The translationally controlled tumor protein is necessary for potyvirus replication

• Ano de defesa: 2016
• Autor(a) principal: Bruckner, Fernanda Prieto
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Potyvirus; Vírus de plantas; Relação hospedeiro-parasita; Genética vegetal; Ciências Agrárias
• Link de acesso: http://www.locus.ufv.br/handle/123456789/11715

The translationally controlled tumor protein (TCTP) is widely distributed among eukaryotes. It is involved in the regulation of basic processes such as cell cycle progression, cell growth, stress protection and apoptosis. During tomato (Solanum lycopersicum) and Nicotiana benthamiana infection by the potyvirus Pepper yellow mosaic virus, an increase of TCTP mRNA levels was observed. Plants silenced for TCTP accumulate fewer viruses than control plants, showing the importance of that gene for potyvirus infection. In this work, TCTP involvement in potyvirus infection was analyzed in details using the potyvirus Turnip mosaic virus (TuMV). N. benthamiana plants silenced for TCTP accumulated fewer viruses than non-silenced plants. In addition, plants overexpressing TCTP transiently accumulated more viruses than control plants, confirming that TCTP has a positive effect on infection by different potyviruses. To study TCTP subcellular localization in potyvirus infected plants, TCTP fused to GFP was co- expressed with TuMV/6K2:mCherry. Confocal analysis has shown that TCTP co- localizes with 6K2-tagged structures such as replicative vesicles and the perinuclear globular structure that is typically observed in potyvirus-infected cells. Cellular fractioning demonstrated that TCTP is mainly present in the soluble fraction but is also associated with membranes. The co-localization of TCTP with 6K2-tagged vesicles and its presence in cellular membranous fractions suggests a possible involvement of TCTP in virus replication. To test this hypothesis, protoplasts obtained from TCTP silenced plants were infected with TuMV and its mutant TuMV VNN , which is defective for replication. The results showed that TuMV accumulation is reduced in silenced protoplasts, indicating that TCTP is necessary for replication. TCTP accumulation during infection was also analyzed. Viral infection induces TCTP mRNA expression, but not protein accumulation, suggesting that the TCTP mRNA and not the protein has a role in viral infection. To check this, we expressed a non-translatable form of TCTP RNA in plants and analyzed its effect in virus accumulation. The results showed that only the expression of a translatable RNA resulting in protein production is able to increase virus infection, indicating that the protein and/or the translation of TCTP is important for potyvirus replication.