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Spontaneous glycan reattachment following N-glycanase treatment of a viral glycoprotein

ABSTRACT: Keating CL, Kuhn E, Cocco AR, Yousif AS, Bals J, Matysiak C, angesland M, Setliff I, Ronsard L, Georgiev I, Balazs AB, Carr SA, Lingwood D. In cells asparagine/N-linked glycans are added to glycoproteins co-translationally, in an attachment process that is thought to be supported by the folding of the nascent polypeptide sequence. We find that following pruning of N-glycan by the amidase PNGase F, the influenza viral spike protein hemagglutinin (HA) autocatalyzed the re-addition of N-glycan to deaminated NXS/T sequons when the amidase was removed from solution. This reaction, which we term N-glycanation, was confirmed by site-specific analysis of HA glycoforms by mass spectrometry prior to PNGase F exposure, during exposure to PNGase F, and after amidase removal. Iterative rounds of de-N-glycosylation followed by N-glycanation that could be repeated at least 3 times. Covalent N-glycan reattachment was dependent on forming a non-covalent assembly between HA and glycan in the presence of the amidase. Linearization of HA prevented the retention of N-glycan and subsequent N-glycanation, indicating that protein surface features can exert dramatic self-organized control over the formation of glycan linkages and that NXS/T sequons may reside within active-site-like configurations that lower the activation threshold for N-glycosylation.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens Neanderthalensis (ncbitaxon:63221)

SUBMITTER: Steven A. Carr

PROVIDER: MSV000084019 | MassIVE | Thu Jun 27 14:34:00 BST 2019

REPOSITORIES: MassIVE

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Spontaneous glycan reattachment following N-glycanase treatment of a viral glycoprotein

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