1
|
Bartels K, Lasitza‐Male T, Hofmann H, Löw C. Single-Molecule FRET of Membrane Transport Proteins. Chembiochem 2021; 22:2657-2671. [PMID: 33945656 PMCID: PMC8453700 DOI: 10.1002/cbic.202100106] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/03/2021] [Indexed: 12/31/2022]
Abstract
Uncovering the structure and function of biomolecules is a fundamental goal in structural biology. Membrane-embedded transport proteins are ubiquitous in all kingdoms of life. Despite structural flexibility, their mechanisms are typically studied by ensemble biochemical methods or by static high-resolution structures, which complicate a detailed understanding of their dynamics. Here, we review the recent progress of single molecule Förster Resonance Energy Transfer (smFRET) in determining mechanisms and timescales of substrate transport across membranes. These studies do not only demonstrate the versatility and suitability of state-of-the-art smFRET tools for studying membrane transport proteins but they also highlight the importance of membrane mimicking environments in preserving the function of these proteins. The current achievements advance our understanding of transport mechanisms and have the potential to facilitate future progress in drug design.
Collapse
Affiliation(s)
- Kim Bartels
- Centre for Structural Systems Biology (CSSB)DESY and European Molecular Biology Laboratory HamburgNotkestrasse 8522607HamburgGermany
| | - Tanya Lasitza‐Male
- Department of Structural BiologyWeizmann Institute of ScienceHerzl St. 2347610001RehovotIsrael
| | - Hagen Hofmann
- Department of Structural BiologyWeizmann Institute of ScienceHerzl St. 2347610001RehovotIsrael
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB)DESY and European Molecular Biology Laboratory HamburgNotkestrasse 8522607HamburgGermany
| |
Collapse
|
2
|
Ayala-Lopez N, Watts SW. Physiology and Pharmacology of Neurotransmitter Transporters. Compr Physiol 2021; 11:2279-2295. [PMID: 34190339 DOI: 10.1002/cphy.c200035] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Regulation of the ability of a neurotransmitter [our focus: serotonin, norepinephrine, dopamine, acetylcholine, glycine, and gamma-aminobutyric acid (GABA)] to reach its receptor targets is regulated in part by controlling the access the neurotransmitter has to receptors. Transporters, located at both the cellular plasma membrane and in subcellular vesicles, carry a myriad of responsibilities that include enabling neurotransmitter release and controlling uptake of neurotransmitter back into a cell or vesicle. Driven largely by electrochemical gradients, these transporters move neurotransmitters. The regulation of the transporters themselves through changes in expression and/or posttranslational modification allows for fine-tuning of this system. Transporters have been best recognized as targets for psychoactive stimulants and remain a mainstay target of primarily central nervous system (CNS) acting drugs for treatment of debilitating diseases such as depression and anxiety. Studies reveal, however, that transporters are found and functional in tissues outside the CNS (gastrointestinal and cardiovascular tissues, for example). The importance of neurotransmitter transporters is underscored with discoveries that dysfunction of transporters can cause life-changing disease. This article provides a high-level review of major classes of both plasma membrane transporters and vesicular transporters. © 2021 American Physiological Society. Compr Physiol 11:2279-2295, 2021.
Collapse
Affiliation(s)
- Nadia Ayala-Lopez
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
| |
Collapse
|
3
|
Perez-Jimenez E, Viana R, Muñoz-Ballester C, Vendrell-Tornero C, Moll-Diaz R, Garcia-Gimeno MA, Sanz P. Endocytosis of the glutamate transporter 1 is regulated by laforin and malin: Implications in Lafora disease. Glia 2020; 69:1170-1183. [PMID: 33368637 DOI: 10.1002/glia.23956] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/10/2020] [Accepted: 12/10/2020] [Indexed: 01/13/2023]
Abstract
Lafora disease (LD) is a fatal rare type of progressive myoclonus epilepsy that appears during early adolescence. The disease is caused by mutations in EPM2A or EPM2B genes, which encode laforin, a glucan phosphatase, and malin, an E3-ubiquitin ligase, respectively. Although the exact roles of laforin and malin are still not well understood, it is known that they work as a complex in which laforin recruits targets that will be ubiquitinated by malin. Recently, we suggested that the type of epilepsy that accompanies LD could be due to deficiencies in the function of the astrocytic glutamate transporter GLT-1. We described that astrocytes from LD mouse models presented decreased levels of GLT-1 at the plasma membrane, leading to increased levels of glutamate in the brain parenchyma. In this work, we present evidence indicating that in the absence of a functional laforin/malin complex (as in LD cellular models) there is an alteration in the ubiquitination of GLT-1, which could be the cause of the reduction in the levels of GLT-1 at the plasma membrane. On the contrary, overexpression of the laforin/malin complex promotes the retention of GLT-1 at the plasma membrane. This retention may be due to the direct ubiquitination of GLT-1 and/or to an opposite effect of this complex on the dynamics of the Nedd4.2-mediated endocytosis of the transporter. This work, therefore, presents new pieces of evidence on the regulation of GLT-1 by the laforin/malin complex, highlighting its value as a therapeutic target for the amelioration of the type of epilepsy that accompanies LD.
Collapse
Affiliation(s)
- Eva Perez-Jimenez
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| | - Rosa Viana
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| | - Carmen Muñoz-Ballester
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| | - Carlos Vendrell-Tornero
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| | - Raquel Moll-Diaz
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| | | | - Pascual Sanz
- Consejo Superior de Investigaciones Científicas, Instituto de Biomedicina de Valencia, Valencia, Spain.,CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Biomedicina de Valencia, Valencia, Spain
| |
Collapse
|