and polyunsaturated fatty acids (PUFAs) by applying electrophysiological and molecular biological techniques to Xenopus oocytes. Xenopus oocytes have a long history of use in the scientific field, but they are still attractive experimental systems for neuropharmacological studies. We will therefore summarize the pharmacological significance, advantages (especially in the study of EAAT2), and experimental techniques that can be applied to Xenopus oocytes; our new findings concerning L-glutamate (L-Glu) transporters and PUFAs; and the significant outcomes of our data. The data obtained from electrophysiological and molecular biological studies of Xenopus oocytes have provided us with further important questions, such as whether or not some PUFAs can modulate EAATs as allosteric modulators and to what extent docosahexaenoic acid (DHA) affects neurotransmission and thereby affects brain functions. Xenopus oocytes have great advantages in the studies about the interactions between molecules and functional proteins, especially in the case when the expression levels of the proteins are small in cell culture systems without transfections. These are also proper to study the mechanisms underlying the interactions. Based on the data collected in Xenopus oocyte experiments, we can proceed to the next step, i.e., the physiological roles of the compounds and their significances. In the case of EAAT2, the effects on the neurotransmission should be examined by electrophysiological approach using acute brain slices. For new drug development, pharmacokinetics pharmacodynamics (PKPD) data and blood brain barrier (BBB) penetration data are also necessary. In order not to miss the promising candidate compounds at the primary stages of drug development, we should reconsider using Xenopus oocytes in the early phase of drug development.
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Grants
- a Research Grant on Regulatory Harmonization and Evaluation of Pharmaceuticals, Medical Devices, Regenerative and Cellular Therapy Products, Gene Therapy Products, and Cosmetics from AMED, Japan Japan Agency for Medical Research and Development
- KAKENHI 18700373, 21700422, 17K08330 Ministry of Education, Culture, Sports, Science and Technology
- a Grant for the Program for Promotion of Fundamental Studies in Health Sciences of NIBIO National Institute of Biomedical Innovation, Health and Nutrition
- a grant for Research on Risks of Chemicals, a Labor Science Research Grant for Research on New Drug Development MHLW
- a Grant-in-Aid from Hoansha Foundation Hoansha Foundation
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Affiliation(s)
| | - Kaoru Sato
- Laboratory of Neuropharmacology, Division of Pharmacology, National Institute of Health Sciences, Kanagawa 210-9501, Japan;
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Zhang Y, Jiang Y, Gao K, Sui D, Yu P, Su M, Wei GW, Hu J. Structural insights into the elevator-type transport mechanism of a bacterial ZIP metal transporter. Nat Commun 2023; 14:385. [PMID: 36693843 PMCID: PMC9873690 DOI: 10.1038/s41467-023-36048-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 01/13/2023] [Indexed: 01/26/2023] Open
Abstract
The Zrt-/Irt-like protein (ZIP) family consists of ubiquitously expressed divalent metal transporters critically involved in maintaining systemic and cellular homeostasis of zinc, iron, and manganese. Here, we present a study on a prokaryotic ZIP from Bordetella bronchiseptica (BbZIP) by combining structural biology, evolutionary covariance, computational modeling, and a variety of biochemical assays to tackle the issue of the transport mechanism which has not been established for the ZIP family. The apo state structure in an inward-facing conformation revealed a disassembled transport site, altered inter-helical interactions, and importantly, a rigid body movement of a 4-transmembrane helix (TM) bundle relative to the other TMs. The computationally generated and biochemically validated outward-facing conformation model revealed a slide of the 4-TM bundle, which carries the transport site(s), by approximately 8 Å toward the extracellular side against the static TMs which mediate dimerization. These findings allow us to conclude that BbZIP is an elevator-type transporter.
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Affiliation(s)
- Yao Zhang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Yuhan Jiang
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Kaifu Gao
- Department of Mathematics, Michigan State University, East Lansing, MI, USA
| | - Dexin Sui
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Peixuan Yu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Min Su
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Guo-Wei Wei
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Department of Mathematics, Michigan State University, East Lansing, MI, USA
| | - Jian Hu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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Wiuf A, Steffen JH, Becares ER, Grønberg C, Mahato DR, Rasmussen SGF, Andersson M, Croll T, Gotfryd K, Gourdon P. The two-domain elevator-type mechanism of zinc-transporting ZIP proteins. SCIENCE ADVANCES 2022; 8:eabn4331. [PMID: 35857505 PMCID: PMC9278863 DOI: 10.1126/sciadv.abn4331] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 05/27/2022] [Indexed: 05/13/2023]
Abstract
Zinc is essential for all organisms and yet detrimental at elevated levels. Hence, homeostasis of this metal is tightly regulated. The Zrt/Irt-like proteins (ZIPs) represent the only zinc importers in metazoans. Mutations in human ZIPs cause serious disorders, but the mechanism by which ZIPs transfer zinc remains elusive. Hitherto, structural information is only available for a model member, BbZIP, and as a single, ion-bound conformation, precluding mechanistic insights. Here, we elucidate an inward-open metal-free BbZIP structure, differing substantially in the relative positions of the two separate domains of ZIPs. With accompanying coevolutional analyses, mutagenesis, and uptake assays, the data point to an elevator-type transport mechanism, likely shared within the ZIP family, unifying earlier functional data. Moreover, the structure reveals a previously unknown ninth transmembrane segment that is important for activity in vivo. Our findings outline the mechanistic principles governing ZIP-protein transport and enhance the molecular understanding of ZIP-related disorders.
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Affiliation(s)
- Anders Wiuf
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Jonas Hyld Steffen
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Eva Ramos Becares
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Christina Grønberg
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Dhani Ram Mahato
- Department of Chemistry, Umeå University, Linnaeus Väg 10, SE-901 87 Umeå, Sweden
| | - Søren G. F. Rasmussen
- Department of Neuroscience, University of Copenhagen, Maersk Tower 7-5, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Magnus Andersson
- Department of Chemistry, Umeå University, Linnaeus Väg 10, SE-901 87 Umeå, Sweden
| | - Tristan Croll
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, Keith Peters Building, Hills Rd., Cambridge CB2 0XY, UK
| | - Kamil Gotfryd
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Mærsk Tower 7-9, Nørre Allé 14, DK-2200 Copenhagen, Denmark
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84 Lund, Sweden
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