A chitinase structurally related to the glycoside hydrolase family 48 is indispensable for the hormonally induced diapause termination in a beetle

Two proteins (APAP I and II) of the glycoside hydrolase family 48 (Family GH48) were isolated from the active adults of the leaf beetle Gastrophysa atrocyanea. Full-length and cDNAs were sequenced. APAP I expression and function were examined in detail. The protein has a chitinase but not a glucanase and cellobiohydrolase activity. It is expressed in the feeding stages, including beetles whose diapause was terminated with a juvenile hormone agonist. Suppression of the APAP I expression by means of RNA interference prevented the hormonal termination of diapause.