First identification of a phosphorylcholine-substituted protein from Caenorhabditis elegans: isolation and characterization of the aspartyl protease ASP-6

Abstract

AbstractCaenorhabditis elegansis a widely accepted model system for parasitic nematodes, drug screening and developmental studies. Similar to parasitic worms,C. elegansexpresses glycosphingolipids and glycoproteins carrying, in part, phosphorylcholine (PCho) substitutions, which might play important roles in nematode development, fertility and, at least in the case of parasites, survival within the host. With the exception of a major secretory/excretory product fromAcanthocheilonema viteae(ES-62), no protein carrying this epitope has been studied in detail yet. Here we report on the identification, characterization and localization of the aspartyl protease ASP-6 ofC. elegans, which is excreted by the nematode in aPCho-substituted form. Within the worm, most prominent expression of the protein is observed in the intestine, while muscle and epithelial cells expressasp-6to a lesser extent. In animals harboring an ASP-6::GFP fusion protein, diffuse fluorescence throughout the body cavity of adult worms indicates that the chimeric protein is secreted.