Abstract: Chemosensory proteins (CSPs), which are assumed to be related with the process of storing and releasing the chemical odors for insects, belong to a class of small soluble polypeptides in insect chemical receptors. In this study, chemosensory protein of Microplitis mediator MmedCSP1 was expressed using pGEX-4T-1/BL21 (DE3) prokaryotic expression system, and then purified using GSTrap FF, and the binding characteristics of MmedCSP1 to 50 kinds of chemical molecules were further studied using bis-ANS (4, 4′-dianilino-1, 1′- binaphthyl- 5, 5′-sulfonate) as fluorescent probes. The results showed that MmedCSP1 could bind to methyl salicylate, pentane, ocimene, β-ionone, 3, 4-dimethylbenzaldehyde, 2-hexanone and cis-3-hexen-l-ol. However, only β-ionone replaced the bis-ANS of MmedCSP1 by 50%, and the binding constant was 16.89 μmol/L. These results suggest that MmedCSP1 is involved in the process of storing and releasing methyl salicylate, pentane, ocimene, β-ionone, 3, 4-dimethylbenzaldehyde, 2-hexanone and cis-3-hexen-l-ol for M. mediator, and has different transport capability in storing and releasing those odorants.

Key words: Microplitis mediator, chemosensory proteins, prokaryotic expression, fluorescent binding assays, βionone