Shoup Daniel, Roth Andrew, Puchalla Jason, Rye Hays S
Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States.
Department of Physics, Princeton University, Princeton, NJ, United States.
Front Mol Biosci. 2022 Jul 7;9:915307. doi: 10.3389/fmolb.2022.915307. eCollection 2022.
Protein aggregation, or the uncontrolled self-assembly of partially folded proteins, is an ever-present danger for living organisms. Unimpeded, protein aggregation can result in severe cellular dysfunction and disease. A group of proteins known as molecular chaperones is responsible for dismantling protein aggregates. However, how protein aggregates are recognized and disassembled remains poorly understood. Here we employ a single particle fluorescence technique known as Burst Analysis Spectroscopy (BAS), in combination with two structurally distinct aggregate types grown from the same starting protein, to examine the mechanism of chaperone-mediated protein disaggregation. Using the core bi-chaperone disaggregase system from as a model, we demonstrate that, in contrast to prevailing models, the overall size of an aggregate particle has, at most, a minor influence on the progression of aggregate disassembly. Rather, we show that changes in internal structure, which have no observable impact on aggregate particle size or molecular chaperone binding, can dramatically limit the ability of the bi-chaperone system to take aggregates apart. In addition, these structural alterations progress with surprising speed, rendering aggregates resistant to disassembly within minutes. Thus, while protein aggregate structure is generally poorly defined and is often obscured by heterogeneous and complex particle distributions, it can have a determinative impact on the ability of cellular quality control systems to process protein aggregates.
蛋白质聚集，即部分折叠的蛋白质不受控制的自组装，对生物体来说是一种始终存在的危险。如果不受阻碍，蛋白质聚集会导致严重的细胞功能障碍和疾病。一类被称为分子伴侣的蛋白质负责拆解蛋白质聚集体。然而，蛋白质聚集体是如何被识别和拆解的，目前仍知之甚少。在这里，我们采用一种称为猝发分析光谱法（BAS）的单粒子荧光技术，结合从同一起始蛋白质生长而来的两种结构不同的聚集体类型，来研究伴侣介导的蛋白质解聚机制。以来自……的核心双伴侣解聚酶系统为模型，我们证明，与主流模型相反，聚集体颗粒的整体大小对聚集体解聚进程至多只有微小影响。相反，我们表明内部结构的变化，虽然对聚集体颗粒大小或分子伴侣结合没有可观察到的影响，但却能极大地限制双伴侣系统拆解聚集体的能力。此外，这些结构改变以惊人的速度发展，使聚集体在几分钟内就对解聚产生抗性。因此，虽然蛋白质聚集体的结构通常定义不明确，且常常被异质和复杂的颗粒分布所掩盖，但它对细胞质量控制系统处理蛋白质聚集体的能力可能具有决定性影响。
