Casein kinase II phosphorylates translation initiation factor 5 (eIF5) in Saccharomyces cerevisiae

Tapan Maiti, Amitabha Bandyopadhyay, Umadas Maitra

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Eukaryotic translation initiation factor 5 (eIF5) interacts with the 40S initiation complex (40S-eIF3-mRNA-Met-tRNAf-eIF2-GTP) to promote the hydrolysis of ribosome-bound GTP. In Saccharomyces cerevisiae, eIF5 is encoded by a single-copy essential gene, TIF5, that is required for cell growth and viability. In this work, we show that eIF5 immunoprecipitated from cell-free extracts of 32P-labelled yeast cells is phosphorylated on multiple serine residues. Phosphopeptide mapping reveals four major sites of phosphorylation that appear to be identical to recombinant yeast eIF5 sites phosphorylated in vitro by casein kinase II. Furthermore, analysis of eIF5 isolated from a yeast strain having a conditional mutant of casein kinase II indicates that phosphorylation of eIF5 is completely abolished at the non-permissive temperature. Additionally, haploid yeast strains were constructed to contain Ser-to-Ala mutations at the five casein kinase II consensus sequences in eIF5; in these cells, eIF5 phosphorylation was absent. Surprisingly, substitution of the TIF5 gene mutated at these sites for the wild-type gene had no obvious effect on cell growth under normal growth conditions. The implications of these results in eIF5 function are discussed.

Original languageEnglish (US)
Pages (from-to)97-108
Number of pages12
JournalYeast
Volume20
Issue number2
DOIs
StatePublished - Jan 30 2003

Fingerprint

Eukaryotic Initiation Factor-5
Eukaryotic Initiation Factors
Casein Kinase II
Casein
Peptide Initiation Factors
Yeast
translation (genetics)
Saccharomyces cerevisiae
Phosphorylation
Genes
Cell growth
Yeasts
yeasts
phosphorylation
Guanosine Triphosphate
cell growth
Growth
Hydrolysis
Substitution reactions
Cells

Keywords

  • Casein kinase II
  • Eukaryotic protein synthesis
  • Protein phosphorylation
  • Saccharomyces cerevisiae
  • Translation initiation factor 5

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biotechnology
  • Bioengineering
  • Microbiology

Cite this

Casein kinase II phosphorylates translation initiation factor 5 (eIF5) in Saccharomyces cerevisiae. / Maiti, Tapan; Bandyopadhyay, Amitabha; Maitra, Umadas.

In: Yeast, Vol. 20, No. 2, 30.01.2003, p. 97-108.

Research output: Contribution to journalArticle

Maiti, Tapan ; Bandyopadhyay, Amitabha ; Maitra, Umadas. / Casein kinase II phosphorylates translation initiation factor 5 (eIF5) in Saccharomyces cerevisiae. In: Yeast. 2003 ; Vol. 20, No. 2. pp. 97-108.
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