Molecular cloning of a preprohormone from Hydra magnipapillata containing multiple copies of Hydra-L Wamide (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 development in cnidarians. Recently, a neuropeptide, < Glu-Gln-Pro-Gly-Leu-Trp-NH2, has been isolated from sea anemones that induces metamorphosis in a hydroid planula larva to become a polyp. Here, we have cloned a preprohormone from Hydra magnipapillata containing 11 (eight different) immature neuropeptide sequences that are structurally related to the metamorphosis-inducing neuropeptide from sea anermones. During the final phase of our cloning experiments, another research team independently isolated and sequenced five of the neuropeptides originally found on the preprohormone. Comparison of these mature neuropeptide structures with the immature neuropeptide sequences on the preprohormone shows that most immature neuropeptide sequences are preceded by Ser or Asn residues, indicating that these residues must be novel processing sites. Thus, the structure of the Hydra preprohormone confirms our earlier findings that cnidarian preprohormones contain unusual or novel processing sites. Nearly all neuropeptide copies located on the Hydra preprohormone will give rise to mature neuropeptides with a C-terminal Gly-Leu-Trp-NH2 sequence (the most frequent one being Gly-Pro-Pro-Pro-Gly-Leu-Trp-NH2; Hydra-LWamide l; three copies). Based on their structural similarities with the metamorphosis-inducing neuropeptide from sea anemones, the mature peptides derived from the Hydra-LWamide preprohormone are potential candidates for being developmentally active neurohormones in Hydra.