MOLECULAR-CLONING OF A PREPROHORMONE FROM HYDRA-MAGNIPAPILLATA CONTAINING MULTIPLE COPIES OF HYDRA-LWAMIDE (LEU-TRP-NH2) NEUROPEPTIDES - EVIDENCE FOR PROCESSING AT SER AND ASN RESIDUES

The simple, freshwater polyp Hydra is often used as a model to study d evelopment in cnidarians. Recently, a neuropeptide, <Glu-Gln-Pro-Gly-L eu-Trp-NH2 has been isolated from sea anemones that induces metamorpho sis in a hydroid planula larva to become a polyp. Here, we have cloned a preprohormone from Hydra magnipapillata containing 11 (eight differ ent) immature neuropeptide sequences that are structurally related to the metamorphosis-inducing neuropeptide from sea anemones. During the final phase of our cloning experiments, another research team independ ently isolated and sequenced five of the neuropeptides originally foun d on the preprohormone. Comparison of these mature neuropeptide struct ures with the immature neuropeptide sequences on the preprohormone sho ws that most immature neuropeptide sequences are preceded by Ser or As n residues, indicating that these residues must be novel processing si tes. Thus, the structure of the Hydra preprohormone confirms our earli er findings that cnidarian preprohormones contain unusual or novel pro cessing sites. Nearly all neuropeptide copies located on the Hydra pre prohormone will give rise to mature neuropeptides with a C-terminal Gl y-Leu-Trp-NH2 sequence (the most frequent one being Gly-Pro-Pro-Pro-Gl y-Leu-Trp-NH2; Hydra-LWamide I; three copies). Based on their structur al similarities with the metamorphosis-inducing neuropeptide from sea anemones, the mature peptides derived from the Hydra-LWamide preprohor mone are potential candidates for being developmentally active neuroho rmones in Hydra.