Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia.
Laboratory of Cell Morphology, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia.
Int J Mol Sci. 2021 May 2;22(9):4828. doi: 10.3390/ijms22094828.
Proteolytic enzymes are known to be involved in the formation and degradation of various monomeric proteins, but the effect of proteases on the ordered protein aggregates, amyloid fibrils, which are considered to be extremely stable, remains poorly understood. In this work we study resistance to proteolytic degradation of lysozyme amyloid fibrils with two different types of morphology and beta-2-microglobulun amyloids. We showed that the proteolytic enzyme of the pancreas, trypsin, induced degradation of amyloid fibrils, and the mechanism of this process was qualitatively the same for all investigated amyloids. At the same time, we found a dependence of efficiency and rate of fibril degradation on the structure of the amyloid-forming protein as well as on the morphology and clustering of amyloid fibrils. It was assumed that the discovered relationship between fibrils structure and the efficiency of their degradation by trypsin can become the basis of a new express method for the analysis of amyloids polymorphism. Unexpectedly lower resistance of both types of lysozyme amyloids to trypsin exposure compared to the native monomeric protein (which is not susceptible to hydrolysis) was attributed to the higher availability of cleavage sites in studied fibrils. Another intriguing result of the work is that the cytotoxicity of amyloids treated with trypsin was not only failing to decline, but even increasing in the case of beta-2-microglobulin fibrils.
蛋白酶已知参与各种单体蛋白质的形成和降解，但蛋白酶对被认为极其稳定的有序蛋白质聚集体——淀粉样纤维的影响仍知之甚少。在这项工作中，我们研究了两种不同形态的溶菌酶淀粉样纤维和β2-微球蛋白淀粉样纤维对蛋白水解降解的抗性。我们表明，胰腺蛋白酶（trypsin）可诱导淀粉样纤维降解，并且该过程的机制对于所有研究的淀粉样纤维都是相同的。同时，我们发现纤维降解的效率和速率与淀粉样形成蛋白的结构以及淀粉样纤维的形态和聚集有关。有人假设，发现的纤维结构与胰蛋白酶降解效率之间的关系可以成为分析淀粉样蛋白多态性的新表达方法的基础。出乎意料的是，与天然单体蛋白质（不易水解）相比，两种溶菌酶淀粉样纤维对胰蛋白酶暴露的抵抗力更低，这归因于研究中的纤维中切割位点的更高可用性。这项工作的另一个有趣结果是，用胰蛋白酶处理后的淀粉样纤维的细胞毒性不仅没有下降，甚至在β2-微球蛋白纤维的情况下还增加了。
