A Transmembrane Crenarchaeal Mannosyltransferase Is Involved in N-Glycan Biosynthesis and Displays an Unexpected Minimal Cellulose-Synthase-like Fold
| Autor: | Dayanand Kalyani, Christina Divne, Rosaria Gandini, Oliver Spadiut, Tom Reichenbach, Tien Chye Tan |
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| Rok vydání: | 2020 |
| Předmět: |
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Molecular Mannosyltransferase Glycosylation Protein Conformation Archaeal Proteins Crystallography X-Ray Mannosyltransferases 03 medical and health sciences 0302 clinical medicine Polysaccharides Structural Biology Crenarchaeota Gene cluster Molecular Biology Integral membrane protein 030304 developmental biology 0303 health sciences biology Chemistry biology.organism_classification Korarchaeota Transmembrane protein Transmembrane domain Biochemistry Pyrobaculum Protein Processing Post-Translational 030217 neurology & neurosurgery Archaea |
| Zdroj: | Journal of Molecular Biology. 432:4658-4672 |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/j.jmb.2020.06.016 |
| Popis: | Protein glycosylation constitutes a critical post-translational modification that supports a vast number of biological functions in living organisms across all domains of life. A seemingly boundless number of enzymes, glycosyltransferases, are involved in the biosynthesis of these protein-linked glycans. Few glycan-biosynthetic glycosyltransferases have been characterized in vitro, mainly due to the majority being integral membrane proteins and the paucity of relevant acceptor substrates. The crenarchaeote Pyrobaculum calidifontis belongs to the TACK superphylum of archaea (Thaumarchaeota, Aigarchaeota, Crenarchaeota, Korarchaeota) that has been proposed as an eukaryotic ancestor. In archaea, N-glycans are mainly found on cell envelope surface-layer proteins, archaeal flagellins and pili. Archaeal N-glycans are distinct from those of eukaryotes, but one noteworthy exception is the high-mannose N-glycan produced by P. calidifontis, which is similar in sugar composition to the eukaryotic counterpart. Here, we present the characterization and crystal structure of the first member of a crenarchaeal membrane glycosyltransferase, PcManGT. We show that the enzyme is a GDP-, dolichylphosphate-, and manganese-dependent mannosyltransferase. The membrane domain of PcManGT includes three transmembrane helices that topologically coincide with "half" of the six-transmembrane helix cellulose-binding tunnel in Rhodobacter spheroides cellulose synthase BcsA. Conceivably, this "half tunnel" would be suitable for binding the dolichylphosphate-linked acceptor substrate. The PcManGT gene (Pcal_0472) is located in a large gene cluster comprising 14 genes of which 6 genes code for glycosyltransferases, and we hypothesize that this cluster may constitute a crenarchaeal N-glycosylation (PNG) gene cluster. |
| Databáze: | OpenAIRE |
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