Isolation, characterization and chemical synthesis of a new insect defensin from Chironomus plumosus (Diptera)

Injection of low doses of bacteria into the aquatic larvae of the dipteran insect Chironomus plumosus induces the appearance in their hemolymph of a p otent antibacterial activity. We have isolated two 36-residue peptides from this hemolymph which are active against Gram-positive bacteria. The peptid es are novel members of the insect defensin family and their sequences pres ent marked differences with those of insect defensins isolated from other d ipteran species. We have developed a method for efficient renaturation of t his cysteine-rich molecule and obtained a highly pure synthetic Chironomus defensin. (C) 1998 Elsevier Science Ltd. All rights reserved.