The mitochondrial calcium uniporter is a multimer that can include a dominant‐negative pore‐forming subunit. (30th July 2013)

• Record Type: Journal Article
• Authors: Raffaello, Anna; De Stefani, Diego; Sabbadin, Davide; Teardo, Enrico; Merli, Giulia; Picard, Anne; Checchetto, Vanessa; Moro, Stefano; Szabò, Ildikò; Rizzuto, Rosario
• Is Part Of: EMBO journal. Volume 32:Number 17(2013)
• Page Start: 2362
• Page End: 2376
• Publication Date: 2013-07-30
• Subjects: Molecular biology -- Periodicals; 572.805
• DOI: 10.1038/emboj.2013.157
• Languages: English
• ISSNs: 0261-4189

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>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 [Ca²⁺]_mt increases evoked by agonist stimulation. Accordingly, <italic>in vitro</italic> 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.</p> </abstract>