Protein dynamics and the immunological evolution of molecular recognition
Protein dynamics and the immunological evolution of molecular recognition
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DOI：
10.1073/pnas.0305745101
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发表时间：
2004-03-16
影响因子：
11.1
通讯作者：
Romesberg, FE
中科院分区：
文献类型：
--
作者：
Jimenez, R;Salazar, G;Romesberg, FE
虽然它是公认的蛋白质的灵活性在蛋白质折叠，催化和分子识别中发挥作用，很少有技术能够严格测量蛋白质运动所需的量化灵活性。三脉冲光子回波位移光谱可用于测量蛋白质运动的时间尺度，我们已经使用这种技术，沿着稳态光谱和结合和结构数据，以研究抗荧光素抗体中蛋白质柔性的免疫学演变。两个轻链体细胞突变使对荧光素的亲和力增加12倍，但也显著影响柔性。具体而言，在三个可观察到的运动中的每一个中都可以看到蛋白质的硬化;两个较慢的运动分别经历了3倍和20倍的位移幅度减小;响应于施加的力，并且与较快运动幅度相关的分布在体细胞突变后变窄。体细胞突变似乎通过更强地将荧光素锚定到蛋白质上并通过更紧密地包装复合物来硬化抗体-荧光素复合物。数据表明，除了亲和力，抗体动力学系统地操纵亲和力成熟过程中，他们暗示，蛋白质的灵活性的演变可能是免疫反应的一个核心组成部分。这些结果也反映了蛋白质刚性化的类型，这可能对其他生物相互作用，如蛋白质-蛋白质，蛋白质-配体或蛋白质-药物，以及酶-底物识别是重要的。
While it is accepted that protein flexibility plays a role in protein folding, catalysis, and molecular recognition, few techniques are capable of the rigorous measurement of protein motions required to quantify flexibility. Three-pulse photon echo shift spectroscopy can be used to measure the time scale of protein motions, and we have used this technique, along with steady-state spectroscopy and binding and structural data, to examine the immunological evolution of protein flexibility in an anti-fluorescein antibody. Two light chain somatic mutations increase affinity for fluorescein by 12-fold but also significantly affect flexibility. Specifically, a rigidification of the protein is seen in each of three observable motions; two slower motions undergo decreased amplitudes of displacement, by 3- and 20-fold, respectively; in response to an applied force, and the distribution associated with the amplitude of a faster motion is narrowed upon somatic mutation. The somatic mutations appear to rigidify the antibody-fluorescein complex by more strongly anchoring fluorescein to the protein and by more tightly packing the complex. The data demonstrate that in addition to affinity, antibody dynamics are systematically manipulated during affinity maturation, and they imply that the evolution of protein flexibility may be a central component of the immune response. The results also reflect the type of protein rigiclification that may be important for other biological interactions, such as protein-protein, protein-ligand or protein-drug, and enzyme-substrate recognition.