Bernardes Natalia E, Takeda Agnes A S, Freitas Fernanda Z, Bertolini Maria Célia, Fontes Marcos R M
Departamento de Física e Biofísica, Instituto de Biociências, UNESP - Universidade Estadual Paulista, Botucatu, SP, Brazil.
Departamento de Bioquímica e Tecnologia Química, Instituto de Química, UNESP - Universidade Estadual Paulista, Araraquara, SP, Brazil.
Acta Crystallogr F Struct Biol Commun. 2014 Apr;70(Pt 4):501-4. doi: 10.1107/S2053230X14005068. Epub 2014 Mar 25.
Importin-α recognizes cargo proteins that contain classical nuclear localization sequences (NLS) and, in complex with importin-β, is able to translocate nuclear proteins through the nuclear pore complex. The filamentous fungus Neurospora crassa is a well studied organism that has been widely used as a model organism for fundamental aspects of eukaryotic biology, and is important for understanding the specific mechanisms of protein transport to the cell nucleus. In this work, the crystallization and preliminary X-ray diffraction analysis of importin-α from N. crassa (IMPα-Nc) complexed with a classical NLS peptide (SV40 NLS) are reported. IMPα-Nc-SV40 NLS crystals diffracted X-rays to 2.0 Å resolution and the structure was solved by molecular-replacement techniques, leading to a monomeric structure. The observation of the electron-density map indicated the presence of SV40 NLSs interacting at both the minor and major NLS-binding sites of the protein.
输入蛋白α识别含有经典核定位序列（NLS）的货物蛋白，并且与输入蛋白β形成复合物后，能够使核蛋白通过核孔复合体进行转运。丝状真菌粗糙脉孢菌是一种经过充分研究的生物，已被广泛用作真核生物学基础方面的模式生物，对于理解蛋白质向细胞核转运的具体机制很重要。在这项工作中，报道了粗糙脉孢菌的输入蛋白α（IMPα-Nc）与经典NLS肽（SV40 NLS）形成复合物的结晶及初步X射线衍射分析。IMPα-Nc-SV40 NLS晶体将X射线衍射到2.0 Å分辨率，并且通过分子置换技术解析了其结构，得到了一个单体结构。电子密度图的观察表明，SV40 NLS在该蛋白的次要和主要NLS结合位点均有相互作用。
