Fibril growth kinetics reveal a region of beta2-microglobulin important for nucleation and elongation of aggregation.
Fibril growth kinetics reveal a region of beta2-microglobulin important for nucleation and elongation of aggregation.
复制标题
DOI：
10.1016/j.jmb.2008.01.092
复制
发表时间：
2008-04-18
影响因子：
5.6
通讯作者：
Radford, Sheena E.
中科院分区：
文献类型：
--
作者：
Platt, Geoffrey W.;Routledge, Katy E.;Homans, Steve W.;Radford, Sheena E.
淀粉样蛋白是一种高度有序的聚集体形式，由长的、直的和不分枝的蛋白质原纤维组成，这些纤维在体外形成具有特征的成核依赖动力学。目前，纤维成核和伸长的结构分子机制还知之甚少。在这里，我们研究了初始单体前体的序列和结构在决定人β2-微球蛋白(β2M)的成核和伸长率中的作用。我们描述了野生型β2M和12个变异体在pH=2.5下种子和自发(非种子)纤维生长的动力学，特别是针对多肽链(残基62-70)的一个芳香丰富区域，该区域已被预测为高度淀粉样变性。结果揭示了在所探索的条件下，β2M序列这一部分的芳香族残基在纤维形成中的重要性，并表明多肽链的这一区域既参与了纤维形成的成核阶段，也参与了纤维形成的伸长阶段。用核磁共振弛豫方法对每个变体的未折叠单体的构象性质进行的结构分析表明，所有变体都包含显著的非随机结构，涉及两个疏水簇，包括区29-51和58-79，其程度严重依赖于序列。然而，在未折叠状态下的非随机结构的程度与纤维成核和伸长率之间没有直接的相关性，这表明聚集的早期阶段涉及与初始未折叠状态相比的显著构象变化。综上所述，这些数据表明了一种β2M淀粉样蛋白形成的模型，在该模型中，涉及由62-70残基组成的高度疏水和富含芳香族的区域的结构特异性相互作用提供了一个互补的界面，该界面是该蛋白质在酸性pH下生成淀粉样纤维的关键。
Amyloid is a highly ordered form of aggregate comprising long, straight and unbranched proteinaceous fibrils that are formed with characteristic nucleation-dependent kinetics in vitro. Currently, the structural molecular mechanism of fibril nucleation and elongation is poorly understood. Here, we investigate the role of the sequence and structure of the initial monomeric precursor in determining the rates of nucleation and elongation of human β2-microglobulin (β2m). We describe the kinetics of seeded and spontaneous (unseeded) fibril growth of wild-type β2m and 12 variants at pH 2.5, targeting specifically an aromatic-rich region of the polypeptide chain (residues 62–70) that has been predicted to be highly amyloidogenic. The results reveal the importance of aromatic residues in this part of the β2m sequence in fibril formation under the conditions explored and show that this region of the polypeptide chain is involved in both the nucleation and the elongation phases of fibril formation. Structural analysis of the conformational properties of the unfolded monomer for each variant using NMR relaxation methods revealed that all variants contain significant non-random structure involving two hydrophobic clusters comprising regions 29–51 and 58–79, the extent of which is critically dependent on the sequence. No direct correlation was observed, however, between the extent of non-random structure in the unfolded state and the rates of fibril nucleation and elongation, suggesting that the early stages of aggregation involve significant conformational changes from the initial unfolded state. Together, the data suggest a model for β2m amyloid formation in which structurally specific interactions involving the highly hydrophobic and aromatic-rich region comprising residues 62–70 provide a complementary interface that is key to the generation of amyloid fibrils for this protein at acidic pH.
登录
查看更多内容
影响因子：
4.8
作者：
Hughes, E;Burke, RM;Doig, AJ
通讯作者：
Doig, AJ
DOI：
10.1073/pnas.0403756101
发表时间：
2004-07-20
影响因子：
11.1
作者：
Ivanova, MI;Sawaya, MR;Eisenberg, D
通讯作者：
Eisenberg, D
影响因子：
5.6
作者：
Faendrich, Marcus
通讯作者：
Faendrich, Marcus
DOI：
10.1016/s0006-291x(03)00543-6
发表时间：
2003-04-25
影响因子：
3.1
作者：
Hasegawa, K;Ohhashi, Y;Naiki, H
通讯作者：
Naiki, H
影响因子：
2.7
作者：
DELAGLIO, F;GRZESIEK, S;BAX, A
通讯作者：
BAX, A