水介导的通讯路径对脂肪酶热稳定性的影响

Effect of Water-Mediated Communication Path on Thermal Stability of Lipase

摘要:

为研究残基和水之间的信号传递对蛋白质热稳定性的影响，以野生型脂肪酶（WTL）及其突变体（6B）在不同温度下的分子动力学模拟轨迹为基础，构建了以残基和水为节点，残基-残基及残基-水的相互作用为边的残基-残基和残基-水相互作用网络。通过Dijkstra算法计算网络中节点之间的最短路径，结果表明，300 K时，WTL和6B的αB与β4之间的loop和αB上的残基频繁与水通讯，降低了该区域的柔性。400 K时，WTL仅仅加强了αC内部的连接，而6B中β7与β8之间的loop、αA以及最长的loop之间相互连接并且与水保持稳定通讯，从而稳定脂肪酶的热稳定性。此外，6B的突变点A20E在突变之后更容易与水形成稳定的氢键作用，突变使脂肪酶热稳定性增强。本研究为理性设计提高蛋白质耐热性提供了理论基础。

Abstract:

To study the effect of signal transmission between residues and water on protein thermo stability, the Residue-Residue and Residue-Water interaction networks were constructed based on the trajectories obtained by molecular dynamics simulation of wild-type lipase (WTL) and its mutant (6B) at different temperatures,with residues and water as nodes and residue-residue and residue-water interactions as edges. The Dijkstra algorithm was used to calculate the shortest path between nodes in the network. The results showed that at 300 K, the residues on loop between αB and β4 and αB in WTL and 6B frequently communicated with water, which reduced the flexibility of this region. At 400 K, WTL only strengthened the internal connection of αC, while in 6B, the loop between β7 and β8, αA and the longest loop were connected to each other and maintained stable communication with water, thus stabilizing the thermal stability of lipase. In addition, the mutation point A20E in 6B was more likely to form stable hydrogen bond with water after the mutation, and the mutation increased the thermal stability of lipase. Thus, this study can provide a theoretical basis for rational design to improve the heat resistance of protein.