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Alternative start codon is associated to production of human non‐hypusinated EIF5A1 isoform A
Author(s) -
Pereira Karina,
Tamborlin Letícia,
Almeida Isadora,
Meneguello Letícia,
Lourenço Rogério,
Luchessi Augusto
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.892.4
Subject(s) - gene isoform , biology , amino acid , biochemistry , in silico , genetics , gene
EIF5A1 protein has a particular amino acid residue, named hypusine, that has never been found in others proteins and is highly conserved in Archaea and Eukarya domains. The hypusine is essential for EIF5A1 action and it is produced by a post‐translational modification using spermidine as substrate. Conversely, the bacterial ortholog EFP is not hypusinated. EIF5A1 has been involved with the process of protein synthesis and recently it was shown that acts on translation of polyproline motifs. In humans, five EIF5A1 transcript variants are described. The variants B, C, D and X5 encode the canonical isoform B and it is predicted that the variant A encodes the isoform A, which has an additional sequence of 30 amino acids at N‐terminus. Checking the genome database it was possible to find putative coding sequences for isoform A in others mammals. In HeLa cells, we found that the variant A was the main EIF5A1 transcript produced; nevertheless the content of isoform B was higher than isoform A. In fact, we observed that the start codon related to isoform A is less recognized by ribosomes compared to isoform B. In addition, we found that HeLa cells maintain the endogenous isoform A not hypusinated. In silico analysis suggested an intriguing connection between the additional amino acids residues at N‐terminal of isoform A and mitochondria. The results obtained so far contribute to characterization of EIF5A1 isoform A, a protein never studied before.