The role of eukaryotic initiation factor 5A and its cellular localization in developing Zea mays plant tissue.

Abstract

Eukaryotic initiation factor 5A is an 18 kDa protein that has been implicated in a wide variety of cellular activities, but its primary role, especially its role in translation, has been a mystery. Investigation of its localization in developing maize endosperm and root and leaf tissue have reinforced the idea that eIF5A has at least a secondary role in cellular proliferation and cell division. The interactions of eIF5A with numerous maize proteins identified through pull down analysis, have provided insight into the primary function of this elusive protein. Identified proteins that interacted with eIF5A were components of the cytoskeleton or involved in cell division (tubulin, legumin, actin), carbohydrate synthesis and modification, amino acid biosynthesis, and translation elongation factors. These interacting proteins all have a link to management and survival under low oxygen conditions in plants, suggesting a role of eIF5A as an elongation factor that is necessary when stress interferes with the cell's primary elongation factors. Three eIF5A isoforms were identified in Zea mays, with eIF5A-1 being the most highly expressed.