Molecular cloning, genomic organization, and expression of a B-type (cricket-type) allatostatin preprohormone from Drosophila melanogaster

The insect allatostatins obtained their names because they block the biosyn thesis of juvenile hormone (a terpenoid) in the corpora allata (two endocri ne organs near the insect brain). Chemically, the allatostatins can be subd ivided into three different peptide groups: the A-type allatostatins, first discovered in cockroaches, which have the C-terminal sequence Y/FXFGLamide in common; the B-type allatostatins, first discovered in crickets, which a ll have the C-terminal sequence W(X)(6)Wamide; and the C-type allatostatins , first discovered in the moth Manduca sexta, which have an unrelated and n onamidated C terminus. We have previously reported the structure of an A-ty pe allatostatin preprohormone from the fruitfly Drosophila melanogaster. He re we describe the molecular cloning of a B-type prepro-allatostatin from D rosophila (DAP-B). DAP-B is 211 amino acid residues long and contains one c opy each of the following putative allatostatins: AWQSLQSSW-amide (drostati n-B1), AWKSMNVAWamide (drostatin-B2), <EAQGWNKFRGAWamide (drostatin-B3), EP TWNNLKGMWamide (drostatin-B4), and DQWQKLHGGWamide (drostatin-B5). All five drostatins are novel peptide structures. The DAP-B gene has one intron and two exons and is located at position 74B1 on the left arm of the third chr omosome. The gene is expressed in all developmental stages, but weakly in e mbryos and strongly in larvae. In situ hybridizations of larvae showed that neurons in the brain and abdominal ganglia and endocrine cells in the gut expressed DAP-B, This is the first published report of a B-type allatostati n preprohormone in insects, and the first paper describing the presence of B-type allatostatins in a representative of the insect order Diptera (flies ). (C) 2001 Academic Press