Acaloleptins A: inducible antibacterial peptides from larvae of the beetle, Acalolepta luxuriosa.

摘要

Three structurally related antibacterial peptides with a molecular mass of 8 kDa (acaloleptins A1, A2 and A3) were purified and characterized from the haemolymph of immunized larvae of Acalolepta luxuriosa. These peptides have the same 6 N-terminalamino acid residues and show potent antibacterial activity against some Gram-negative bacteria. The three peptides are thought to be isoforms. Reverse phase HPLC analysis of the haemolymph of immunized and naive larvae showed that acaloleptins A1, A2 andA3 were inducible and suggested that all three peptides were produced in a single insect. The complete amino acid sequence of acaloleptin A1 was determined. Acaloleptin A1 consists of 71 amino acid residues and shares significant sequence similarity with coleoptericin and holotricin 2, which were isolated from other coleopteran insects. Furthermore, the 29 C-terminal residues of acaloleptin A1 had 40% identity with the 30 C-terminal residues of hymenoptaecin found in Apis mellifera.