| Abstract: | ABSTRACT: BACKGROUND: Peptide: N glycanase (PNG) enzyme cleaves oligosaccharides from the misfolded glycoproteins and prepares them for degradation. This enzyme plays a role in the endoplasmic reticulum associated degradation (ERAD) pathway in yeast and mice but its biological importance and role in multicellular development remain largely unknown. RESULTS: In this study, the PNG from the cellular slime mold, Dictyostelium discoideum (DdPNG) was identified based on the presence of a common TG (transglutaminase) core domain and its sequence homology with the known PNGs. The domain architecture and the sequence comparison validated the presence of probable functional domains in DdPNG. The tertiary structure matched with the mouse PNG. Here we show that DdPNG is an essential protein, required for aggregation during multicellular development and a knock out strain of it results in small sized aggregates, all of which do not form fruiting bodies. The in situ hybridization and RT PCR results show higher level of expression during the aggregate stage. The expression gets restricted to the prestalk region during later developmental stages. DdPNG is a functional peptide-N-glycanase enzyme possessing deglycosylation activity, but does not possess any significant transamidation activity. CONCLUSIONS: We have identified and characterized a novel PNG from D. discoideum and confirmed its deglycosylation activity. The results emphasize the importance of PNG in aggregation during multicellular development of this organism. |
