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The mitochondrial calcium uniporter is a multimer that can include a dominant‐negative pore‐forming subunit
Author(s) -
Raffaello Anna,
De Stefani Diego,
Sabbadin Davide,
Teardo Enrico,
Merli Giulia,
Picard Anne,
Checchetto Vanessa,
Moro Stefano,
Szabò Ildikò,
Rizzuto Rosario
Publication year - 2013
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2013.157
Subject(s) - biology , uniporter , protein subunit , calcium , mitochondrion , biophysics , microbiology and biotechnology , biochemistry , gene , cytosol , medicine , enzyme
Mitochondrial calcium uniporter (MCU) channel is responsible for Ruthenium Red‐sensitive mitochondrial calcium uptake. Here, we demonstrate MCU oligomerization by immunoprecipitation and Förster resonance energy transfer (FRET) and characterize a novel protein (MCUb) with two predicted transmembrane domains, 50% sequence similarity and a different expression profile from MCU. Based on computational modelling, MCUb includes critical amino‐acid substitutions in the pore region and indeed MCUb does not form a calcium‐permeable channel in planar lipid bilayers. In HeLa cells, MCUb is inserted into the oligomer and exerts a dominant‐negative effect, reducing the [Ca 2+ ] mt increases evoked by agonist stimulation. Accordingly, in vitro co‐expression of MCUb with MCU drastically reduces the probability of observing channel activity in planar lipid bilayer experiments. These data unveil the structural complexity of MCU and demonstrate a novel regulatory mechanism, based on the inclusion of dominant‐negative subunits in a multimeric channel, that underlies the fine control of the physiologically and pathologically relevant process of mitochondrial calcium homeostasis.