Unique Posttranslational Modifications of Chitin-Binding Lectins of Entamoeba invadens Cyst Walls

摘要: Entamoeba histolytica, which causes amebic dysentery and liver abscesses, is spread via chitin-walled cysts. The most abundant protein in the cyst wall of invadens, a model for encystation, lectin called EiJacob1. EiJacob1 has five tandemly arrayed, six-Cys chitin-binding domains separated by lowcomplexity Ser- Thr-rich spacers. E. histolytica also numerous predicted Jessie lectins chitinases, contain single, N-terminal eight-Cys domain. We hypothesized that invadens walls are composed entirely proteins with or some these sugars. genomic sequences seven Jacob lectins, three chitinases. Reverse transcription-PCR analysis showed mRNAs encoding Jacobs, Jessies, chitinases increased during while mass spectrometry an 30:70 mix (cross-linking proteins) chitinase (possible enzymes). Three were cleaved prior to Lys at conserved sites (e.g., TPSVDK) spacers between domains. A peptide was same site papain Cys proteases, suggesting latter cleave vivo. Some had O-phosphodiester-linked carbohydrates, one hexoses long deoxysugars reducing ends. concluded major components all chitinbinding (chitinases, lectins) differentially modified site-specific proteases glycans.