The GDP-Bound State of Mitochondrial Mfn1 Induces Membrane Adhesion of Apposing Lipid Vesicles through a Cooperative Binding Mechanism

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Tolosa Díaz, Andrés and Almendro Vedia, Víctor G. and Natale, Paolo and López Montero, Iván (2020) The GDP-Bound State of Mitochondrial Mfn1 Induces Membrane Adhesion of Apposing Lipid Vesicles through a Cooperative Binding Mechanism. Biomolecules, 10 (7). p. 1085. ISSN 2218-273X

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Official URL: https://doi.org/10.3390/biom10071085




Abstract

Mitochondria are double-membrane organelles that continuously undergo fission and fusion. Outer mitochondrial membrane fusion is mediated by the membrane proteins mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2), carrying a GTP hydrolyzing domain (GTPase) and two coiled-coil repeats. The detailed mechanism on how the GTP hydrolysis allows Mfns to approach adjacent membranes into proximity and promote their fusion is currently under debate. Using model membranes built up as giant unilamellar vesicles (GUVs), we show here that Mfn1 promotes membrane adhesion of apposing lipid vesicles. The adhesion forces were sustained by the GDP-bound state of Mfn1 after GTP hydrolysis. In contrast, the incubation with the GDP:AlF− 4 , which mimics the GTP transition state, did not induce membrane adhesion. Due to the flexible nature of lipid membranes, the adhesion strength depended on the surface concentration of Mfn1 through a cooperative binding mechanism. We discuss a possible scenario for the outer mitochondrial membrane fusion based on the modulated action of Mfn1.


Item Type:Article
Uncontrolled Keywords:mitochondria; membrane fusion; GTPase; mitofusin 1; giant vesicles
Subjects:Medical sciences > Biology > Cytology
ID Code:67538
Deposited On:27 Aug 2021 09:50
Last Modified:27 Aug 2021 09:50

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