Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VIIM, Kolkata 700054, India.
Department of Physics, Bose Institute, 93/1, APC Road, Kolkata 700009, India.
Biochim Biophys Acta Gen Subj. 2017 May;1861(5 Pt A):977-986. doi: 10.1016/j.bbagen.2017.02.007. Epub 2017 Feb 13.
Accessory cholera enterotoxin (Ace) is a classical enterotoxin produced by Vibrio cholerae, the causative agent for cholera. Considering the crucial role of Ace in pathogenesis of cholera, we explored the modulation of structure/function of Ace using gold nanoparticles (AuNPs) of different size and shape - spherical (AuNS10 and AuNS100, the number indicating the diameter in nm) and rod (AuNR10).
Biophysical techniques have been used to find out structural modulation of Ace by AuNPs. Effect of AuNP on Ace conformation was monitored by far-UV CD; urea-induced unfolding and binding of Ace to various AuNPs were studied by tryptophan fluorescence. In vivo experiments using mouse ileal loop and Ussing chamber were carried out to corroborate biophysical data.
Biophysical data revealed degradation of Ace by AuNR10 and AuNS100, not by AuNS10. The feature of AuNR10 having high aspect ratio, but with the same transverse diameter as that of AuNS10 enabled us to explore the importance of morphology on modulation of protein structure/function. The equilibration time for adsorption shows dependence on the radius of curvature, being largest for AuNR10. In vivo experiments revealed the efficacy of AuNR10 and AuNS100 for reduced fluid accumulation, indicative of the loss of activity of Ace.
We show how biophysical studies and in vivo experiments go hand-in-hand in establishing the efficacy and role of size/shape of AuNPs on a toxin structure.
The effect of AuNP on toxin depends on its morphology. The targeted modulation of Ace could be of therapeutic benefit for gastrointestinal disorders.
副霍乱肠毒素（Ace）是由霍乱弧菌产生的一种经典肠毒素，霍乱弧菌是霍乱的病原体。鉴于 Ace 在霍乱发病机制中的关键作用，我们使用不同尺寸和形状的金纳米粒子（AuNPs）——球形（AuNS10 和 AuNS100，数字表示直径，单位为纳米）和棒状（AuNR10）——探索了 Ace 的结构/功能的调节。
使用生物物理技术发现 AuNPs 对 Ace 的结构调节。通过远紫外 CD 监测 AuNP 对 Ace 构象的影响；通过色氨酸荧光研究脲诱导的 Ace 变性和 Ace 与各种 AuNPs 的结合。使用小鼠回肠环和 Ussing 室进行体内实验以证实生物物理数据。
生物物理数据显示 AuNR10 和 AuNS100 降解了 Ace，但 AuNS10 没有。AuNR10 具有高纵横比的特点，但横向直径与 AuNS10 相同，这使我们能够探索形态对调节蛋白质结构/功能的重要性。吸附的平衡时间取决于曲率半径，AuNR10 的平衡时间最长。体内实验表明 AuNR10 和 AuNS100 可减少液体积累，表明 Ace 的活性丧失。
我们展示了生物物理研究和体内实验如何携手合作，确定 AuNP 的大小/形状对毒素结构的功效和作用。对 Ace 的靶向调节可能对胃肠道疾病具有治疗益处。
AuNP 对毒素的影响取决于其形态。Ace 的靶向调节可能对胃肠道疾病具有治疗益处。
