The Saccharomyces cerevisiae 14-3-3 proteins are required for the G1/S transition, actin cytoskeleton organization and cell wall integrity.
14-3-3 proteins are highly conserved polypeptides that participate in many biological processes by binding phosphorylated target proteins. The Saccharomyces cerevisiae BMH1 and BMH2 genes, whose concomitant deletion is lethal, encode two functionally redundant 14-3-3 isoforms. To gain insights into the essential function(s) shared by these proteins, we searched for high-dosage suppressors of the growth defects of temperature-sensitive bmh mutants. Both the protein kinase C1 (Pkc1) and its upstream regulators Wsc2 and Mid2 were found to act as high dosage suppressors of bmh mutants' temperature sensitivity, indicating a functional interaction between 14-3-3 and Pkc1. Consistent with a role of 14-3-3 proteins in Pkc1-dependent cellular processes, shift to the restrictive temperature of bmh mutants severely impaired initiation of DNA replication, polarization of the actin cytoskeleton, and budding, as well as cell wall integrity. Because Pkc1 acts in concert with the Swi4-Swi6 (SBF) transcriptional activator to control all these processes, the defective G(1)/S transition of bmh mutants might be linked to impaired SBF activity. Indeed, the levels of the G(1) cyclin CLN2 transcripts, which are positively regulated by SBF, were dramatically reduced in bmh mutants. Remarkably, budding and DNA replication defects of bmh mutants were suppressed by CLN2 expression from an SBF-independent promoter, suggesting that 14-3-3 proteins might contribute to regulating the late G(1) transcriptional program.
Lottersberger
Francisca
F
Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy.
Panza
Andrea
A
Lucchini
Giovanna
G
Piatti
Simonetta
S
Longhese
Maria Pia
MP
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D016193:G1 Phase; D018628:Gene Dosage; D005800:Genes, Fungal; D016153:Genes, Suppressor; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009995:Osmosis; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
D048948:14-3-3 Proteins; D000199:Actins; C075852:BMH1 protein, S cerevisiae; C097164:BMH2 protein, S cerevisiae; D002135:Calcium-Binding Proteins; D004271:DNA, Fungal; D047908:Intracellular Signaling Peptides and Proteins; C091625:MID2 protein, S cerevisiae; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C120218:WSC2 protein, S cerevisiae; C490702:PKC1 protein, S cerevisiae; D011493:Protein Kinase C