The human mitochondrial Hsp60 in the APO conformation forms a stable tetradecameric complex

作者：Enriquez Adrian S; Rojo Humberto M; Bhatt Jay M; Molugu Sudheer K; Hildenbrand Zacariah L; Bernal Ricardo A^*

来源：Cell Cycle, 2017, 16(13): 1309-1319.

DOI：10.1080/15384101.2017.1321180

• Human mitochondrial chaperonin
• negative stain
• transmission electron microscopy

The human mitochondrial chaperonin is a macromolecular machine that catalyzes the proper folding of mitochondrial proteins and is of vital importance to all cells. This chaperonin is composed of 2 distinct proteins, Hsp60 and Hsp10, that assemble into large oligomeric complexes that mediate the folding of non-native polypeptides in an ATP dependent manner. Here, we report the bacterial expression and purification of fully assembled human Hsp60 and Hsp10 recombinant proteins and that Hsp60 forms a stable tetradecameric double-ring conformation in the absence of co-chaperonin and nucleotide. Evidence of the stable double-ring conformation is illustrated by the 15 angstrom resolution electron microscopy reconstruction presented here. Furthermore, our biochemical analyses reveal that the presence of a non-native substrate initiates ATP-hydrolysis within the Hsp60/10 chaperonin to commence protein folding. Collectively, these data provide insight into the architecture of the intermediates used by the human mitochondrial chaperonin along its protein folding pathway and lay a foundation for subsequent high resolution structural investigations into the conformational changes of the mitochondrial chaperonin.

• 出版日期2017