A VDAC1-mediated NEET protein chain transfers 2Fe-2S clusters between the mitochondria and the cytosol and impacts mitochondrial dynamics

Mitochondrial inner NEET (MiNT) and the outer mitochondrial membrane (OMM) mitoNEET (mNT) proteins belong to the NEET protein family. This family plays a key role in mitochondrial labile iron and reactive oxygen species (ROS) homeostasis. NEET proteins contain labile 2Fe-2S clusters which can be transferred to apo-acceptor proteins. In eukaryotes, the biogenesis of 2Fe-2S clusters occurs within the mitochondria by the iron-sulfur cluster (ISC) system; the clusters are then transferred to 2Fe-2S proteins within the mitochondria or exported to cytosolic proteins and the cytosolic iron-sulfur cluster assembly (CIA) system. The last step of export of the 2Fe-2S is not yet fully characterized. Here we show that MiNT interacts with voltage-dependent anion channel 1 (VDAC1), a major OMM protein that connects the intermembrane space with the cytosol and participates in regulating the levels of different ions including mitochondrial labile iron (mLI). We further show that VDAC1 is mediating the interaction between MiNT and mNT, in which MiNT transfers its 2Fe-2S clusters from inside the mitochondria to mNT that is facing the cytosol. This MiNT-VDAC1-mNT interaction is shown both experimentally and by computational calculations. Additionally, we show that modifying MiNT expression in breast cancer cells affects the dynamics of mitochondrial structure and morphology, mitochondrial function, and breast cancer tumor growth. Our findings reveal a pathway for the transfer of 2Fe-2S clusters, which are assembled inside the mitochondria, to the cytosol.