Characterization of RR-1 and RR-2 cuticular proteins from Myzus persicae

A cDNA library for Myzus persicae has served to identify sequences coding for cuticular proteins (CPs) with RR-1 and RR-2 consensus. Two putative CPs showed a common RR-2 chitin binding domain (CBD) but differed in their C and N terminals. Two other predicted CPs showed a typical RR-1 CBD but differed in size and sequence of the C and N terminals. An additional sequence encoding for a protein that showed terminal amino acid repeats similar to those of putative CPs from M. persicae, but lacked the R & R consensus, was also described. A comparison of the sequences obtained from the cDNA library with those attained from the genomic DNA, confirmed their identity as cuticular proteins genes. Presence of introns was revealed in the Mpcp4 and Mpcp5 genes coding for CPs with an RR-1 consensus. The Mpcp4 has a single large intron, while the Mpcp5 has two shorter ones. Introns were not found in the Mpcp2 and Mpcp3 genes encoding for CPs with RR-2 consensus. Differences were also noticed for 3' UTR and 5' UTR of both the RR-1 and RR-2 CPs. CPs genes were expressed in bacteria, and the resulting protein was identified as a CP by amino acid sequencing.