Premium
Structural modeling and mutational analysis of yeast eukaryotic translation initiation factor 5A reveal new critical residues and reinforce its involvement in protein synthesis
Author(s) -
Dias Camila A. O.,
Cano Veridiana S. P.,
Rangel Suzana M.,
Apponi Luciano H.,
Frigieri Mariana C.,
Muniz João R. C.,
Garcia Wanius,
Park Myung H.,
Garratt Richard C.,
Zanelli Cleslei F.,
Valentini Sandro R.
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06345.x
Subject(s) - biology , eukaryotic translation , saccharomyces cerevisiae , initiation factor , mutant , eif4ebp1 , eukaryotic initiation factor , biochemistry , eif4a1 , eukaryotic translation initiation factor 4 gamma , translation (biology) , microbiology and biotechnology , genetics , yeast , messenger rna , gene
Eukaryotic translation initiation factor 5A (eIF5A) is a protein that is highly conserved and essential for cell viability. This factor is the only protein known to contain the unique and essential amino acid residue hypusine. This work focused on the structural and functional characterization of Saccharomyces cerevisiae eIF5A. The tertiary structure of yeast eIF5A was modeled based on the structure of its Leishmania mexicana homologue and this model was used to predict the structural localization of new site‐directed and randomly generated mutations. Most of the 40 new mutants exhibited phenotypes that resulted from eIF‐5A protein‐folding defects. Our data provided evidence that the C‐terminal α‐helix present in yeast eIF5A is an essential structural element, whereas the eIF5A N‐terminal 10 amino acid extension not present in archaeal eIF5A homologs, is not. Moreover, the mutants containing substitutions at or in the vicinity of the hypusine modification site displayed nonviable or temperature‐sensitive phenotypes and were defective in hypusine modification. Interestingly, two of the temperature‐sensitive strains produced stable mutant eIF5A proteins – eIF5A K56A and eIF5A Q22H,L93F – and showed defects in protein synthesis at the restrictive temperature. Our data revealed important structural features of eIF5A that are required for its vital role in cell viability and underscored an essential function of eIF5A in the translation step of gene expression.