Wolwertz Mathieu Laporte, Nguyen Phuong Trang, Quittot Noé, Bourgault Steve
Department of Chemistry, Pharmaqam, University of Québec in Montreal, Montreal, QC, Canada, H3C 3P8; Quebec Network for Research on Protein Function, Engineering, and Applications, PROTEO, Canada.
Department of Chemistry, Pharmaqam, University of Québec in Montreal, Montreal, QC, Canada, H3C 3P8; Quebec Network for Research on Protein Function, Engineering, and Applications, PROTEO, Canada.
Biochim Biophys Acta. 2016 Apr;1864(4):409-18. doi: 10.1016/j.bbapap.2016.01.009. Epub 2016 Jan 21.
Light chain amyloidosis (AL) is a lethal disease associated with the deposition of misfolded immunoglobulin light chains (LC) as amyloid fibrils in the extracellular space of vital organs. The exact mechanisms of LC self-assembly and the molecular basis leading to cellular and organ failure still remain poorly understood. In this study, we investigated the relationship between the quaternary structure, the stability and the amyloidogenecity of LC variable domain (VL) from the λ6 germline. We observed that the amyloidogenic λ6 Wil and its non-amyloidogenic counterpart Jto dimerize in a concentration-dependent manner and that the dimer affinity is considerably decreased in the presence of a high ionic strength. Our results showed that the dimeric state delays the structural conversion associated with amyloid formation and that the monomer is critical to initiate amyloidogenesis. Thermal and chemical unfolding studies revealed that the dimeric state of VL λ6 has an equivalent stability to the monomer. This indicates that the protective effect of dimerization is not related to thermodynamic stability but, most likely, resides in specific structural features. The toxicity of monomeric Jto and Wil as well as fibrillar aggregates was evaluated on cardiomyoblasts and ThT-negative proteospecies reduced cellular viability when employed at high concentration. This study provides novel insights into the complex process of LC amyloidogenesis and suggests that dimer stabilization constitutes a promising strategy to prevent self-assembly and amyloid deposition.
轻链淀粉样变性（AL）是一种致命疾病，与错误折叠的免疫球蛋白轻链（LC）以淀粉样纤维形式沉积在重要器官的细胞外空间有关。LC自组装的确切机制以及导致细胞和器官衰竭的分子基础仍知之甚少。在本研究中，我们研究了来自λ6种系的LC可变结构域（VL）的四级结构、稳定性与淀粉样变性之间的关系。我们观察到，具有淀粉样变性的λ6 Wil及其非淀粉样变性对应物Jto以浓度依赖的方式二聚化，并且在高离子强度存在下二聚体亲和力显著降低。我们的结果表明，二聚体状态延迟了与淀粉样形成相关的结构转变，并且单体对于启动淀粉样变性至关重要。热变性和化学变性研究表明，VL λ6的二聚体状态与单体具有同等稳定性。这表明二聚化的保护作用与热力学稳定性无关，而很可能存在于特定的结构特征中。在心肌母细胞上评估了单体Jto和Wil以及纤维状聚集体的毒性，当高浓度使用时，ThT阴性蛋白种类降低了细胞活力。本研究为LC淀粉样变性的复杂过程提供了新的见解，并表明二聚体稳定化是防止自组装和淀粉样沉积的一种有前景的策略。
