Characterization of N-glycosylations in Entamoeba histolytica ubiquitin.

Entamoeba histolytica harbors an extensive intracellular distribution of ubiquitin-proteasome systems important for numerous cellular processes. However, glycosylation studies of ubiquitin-proteasome components have not yet been elucidated. Here we report the partial characterization of N-linked glycosylation profile in E. histolytica ubiquitin by Fluorophore-Assisted Carbohydrate Electrophoresis (FACE), Nanoelectrospray Ionization-Tandem Mass Spectrometry (NSI-MS), Matrix-Assisted Laser-Desorption time-of-flight Mass Spectrometry (MALDI-TOF MS) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. To our knowledge, the data presented in this report represents the first structural glycomics analysis of E. histolytica ubiquitin, while most of the reports are performed on whole parasitic glycan profiles. The glycan profile of E. histolytica ubiquitin has high mannose N-glycan structures. The N-linked glycan profile showed fragments from HexHexNAc to HexHexNAc. Based in our findings and ubiquitin function, we hypothesize that the same ubiquitin Asn-Asp-Ser sequon carries heterogenic glycosylations, at different metabolic pathway stages according to ubiquitin functional requirements. Finally, we propose a set of possible high mannose N-glycan structures that will help to elucidate the ubiquitin biochemical composition and may well represent good targets for anti-amoebic drugs.