一种桔小实蝇Minus-C气味结合蛋白的分子克隆和结合特征分析

Molecular Cloning and Binding Characterization of the Minus-C Odorant Binding Protein in Bactrocera dorsalis

为了更好地了解昆虫气味结合蛋白(odorant binding proteins,OBPs)在桔小实蝇Bactrocera dorsalis嗅觉识别中的作用,并明确其与寄主挥发物的结合特性,本研究克隆了一个"Minus-C"OBP基因Bdor OBP1a。BdorOBP1a基因长480 bp,编码159个氨基酸,其N端含有26个氨基酸的信号肽,去信号肽氨基酸序列中有4个保守的半胱氨酸。利用荧光竞争结合实验对Bdor OBP1a与21种寄主挥发物进行结合特征的测定,结果表明Bdor OBP1a可以与15种寄主挥发物结合,其中结合能力最强的是β-紫罗兰酮和苯甲醛,解离常数分别为31.1、31.8μmol/L。行为反应表明桔小实蝇对β-紫罗兰酮,乙酸异戊酯,苯甲醛和己酸乙酯都具有趋性。由此推断,Bdor OBP1a具有选择性识别和结合各种配基的特性,并在桔小实蝇对寄主植物气味的定位过程中起着重要的作用。

To study the function of the odorant binding proteins in the Bactrocera dorsalis and the characteristics of its binding with host volatiles,a full-length cDNA of a Minus-C OBP gene was cloned,which was named BdorOBP1a.The sequence of BdorOBP1a contains a 480 bp open reading frame that encodes 159 amino acids,including a signal peptide of 26 amino acid at the N terminus and the four conserved cysteins of Minus-C OBP.The binding affinity of BdorOBP1a with 21 plant volatiles indicated that BdorOBP1a could bind 15 plant volatiles,exhibiting a stronger capability of bindingβ-ionone and Benzaldehyde with the dissociation constants of 31.1 and 31.8μmol/L,respectively.Behavioral responses indicated that Bactrocera dorsalis had taxis toβ-ionone,Isoamyl acetate,Benzaldehyde and Ethyl caproate.So it can be inferred that BdorOBP1a protein has characteristics of selective binding with various ligands and plays a role in the positioning of the odorants of host plants by Bactrocera dorsalis.