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The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases
We recently presented a model for site-specific protein N-glycosylation in Trypanosoma brucei whereby the TbSTT3A oligosaccharyltransferase (OST) first selectively transfers biantennary Man(5)GlcNAc(2) from the lipid-linked oligosaccharide (LLO) donor Man(5)GlcNAc(2)-PP-Dol to N-glycosylation sequon...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Oxford University Press
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3311286/ https://www.ncbi.nlm.nih.gov/pubmed/22241825 http://dx.doi.org/10.1093/glycob/cws003 |
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author | Izquierdo, Luis Mehlert, Angela Ferguson, Michael AJ |
author_facet | Izquierdo, Luis Mehlert, Angela Ferguson, Michael AJ |
author_sort | Izquierdo, Luis |
collection | PubMed |
description | We recently presented a model for site-specific protein N-glycosylation in Trypanosoma brucei whereby the TbSTT3A oligosaccharyltransferase (OST) first selectively transfers biantennary Man(5)GlcNAc(2) from the lipid-linked oligosaccharide (LLO) donor Man(5)GlcNAc(2)-PP-Dol to N-glycosylation sequons in acidic to neutral peptide sequences and TbSTT3B selectively transfers triantennary Man(9)GlcNAc(2) to any remaining sequons. In this paper, we investigate the specificities of the two OSTs for their preferred LLO donors by glycotyping the variant surface glycoprotein (VSG) synthesized by bloodstream-form T. brucei TbALG12 null mutants. The TbALG12 gene encodes the α1-6-mannosyltransferase that converts Man(7)GlcNAc(2)-PP-Dol to Man(8)GlcNAc(2)-PP-Dol. The VSG synthesized by the TbALG12 null mutant in the presence and the absence of α-mannosidase inhibitors was characterized by electrospray mass spectrometry both intact and as pronase glycopetides. The results show that TbSTT3A is able to transfer Man(7)GlcNAc(2) as well as Man(5)GlcNAc(2) to its preferred acidic glycosylation site at Asn263 and that, in the absence of Man(9)GlcNAc(2)-PP-Dol, TbSTT3B transfers both Man(7)GlcNAc(2) and Man(5)GlcNAc(2) to the remaining site at Asn428, albeit with low efficiency. These data suggest that the preferences of TbSTT3A and TbSTT3B for their LLO donors are based on the c-branch of the Man(9)GlcNAc(2) oligosaccharide, such that the presence of the c-branch prevents recognition and/or transfer by TbSTT3A, whereas the presence of the c-branch enhances recognition and/or transfer by TbSTT3B. |
format | Online Article Text |
id | pubmed-3311286 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | Oxford University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-33112862012-03-23 The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases Izquierdo, Luis Mehlert, Angela Ferguson, Michael AJ Glycobiology Original Articles We recently presented a model for site-specific protein N-glycosylation in Trypanosoma brucei whereby the TbSTT3A oligosaccharyltransferase (OST) first selectively transfers biantennary Man(5)GlcNAc(2) from the lipid-linked oligosaccharide (LLO) donor Man(5)GlcNAc(2)-PP-Dol to N-glycosylation sequons in acidic to neutral peptide sequences and TbSTT3B selectively transfers triantennary Man(9)GlcNAc(2) to any remaining sequons. In this paper, we investigate the specificities of the two OSTs for their preferred LLO donors by glycotyping the variant surface glycoprotein (VSG) synthesized by bloodstream-form T. brucei TbALG12 null mutants. The TbALG12 gene encodes the α1-6-mannosyltransferase that converts Man(7)GlcNAc(2)-PP-Dol to Man(8)GlcNAc(2)-PP-Dol. The VSG synthesized by the TbALG12 null mutant in the presence and the absence of α-mannosidase inhibitors was characterized by electrospray mass spectrometry both intact and as pronase glycopetides. The results show that TbSTT3A is able to transfer Man(7)GlcNAc(2) as well as Man(5)GlcNAc(2) to its preferred acidic glycosylation site at Asn263 and that, in the absence of Man(9)GlcNAc(2)-PP-Dol, TbSTT3B transfers both Man(7)GlcNAc(2) and Man(5)GlcNAc(2) to the remaining site at Asn428, albeit with low efficiency. These data suggest that the preferences of TbSTT3A and TbSTT3B for their LLO donors are based on the c-branch of the Man(9)GlcNAc(2) oligosaccharide, such that the presence of the c-branch prevents recognition and/or transfer by TbSTT3A, whereas the presence of the c-branch enhances recognition and/or transfer by TbSTT3B. Oxford University Press 2012-05 2012-01-12 /pmc/articles/PMC3311286/ /pubmed/22241825 http://dx.doi.org/10.1093/glycob/cws003 Text en © 2012 The Author(s). Published by Oxford University Press. All rights reserved. http://creativecommons.org/licenses/by-nc/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses?by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Original Articles Izquierdo, Luis Mehlert, Angela Ferguson, Michael AJ The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title | The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title_full | The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title_fullStr | The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title_full_unstemmed | The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title_short | The lipid-linked oligosaccharide donor specificities of Trypanosoma brucei oligosaccharyltransferases |
title_sort | lipid-linked oligosaccharide donor specificities of trypanosoma brucei oligosaccharyltransferases |
topic | Original Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3311286/ https://www.ncbi.nlm.nih.gov/pubmed/22241825 http://dx.doi.org/10.1093/glycob/cws003 |
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