Expression,Purification,Structure Prediction And Function Of 12 Odorant Binding Proteins In Apolygus Lucorum (Hemiptera:Miridae)

Apolygus lucorum is one of the most important cotton pests in China.It is difficult to control because of its wide host ranges and high concealment.Chemosensory behavior plays an essential role in many key stages of life of A.lucorum,such as identification of sex pheromones and host plant volatiles during courtship and host transfer.Odorant binding proteins(OBPs)can transport hydrophobic odor molecules to sensory lymph,which is the first step in insect chemosensitivity.In this study,twelve OBPs of A.lucorum were used as research objects.With the help of computational and molecular biology methods,the structures and functions of the OBPs were predicted and validated.This study will help to reveal the interaction mechanism between A.lucorum and host plants,and provide theoretical guidance for the integrated control of A.lucorum.The main results are as follows:1.12 OBPs of A.lucorum were successfully expressed and purified,including 4 proteins expressed in supernatant and 8 in inclusion bodies.2.12 tertiary structures of OBPs were successfully predicted by folding recognition method.7 of them contained six alpha helixes and three disulfide bonds and 5 OBPs contained more than 6 alpha helixes and over 4 disulfide bonds.All 12 odorant binding proteins could form pocket-shaped spatial structures,which may be hydrophobic cavities for odorant ligand binding.3.The function of AlucOBP2,AlucOBP6,AlucOBP10,AlucOBP12,AlucOBP19,AlucOBP25 and AlucOBP33 is to combine with common plant volatiles,presumed as the common odorant binding proteins in host transfer and localization;AlucOBP27,AlucOBP28,AlucOBP30,AlucOBP34 are combined with pheromone analogues and common plant volatiles,presumed as the pheromone-binding proteins.4.Among the 12 OBPs,10 can bind to beta-ionone,11 can bind to anisaldehyde and 11 can bind to beta-ionone derivatives.The binding ability with beta-ionone,beta-ionone derivatives and anisaldehyde of all AlucOBPs was measured comprehensively.The result showed that the binding ability with beta-ionone derivatives was the highest,followed by beta-ionone and anisaldehyde,implying beta-ionone derivatives could be a new and potential attractant for A.lucorum in the future.5.AlucOBP19,AlucOBP25 and AlucOBP33 with high expression in oral needles can specifically recognize the taste ligands,such as quercetin,gossypol,rutin and tannic acid,which may be involved in the process of taste recognition.