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Structures of solute carrier membrane transport proteins

English title Structures of solute carrier membrane transport proteins
Applicant Fotiadis Dimitrios
Number 184980
Funding scheme Project funding (Div. I-III)
Research institution Institut für Biochemie und Molekulare Medizin Universität Bern
Institution of higher education University of Berne - BE
Main discipline Biophysics
Start/End 01.07.2019 - 30.06.2023
Approved amount 672'000.00
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All Disciplines (2)

Discipline
Biophysics
Biochemistry

Keywords (9)

membrane protein; glucose transport protein; three-dimensional crystal; cryo-electron microscopy; monocarboxylate transport protein; crystallization; structure; membrane transport protein; X-ray crystallography

Lay Summary (German)

Lead
Die in diesem Projekt ermittelten Strukturen von Monocarboxylat- und Glucosetransportern werden ihre Wirkmechanismen auf molekularer Ebene enthüllen. Darüber hinaus werden Strukturen pharmakologisch relevanter Monocarboxylat-Transporter wertvoll sein, um die molekularen Ursachen spezifischer genetischer Erkrankungen zu verstehen und das strukturbasierte Wirkstoffdesign zu unterstützen.
Lay summary

Transporter sind Proteine, die in biologischen Membranen eingebettet sind und für den Transfer von gelösten Stoffen in und aus Zellen und Zellorganellen verantwortlich sind. Transportierte gelöste Stoffe umfassen Ionen, Nährstoffe, Metaboliten und zelluläre Abfallprodukte. Fehlfunktionen oder Überexpression bestimmter Transporter können zu schweren Erkrankungen des Menschen wie Krebs, Diabetes, Bluthochdruck, Osteoporose, neurologischen Erkrankungen und psychischen Störungen führen.

Dreidimensionale (3D-) Strukturen von Transportern, d. h., die 3D-Anordnung von Atomen im Protein, sind für das Verständnis ihrer molekularen Wirkmechanismen und für das strukturbasierte Wirkstoffdesign von großem Wert. Darüber hinaus können Strukturen verwendet werden, um die Ursachen spezifischer genetischer Störungen auf molekularer Ebene zu verstehen. Die Anzahl hochaufgelöster Strukturen von Transportproteinen sind jedoch gering und die Strukturen äußerst schwierig zu erhalten.

In diesem Projektantrag des Schweizerischen Nationalfonds sollen die Strukturen spezifischer bakterieller und humaner Monocarboxylat-Transporter (MCTs) sowie eines bakteriellen Glukosetransporters (IICB) mittels Kristallographie und hochauflösender Elektronenmikroskopie bestimmt werden. Diese Zieltransporter sind hochinteressant, da sie eine Schlüsselrolle bei der Proliferation, Invasion und Metastasierung von Tumorzellen (MCTs) und bei der Aufnahme von Glucose (einer wichtigen Energiequelle) in Bakterien (IICB) spielen. Die Kenntnis der Strukturen dieser Transporter sowie funktionelle Studien werden unser Verständnis der molekularen Transportmechanismen erheblich verbessern. Darüber hinaus werden Strukturen spezifischer MCT die Entwicklung von Arzneimitteln für pharmazeutische Anwendungen durch strukturbasiertes Wirkstoffdesign erleichtern.

Direct link to Lay Summary Last update: 17.06.2019

Responsible applicant and co-applicants

Project partner

Associated projects

Number Title Start Funding scheme
162581 Structure and supramolecular organization of membrane transport proteins 01.12.2015 Project funding (Div. I-III)
157704 Direct electron detector and phase plate for cryo-transmission electron microscopy of biological samples 01.12.2014 R'EQUIP
162581 Structure and supramolecular organization of membrane transport proteins 01.12.2015 Project funding (Div. I-III)

Abstract

Transport proteins are the gatekeepers of cells and cell organelles, and are involved in cellular nutrition, ionic homeostasis, disposal of waste products and uptake of certain drugs. Dysfunction of these membrane proteins leads to a number of serious human diseases. Yet the structural information required for understanding cellular transport and genetic disorders, and to design effective drugs is sparse. The number of high-resolution structures of pro- and eukaryotic transport proteins, and of membrane proteins in general, is relatively low compared to structures of water-soluble proteins. The reasons for this are mainly attributed to challenges in handling the amphiphilic nature of membrane proteins and the difficulty to overexpress them heterologously to obtain microgram and milligram amounts of pure and homogenous proteins for structural studies.This Swiss National Science Foundation (SNSF) project proposal aims at elucidating the structures and molecular working mechanisms of selected transport proteins using X-ray crystallography and cryo-electron microscopy. Promising preliminary results are presented and form the basis of this SNSF proposal. Our target transport proteins are the bacterial and human monocarboxylate transporters bMCT, and MCT1 and MCT4 from the SLC16 solute carrier family, and the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) glucose transporter IICB from Escherichia coli, respectively. We address important open mechanistic questions from the membrane transport protein field and aim at answering them by determining the structures of these target proteins together with structure-function studies. Questions include the substrate and ligand binding, and transport mechanisms of bacterial and human monocarboxylate transporters. MCT1 and MCT4 are proton-dependent, L-lactate transporters that are overexpressed in certain cancer cells and play key roles in tumor cell proliferation, invasion and metastasis. High-affinity inhibitors blocking the import and export of L-lactate through MCT1 and MCT4 are highly desirable since they would induce cancer cell apoptosis through starvation and intracellular acidification. For the identification of potent inhibitors by structure-based drug design as tool compounds and for potential pharmaceutical applications, robust uptake assays and high-resolution structures of human MCT1 and MCT4 would be highly valuable. Both, assay design and structure solution of these transporters are addressed in this proposal.The PTS is unique to bacteria and couples solute transport with its concomitant phosphorylation. The phosphorylation mechanism of sugars in the PTS is yet unresolved and we aim at elucidating the interactions between the IIC and the IIB domain by solving the structure of the substrate bound glucose IICB protein from E. coli.In summary, knowledge of the structures of these transporters accompanied by functional studies of specific mutants that were selected based on the obtained structures will significantly improve our general understanding of their molecular transport mechanisms.
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