Caracterização funcional da proteína MxA: estudo do seu envolvimento com a mauinaria de SUMOilação

• Ano de defesa: 2014
• Autor(a) principal: Carvalho, Carlos Eduardo Brantis de [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Biotecnologia; Virus da estomatite vesicular; Interferon; Anticorpos policlonais; Polyclonal
• Link de acesso: http://hdl.handle.net/11449/110838

The human MxA protein is a member of the superfamily of GTPases dynamins. The so called Mx proteins are present in the majority of the vertebrate organisms investigated so far and contain two structural domains, named GTPase and CID-GED (stalk), besides the capabilities of homo-oligomerization and association with intracellular membranes. Moreover, the Mx proteins are strictly produced upon cell sensibilization with type I and III interferons. The vast antiviral activity against RNA and DNA viruses, including the Influenza virus and members of the bunyaviridae family, is among the functional properties of MxA. Moreover, MX1 epigenetic silencing is associated with cellular immortalization in neoplasias. Therefore, the study of MxA is of great interest as it is a key component of the Interferon-mediated pathways and cell proliferation control. Recentely, in a two-hybrid screen using a fetal brain cDNA library, it was possible to reveal that MxA interacts with proteins related to the post-translational modification process named SUMOylation and to the assemble of the nuclear bodies named PML-NBs and with proteins implicated in the control of transcription and apoptose. In this study, it was investigated the interaction between MxA and the components of the protein SUMOylation pathway. It was possible to confirm the physical interaction between MxA and Ubc9 and SUMO1, using co-immunopreciptation assay. Then, using the yeast two-hybrid system, it was possible to determine that the EIL (E67-interacting loop) region on SUMO1 interacts with the CID-GED domain of MxA without the requirement of the SIM sequences (SUMO-interacting motif) present in MxA. Moreover, it was determined that Ubc9 interacts with the GTPase domain of MxA and that MxA homo-oligomerization is important for its interaction with SUMO1 and Ubc9. Also, we were able to demonstrate for the first time that the protein MxA undergoes SUMOylation by SUMO1, SUMO2 and SUMO3. Finally, it ...