Glutathionylated and Fe-S cluster containing hMIA40 (CHCHD4) regulates ROS and mitochondrial complex III and IV activities of the electron transport chain.
Human MIA40, an intermembrane space (IMS) import receptor of mitochondria harbors twin CX9C motifs for stability while its CPC motif is known to facilitate the import of IMS bound proteins. Site-directed mutagenesis complemented by MALDI on in vivo hMIA40 protein shows that a portion of MIA40 undergoes reversible S-glutathionylation at three cysteines in the twin CX9C motifs and the lone cysteine 4 residue. We find that HEK293T cells expressing hMIA40 mutant defective for glutathionylation are compromised in the activities of complexes III and IV of the Electron Transport Chain (ETC) and enhance Reactive Oxygen Species (ROS) levels. Immunocapture studies show MIA40 interacting with complex III. Interestingly, glutathionylated MIA40 can transfer electrons to cytochrome C directly. However, Fe-S clusters associated with the CPC motif are essential to facilitate the two-electron to one-electron transfer for reducing cytochrome C. These results suggest that hMIA40 undergoes glutathionylation to maintain ROS levels and for optimum function of complexes III and IV of ETC. Our studies shed light on a novel post-translational modification of hMIA40 and its ability to act as a redox switch to regulate the ETC and cellular redox homeostasis.
['Thiriveedi|Venkata Ramana|VR|', 'Mattam|Ushodaya|U|', 'Pattabhi|Prasad|P|', 'Bisoyi|Vandana|V|', 'Talari|Noble Kumar|NK|', 'Krishnamoorthy|Thanuja|T|', 'Sepuri|Naresh Babu V|NBV|']
D004579:Electron Transport D014450:Electron Transport Complex III D003576:Electron Transport Complex IV D057809:HEK293 Cells D006801:Humans D033681:Mitochondrial Membrane Transport Proteins D024101:Mitochondrial Proteins D010084:Oxidation-Reduction D021381:Protein Transport D017382:Reactive Oxygen Species
Glutathionylation Complex III and IV Electron transport chain Reactive oxygen species Fe–S clusters MIA40 (CHCHD4)