Division of Nephrology, University of São Paulo School of Medicine, 01246-903 São Paulo, Brazil.
Proc Natl Acad Sci U S A. 2011 Jun 14;108(24):9833-8. doi: 10.1073/pnas.1106766108. Epub 2011 May 27.
Mutations in PKD2 are responsible for approximately 15% of the autosomal dominant polycystic kidney disease cases. This gene encodes polycystin-2, a calcium-permeable cation channel whose C-terminal intracytosolic tail (PC2t) plays an important role in its interaction with a number of different proteins. In the present study, we have comprehensively evaluated the macromolecular assembly of PC2t homooligomer using a series of biophysical and biochemical analyses. Our studies, based on a new delimitation of PC2t, have revealed that it is capable of assembling as a homotetramer independently of any other portion of the molecule. Our data support this tetrameric arrangement in the presence and absence of calcium. Molecular dynamics simulations performed with a modified all-atoms structure-based model supported the PC2t tetrameric assembly, as well as how different populations are disposed in solution. The simulations demonstrated, indeed, that the best-scored structures are the ones compatible with a fourfold oligomeric state. These findings clarify the structural properties of PC2t domain and strongly support a homotetramer assembly of PC2.
PKD2 基因突变约占常染色体显性遗传性多囊肾病病例的 15%。该基因编码多囊蛋白-2，一种钙通透性阳离子通道，其胞质尾端（PC2t）在与许多不同蛋白的相互作用中发挥重要作用。本研究采用一系列生物物理和生化分析方法，全面评估了 PC2t 同源寡聚体的大分子组装。基于对 PC2t 的新界定，我们的研究表明，它能够独立于分子的任何其他部分组装成同源四聚体。我们的数据支持在存在和不存在钙的情况下这种四聚体排列。使用改良的基于全原子结构的模型进行的分子动力学模拟支持 PC2t 四聚体组装，以及不同聚集体在溶液中的分布。模拟结果表明，评分最高的结构与四聚体状态一致。这些发现阐明了 PC2t 结构域的结构特性，并强烈支持 PC2 的同源四聚体组装。
