The Conformational Properties of the Glc3Man Unit Suggest Conformational Biasing within the Chaperone-assisted Glycoprotein Folding Pathway

Muhammad Mukram Mohamed Mackeen, Andrew Almond, Michael Deschamps, Ian Cumpstey, Antony J. Fairbanks, Clarence Tsang, Pauline M. Rudd, Terry D. Butters, Raymond A. Dwek, Mark R. Wormald

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

A major puzzle is: are all glycoproteins routed through the ER calnexin pathway irrespective of whether this is required for their correct folding? Calnexin recognizes the terminal Glcα1-3Manα linkage, formed by trimming of the Glcα1-2Glcα1-3Glcα1-3Manα (Glc3Man) unit in Glc3Man9GlcNAc2. Different conformations of this unit have been reported. We have addressed this problem by studying the conformation of a series of N-glycans; i.e. Glc3ManOMe, Glc3Man4,5,7GlcNAc2 and Glc1Man9GlcNAc2 using 2D NMR NOESY, ROESY, T-ROESY and residual dipolar coupling experiments in a range of solvents, along with solution molecular dynamics simulations of Glc3ManOMe. Our results show a single conformation for the Glcα1-2Glcα and Glcα1-3Glcα linkages, and a major (65%) and a minor (30%) conformer for the Glcα1-3Manα linkage. Modeling of the binding of Glc1Man9GlcNAc2 to calnexin suggests that it is the minor conformer that is recognized by calnexin. This may be one of the mechanisms for controlling the rate of recruitment of proteins into the calnexin/calreticulin chaperone system and enabling proteins that do not require such assistance for folding to bypass the system. This is the first time evidence has been presented on glycoprotein folding that suggests the process may be optimized to balance the chaperone-assisted and chaperone-independent pathways.

Original languageEnglish
Pages (from-to)335-347
Number of pages13
JournalJournal of Molecular Biology
Volume387
Issue number2
DOIs
Publication statusPublished - 27 Mar 2009
Externally publishedYes

Fingerprint

Calnexin
Glycoproteins
Calreticulin
Molecular Dynamics Simulation
Polysaccharides
Proteins

Keywords

  • calnexin/calreticulin
  • glucosidase II
  • glucosylated N-glycan conformation
  • glycoprotein folding
  • NMR

ASJC Scopus subject areas

  • Molecular Biology

Cite this

The Conformational Properties of the Glc3Man Unit Suggest Conformational Biasing within the Chaperone-assisted Glycoprotein Folding Pathway. / Mohamed Mackeen, Muhammad Mukram; Almond, Andrew; Deschamps, Michael; Cumpstey, Ian; Fairbanks, Antony J.; Tsang, Clarence; Rudd, Pauline M.; Butters, Terry D.; Dwek, Raymond A.; Wormald, Mark R.

In: Journal of Molecular Biology, Vol. 387, No. 2, 27.03.2009, p. 335-347.

Research output: Contribution to journalArticle

Mohamed Mackeen, MM, Almond, A, Deschamps, M, Cumpstey, I, Fairbanks, AJ, Tsang, C, Rudd, PM, Butters, TD, Dwek, RA & Wormald, MR 2009, 'The Conformational Properties of the Glc3Man Unit Suggest Conformational Biasing within the Chaperone-assisted Glycoprotein Folding Pathway', Journal of Molecular Biology, vol. 387, no. 2, pp. 335-347. https://doi.org/10.1016/j.jmb.2009.01.043
Mohamed Mackeen, Muhammad Mukram ; Almond, Andrew ; Deschamps, Michael ; Cumpstey, Ian ; Fairbanks, Antony J. ; Tsang, Clarence ; Rudd, Pauline M. ; Butters, Terry D. ; Dwek, Raymond A. ; Wormald, Mark R. / The Conformational Properties of the Glc3Man Unit Suggest Conformational Biasing within the Chaperone-assisted Glycoprotein Folding Pathway. In: Journal of Molecular Biology. 2009 ; Vol. 387, No. 2. pp. 335-347.
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AU - Cumpstey, Ian

AU - Fairbanks, Antony J.

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