Identification of two allatostatins from the CNS of the cockroach Periplaneta americana: Novel members of a family of neuropeptide inhibitors of insect juvenile hormone biosynthesis

Abstract

Two novel peptide inhibitors of juvenile hormone synthesis, designated P. americana allatostatins 1 and 2, have been purified from brains of the cockroach Periplaneta americana. The primary structures of these peptides have been assigned as Ser-Pro-Ser-Gly-Met-Gln-Arg-Leu-Tyr-Gly-Phe-Gly-Leu- NH 2 (Pea-AST 1), and Ala-Asp-Gly-Arg-Leu-Tyr-Ala-Phe-Gly-Leu-NH 2 (Pea-AST 2). Each of the peptides shows similarity to an individual member of a family of five allatostatins isolated from the cockroach Diploptera punctata. Pea-AST 1 differs from Dip-AST 1 by having serine and methionine substitutions for alanines at position 1 and 5, respectively. Pea-AST 2 differs from Dip-AST 2 merely by having an alanine residue instead of glycine at position 1. Bioassays show that both peptides are potent inhibitors of juvenile hormone synthesis by corpora allata from virgin females of both P. americana and D. punctata.