Molecular basis of Colorado potato beetle adaptation to potato plant defence at the level of digestive cysteine proteinases.

摘要: Potato synthesises high levels of proteinase inhibitors in response to insect attack. This can adversely affect protein digestion the insects, leading reduced growth, delayed development and lowered fecundity. Colorado potato beetle overcomes this defence mechanism by changing composition its digestive proteinases. The induced cysteine proteinases adapted gut sustain a normal rate hydrolysis either inactivating cleavage or insensitivity as result Kis. In study cDNA clones guts were isolated nested PCR on basis N-terminal sequences previously determined for purified enzymes (Gruden et al., 2003). cDNAs be classified into three groups: intestains A, B C. amino acid identity is more than 91% within 35–62% between groups. They share 43–50% mammalian cathepsins S, L, K, H, J cathepsin-like from different arthropods. Homology modelling predicts that C follow general fold papain-like Intestains each group, however, differ some specific structural characteristics S1 S2 binding sites could influence enzyme–inhibitor interaction thus, provide mechanisms resistance enzymes. Gene expression analysis revealed A C, but not B, are twofold plants with inhibitors.