Asc1p/RACK1 Connects Ribosomes to Eukaryotic Phosphosignaling.
WD40 repeat proteins fold into characteristic β-propeller structures and control signaling circuits during cellular adaptation processes within eukaryotes. The RACK1 protein of Saccharomyces cerevisiae, Asc1p, consists exclusively of a single seven-bladed β-propeller that operates from the ribosomal base at the head region of the 40S subunit. Here we show that the R38D K40E ribosomal binding-compromised variant (Asc1DEp) is severely destabilized through mutation of phosphosite T143 to a dephosphorylation-mimicking alanine, probably through proteasomal degradation, leading to asc1-phenotypes. Phosphosite Y250 contributes to resistance to translational inhibitors but does not influence Asc1DEp stability. Beyond its own phosphorylation at T143, Y250, and other sites, Asc1p heavily influences the phosphorylation of as many as 90 proteins at 120 sites. Many of these proteins are regulators of fundamental processes ranging from mRNA translation to protein transport and turnover, cytoskeleton organization, and cellular signaling. Our data expose Asc1p/RACK1 as a key factor in phosphosignaling and manifest it as a control point at the head of the ribosomal 40S subunit itself regulated through posttranslational modification.
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Kerstin
K
Schmitt
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Nadine
N
Smolinski
Department of Molecular Structural Biology and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Piotr
P
Neumann
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Samantha
S
Schmaul
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Verena
V
Hofer-Pretz
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany.
Gerhard H
GH
Braus
Department of Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany ovaleri@gwdg.de.
Oliver
O
Valerius
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D013058:Mass Spectrometry; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D020543:Proteome / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
C111825:ASC1 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; D010750:Phosphoproteins; D011500:Protein Synthesis Inhibitors; D020543:Proteome; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins
Asc1/RACK1; Saccharomyces cerevisiae; protein phosphorylation; quantitative proteomics; ribosome; signal transduction network