NMR studies of oligosaccharides and glycoprotein conformation and dynamics
Co-workers: Prof R.A. Dwek, Dr M. Mackeen, Dr J. Offer, Dr A. Petrescu (Romanian Academy of Sciences), Prof G.W.J.F. Fleet (Chemistry, Oxford), Prof B. Davis (Chemistry, Oxford)
NMR spectroscopy is used to determine the conformation and dynamics of oligosaccharides, and the effects on the conformation and dynamics of glycosylation of peptides and proteins. Current targets include the glucosylated oligomannose glycans which are involved in recognition events in the early stages of glycoprotein biosynthesis and chaperone mediated folding.
Oligosaccharide conformational databases
In collaboration with Dr Andre Petrescu, Romanian Academy of Sciences, we have compiled and maintain databases of oligosaccharide conformations and structural properties of protein N-linked glycosylation sites, both derived from mining crystallographic data. The first provides experimental “Ramachandran-like” plots for oligosaccharide linkages, used to test new structures and provide the basis for molecular modeling of any oligosaccharide of interest.
The second database provides insight into the range protein glycosylation sites, the factors that may determine site occupancy and the range of interactions that glycans can make with the proteins to which they are attached.
The extensive experimental information on oligosaccharide conformations and glycosylation sites enables more reliable molecular modelling of specific oligosaccharides and glycoproteins. This has been used to model structures where experimental data are either partial or not available, such as the HIV GP120 coat protein, and also to model the interactions of such proteins with other carbohydrate recognising proteins, such the 2G12 antibody to GP120.
- The conformational properties of the Glc3Man unit suggest conformational biasing within the chaperone-assisted glycoprotein folding pathway. M. Mackeen, A. Almond, M. Deschamps, I. Cumpstey, A.J. Fairbanks, C. Tsang, P.M. Rudd, T.D. Butters, R.A. Dwek and M.R. Wormald (2009) J. Mol. Biol., 387, 335-347
- The impact of glycosylation on the biological functions of human immunoglobulins. J.N. Arnold, M.R. Wormald, R.B. Sim, P.M. Rudd and R.A. Dwek (2007) Ann. Rev. Immunol., 25, 21-50
- Structural aspects of glycomes with a focus on N-glycosylation and glycoprotein folding. A.J. Petrescu, M.R. Wormald and R.A. Dwek (2006) Curr. Op. Struc. Biol., 16, 600-607
- Antibody domain exchange is an immunological solution to carbohydrate cluster recognition. D.A. Calarese, C.N. Scanlan, M.B. Zwick, S. Deechongkit, Y. Mimura, R. Kunert, P. Zhu, M.R. Wormald, R.L. Stanfield, K.H. Roux, J.W. Kelly, P.M. Rudd, R.A. Dwek, H. Katinger, D.R. Burton and I.A. Wilson (2003) Science, 300, p.2065-2071
- Conformational studies of oligosaccharides and glycopeptides: the complementarity of NMR, X-ray crystallography and molecular modelling. M.R. Wormald, A.J. Petrescu, Y.-L. Pao, A. Glithero, T. Elliott and R.A. Dwek (2002), Chemical Rev., 102, p.371-386
Figure 1: 500 MHz NOESY and ROESY spectra of the Glcα1-3Glc linkage
Figure 2: Torsion angle plot for the Manα1-6Manα linkage (database of glycosidic linkage conformations)
Figure 3: Molecular model of prion protein (PrP 90-231) showing the conformational space available to the two N-linked glycans
Figure 4: Binding to HIV GP120 (top) by the novel antibody 2G12 (bottom) involves recognition of the GP120 glycans
Graduate Student and Postdoctoral Positions: Enquiries with CV welcome