Rose Eukaryotic Initiation Factor 5a (eif5a) Gene Function

Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein known to contain the unusual amino acid hypusine. It is a highly conserved protein found in all eukaryotic organisms. Although originally identified as a translation initiation factor, recent studies suggest that eIF5A is mainly involved in translation elongation, mRNA turnover and decay, cell proliferation, and programmed cell death. However, the precise cellular function of eIF5A remains largely unknown, especially in plants. In this work, we characterized the RceIF5A from Rosa chinensis. Subcellular localization of RceIF5A showed that it localized predominantly to the cytoplasm of onion epidermal cells. RceIF5A expression is up-regulated in Rosa chinensis under high temperature, oxidative and osmotic stress conditions. Recombinant RceIF5A was overexpressed in Pichia pastoris strain SMD1168 to study its possible function under stress conditions. The recombinant SMD1168 cells that accumulated RceIF5A showed improved viability under thermal and oxidative stress conditions compared to control cultures. We then produced transgenic Arabidopsis that constitutively enhanced or suppressed expression of RceIF5A. The RceIF5A over-expression plants exhibited increased resistance to heat, oxidative and osmotic stresses, while the suppressed expression plant (three AteIF5A isoforms in Arabidopsis were down-regulated) showed more susceptibility to these stresses.