Cold Temperature Induces the Reprogramming of Proteolytic Pathways in Yeast

Despite much evidence of the involvement of the proteasomeubiquitin signaling system in temperature stress response, the dynamics of the ubiquitylome during cold response has not yet been studied. Here, we have compared quantitative ubiquitylomes from a strain deficient in proteasome substrate recruitment and a reference strain during cold response. We have observed that a large group of proteins showing increased ubiquitylation in the proteasome mutant at low temperature is comprised by reverses suppressor of Ty-phenotype 5 (Rsp5)-regulated plasma membrane proteins. Analysis of internalization and degradation of plasma membrane proteins at low temperature showed that the proteasome becomes determinant for this process, whereas, at 30 °C, the proteasome is dispensable. Moreover, our observations indicate that proteasomes have increased capacity to interact with lysine 63-polyubiquitylated proteins during low temperature in vivo. These unanticipated observations indicate that, during cold response, there is a proteolytic cellular reprogramming in which the proteasome acquires a role in the endocytic-vacuolar pathway.
This work was supported by Spanish Government (Ministry of Economy and Competitiveness) Grants BFU2009-06985 and BFU2012-35716, Agència de Gestió d'Ajuts Universitaris i de Recerca Grants 2009SGR-1482 and FI-DGR 2013, and European Molecular Biology Organization Fellowship ASTF 363.00-2010