The mitochondrial calcium uniporter is a highly selective ion channel composed of species- and tissue-specific subunits. However, the functional role of each component still remains unclear. Here, we establish a synthetic biology approach to dissect the interdependence between the pore-forming subunit MCU and the calcium-sensing regulator MICU1. Correlated evolutionary patterns across 247 eukaryotes indicate that their co-occurrence may have conferred a positive fitness advantage. We find that, while the heterologous reconstitution of MCU and EMRE in vivo in yeast enhances manganese stress, this is prevented by co-expression of MICU1. Accordingly, MICU1 deletion sensitizes human cells to manganese-dependent cell death by disinhibiting MCU-mediated manganese uptake. As a result, manganese overload increases oxidative stress, which can be effectively prevented by NAC treatment. Our study identifies a critical contribution of MICU1 to the uniporter selectivity, with important implications for patients with MICU1 deficiency, as well as neurological disorders arising upon chronic manganese exposure.

We acknowledge support from the German Research Foundation (DFG) under the Emmy Noether Programme (PE 2053/1-1 to F.P. and J.W.), the Munich Center for Systems Neurology (SyNergy EXC 1010 to F.P.), the Juniorverbund in der Systemmedizin “mitOmics” (FKZ 01ZX1405B to V.G. and A.L.), The Bert L & N Kuggie Vallee Foundation (to F.P. and D.M.A.), the DFG (MO1944/1-2 to D.M.), the Spanish Ministry of Economy, Industry, and Competitiveness (MEIC; BFU2015-67107), the European Union’s Horizon 2020 research and innovation program under grant agreement ERC-2016-724173 (to T.G. and A.A.P.), and the NIH (RO1 GM102724 to G.H.).