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TOR complex 2–regulated protein kinase Ypk1 controls sterol distribution by inhibiting StARkin domain–containing proteins located at plasma membrane–endoplasmic reticulum contact sites

In our proteome-wide screen, Ysp2 (also known as Lam2/Ltc4) was identified as a likely physiologically relevant target of the TOR complex 2 (TORC2)–dependent protein kinase Ypk1 in the yeast Saccharomyces cerevisiae. Ysp2 was subsequently shown to be one of a new family of sterol-binding proteins lo...

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Detalles Bibliográficos
Autores principales: Roelants, Françoise M., Chauhan, Neha, Muir, Alexander, Davis, Jameson C., Menon, Anant K., Levine, Timothy P., Thorner, Jeremy
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6232965/
https://www.ncbi.nlm.nih.gov/pubmed/29927351
http://dx.doi.org/10.1091/mbc.E18-04-0229
Descripción
Sumario:In our proteome-wide screen, Ysp2 (also known as Lam2/Ltc4) was identified as a likely physiologically relevant target of the TOR complex 2 (TORC2)–dependent protein kinase Ypk1 in the yeast Saccharomyces cerevisiae. Ysp2 was subsequently shown to be one of a new family of sterol-binding proteins located at plasma membrane (PM)–endoplasmic reticulum (ER) contact sites. Here we document that Ysp2 and its paralogue Lam4/Ltc3 are authentic Ypk1 substrates in vivo and show using genetic and biochemical criteria that Ypk1-mediated phosphorylation inhibits the ability of these proteins to promote retrograde transport of sterols from the PM to the ER. Furthermore, we provide evidence that a change in PM sterol homeostasis promotes cell survival under membrane-perturbing conditions known to activate TORC2-Ypk1 signaling. These observations define the underlying molecular basis of a new regulatory mechanism for cellular response to plasma membrane stress.