The Saccharomyces homolog of mammalian RACK1, Cpc2/Asc1p, is required for FLO11-dependent adhesive growth and dimorphism.
Nutrient starvation results in the interaction of Saccharomyces cerevisiae cells with each other and with surfaces. Adhesive growth requires the expression of the FLO11 gene regulated by the Ras/cAMP/cAMP-dependent protein kinase, the Kss1p/MAPK, and the Gcn4p/general amino acid control pathway, respectively. Proteomics two-dimensional DIGE experiments revealed post-transcriptionally regulated proteins in response to amino acid starvation including the ribosomal protein Cpc2p/Asc1p. This putative translational regulator is highly conserved throughout the eukaryotic kingdom and orthologous to mammalian RACK1. Deletion of CPC2/ASC1 abolished amino acid starvation-induced adhesive growth and impaired basal expression of FLO11 and its activation upon starvation in haploid cells. In addition, the diploid Flo11p-dependent pseudohyphal growth during nitrogen limitation was CPC2/ASC1-dependent. A more detailed analysis revealed that a CPC2/ASC1 deletion caused increased sensitivity to cell wall drugs suggesting that the gene is required for general cell wall integrity. Phosphoproteome and Western hybridization data indicate that Cpc2p/Asc1p affected the phosphorylation of the translational initiation factors eIF2 alpha and eIF4A and the ribosome-associated complex RAC. A crucial role of Cpc2p/Asc1p at the ribosomal interface coordinating signal transduction, translation initiation, and transcription factor formation was corroborated.
Valerius
Oliver
O
Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany.
Kleinschmidt
Malte
M
Rachfall
Nicole
N
Schulze
Florian
F
López Marín
Sarai
S
Hoppert
Michael
M
Streckfuss-Bömeke
Katrin
K
Fischer
Claudia
C
Braus
Gerhard H
GH
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000172:deficiency; D002448:Cell Adhesion / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D019204:GTP-Binding Proteins; D017353:Gene Deletion; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis; D020543:Proteome / Q000032:analysis; D040901:Proteomics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D012727:Sex Characteristics
C111825:ASC1 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; D000596:Amino Acids; D015852:Eukaryotic Initiation Factor-2; C110690:FLO11 protein, S cerevisiae; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D020543:Proteome; D029701:Saccharomyces cerevisiae Proteins; C075833:eIF-4; D019204:GTP-Binding Proteins