title: Role of Scd5, a protein phosphatase-1 targeting protein, in phosphoregulation of Sla1 during endocytosis.
abstract: Phosphorylation regulates assembly and disassembly of proteins during endocytosis. In yeast, Prk1 and Ark1 phosphorylate factors after vesicle internalization leading to coat disassembly. Scd5, a protein phosphatase-1 (PP1)-targeting subunit, is proposed to regulate dephosphorylation of Prk1/Ark1 substrates to promote new rounds of endocytosis. In this study we analyzed scd5-PP1Δ2, a mutation causing impaired PP1 binding. scd5-PP1Δ2 caused hyperphosphorylation of several Prk1 endocytic targets. Live-cell imaging of 15 endocytic components in scd5-PP1Δ2 revealed that most factors arriving before the invagination/actin phase of endocytosis had delayed lifetimes. Severely affected were early factors and Sla2 (Hip1R homolog), whose lifetime was extended nearly fourfold. In contrast, the lifetime of Sla1, a Prk1 target, was extended less than twofold, but its cortical recruitment was significantly reduced. Delayed Sla2 dynamics caused by scd5-PP1Δ2 were suppressed by SLA1 overexpression. This was dependent on the LxxQxTG repeats (SR) of Sla1, which are phosphorylated by Prk1 and bind Pan1, another Prk1 target, in the dephosphorylated state. Without the SR, Sla1ΔSR was still recruited to the cell surface, but was less concentrated in cortical patches than Pan1. sla1ΔSR severely impaired endocytic progression, but this was partially suppressed by overexpression of LAS17, suggesting that without the SR region the SH3 region of Sla1 causes constitutive negative regulation of Las17 (WASp). These results demonstrate that Scd5/PP1 is important for recycling Prk1 targets to initiate new rounds of endocytosis and provide new mechanistic information on the role of the Sla1 SR domain in regulating progression to the invagination/actin phase of endocytosis.
authors: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL 33136, USA.
authors: Richard J
authors: RJ
authors: Chi
authors: Onaidy T
authors: OT
authors: Torres
authors: Verónica A
authors: VA
authors: Segarra
authors: Tanya
authors: T
authors: Lansley
authors: Ji Suk
authors: JS
authors: Chang
authors: Thomas M
authors: TM
authors: Newpher
authors: Sandra K
authors: SK
authors: Lemmon
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis; D015966:Gene Expression Regulation, Fungal; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D054645:Protein Phosphatase 1 / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D002966:Clathrin; D003598:Cytoskeletal Proteins; C480361:LAS17 protein, S cerevisiae; C100586:SCD5 protein, S cerevisiae; C082265:SLA1 protein, S cerevisiae; C082266:SLA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051316:Wiskott-Aldrich Syndrome Protein; C491504:ARK1 protein, S cerevisiae; C094326:PRK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D054645:Protein Phosphatase 1