The Eukaryotic Translation Initiation Factor 5, eIF-5, a Protein fromZea mays,Containing a Zinc-Finger Structure, Binds Nucleic Acids in a Zinc-Dependent Manner

A maize cDNA encoding the eukaryotic translation initiation factor 5 (eIF-5) has been isolated from an 8-day-old seedling cDNA library, The 1975 bp cDNA encodes a protein of 451 amino acids, with a predicted molecular weight of 49.04 kDa, and hybridizes to a single sequence in the maize genome. The deduced sequence contains motifs characteristic of proteins belonging to the GPTase superfamily, a zinc finger well conserved in all the protein sequences for eIF-5 reported so far, and a fragment also present in prokaryotic and chloroplast L11 ribosomal protein, Polymer-binding assays have been used to assess the predicted RNA binding property of the protein and to characterize its function. It is shown. that the eIF-5-encoded protein binds to single-stranded DNA and to polyuridylic acid and that the binding is dependent on the presence of Zn2+ ions. These results suggest that the zinc-finger structure is involved in the binding of the eIF-5 protein to RNA. (C) 1997 Academic Press.