title: Alternative Start Codon Connects eIF5A to Mitochondria.
abstract: Eukaryotic translation initiation factor 5A (eIF5A), a protein containing the amino acid residue hypusine required for its activity, is involved in a number of physiological and pathological cellular processes. In humans, several EIF5A1 transcript variants encode the canonical eIF5A1 isoform B, whereas the hitherto uncharacterized variant A is expected to code for a hypothetical eIF5A1 isoform, referred to as isoform A, which has an additional N-terminal extension. Herein, we validate the existence of eIF5A1 isoform A and its production from transcript variant A. In fact, variant A was shown to encode both eIF5A1 isoforms A and B. Mutagenic assays revealed different efficiencies in the start codons present in variant A, contributing to the production of isoform B at higher levels than isoform A. Immunoblotting and mass spectrometric analyses showed that isoform A can undergo hypusination and acetylation at specific lysine residues, as observed for isoform B. Examination of the N-terminal extension suggested that it might confer mitochondrial targeting. Correspondingly, we found that isoform A, but not isoform B, co-purified with mitochondria when the proteins were overproduced. These findings suggest that eIF5A1 isoform A has a role in mitochondrial function. J. Cell. Physiol. 231: 2682-2689, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.|Institute of Biosciences, São Paulo State University, Rio Claro, São Paulo, Brazil.
authors.forename: Karina Danielle
authors.initials: KD
authors.lastname: Pereira
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.
authors.forename: Letícia
authors.initials: L
authors.lastname: Tamborlin
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.|Institute of Biosciences, São Paulo State University, Rio Claro, São Paulo, Brazil.
authors.forename: Letícia
authors.initials: L
authors.lastname: Meneguello
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.
authors.forename: André Ricardo Gomes
authors.initials: AR
authors.lastname: de Proença
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.
authors.forename: Isadora Cristina de Paula Andrade
authors.initials: IC
authors.lastname: Almeida
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.
authors.forename: Rogério Ferreira
authors.initials: RF
authors.lastname: Lourenço
authors.affiliation: Laboratory of Biotechnology, School of Applied Sciences, University of Campinas, Limeira, São Paulo, Brazil.|Institute of Biosciences, São Paulo State University, Rio Claro, São Paulo, Brazil.
authors.forename: Augusto Ducati
authors.initials: AD
authors.lastname: Luchessi
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D018387:Codon, Initiator / Q000235:genetics*; D003198:Computer Simulation; D006367:HeLa Cells; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D018387:Codon, Initiator; D008239:Lysine; D010448:Peptide Initiation Factors; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A; C100028:hypusine