眼睛是视觉系统中的重要器官,由透明的血管组织组成。αB-晶状体蛋白,在晶状体中发现的一种重要蛋白质,在我们对晶状体疾病的理解中起着至关重要的作用。αB-晶状体蛋白的突变可引起晶状体疾病,如白内障和肌病。然而,R120G突变的分子机制尚不完全清楚.在这项研究中,我们利用分子动力学模拟来说明,原子细节,R120G突变如何导致晶状体中αB-晶状体蛋白的聚集和光的散射。我们的发现表明,R120G突变改变了αB-晶状体蛋白的动态和结构特性。具体来说,这种突变导致发夹在C末端的角度从80°增加到150°,同时将残基10和44-55周围的疏水斑块之间的距离从1.5nm减小到1nm。此外,我们的结果表明,突变可以破坏IPI基序-β4/β8的相互作用。这种相互作用的破坏可能会影响αB-晶状体蛋白的寡聚化和伴侣活性。在IPI基序-β4/β8处暴露的疏水区域可能成为蛋白间相互作用的主要位点,负责大规模聚合。我们已经证明,在野生型αB-晶状体蛋白中,形成盐桥R120和D109、R107和D80。然而,在R120G突变的情况下,盐桥R120和R109被破坏,形成了具有不同模式的新盐桥。在我们的研究中,已经发现与R120G突变相关的所有变化都位于链A和B的界面,这可能会影响αB-晶状体蛋白的多聚化。先前对K92-E99残基的研究表明,二聚体I中的盐桥可以降低蛋白质的伴侣活性。此外,盐桥接R120和D109,以及二聚体II中的R107和D80,诱导α-晶状体蛋白结构域(ACD)中β-折叠的疏水包膜的变化。这些变化可能对αB-晶状体蛋白的多聚化产生影响,导致低聚物结构的破坏和聚集。此外,由R120G突变引起的αB-晶状体蛋白的变化可能导致与其他蛋白质的错误相互作用,这可以导致αB-晶状体蛋白与其他蛋白质的聚集,比如Desmin.这些发现可能为晶状体疾病治疗的发展提供新的见解。由RamaswamyH.Sarma沟通。
The eye is a vital organ in the visual system, which is composed of transparent vascular tissue. αB-crystallin, a significant protein found in the lens, plays a crucial role in our understanding of lens diseases. Mutations in the αB-crystallin protein can cause lens diseases, such as cataracts and myopathy. However, the molecular mechanism underlying the R120G mutation is not fully understood. In this
study, we utilized molecular dynamics simulations to illustrate, in atomic detail, how the R120G mutation leads to the aggregation of αB-crystallin and scattering of light in the lens. Our findings show that the R120G mutation alters the dynamic and structural properties of the αB-crystallin protein. Specifically, this mutation causes the angle of the hairpin at the C-terminal to increase from 80° to 150°, while reducing the distance between the hydrophobic patches around residues 10 and 44-55 from 1.5 nm to 1 nm. In addition, our results showed that the mutation could disrupt the IPI motif - β4/β8 interaction. The disruption of this interaction could affect the αB-crystallin oligomerization and the chaperone activity of αB-crystallin protein. The exposed hydrophobic area at the IPI motif - β4/β8 could become the primary site for interprotein interactions, which are responsible for large-scale aggregation. We have demonstrated that, in wild-type αB-crystallin protein, salt bridges R120 and D109, R107 and D80 are formed. However, in the case of the R120G mutation, the salt bridges R120 and R109 are disrupted, and a new salt bridge with a different pattern is formed. In our
study, it has been found that all of the changes associated with the R120G mutation are located at the interface of chains A and B, which could impact the multimerization of the αB-crystallin. Previous research on the K92-E99 residue has shown that a salt bridge in the dimer I can reduce the chaperone activity of the protein. Furthermore, the salt bridges R120 and D109, as well as R107 and D80 in dimer II, induce changes in the hydrophobic envelope of β-sheets in the α-crystallin domain (ACD). These changes could have an impact on the multimerization of the αB-crystallin, leading to disruption of the oligomer structure and aggregation. Moreover, the changes in the αB-crystallin resulting from the R120G mutation can lead to faulty interactions with other proteins, which can cause the aggregation of αB-crystallin with other proteins, such as desmin. These findings may provide new insights into the development of treatments for lens diseases.Communicated by Ramaswamy H. Sarma.