Efeitos de deleções pontuais em resíduos da região linker das sequências de localização nuclear clássicas nas interações com a Importina-α

• Autor(a) principal: Nakamura, Thábatta Karollynne Estevam [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/202892; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2019-01-28/000900549.pdf
• topic: Carioferinas; Mutagênese insercional; Transporte ativo do núcleo celular; Mutagenesis, Insertional

The nuclear import pathway is an important subject of studies because is related to several cell functionality processes. In the classical nuclear import pathway, proteins are translocated via the complex comprised of Importin-α and Importin-β proteins. Importin-α is a solenoid protein composed of ten Armadillo (ARM) repeats, each one formed by three α-helices. Importin-α is capable of adopting different conformations, depending on the protein bound to it because of its solenoid architecture. The classical process of nuclear import starts with the recognition of nuclear localization sequences (NLS) within the cargo proteins. The classical NLSs (cNLSs) bind directly to Importin-α and are classified as monopartite or bipartite. Bipartite cNLSs have two binding sites (major and minor) separated by an intermediary region named as linker, which is comprised of ten to twelve residues. Literature data shows that point mutations at the linker region do not affect nuclear import, however, deletions in this region prevent the nuclear import process. In this project, we analyzed the effect of linker point mutations on the formation of the Importin-α:cNLS complex. Three models were used: the canonical structure of Importin-α bound to the Nucleoplasmin NLS and two structures with point deletions in the linker at residues NplA159 (instable contact) and NplK162 (stable contact). All models were submitted to normal modes calculations, and the interaction analyses between the bipartite cNLS and Importin-α residues were carried out accordingly to their interaction frequencies, fluctuation values, residues correlations and Importin-α flexibility. The results showed that interactions in the major site enhanced by reducing the contacts in the minor site, and vice-versa, as a consequence of a shorter linker region. Moreover, the residues fluctuations were increased, primarily in the linker, and could be related to an attempt of Importin-α...