CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
Sci Adv. 2020 Oct 23;6(43). doi: 10.1126/sciadv.abd7182. Print 2020 Oct.
Many important proteins undergo pH-dependent conformational changes resulting in "on-off" switches for protein function, which are essential for regulation of life processes and have wide application potential. Here, we report a pair of cellulosomal assembly modules, comprising a cohesin and a dockerin from , which interact together following a unique pH-dependent switch between two functional sites rather than on-off states. The two cohesin-binding sites on the dockerin are switched from one to the other at pH 4.8 and 7.5 with a 180° rotation of the bound dockerin. Combined analysis by nuclear magnetic resonance spectroscopy, crystal structure determination, mutagenesis, and isothermal titration calorimetry elucidates the chemical and structural mechanism of the pH-dependent switching of the binding sites. The pH-dependent dual-binding-site switch not only represents an elegant example of biological regulation but also provides a new approach for developing pH-dependent protein devices and biomaterials beyond an on-off switch for biotechnological applications.
许多重要的蛋白质会发生依赖于 pH 值的构象变化，从而导致蛋白质功能的“开-关”开关，这对于生命过程的调节至关重要，并且具有广泛的应用潜力。在这里，我们报告了一对来自 的纤维素酶组装模块，包括一个粘着蛋白和一个 dockerin，它们在两个功能位点之间发生独特的依赖于 pH 值的开关，而不是开-关状态，从而相互作用。在 pH 值为 4.8 和 7.5 时，dockerin 上的两个粘着蛋白结合位点发生切换，结合的 dockerin 发生 180°旋转。通过核磁共振波谱、晶体结构测定、突变和等温热滴定法的综合分析，阐明了结合位点依赖于 pH 值的切换的化学和结构机制。这种依赖于 pH 值的双结合位点开关不仅代表了生物学调节的一个优雅范例，而且还为开发 pH 依赖型蛋白质设备和生物材料提供了一种新方法，超越了生物技术应用中开-关开关。
