Identification of positive-acting domains in GCN2 protein kinase required for translational activation of GCN4 expression

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Molecular and Cellular Biology; (USA)

DOI:https://doi.org/10.1128/MCB.10.6.2820· OSTI ID:6422516

Wek, R C; Ramirez, M; Jackson, B M; Hinnebusch, A G ^[1]

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1. Unit on Molecular Genetics of Lower Eukaryotes, Lab. of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, MD (US)

GCN4 is a transcriptional activator of amino acid-biosynthetic genes in the yeast {ital Saccharomyces cerevisiae}. GCN2, a translational activator of {ital GCN4} expression, contains a domain homologous to the catalytic subunit of eukaryotic protein kinases. Substitution of a highly conserved lysine residue in the kinase domain abolished GCN2 regulatory function in vivo and its ability to autophosphorylate in vitro, indicating that GCN2 acts as a protein kinase in stimulating {ital GCN4} expression. Elevated {ital GCN2} gene dosage led to depression of {ital GCN4} under nonstarvation conditions; however, the authors found that {ital GCN2} mRNA and protein levels did not increase in wild-type cells in response to amino acid starvation. Therefore, it appears that GCN2 protein kinase function is stimulated postranslationally in amino acid-starved cells. Three dominant-constitutive {ital GCN2} point mutations were isolated that led to derepressed {ital GCN4} expression under nonstarvation conditions. Two of the {ital GCN2}(Con) mutations mapped in the kinase domain itself. The third mapped just downstream from a carboxyl-terminal segment homologous to histidyl-tRNA synthetase (HisRS), which the authors suggest might function to detect uncharged tRNA in amino acid-starved cells and activate the adjacent protein kinase moiety.

• OSTI ID: 6422516
• Journal Information: Molecular and Cellular Biology; (USA), Journal Name: Molecular and Cellular Biology; (USA) Vol. 10:6; ISSN MCEBD; ISSN 0270-7306
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
550400* -- Genetics
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
ENZYMES
EUMYCOTA
FUNGI
GENE AMPLIFICATION
GENE MUTATIONS
GENE REGULATION
GENE REPRESSORS
GENES
GENETIC MAPPING
LIGASES
MAPPING
MICROORGANISMS
MOLECULAR STRUCTURE
MUTATIONS
NUCLEIC ACIDS
NUCLEOPROTEINS
ORGANIC COMPOUNDS
PHENOTYPE
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PLANTS
PROTEINS
RNA
SACCHAROMYCES
SACCHAROMYCES CEREVISIAE
TRANSCRIPTION FACTORS
TRANSFER RNA
TRANSFERASES
YEASTS