Conformations of Neisseria meningitidis serogroup A and X polysaccharides: the effects of chain length and O-acetylation.

Hlozek, Jason and Kuttel, Michelle and Ravenscroft, Neil (2018) Conformations of Neisseria meningitidis serogroup A and X polysaccharides: the effects of chain length and O-acetylation., Carbohydrate Research, 465, 44-51, Elsevier.

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Neisseria meningitidis is a major cause of bacterial meningitis worldwide especially in Africa. The capsular polysaccharide (CPS) is the main virulence factor and the target antigen for polysaccharide and conjugate vaccines. The high burden of serogroup A disease in the Meningitis Belt of sub-Saharan Africa led to the introduction of MenAfriVac®, which has successfully reduced the number of cases of group A disease. However, several outbreaks caused by other serogroups have been reported, including those due to serogroup X. The capsular polysaccharides of serogroups A and X are both homopolymers of amino sugars (α-D-ManNAc and α-DGlcNAc) containing phosphodiester linkages at C-6 and C-4, respectively. The similarity of the primary structures of the two polysaccharides suggests that serogroup A vaccination may provide cross-protection against serogroup X disease. Molecular dynamics simulations of a series of serogroup A and X oligosaccharides reveal that the MenA CPS behaves as a flexible random coil which becomes less conformationally defined as the length increases, whereas serogroup X forms a more stable regular helical structure. The presence of the MenX helix is supported by NMR analysis; it has four residues per turn and becomes more stable as the chain length increases. Licensed MenA vaccines are largely O-acetylated at C-3: simulations show that these O-acetyl groups are highly solvent exposed and their presence favors more extended conformations compared to the more compact conformations of MenA without O-acetylation. These findings may have implications for the design of optimal conjugate vaccines.

Item Type: Journal article (paginated)
Uncontrolled Keywords: Neisseria meningitidis Capsular polysaccharide Molecular modeling Antigen conformation
Subjects: Applied computing > Life and medical sciences
Computing methodologies > Modeling and simulation
Date Deposited: 09 Nov 2018
Last Modified: 10 Oct 2019 15:31

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