title: Toxic polypeptides of the hydra--a bioinformatic approach to cnidarian allomones.
abstract: Cnidarians such as hydrae and sea anemones are sessile, predatory, soft bodied animals which depend on offensive and defensive allomones for prey capture and survival. These allomones are distributed throughout the entire organism both in specialized stinging cells (nematocytes) and in the body tissues. The cnidarian allomonal system is composed of neurotoxins, cytolysins and toxic phospholipapses. The present bioinformatic survey was motivated by the fact that while hydrae are the most studied model cnidarian, little is known about their allomones. A large-scale EST database from Hydra magnipapillata was searched for orthologs of known cnidarian allomones, as well as for allomones found in other venomous organisms. We show that the hydrae express orthologs of cnidarian phospholipase A2 toxins and cytolysins belonging to the actinoporin family, but could not find orthologs of the 'classic' short chain neurotoxins affecting sodium and potassium conductance. Hydrae also express proteins similar to elapid-like phospholipases, CRISP proteins, Prokineticin-like polypeptides and toxic deoxyribonucleases. Our results illustrate a high level of complexity in the hydra allomonal system, suggest that several toxins represent a basal component of all cnidarian allomones, and raise the intriguing possibility that similar proteins may fulfill both endogenous and allomonal roles in cnidaria.
authors.affiliation: Department of Cell and Animal Biology, Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel. dsher@pob.huji.ac.il
authors.forename: Daniel
authors.initials: D
authors.lastname: Sher
authors.forename: Alin
authors.initials: A
authors.lastname: Knebel
authors.forename: Tamar
authors.initials: T
authors.lastname: Bsor
authors.forename: Nir
authors.initials: N
authors.lastname: Nesher
authors.forename: Tzachy
authors.initials: T
authors.lastname: Tal
authors.forename: David
authors.initials: D
authors.lastname: Morgenstern
authors.forename: Eran
authors.initials: E
authors.lastname: Cohen
authors.forename: Yelena
authors.initials: Y
authors.lastname: Fishman
authors.forename: Eliahu
authors.initials: E
authors.lastname: Zlotkin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003064:Cnidarian Venoms / Q000235:genetics*; D019295:Computational Biology; D030562:Databases, Protein; D020224:Expressed Sequence Tags; D006829:Hydra / Q000235:genetics / Q000378:metabolism; D010455:Peptides; D010675:Pheromones / Q000235:genetics*; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2
chemical_list: D003064:Cnidarian Venoms; D010455:Peptides; D010675:Pheromones; D010741:Phospholipases A; D054467:Phospholipases A2