The prion-like protein kinase Sky1 is required for efficient stress granule disassembly

Abstract

Stress granules are membraneless protein- and mRNA-rich organelles that form in response to perturbations in environmental conditions. Stress granule formation is reversible, and persistent stress granules have been implicated in a variety of neurodegenerative disorders, including amyotrophic lateral sclerosis. However, characterization of the factors involved in dissolving stress granules is incomplete. Many stress granule proteins contain prion-like domains (PrLDs), some of which have been linked to stress granule formation. Here, we demonstrate that the PrLD-containing yeast protein kinase Sky1 is a stress granule component. Sky1 is recruited to stress granules in part via its PrLD, and Sky1’s kinase activity regulates timely stress granule disassembly during stress recovery. This effect is mediated by phosphorylation of the stress granule component Npl3. Sky1 can compensate for defects in chaperone-mediated stress granule disassembly and vice-versa, demonstrating that cells have multiple overlapping mechanisms for re-solubilizing stress granule components.

Composition-based prediction and rational manipulation of prion-like domain recruitment to stress granules

“…We recently identified Sky1 as a stress granule component and regulator of stress granule dynamics (8). However, while the Sky1 PrLD is sufficient for stress granule recruitment, deletion of the PrLD diminishes, but does not prevent, recruitment, highlighting a role for regions outside the PrLD (8). Like Sky1, some other full-length proteins containing assembly-prone PrLDs from our screen appear to localize to stress granules (SI Appendix, Fig.…”

“…PrLDs Form Reversible Assemblies upon Heat Shock. We recently showed that the PrLDs of Sky1, Cdc39, and Ded1 are sufficient for recruitment to stress granules upon heat stress (8). To determine how common this feature is among PrLDs, and to gain a greater understanding of how PrLDs might promote stress granule recruitment, we investigated the behavior of other isolated PrLDs in response to stress.…”

“…The PrLD-containing protein kinase Sky1 is a good example of this concept. We recently identified Sky1 as a stress granule component and regulator of stress granule dynamics (8). However, while the Sky1 PrLD is sufficient for stress granule recruitment, deletion of the PrLD diminishes, but does not prevent, recruitment, highlighting a role for regions outside the PrLD (8).…”

“…The relationship between PrLDs and stress granules has attracted research interest for a few reasons. First, some of these domains have been shown to help target proteins to stress granules (7,8). Second, intrinsically disordered regions (IDRs), of which PrLDs are a subclass, are thought to provide promiscuous, but potentially stabilizing interactions in RNP granules (9).…”

Dance with the Devil: Stress Granules and Signaling in Antiviral Responses

“…These include for example components of mTORC1 complex, JNK and its scaffold protein WDR62, the ubiquitin peptidase USP10, the protein arginine methyltransferase (PRMT) 1 and PRMT5, the glycosyltransferase OGG1, and the poly-ADP-ribose polymerase PARP12 [70,408]. Accordingly, proteins within SGs were found to carry a plethora of posttranslational modifications including phosphorylation [250,409], GlcNac glycosylation [408], sumoylation [410], neddylation [411], ubiquitination [380], and ADP-ribosylation [264].…”