The Panicum mosaic virus-like 3' cap-independent translation element: A translation enhancer that functions in mammalian systems

• Main Author: Peterson, Mariko Sada
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2013
• Subjects: Biochemistry; Molecular biology; Virology
• ISBN: 9781303169038; 1303169037

In canonical eukaryotic translation initiation, the recognition of mRNA by the translation machinery is facilitated through the binding of the 5' m7G cap structure to eukaryotic initiation factor 4E (eIF4E). This recognition is necessary for efficient translation of the message to occur. In contrast, some viruses lack the 5' cap structure but have alternative mechanisms to initiate translation and express the viral proteins necessary for replication. The positive-strand RNA plant viruses of the panico-, carmo-, umbra-, (1-3) and aureusviruses (4) contain an RNA structure in their 3' UTRs that binds eIF4E (2) and through communication with the 5' UTR, are able to efficiently initiate translation in their hosts. This interaction is proposed to occur through a guanosine residue that interacts with the cap-binding pocket of the protein in a similar way to the m7G cap (3). Control of eIF4E expression has important implications in plant susceptibility to viral infection and has been used to design more resistant crops (5-7). Its control is also important in mammalian systems: deregulated eIF4E has been implicated in many cancers including those of the breast (8), lung (9) and prostate (10), chronic human diseases such as diabetes (11), and developmental disorders such as autism (12). As eIF4E structure and function are highly conserved across kingdoms, and characterizing novel interactions with this protein have potential use in disease control, we sought to characterize this element in mammalian systems . We optimized translation in rabbit reticulocyte lysate and HeLa lysate for salt, RNA concentration and incubation time (Aim 1), compared the translation efficiency of reporter RNAs containing PTEs of 9 different viruses in lysates and whole cells (Aim 2), and investigated the ability of the PTE to act as an inhibitor (Aim 3).