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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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Autores principales: Izquierdo, Luis, Mehlert, Angela, Ferguson, Michael AJ
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2012
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.
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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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