Cloning, expression and characterisation of a novel gene encoding a chemosensory protein from Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)
Chemosensory proteins (CSPs) are thought to play an important role in olfactory mediating perception, identification, transportation, and transduction of semio-chemicals. These proteins are also associated with the regulation of circadian rhythms and maturation of certain tissues or appendages. In this study, a cDNA from Bemisia tabaci encoding a CSP (GU250808), denoted BtabCSP was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) technique. The genomic DNA sequence comparisons revealed a 1490 bp intron flanking the full length cDNA. Sequencing and structural analyses of the full length cDNA indicated that BtabCSP is 381 bp in length, encoding 126 amino acid residues of which a 22 amino acid residue coded for a signal peptide. The predicted molecular weight of BtabCSP is 14.17 kDa. The BtabCSP amino acid residues deduced from the respective full-length cDNA shares four conserved cysteine motifs with known CSPs from other insects. Homology modelling indicated a very good fit between the structural conformation of BtabCSP and a moth CSP molecule. The results of phylogenetic analyses indicates that the CSPs gene of Hemipteran insects have two more sub-families. The recombinant BtabCSP was successfully expressed in Escherichia coli cells. This is the first report on the existence of chemosensory protein-coding gene in whiteflies. It will help us to elucidate the molecular basis of whitefly behaviour, and explore new approach for the management of this major pest.
Key words: Whitefly, chemosensory protein, rapid amplification of cDNA ends (RACE), genomic organisation, sequence analysis.