Acceleration of nucleation of prion protein during continuous ultrasonication
Acceleration of nucleation of prion protein during continuous ultrasonication
复制标题
连续超声处理过程中朊病毒蛋白成核加速
DOI：
10.1093/jb/mvy015
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Kuwata Kazuo
中科院分区：
文献类型：
--
作者：
Yamaguchi Kei-ichi;Honda Ryo P.;Elhelaly Abdelazim Elsayed;Kuwata Kazuo
虽然超声脉冲辐射常用于体外产生淀粉样蛋白原纤维，但在连续超声处理过程中诱导蛋白质的淀粉样蛋白原纤维化的可能性尚不清楚。在这项研究中，我们实现了一个连续照射系统，并测量远紫外圆二色性在实时的方式。在连续超声处理过程中，全长小鼠朊蛋白（mPrP）的构象迅速发生变化，在pH2.2、4.0和9.1条件下分别形成扭曲的原纤维、β-寡聚体和无定形聚集体。同样，鸡蛋白色溶菌酶形成扭曲的原纤维和小的和大的无定形聚集体，分别在pH 2.2和7.1和11.9，没有滞后时间。初始速率的浓度依赖性在两个系统之间是不同的。mPrP的聚集体形成遵循一级反应，而溶菌酶的聚集体形成遵循零级反应。重要的是，通过关闭超声处理立即停止反应，并且当超声处理重新开始时立即重新开始。因此，连续超声处理显着加速成核的mPrP和溶菌酶聚集体之间的相互作用单体和空化气泡。这些空化气泡可以作为催化剂，降低成核的活化自由能，这是低的mPrP和高的溶菌酶。
Although pulsatile irradiation of ultrasonication is frequently used for generating amyloid fibrilsin vitro, the potential for inducing amyloid fibrillation of proteins during continuous ultrasonication is unknown. In this study, we implemented a continuous irradiation system and measured far-ultraviolet circular dichroism in a real-time manner. During the continuous ultrasonication, the conformation of full-length mouse prion protein (mPrP) was rapidly altered without a lag time and electron microscopy revealed that distorted fibrils, β-oligomers and amorphous aggregates were formed at pH 2.2, 4.0 and 9.1, respectively. Similarly, hen egg white lysozyme formed distorted fibrils and small and large amorphous aggregates at pH 2.2 and 7.1 and 11.9, respectively, without a lag time. The concentration dependencies of the initial rates were different between the two systems. The aggregate formation of mPrP followed a first-order reaction, whereas that of lysozyme followed the zeroth-order reaction. Importantly, the reactions were immediately stopped by switching off ultrasonication, and restarted instantaneously when ultrasonication was restarted. Thus, the continuous ultrasonication significantly accelerates the nucleations of mPrP and lysozyme aggregates by the interaction between monomer and cavitation bubble. These cavitation bubbles may act as catalysts that decrease the activation free energy for nucleation, which is low in mPrP and high in lysozyme.