The most abundant cyst wall proteins of Acanthamoeba castellanii are three sets of lectins that bind cellulose and chitin and localize to distinct structures in cyst walls

摘要: ABSTRACT Acanthamoeba castellanii, cause of keratitis and blindness, is an emerging pathogen because its association with contact lens use. The cyst wall contributes to pathogenesis as cysts are resistant sterilizing reagents in solutions antibiotics applied the eye. We used transmission electron microscopy, well structured illumination microscopy probes for cellulose chitin, show that purified walls A. castellanii retain outer ectocyst layer, inner endocyst conical ostioles connect layers. Mass spectrometry showed candidate proteins dominated by three families lectins (named here Luke, Leo, Jonah), each which binds microcrystalline a lesser degree chitin. A Jonah lectin, has one choice-of-anchor (CAA) domain, localizes layer mature walls. Luke lectins, have two or carbohydrate-binding modules (CBM49), localize ostioles. Leo domains eight Cys residues (8-Cys), also In summary, most abundant sets conserved (CBM49s Luke), newly characterized (CAA unique Acanthamoebae (8-Cys Leo). Despite their lack common ancestry, both ostioles, while lectin layer. IMPORTANCE Fifty years ago, investigators identified wall, Here we contain chitin large cellulose- chitin-binding distinct localizations. therefore, more complicated than Entamoeba Giardia (causes dysentery diarrhea, respectively), single glycopolymer, small lectins. contrast, far simpler fungi plants, multiple layers, numerous glycopolymers, hundreds proteins. addition providing better understanding cell biology biochemistry these studies may lead diagnostic antibodies bind and/or therapeutics target