Expression of a phosphorylation-resistant eukaryotic initiation factor 2 alpha-subunit mitigates heat shock inhibition of protein synthesis

• Published in: The Journal of biological chemistry 1993-06, Vol.268 (17), p.12946-12951
• Main Authors: Murtha-Riel, P, Davies, M V, Scherer, B J, Choi, S Y, Hershey, J W, Kaufman, R J
• Format: Article
• Language: English
• Subjects: Alanine; Amino Acid Sequence; Animals; Biological and medical sciences; CHO Cells; Cloning, Molecular; Cricetinae; Eukaryotic Initiation Factor-2 - genetics; Eukaryotic Initiation Factor-2 - isolation & purification; Eukaryotic Initiation Factor-2 - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression; Hot Temperature; Macromolecular Substances; Molecular and cellular biology; Molecular genetics; Mutagenesis, Site-Directed; Phosphorylation; Protein Biosynthesis; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Serine; Transfection; Translation. Translation factors. Protein processing
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)31477-7

Protein synthesis is dramatically reduced upon exposure of cells to elevated temperature. Concordant with this inhibition, multiple phosphorylation and dephosphorylation reactions occur on specific eukaryotic initiation factors that are required for protein synthesis. Most notably, phosphorylation of the alpha-subunit of eukaryotic initiation factor-2 (eIF-2 alpha) on serine residue 51 occurs. To identify the importance of phosphorylation in control of protein synthesis, we have evaluated the effects of expression of a mutant eIF-2 alpha which is resistant to phosphorylation. Expression of a serine to alanine mutant at residue 51 of eIF-2 alpha partially protected cells from the inhibition of protein synthesis in response to heat treatment. The overexpressed serine to alanine 51 mutant subunit was incorporated into the eIF-2 heterotrimer and was resistant to phosphorylation. These results are consistent with the hypothesis that heat shock inhibition of translation is mediated in part through phosphorylation of eIF-2 alpha. Expression of the wild type or mutant eIF-2 alpha did not affect cell survival or induction of hsp70 mRNA upon heat shock, indicating that although eIF-2 alpha is a heat shock-induced protein, its increased synthesis during heat shock does not alter the heat-shock response.