Characterization of the Astacin Family of Metalloproteases in C. elegans

Background: Astacins are a large family of zinc metalloproteases found in bacteria and animals. They have diverseroles ranging from digestion of food to processing of extracellular matrix components. The C. elegans genomecontains an unusually large number of astacins, of which the majority have not been functionally characterized yet.Results: We analyzed the expression pattern of previously uncharacterized members of the astacin family to tryand obtain clues to potential functions. Prominent sites of expression for many members of this family are thehypodermis, the alimentary system and several specialized cells including sensory sheath and sockets cells, whichare located at openings in the body wall. We isolated mutants affecting representative members of the varioussubfamilies. Mutants in nas-5, nas-21 and nas-39 (the BMP-1/Tolloid homologue) are viable and have no apparentphenotypic defects. Mutants in nas-6 and nas-6; nas-7 double mutants are slow growing and have defects in thegrinder of the pharynx, a cuticular structure important for food processing.Conclusions: Expression data and phenotypic characterization of selected family members suggest a diversity offunctions for members of the astacin family in nematodes. In part this might be due to extracellular structuresunique to nematodes.