Identification of 86 kDa protein as methionine rich hexamerin in the rice moth, Corcyra cephalonica

Abstract

We cloned the complete cDNA of methionine rich hexamerin from rice moth, Corcyra cephalonica using RACE strategy. The amplicon size was 2.5 kb with an ORF of 2.31 kb. The cDNA clone showed high percentage of methionine (4.8%), which is consistent with the previously reported sequences in other insects. The Southern and Northern analysis carried out showed that methionine rich hexamerin in rice moth is a single copy gene. Multiple alignment analysis of amino acid sequence revealed that the cDNA clone is most similar to Plodia interpunctella hexamerin storage protein (74% identity). The calculated isoelectric point is 9.2. The deduced amino acid sequence corresponded to 86 kDa subunit of hexamerin protein in rice moth. The 86 kDa protein (methionine rich subunit) was purified and polyclonal antibodies were raised against the subunit to check the specificity of the purified subunit. The developmental profile of 86 kDa subunit during the larval stages both in the fat body and haemolymph show that it is present at a higher concentration during the LLI (late-last instar) larval stage compared to the previous stages. The present work carried out shows that the methionine rich hexamerin cloned is the 86 kDa subunit of hexamerin which was identified previously by our group in rice moth, C. cephalonica.