The mitochondrial heat shock protein 70 (Hsp70) and Hsp10 cooperate in the formation of Hsp60 complexes [Cell Biology]

March 18th, 2015 by Boettinger, L., Oelȷeklaus, S., Guiard, B., Rospert, S., Warscheid, B., Becker, T.

The mitochondrial Hsp70 (mtHsp70) mediates essential functions for mitochondrial biogenesis like import and folding of proteins. In these processes the chaperone cooperates with co-chaperones, the presequence translocase and other chaperone systems. The chaperonin Hsp60 together with its co-factor Hsp10 catalyzes folding of a subset of mtHsp70 client proteins. Hsp60 forms heptameric ring structures, which provide a cavity for protein folding. How the Hsp60 rings are assembled is poorly understood. In a comprehensive interaction study we found that mtHsp70 associates with Hsp60 and Hsp10. Surprisingly, mtHsp70 interacts with Hsp10 independently of Hsp60. The mtHsp70-Hsp10 complex binds to unassembled Hsp60 precursor to promote its assembly into the mature Hsp60 complexes. We conclude that coupling to Hsp10 recruits mtHsp70 to mediate biogenesis of the heptameric Hsp60 rings.