Molecular and functional characteristics of a short-chain odorant binding protein gene PstrOBP-sc from Phyllotreta striolata

【Objective】The study aimed to analyze the molecular and functional characteristics of the short-chain odorant binding protein（OBP）gene PstrOBP-sc from Phyllotreta striolata，providing reference for exploring the function of short-chain OBP genes in insects.【Method】The short-chain Classic OBP gene from P. striolata was cloned using reverse transcription-polymerase chain reaction（RT-PCR）and subjected to bioinformatics analysis. The expression of the shortchain OBP gene in different tissues of male and female adult P. striolata was analyzed by RT-PCR. A recombinant expression vector was constructed for the heterologous expression of the short chain OBP gene，and the target protein was verified using sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE）and Western blotting techniques. The ligand-binding ability of the short-chain OBP was detected using fluorescence binding assay.【Result】A short-chain OBP gene（PstrOBP-sc）from P. striolata with a complete open reading frame was successfully obtained through RT-PCR cloning and verification. The PstrOBP-sc gene contained an open reading frame of 357 bp，encoding 118 amino acid residues，with a signal peptide of 20 amino acid residues at the N-terminal end. The mature protein PSTROBP-SC consisted of only 98 amino acid residues and contained 6 conserved cysteines in its sequence，making it a typical short-chain OBP gene. Protein secondary structure prediction showed that the PSTROBP-SC protein contained only 5 α-helixes，and there were only 2 amino acid residues in the downstream of the fifth α-helix. The tissue expression pattern of the PstrOBP-sc gene and the ligand-binding ability of the heterologously expressed PSTROBP-SC protein showed that the PstrOBP-sc gene was expressed in all tested tissues of male and female adult P. striolata，and was not specifically expressed in olfactory organs. Additionally，the heterologously expressed PSTROBP-SC could not bind to the fluorescence probe 1-NPN. 【Conclusion】The molecular and functional characteristics of PstrOBP-sc gene are different from those of the currently widely studied medium-long chain OBP genes，and it is likely to perform other physiological functions besides olfaction in the organism.