Pkc1 acts through Zds1 and Gic1 to suppress growth and cell polarity defects of a yeast eIF5A mutant.
eIF5A is a highly conserved putative eukaryotic translation initiation factor that has been implicated in translation initiation, nucleocytoplasmic transport, mRNA decay, and cell proliferation, but with no precise function assigned so far. We have previously shown that high-copy PKC1 suppresses the phenotype of tif51A-1, a temperature-sensitive mutant of eIF5A in S. cerevisiae. Here, in an attempt to further understand how Pkc1 functionally interacts with eIF-5A, it was determined that PKC1 suppression of tif51A-1 is independent of the cell integrity MAP kinase cascade. Furthermore, two new suppressor genes, ZDS1 and GIC1, were identified. We demonstrated that ZDS1 and ZDS2 are necessary for PKC1, but not for GIC1 suppression. Moreover, high-copy GIC1 also suppresses the growth defect of a PKC1 mutant (stt1), suggesting the existence of a Pkc1-Zds1-Gic1 pathway. Consistent with the function of Gic1 in actin organization, the tif51A-1 strain shows an actin polarity defect that is partially recovered by overexpression of Pkc1 and Zds1 as well as Gic1. Additionally, PCL1 and BNI1, important regulators of yeast cell polarity, also suppress tif51A-1 temperature sensitivity. Taken together, these data strongly support the correlated involvement of Pkc1 and eIF5A in establishing actin polarity, which is essential for bud formation and G1/S transition in S. cerevisiae.
Zanelli
Cleslei F
CF
Department of Biological Sciences, School of Pharmaceutical Sciences, São Paulo State University, UNESP, Rodovia Araraquara-Jaú, Km. 01, Araraquara, São Paulo 14801-902, Brazil.
Valentini
Sandro R
SR
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism*; D016764:Cell Polarity / Q000235:genetics*; D049109:Cell Proliferation; D017931:DNA Primers; D015723:Gene Library; D008856:Microscopy, Fluorescence; D009154:Mutation / Q000235:genetics; D010448:Peptide Initiation Factors / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011493:Protein Kinase C / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D000097574:Eukaryotic Translation Initiation Factor 5A
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D017931:DNA Primers; D010448:Peptide Initiation Factors; D011493:Protein Kinase C; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A; C109252:GIC1 protein, S cerevisiae; C101740:ZDS1 protein, S cerevisiae; C490702:PKC1 protein, S cerevisiae