Mapping eIF5A binding sites for Dys1 and Lia1: in vivo evidence for regulation of eIF5A hypusination

• Published in: FEBS letters Vol. 555; no. 3; pp. 464 - 468
• Main Authors: Thompson, Gloria M, Cano, Veridiana S.P, Valentini, Sandro R
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 18-12-2003
• Subjects: Binding Sites; DNA, Complementary - chemistry; DNA, Complementary - genetics; DYS1; eIF5A; Eukaryotic Translation Initiation Factor 5A; Fungal Proteins - genetics; Fungal Proteins - metabolism; Genes, Reporter; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Hypusination; LIA1; Ligands; Models, Molecular; Oxidoreductases Acting on CH-NH Group Donors - chemistry; Oxidoreductases Acting on CH-NH Group Donors - genetics; Oxidoreductases Acting on CH-NH Group Donors - metabolism; Peptide Initiation Factors - genetics; Peptide Initiation Factors - metabolism; Protein Processing, Post-Translational; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; RNA-Binding Proteins; Saccharomyces cerevisiae - genetics; Two-hybrid; Two-Hybrid System Techniques; YJR070C; YJR070C; DYS1; Hypusination; LIA1; eIF5A; Two-hybrid
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(03)01305-X

The evolutionarily conserved factor eIF5A is the only protein known to undergo hypusination, a unique posttranslational modification triggered by deoxyhypusine synthase (Dys1). Although eIF5A is essential for cell viability, the function of this putative translation initiation factor is still obscure. To identify eIF5A-binding proteins that could clarify its function, we screened a two-hybrid library and identified two eIF-5A partners in
S. cerevisiae: Dys1 and the protein encoded by the gene
YJR070C, named Lia1 (
L
igand of e
I
F5
A
). The interactions were confirmed by GST pulldown. Mapping binding sites for these proteins revealed that both eIF5A domains can bind to Dys1, whereas the C-terminal domain is sufficient to bind Lia1. We demonstrate for the first time in vivo that the N-terminal α-helix of Dys1 can modulate enzyme activity by inhibiting eIF5A interaction. We suggest that this inhibition be abrogated in the cell when hypusinated and functional eIF5A is required.