Inter- and intra-octarepeat Cu(II) site geometries in the prion protein -: Implications in Cu(II) binding cooperativity and Cu(II)-mediated assemblies
Inter- and intra-octarepeat Cu(II) site geometries in the prion protein -: Implications in Cu(II) binding cooperativity and Cu(II)-mediated assemblies
复制标题
DOI：
10.1074/jbc.m312860200
复制
发表时间：
2004-03-19
影响因子：
4.8
通讯作者：
Gasset, M
中科院分区：
文献类型：
--
作者：
Morante, S;González-Iglesias, R;Gasset, M
Cu（II）与α朊病毒蛋白（alphaPrP）的结合可以是分子内和分子间的。在铜K-边的X-射线吸收光谱已被用于探索在每种结合模式下的位点几何形状，使用不溶性聚合Cu（II）.alphaBoPrP-（24-242）（牛PrP）络合物和含有一个、两个和四个八重复拷贝的肽的可溶性Cu（II）络合物。使用多重散射方法的光谱的扩展区域的分析显示两种类型的网站不同的数目在第一配位壳的Cu（II）的His残基。含有一个和两个octurepeat拷贝亚化学计量的Cu（II）配合物中的肽显示了直接结合的一个单一的组氨酸在雅阁与晶体学内重复的几何形状。或者，聚合的Cu（II）. aBoPrP-（24-242）复合物和在其可溶性复合物中的Cu（II）与半位点占据的四个八重复肽显示Cu（II）直接结合到两个His残基，与重复序列间结合模式一致。增加Cu（II）的网站占有率从0.5到0.75的肽含有四个octerepeats导致的光谱特征是中间的那些间和内重复模式。从His-Cu-His（间重复）过渡到Cu-His（内重复）增加Cu（II）饱和度提供了阳离子结合过程的正协同性的结构基础，并解释了alphaPrP参与Cu（II）介导的分子间相互作用的能力。
Cu(II) binding to the alpha prion protein (alphaPrP) can be both intramolecular and intermolecular. X-ray absorption spectroscopy at the copper K-edge has been used to explore the site geometry under each binding mode using both insoluble polymeric Cu(II).alphaBoPrP-(24-242) (bovine PrP) complexes and soluble Cu(II) complexes of peptides containing one, two, and four copies of the octarepeat. Analysis of the extended region of the spectra using a multiple scattering approach revealed two types of sites differing in the number of His residues in the first coordination shell of Cu(II). Peptides containing one and two-octarepeat copies in sub-stoichiometric Cu(II) complexes showed the direct binding of a single His in accord with crystallographic intra-repeat geometry. Alternatively, the polymeric Cu(II).alphaBoPrP-(24-242) complex and Cu(II) in its soluble complex with a four-octarepeat peptide at half-site-occupancy showed Cu(II) directly bound to two His residues, consistent with an inter-repeat binding mode. Increasing the Cu(II) site occupancy from 0.5 to 0.75 in the peptide containing four octarepeats resulted in spectral features that are intermediate to those of the inter-and intra-repeat modes. The transition from His-Cu-His (inter-repeat) to Cu-His (intra-repeat) on increasing Cu(II) saturation offers a structural basis for the positive cooperativity of the cation binding process and explains the capacity of alphaPrP to participate in Cu(II)-mediated intermolecular interactions.