The Yeast AAA⁺ Chaperone Hsp104 Is Part of a Network That Links the Actin Cytoskeleton with the Inheritance of Damaged Proteins

Abstract

The yeast AAA⁺ chaperone Hsp104 is essential for the development of thermotolerance and for the inheritance of prions. Recently, Hsp104, together with the actin cytoskeleton, has been implicated in the asymmetric distribution of carbonylated proteins. Here, we investigated the interplay between Hsp104 and actin by using a dominant-negative variant of Hsp104 (HAP/ClpP) that degrades substrate proteins instead of remodeling them. Coexpression of HAP/ClpP causes defects in morphology and the actin cytoskeleton. Taking a candidate approach, we identified Spa2, a member of the polarisome complex, as an Hsp104 substrate. Furthermore, we provided genetic evidence that links Spa2 and Hsp104 to Hof1, a member of the cytokinesis machinery. Spa2 and Hof1 knockout cells are affected in the asymmetric distribution of damaged proteins, suggesting that Hsp104, Spa2, and Hof1 are members of a network controlling the inheritance of carbonylated proteins.

ACKNOWLEDGMENTS

We are grateful to S. Lindquist, B. Dobberstein, and E. Schiebel for strains and plasmids and to M. Snyder for Spa2 antibody. We thank Stefan Jentsch (Max Planck Institute of Biochemistry, Martinsried, Germany) for support and help with the synthetic-lethal screen.

M.S. is a Ph.D. student working with Stefan Jentsch. This work was supported by grants from the Fonds der Chemischen Industrie to B.B. and P.T. (Kekulé scholarship), a Heisenberg fellowship from the Deutsche Forschungsgemeinschaft to A.M., and the Network of Aging Research of the Land Baden-Württemberg.