title: Molecular cloning, expression profile, odorant affinity, and stability of two odorant-binding proteins in Macrocentrus cingulum Brischke (Hymenoptera: Braconidae).
abstract: The polyembryonic endoparasitoid wasp Macrocentrus cingulum Brischke (Hymenoptera: Braconidae) is deployed successfully as a biocontrol agent for corn pest insects from the Lepidopteran genus Ostrinia in Europe and throughout Asia, including Japan, Korea, and China. The odorants are recognized, bound, and solubilized by odorant-binding protein (OBP) in the initial biochemical recognition steps in olfaction that transport them across the sensillum lymph to initiate behavioral response. In the present study, we examine the odorant-binding effects on thermal stability of McinOBP2, McinOBP3, and their mutant form that lacks the third disulfide bonds. Real-time PCR experiments indicate that these two are expressed mainly in adult antennae, with expression levels differing by sex. Odorant-binding affinities of aldehydes, terpenoids, and aliphatic alcohols were measured with circular dichroism spectroscopy based on changes in the thermal stability of the proteins upon their affinities to odorants. The obtained results reveal higher affinity of trans-caryophelle, farnesene, and cis-3-Hexen-1-ol exhibits to both wild and mutant McinOBP2 and McinOBP3. Although conformational flexibility of the mutants and shape of binding cavity make differences in odorant affinity between the wild-type and mutant, it suggested that lacking the third disulfide bond in mutant proteins may have chance to incorrect folded structures that reduced the affinity to these odorants. In addition, CD spectra clearly indicate proteins enriched with α-helical content.
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.|Bangladesh Sugar Crop Research Institute, Ishurdi, Pabna, Bangladesh.
authors.forename: Tofael
authors.initials: T
authors.lastname: Ahmed
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Tiantao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Zhenying
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Kanglai
authors.initials: K
authors.lastname: He
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Shuxiong
authors.initials: S
authors.lastname: Bai
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000378:metabolism*; D003001:Cloning, Molecular; D005260:Female; D006838:Hydrocarbons / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009154:Mutation; D009812:Odorants; D011485:Protein Binding; D017433:Protein Structure, Secondary; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*; D012903:Smell; D059467:Transcriptome; D014863:Wasps / Q000378:metabolism*; D003313:Zea mays / Q000737:chemistry
chemical_list: D006838:Hydrocarbons; D019476:Insect Proteins; D018035:Receptors, Odorant; C045648:odorant-binding protein
keywords: binding affinity; circular dichroism; odorant-binding protein; thermal stability