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Hybrid Clear/Blue Native Electrophoresis for the Separation and Analysis of Mitochondrial Respiratory Chain Supercomplexes
Published on: May 19, 2019
A Single Adaptable Cochaperone-Scaffold Complex Delivers Nascent Iron-Sulfur Clusters to Mammalian Respiratory Chain
Nunziata Maio1, Ki Soon Kim1, Anamika Singh1
1Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Abstract:
The iron-sulfur (Fe-S) cluster of the Rieske protein, UQCRFS1, is essential for Complex III (CIII) activity, though the mechanism for Fe-S cluster transfer has not previously been elucidated. Recent studies have shown that the co-chaperone HSC20, essential for Fe-S cluster biogenesis of SDHB, directly binds LYRM7, formerly described as a chaperone that stabilizes UQCRFS1 prior to its insertion into CIII. Here we report that a transient subcomplex involved in CIII assembly, composed of LYRM7 bound to UQCRFS1, interacts with components of an Fe-S transfer complex, consisting of HSC20, its cognate chaperone HSPA9, and the holo-scaffold ISCU. Binding of HSC20 to the LYR motif of LYRM7 in a pre-assembled UQCRFS1-LYRM7 intermediate in the mitochondrial matrix facilitates Fe-S cluster transfer to UQCRFS1. The five Fe-S cluster subunits of Complex I also interact with HSC20 to acquire their clusters, highlighting the crucial role of HSC20 in the assembly of the mitochondrial respiratory chain.
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