Research Overview

A combined AAA+ disaggregase and chaperonin

Chaperones comprised of ring-forming AAA+ ATPases , represented by ClpB in bacteria and Hap104 in yeast, can solubilize existing protein aggregates and are essential for protecting organisms from protein misfolding stress. In metazoans, a partial ClpB homolog Skd3 resides in the mitochondrial intermembrane space (IMS) is critical for human health. Skd3 is unusual in that it comprises a self-sufficient system that can efficiently rescue the folding of aggregated model substrates. Using a combination of cryoEM and biochemical analysis, we recently uncovered the molecular basis underlying the remarkable chaperone activity of Skd3: it cycles between a hexameric state, in which it acts as a potent disaggregase, and a dodecameric state, in which it provides a protected environment to facilitate the folding of solubilized client proteins. By exploring this system, we aim to establish a mechanistic precedent for how multiple activities are built into a single chaperone to provide an effective ‘repair’ mechanism for misfolded proteins, and to better understand protein folding and quality control in mitochondria.

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