Monomeric 伪-Synuclein Binds Congo Red Micelles in a Disordered Manner
详细信息 查看全文
- 作者：Alexander S. Maltsev ; Alexander Grishaev ; Ad Bax
- 刊名：Biochemistry
- 出版年：2012
- 出版时间：January 17, 2012
- 年：2012
- 卷：51
- 期：2
- 页码：631-642
- 全文大小：518K
- 年卷期：v.51,no.2(January 17, 2012)
- ISSN：1520-4995
文摘
The histological dye Congo Red (CR) previously has been shown to inhibit 伪-synuclein (aS) fibrillation, but the mode of this inhibition remained unclear. Because of favorable exchange kinetics, interaction between CR and aS lends itself to a detailed nuclear magnetic resonance study, and relaxation dispersion measurements yield the bound fraction and time scales for the interaction of aS with CR. We find that at pH 6, CR exists as a micelle, and at a CR:aS molar ratio of 1, only a small fraction of aS (2%) is bound to these micelles. Rapid exchange (kex 3000 s鈥?) between the free and CR-bound states broadens and strongly attenuates resonances of aS by two processes: a magnetic field-dependent contribution, caused by the chemical shift difference between the two states, and a nearly field-independent contribution caused by slower tumbling of aS bound to the CR micelle. The salt dependence of the interaction suggests a predominantly electrostatic mechanism for the 60 N-terminal residues, while the weaker interaction between residues 61鈥?00 and CR is mostly hydrophobic. Chemical shift and transferred NOE data indicate that aS becomes slightly more helical but remains largely disordered when bound to CR. Results indicate that inhibition of fibril formation does not result from binding of CR to free aS and, therefore, must result from interaction of aS fibrils or protofibrils with CR micelles.