光谱分析Q型烟粉虱化学感受蛋白CSP1与β-紫罗兰酮的相互作用
Spectroscopic analysis of the interaction between β-ionone and chemosensory protein 1 (CSP1) in Bemisia tabaci biotype Q

为明确烟粉虱在入侵过程中的寄主选择性与其化学感受系统对寄主植物挥发物的分子识别之间的相互作用和化学机理,通过荧光、紫外光谱和圆二色谱等技术分析了烟粉虱化学感受蛋白BtCSP1与一种重要的植物挥发物成分—β-紫罗兰酮之间的相互作用.结果表明,β-紫罗兰酮与BtCSP1在不同温度时的猝灭机理不同,300 K(27℃)时二者的亲和力较弱,表观结合常数KA为2.44×105 L/mol,较低温290 K(17℃)和高温310 K(37℃)时的3.22×105 L/mol和3.23×105 L/mol均要低,表明BtCSP1与β-紫罗兰酮在不同的温度下呈现不同的结合机理,低温时为静态猝灭,而高温时为动态猝灭.通过热力学参数和非辐射能量转移理论分析,β-紫罗兰酮与BtCSP1蛋白结合时发生了荧光共振能量转移,结合距离为5.2 nm.圆二色谱结果显示,随着β-紫罗兰酮浓度的升高,BtCSP1蛋白中α-螺旋比例逐渐减少,由纯蛋白时的63％下降到55.9％,二级结构发生了变化.
To study the chemosensory system's function of the whitefly Bemisia tabaci in selecting and recognizing host volatiles in the biological invasion process, fluorescence, ultroviolet (UV) spectroscopy and circular dichroism (CD) were used to discover and interpret the binding interaction between a chemosensory protein BtCSP1 and a tomato fruit volatile β-ionone. The results showed that the quenching mechanism was different at different temperatures, and the binding affinity (KA) was 2.44×105 L/mol at 300 K (27℃), lower than those at the low temperature 290 K (17℃) and high temperature 310 K (37℃), with a KA of 3.22×105 L/mol and 3.23×105 L/mol, respectively. This suggested that the low temperature presented static quench, and high temperature presented dynamic quench. The results of fluorescence and UV showed that fluorescence resonance energy transfer (FRET) occurred in the binding process, and the binding distance was calculated as 5.2 nm. CD data of the α-helix of BtCSP1 decreased to 55.9％ with increasing β-ionone concentration, indicating that the dimensional structure of BtCSP1 extended.