Characterization of transcriptionally active atwwp1 nuclear bodies that confer partial immunity against begomoviruses

• Ano de defesa: 2017
• Autor(a) principal: Calil, Iara Pinheiro
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Begomuvírus; DNA - Análise; Proteínas; Imunidade; Genética Molecular e de Microorganismos
• Link de acesso: http://www.locus.ufv.br/handle/123456789/11661

As DNA viruses, which replicate in the nucleus of infected cells, the bipartite begomoviruses (Geminiviridae family) encode the nuclear shuttle protein to facilitate the translocation of viral DNA from the nucleus to the cytoplasm via nuclear pores. This intracellular trafficking of NSP-DNA complexes is accessorized by the NSP- interacting GTPase (NIG) at the cytosolic side. Here, we report the characterization of AtWWP1, a WW domain-containing protein, identified as a NIG partner. In the chapter II, we demonstrated that AtWWP1 forms nuclear bodies (NBs) via its WW domains and relocates NIG from the cytoplasm to the nucleus where it is confined to AtWWP1-NBs.Therefore, the NIG-AtWWP1 interaction, which also occurs via the WW domains, may interfere with the NIG pro-viral function that is associated with its cytosolic localization. Consistent with this hypothesis, loss of AtWWP1 function debilitates further the plant upon begomovirus infection and overexpression of AtWWP1 confers tolerance to begomovirus. The antiviral function of AtWWP1-NBs, however, may be antagonized by viral infection, which was demonstrated to induce either a decrease in the number or disruption of AtWWP1-NBs. Our data established that AtWWP1 organizes nuclear structures as nuclear foci, which provide intrinsic immunity against begomovirus infection. Nevertheless, the underlying biochemical function of these AtWWP1-NBs has yet to be elucidated. In Chapter III, we demonstrated that AtWWP1-NB co-localizes with CDKC;2-NB, which has been shown to be involved in transcription and RNA processing. Like CDKC2, which modulates the phosphorylation status of RNA polymerase II C-terminal domain (CTD-RNA pol II), we showed that AtWWP1 interacts with CTD-RNA pol II within NBs. AtWWP1-NBs were disintegrated into diffuse pattern or converted to larger structures upon treatment with transcriptional inhibitors, a feature that resembles the CDKC2-NB dynamic organization, which depends on the transcriptional status of the cells. As further evidence for a role in transcription, we also demonstrated that AtWWP1 displays DNA binding activity and AtWWP1-NBs associate with active chromatin regions. Accordingly, the manipulation of the AtWWP1 levels promoted an enrichment of differentially expressed transcriptional factors in transgenic lines. Collectively, our data establish that the nuclear bodies formed by AtWWP1 are associated with active gene expression or co-transcriptional RNA processing.