Molecular cloning, genomic organization, and expression of a C-type (Manduca sexta-type) allatostatin preprohormone from Drosophila melanogaster

The insect allatostatins are a diverse group of neuropeptides that obtained their names by their inhibitory actions on the corpora allata (two endocri ne glands near the insect brain), where they block the biosynthesis of juve nile hormone (a terpenoid important for development and reproduction). Chem ically, the allatostatins can be subdivided into three different peptide gr oups: the large group of A-type (cockroach-type) allatostatins, which have the common C-terminal sequence Y/FXFGLamide; the B-type (cricket-type) alla tostatins, which have the C-terminal sequence W(X-6)Wamide in common; and a single allatostatin that we now call C-type allatostatin that was first di scovered in the moth Manduca sexta, and which has a nonamidated C terminus, and a structure unrelated to the A- and B-type allatostatins. We have prev iously cloned the preprohormones for the A- and B-type allatostatins from D rosophila melanogaster. Here we report on the cloning of a Drosophila C typ e allatostatin preprohormone (DAP-C). DAP-C is 121 amino acid residues long and contains one copy of a peptide sequence that in its processed form has the sequence <EVRYRQCYFNPISCF (drostatin-C). This drostatin-C sequence is only one amino acid residue different (F --> Y in position 4) from the Mand uca sexta C-type allatostatin. The DAP-C gene has three introns and four ex ons and is located at position 32D2-3 on the left arm of the second chromos ome. Northern blots show that the gene is strongly expressed in larvae and adult flies, but less in pupae and embryos. In situ hybridizations of larva e show that the gene is expressed in various neurons of the brain and abdom inal ganglia and in endocrine cells of the midgut. This is the first public ation on the structure of a C-type allatostatin from insects other than mot hs and the first report on the presence of all three types of allatostatins in a representative of the insect order Diptera (flies). (C) 2001 Academic Press.