Mitochondrial stress signaling: a pathway unfolds.

Disruption of protein homeostasis in mitochondria elicits a cellular response, which upregulates mitochondrial chaperones and other factors that serve to remodel the mitochondrial-folding environment. In a recent study, Haynes and colleagues uncovered a novel signal transduction pathway underlying this process. The upstream mitochondrial component of this pathway is an orthologue of Escherichia coli ClpP, which functions in the bacterial heat-shock response. These findings suggest that molecular aspects of stress sensing might be conserved between bacteria and mitochondria.