Truncated protein phosphatase GLC7 restores translational activation of GCN4 expression in yeast mutants defective for the eIF-2α kinase GCN2

Ronald Wek, John F. Cannon, Thomas E. Dever, Alan G. Hinnebusch

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

GCN2 is a protein kinase in Saccharomyces cerevisiae that is required for increased expression of the transcriptional activator GCN4 in amino acid-starved cells. GCN2 stimulates GCN4 synthesis at the translational level by phosphorylating the at subunit of eukaryotic translation initiation factor 2 (eIF-2). We identified a truncated form of the GLC7 gene, encoding the catalytic subunit of a type 1 protein phosphatase, by its ability to restore derepression of GCN4 expression in a strain containing the partially defective gcn2-507 allele. Genetic analysis suggests that the truncated GLC7 allele has a dominant negative phenotype, reducing the level of native type 1 protein phosphatase activity in the cell. The truncated form of GLC7 does not suppress the regulatory defect associated with a gcn2 deletion or a mutation in the phosphorylation site of eIF-2α (Ser-51). In addition, the presence of multiple copies of wild-type GLC7 impairs the derepression of GCN4 that occurs in response to amino acid starvation or dominant-activating mutations in GCN2. These findings suggest that the phosphatase activity of GLC7 acts in opposition to the kinase activity of GCN2 in modulating the level of eIF-2α phosphorylation and the translational efficiency of GCN4 mRNA. This conclusion is supported by biochemical studies showing that the truncated GLC7 allele increases the level of eIF-2α Phosphorylation in the gcn2-507 mutant to a level approaching that seen in wild-type cells under starvation conditions. The truncated GLC7 allele also leads to reduced glycogen accumulation, indicating that this protein phosphatase is involved in regulating diverse metabolic pathways in yeast cells.

Original languageEnglish
Pages (from-to)5700-5710
Number of pages11
JournalMolecular and Cellular Biology
Volume12
Issue number12
StatePublished - Dec 1992

Fingerprint

Eukaryotic Initiation Factor-2
Eukaryotic Initiation Factors
Phosphoprotein Phosphatases
Phosphotransferases
Yeasts
Alleles
Protein Phosphatase 1
Phosphorylation
Starvation
Amino Acids
Mutation
Metabolic Networks and Pathways
Glycogen
Phosphoric Monoester Hydrolases
Protein Kinases
Saccharomyces cerevisiae
Phenotype
Messenger RNA
Genes

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

Truncated protein phosphatase GLC7 restores translational activation of GCN4 expression in yeast mutants defective for the eIF-2α kinase GCN2. / Wek, Ronald; Cannon, John F.; Dever, Thomas E.; Hinnebusch, Alan G.

In: Molecular and Cellular Biology, Vol. 12, No. 12, 12.1992, p. 5700-5710.

Research output: Contribution to journalArticle

@article{713bfd3fc54e434082dbf4c4e73f45ef,
title = "Truncated protein phosphatase GLC7 restores translational activation of GCN4 expression in yeast mutants defective for the eIF-2α kinase GCN2",
abstract = "GCN2 is a protein kinase in Saccharomyces cerevisiae that is required for increased expression of the transcriptional activator GCN4 in amino acid-starved cells. GCN2 stimulates GCN4 synthesis at the translational level by phosphorylating the at subunit of eukaryotic translation initiation factor 2 (eIF-2). We identified a truncated form of the GLC7 gene, encoding the catalytic subunit of a type 1 protein phosphatase, by its ability to restore derepression of GCN4 expression in a strain containing the partially defective gcn2-507 allele. Genetic analysis suggests that the truncated GLC7 allele has a dominant negative phenotype, reducing the level of native type 1 protein phosphatase activity in the cell. The truncated form of GLC7 does not suppress the regulatory defect associated with a gcn2 deletion or a mutation in the phosphorylation site of eIF-2α (Ser-51). In addition, the presence of multiple copies of wild-type GLC7 impairs the derepression of GCN4 that occurs in response to amino acid starvation or dominant-activating mutations in GCN2. These findings suggest that the phosphatase activity of GLC7 acts in opposition to the kinase activity of GCN2 in modulating the level of eIF-2α phosphorylation and the translational efficiency of GCN4 mRNA. This conclusion is supported by biochemical studies showing that the truncated GLC7 allele increases the level of eIF-2α Phosphorylation in the gcn2-507 mutant to a level approaching that seen in wild-type cells under starvation conditions. The truncated GLC7 allele also leads to reduced glycogen accumulation, indicating that this protein phosphatase is involved in regulating diverse metabolic pathways in yeast cells.",
author = "Ronald Wek and Cannon, {John F.} and Dever, {Thomas E.} and Hinnebusch, {Alan G.}",
year = "1992",
month = "12",
language = "English",
volume = "12",
pages = "5700--5710",
journal = "Molecular and Cellular Biology",
issn = "0270-7306",
publisher = "American Society for Microbiology",
number = "12",

}

TY - JOUR

T1 - Truncated protein phosphatase GLC7 restores translational activation of GCN4 expression in yeast mutants defective for the eIF-2α kinase GCN2

AU - Wek, Ronald

AU - Cannon, John F.

AU - Dever, Thomas E.

AU - Hinnebusch, Alan G.

PY - 1992/12

Y1 - 1992/12

N2 - GCN2 is a protein kinase in Saccharomyces cerevisiae that is required for increased expression of the transcriptional activator GCN4 in amino acid-starved cells. GCN2 stimulates GCN4 synthesis at the translational level by phosphorylating the at subunit of eukaryotic translation initiation factor 2 (eIF-2). We identified a truncated form of the GLC7 gene, encoding the catalytic subunit of a type 1 protein phosphatase, by its ability to restore derepression of GCN4 expression in a strain containing the partially defective gcn2-507 allele. Genetic analysis suggests that the truncated GLC7 allele has a dominant negative phenotype, reducing the level of native type 1 protein phosphatase activity in the cell. The truncated form of GLC7 does not suppress the regulatory defect associated with a gcn2 deletion or a mutation in the phosphorylation site of eIF-2α (Ser-51). In addition, the presence of multiple copies of wild-type GLC7 impairs the derepression of GCN4 that occurs in response to amino acid starvation or dominant-activating mutations in GCN2. These findings suggest that the phosphatase activity of GLC7 acts in opposition to the kinase activity of GCN2 in modulating the level of eIF-2α phosphorylation and the translational efficiency of GCN4 mRNA. This conclusion is supported by biochemical studies showing that the truncated GLC7 allele increases the level of eIF-2α Phosphorylation in the gcn2-507 mutant to a level approaching that seen in wild-type cells under starvation conditions. The truncated GLC7 allele also leads to reduced glycogen accumulation, indicating that this protein phosphatase is involved in regulating diverse metabolic pathways in yeast cells.

AB - GCN2 is a protein kinase in Saccharomyces cerevisiae that is required for increased expression of the transcriptional activator GCN4 in amino acid-starved cells. GCN2 stimulates GCN4 synthesis at the translational level by phosphorylating the at subunit of eukaryotic translation initiation factor 2 (eIF-2). We identified a truncated form of the GLC7 gene, encoding the catalytic subunit of a type 1 protein phosphatase, by its ability to restore derepression of GCN4 expression in a strain containing the partially defective gcn2-507 allele. Genetic analysis suggests that the truncated GLC7 allele has a dominant negative phenotype, reducing the level of native type 1 protein phosphatase activity in the cell. The truncated form of GLC7 does not suppress the regulatory defect associated with a gcn2 deletion or a mutation in the phosphorylation site of eIF-2α (Ser-51). In addition, the presence of multiple copies of wild-type GLC7 impairs the derepression of GCN4 that occurs in response to amino acid starvation or dominant-activating mutations in GCN2. These findings suggest that the phosphatase activity of GLC7 acts in opposition to the kinase activity of GCN2 in modulating the level of eIF-2α phosphorylation and the translational efficiency of GCN4 mRNA. This conclusion is supported by biochemical studies showing that the truncated GLC7 allele increases the level of eIF-2α Phosphorylation in the gcn2-507 mutant to a level approaching that seen in wild-type cells under starvation conditions. The truncated GLC7 allele also leads to reduced glycogen accumulation, indicating that this protein phosphatase is involved in regulating diverse metabolic pathways in yeast cells.

UR - http://www.scopus.com/inward/record.url?scp=0026490040&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0026490040&partnerID=8YFLogxK

M3 - Article

VL - 12

SP - 5700

EP - 5710

JO - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

SN - 0270-7306

IS - 12

ER -