Mutations of the CK2 phosphorylation site of Sic1 affect cell size and S-Cdk kinase activity in Saccharomyces cerevisiae.
By sequence analysis we found an amino acid stretch centred on Serine201 matching a stringent CK2 consensus site within the C-terminal, inhibitory domain of Sic1. Here we show by direct mass spectrometry analysis that Sic1, but not a mutant protein whose CK2 phospho-acceptor site has been mutated to alanine, Sic1S201A, is actually phosphorylated in vitro by CK2 on Serine 201. Mutation of Serine 201 alters the coordination between growth and cell cycle progression. A significant increase of average protein content and of the average protein content at the onset of DNA synthesis is observed for exponentially growing cells harbouring the Sic1S201A protein. A strong reduction of the same parameters is observed in cells harbouring Sic1S201E. The deregulated coordination between cell size and cell cycle is also apparent at the level of S-Cdk activity.
Coccetti
Paola
P
Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca, P. zza della Scienza 2, 20126 Milano, Italy.
Rossi
Riccardo L
RL
Sternieri
Flora
F
Porro
Danilo
D
Russo
Gian Luigi
GL
di Fonzo
Andrea
A
Magni
Fulvio
F
Vanoni
Marco
M
Alberghina
Lilia
L
D001483:Base Sequence; D047390:Casein Kinase II; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D005434:Flow Cytometry; D005822:Genetic Vectors; D006238:Haploidy; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010957:Plasmids / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D012694:Serine; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D009838:Oligodeoxyribonucleotides; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases