Table_1_Identification and Functional Analysis of SlitOBP11 From Spodoptera litura.docx

Odorant binding proteins (OBPs) play a key role in the olfactory recognition of insects, whose functions have been extensively studied in adult insects but rarely in larvae. In this study, one OBP (SlitOBP11) with high expression in larval antenna but low expression in adult antenna of Spodoptera litura was screened by RNA-seq and verified by quantitative real-time PCR. Furthermore, the function of SlitOBP11 was explored by analysis of the expression patterns and prokaryotic expression of proteins as well as assays of competitive binding. Competitive binding assay demonstrated that SlitOBP11 had high binding affinity to all four female sex pheromone components, but exhibited almost no binding affinity to plant volatiles except for a low affinity to Phenylacetaldehyde and Phenethyl acetate. Homology modeling and molecular docking implied that the shape of these four sex pheromones were linear, which were appropriate for the binding channel of SlitOBP11 and the amino acid residue Asn99 of SlitOBP11 might play an important role in binding. Taken together, our results indicate that SlitOBP11 may be involved in the perception of female sex pheromones by S. litura larvae, and OBPs in the larvae of S. litura play an important role in the olfactory perception process.

气味结合蛋白（Odorant binding proteins, OBPs）在昆虫嗅觉识别过程中发挥关键作用，目前其功能已在昆虫成虫中得到广泛研究，但针对幼虫的相关研究却较为少见。本研究通过转录组测序（RNA-seq）筛选得到斜纹夜蛾（Spodoptera litura）的一个OBP基因SlitOBP11，该基因在幼虫触角中高表达，而在成虫触角中表达量较低，并通过实时荧光定量PCR（quantitative real-time PCR）对其表达模式进行了验证。随后，本研究通过分析基因表达谱、蛋白原核表达以及竞争性结合实验，对SlitOBP11的功能展开了探究。竞争性结合实验结果显示，SlitOBP11对四种雌性性信息素组分均具有较高结合亲和力，仅对苯乙醛（Phenylacetaldehyde）和乙酸苯乙酯（Phenethyl acetate）表现出低亲和力，几乎不与其余植物挥发物结合。同源建模与分子对接分析表明，这四种性信息素组分均为线性结构，可适配SlitOBP11的结合通道；且SlitOBP11的天冬酰胺99（Asn99）氨基酸残基可能在结合过程中发挥关键作用。综上，本研究结果表明，SlitOBP11可能参与斜纹夜蛾（S. litura）幼虫对雌性性信息素的感知过程，而斜纹夜蛾幼虫体内的OBPs在嗅觉感知过程中具有重要作用。