Machado Vitor Brassolatti, Maróstica de Sá Jéssica, Miranda Prado Ana Karla, Alves de Toledo Karina, Regasini Luis Octávio, Pereira de Souza Fátima, Caruso Ícaro Putinhon, Fossey Marcelo Andres
Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Biology, São José do Rio Preto, SP, Brazil.
Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil.
Heliyon. 2019 Mar 25;5(3):e01394. doi: 10.1016/j.heliyon.2019.e01394. eCollection 2019 Mar.
The human Respiratory Syncytial Virus (hRSV) is the major causative agent of lower respiratory tract diseases in infants, young children and elderly. The membrane protein G is embedded in the viral lipid envelope and plays an adhesion function of the virus to host cells. The present study reports the production of the group A hRSV recombinant G protein ectodomain (edG) and its characterization of secondary structure and thermal unfolding by circular dichroism (CD), as well as the binding investigation of flavonoids quercetin and morin to this protein by fluorescent quenching. CD data reveal that edG is composed mostly of β-structure and its melting temperature is of 325 K. Fluorescence quenching experiments of hRSV edG show that the dissociation constants for the flavonoids binding are micromolar and the binding affinity for the edG/quercetin complex is inversely dependent on rising temperature while is directly dependent for the edG/morin interaction. The thermodynamic parameters suggest that hydrophobic contacts are important for the edG/morin association while van der Waals forces and hydrogen bonds contribute to the stabilization of the edG/quercetin complex. Thus, data reported herein may contribute to the development of new treatment strategies that prevent the viral infection by hRSV.
人类呼吸道合胞病毒（hRSV）是婴幼儿和老年人下呼吸道疾病的主要病原体。膜蛋白G嵌入病毒脂质包膜中，发挥病毒与宿主细胞的黏附功能。本研究报道了A组hRSV重组G蛋白胞外域（edG）的产生及其通过圆二色性（CD）对二级结构和热解折叠的表征，以及通过荧光猝灭研究黄酮类化合物槲皮素和桑色素与该蛋白的结合。CD数据表明，edG主要由β-结构组成，其解链温度为325K。hRSV edG的荧光猝灭实验表明，黄酮类化合物结合的解离常数为微摩尔级，edG/槲皮素复合物的结合亲和力与温度升高呈负相关，而与edG/桑色素相互作用呈正相关。热力学参数表明，疏水接触对edG/桑色素缔合很重要，而范德华力和氢键有助于edG/槲皮素复合物的稳定。因此，本文报道的数据可能有助于开发预防hRSV病毒感染的新治疗策略。
