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Structures of B-lymphotropic polyomavirus VP1 in complex with oligosaccharide ligands.

Neu U, Khan ZM, Schuch B, Palma AS, Liu Y, Pawlita M, Feizi T, Stehle T - PLoS Pathog. (2013)

Bottom Line: High-resolution crystal structures of the LPyV capsid protein VP1 alone and in complex with the trisaccharide ligands 3'-sialyllactose and 3'-sialyl-N-acetyl-lactosamine (3SL and 3SLN, respectively) show essentially identical interactions.Our analysis provides a structural basis for the observed specificity of LPyV for linear glycan motifs terminating in α2,3-linked sialic acid, and links the different tropisms of known LPyV strains to the receptor binding site.It also serves as a useful template for understanding the ligand-binding properties and serological crossreactivity of HPyV9.

View Article: PubMed Central - PubMed

Affiliation: Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany.

ABSTRACT
B-Lymphotropic Polyomavirus (LPyV) serves as a paradigm of virus receptor binding and tropism, and is the closest relative of the recently discovered Human Polyomavirus 9 (HPyV9). LPyV infection depends on sialic acid on host cells, but the molecular interactions underlying LPyV-receptor binding were unknown. We find by glycan array screening that LPyV specifically recognizes a linear carbohydrate motif that contains α2,3-linked sialic acid. High-resolution crystal structures of the LPyV capsid protein VP1 alone and in complex with the trisaccharide ligands 3'-sialyllactose and 3'-sialyl-N-acetyl-lactosamine (3SL and 3SLN, respectively) show essentially identical interactions. Most contacts are contributed by the sialic acid moiety, which is almost entirely buried in a narrow, preformed cleft at the outer surface of the capsid. The recessed nature of the binding site on VP1 and the nature of the observed glycan interactions differ from those of related polyomaviruses and most other sialic acid-binding viruses, which bind sialic acid in shallow, more exposed grooves. Despite their different modes for recognition, the sialic acid binding sites of LPyV and SV40 are half-conserved, hinting at an evolutionary strategy for diversification of binding sites. Our analysis provides a structural basis for the observed specificity of LPyV for linear glycan motifs terminating in α2,3-linked sialic acid, and links the different tropisms of known LPyV strains to the receptor binding site. It also serves as a useful template for understanding the ligand-binding properties and serological crossreactivity of HPyV9.

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Glycan microarray screening analysis of LPyV VP1 pentamers.Glycan microarray analysis of LPyV VP1 showing selective binding to the short 3SL and 3SLN-related trisaccharide probes with ring-opened flexible cores but not to the N-glycan probe with 3SLN-terminating antennae, complex gangliosides, nor to any of the 6SL and 6SLN-related probes. Numerical scores for the binding intensity are shown as means of fluorescence intensities of duplicate spots at 2 and 5 fmol/spot. Error bars represent half of the difference between the two values. The microarrays consisted of lipid-linked oligosaccharide probes and the sequences are listed in Table S1. The probes are arranged according to terminal sialic acid linkage, oligosaccharide backbone chain length and sequence. The various types of terminal sialic acid linkage are indicated by the colored panels as defined at the bottom of the figure. The expanded region of the microarray highlights the sequences of the probes bound and the selective binding of LPyV VP1 to 3SL and 3SLN-related trisaccharide probes.
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ppat-1003714-g001: Glycan microarray screening analysis of LPyV VP1 pentamers.Glycan microarray analysis of LPyV VP1 showing selective binding to the short 3SL and 3SLN-related trisaccharide probes with ring-opened flexible cores but not to the N-glycan probe with 3SLN-terminating antennae, complex gangliosides, nor to any of the 6SL and 6SLN-related probes. Numerical scores for the binding intensity are shown as means of fluorescence intensities of duplicate spots at 2 and 5 fmol/spot. Error bars represent half of the difference between the two values. The microarrays consisted of lipid-linked oligosaccharide probes and the sequences are listed in Table S1. The probes are arranged according to terminal sialic acid linkage, oligosaccharide backbone chain length and sequence. The various types of terminal sialic acid linkage are indicated by the colored panels as defined at the bottom of the figure. The expanded region of the microarray highlights the sequences of the probes bound and the selective binding of LPyV VP1 to 3SL and 3SLN-related trisaccharide probes.

Mentions: The purified pentamers were analyzed on a glycan microarray containing 117 sialylated and 6 non-sialylated lipid-linked oligosaccharide probes, representing sequences occurring on N- and O-linked glycoproteins as well as glycolipids. We detected LPyV VP1 binding signals above background to α2,3-sialylated probes bearing sequences related to 3SL and 3SLN (Fig. 1, probes 12 and 29). Both 3SL and 3SLN are linear trisaccharides with sequences Neu5Ac-α2,3-Gal-β1,4-Glc and Neu5Ac-α2,3-Gal-β1,4-GlcNAc, respectively (Fig. 1 and Table S1). The two additional probes (31 and 33) that yielded signals are chemically synthesized derivatives of 3SLN with additional 6-N-acetyl and 6-N-benzoyl functional groups, respectively, at the Gal moiety. There was no binding to a 3SL-derived structure bearing 4-O-acetylated Neu5Ac (probe 6), nor to the α2,6-linked sialyl analogs of 3SL and 3SLN (probes 77 and 81) or the α2,8-linked disialyl analog of 3SL (probe 104). A 3SLN analog with a β1,3 linkage between Gal and GlcNAc (probe 27) did not elicit a signal. In addition, ganglioside sequences that are branched at the Gal residue (e.g. probes 67 and 72) were not recognized. Taken together, glycan microarray analysis shows that binding to 3SL/3SLN is specific for defined linkages between each disaccharide, and only select modifications of individual sugar moieties can be tolerated.


Structures of B-lymphotropic polyomavirus VP1 in complex with oligosaccharide ligands.

Neu U, Khan ZM, Schuch B, Palma AS, Liu Y, Pawlita M, Feizi T, Stehle T - PLoS Pathog. (2013)

Glycan microarray screening analysis of LPyV VP1 pentamers.Glycan microarray analysis of LPyV VP1 showing selective binding to the short 3SL and 3SLN-related trisaccharide probes with ring-opened flexible cores but not to the N-glycan probe with 3SLN-terminating antennae, complex gangliosides, nor to any of the 6SL and 6SLN-related probes. Numerical scores for the binding intensity are shown as means of fluorescence intensities of duplicate spots at 2 and 5 fmol/spot. Error bars represent half of the difference between the two values. The microarrays consisted of lipid-linked oligosaccharide probes and the sequences are listed in Table S1. The probes are arranged according to terminal sialic acid linkage, oligosaccharide backbone chain length and sequence. The various types of terminal sialic acid linkage are indicated by the colored panels as defined at the bottom of the figure. The expanded region of the microarray highlights the sequences of the probes bound and the selective binding of LPyV VP1 to 3SL and 3SLN-related trisaccharide probes.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3814675&req=5

ppat-1003714-g001: Glycan microarray screening analysis of LPyV VP1 pentamers.Glycan microarray analysis of LPyV VP1 showing selective binding to the short 3SL and 3SLN-related trisaccharide probes with ring-opened flexible cores but not to the N-glycan probe with 3SLN-terminating antennae, complex gangliosides, nor to any of the 6SL and 6SLN-related probes. Numerical scores for the binding intensity are shown as means of fluorescence intensities of duplicate spots at 2 and 5 fmol/spot. Error bars represent half of the difference between the two values. The microarrays consisted of lipid-linked oligosaccharide probes and the sequences are listed in Table S1. The probes are arranged according to terminal sialic acid linkage, oligosaccharide backbone chain length and sequence. The various types of terminal sialic acid linkage are indicated by the colored panels as defined at the bottom of the figure. The expanded region of the microarray highlights the sequences of the probes bound and the selective binding of LPyV VP1 to 3SL and 3SLN-related trisaccharide probes.
Mentions: The purified pentamers were analyzed on a glycan microarray containing 117 sialylated and 6 non-sialylated lipid-linked oligosaccharide probes, representing sequences occurring on N- and O-linked glycoproteins as well as glycolipids. We detected LPyV VP1 binding signals above background to α2,3-sialylated probes bearing sequences related to 3SL and 3SLN (Fig. 1, probes 12 and 29). Both 3SL and 3SLN are linear trisaccharides with sequences Neu5Ac-α2,3-Gal-β1,4-Glc and Neu5Ac-α2,3-Gal-β1,4-GlcNAc, respectively (Fig. 1 and Table S1). The two additional probes (31 and 33) that yielded signals are chemically synthesized derivatives of 3SLN with additional 6-N-acetyl and 6-N-benzoyl functional groups, respectively, at the Gal moiety. There was no binding to a 3SL-derived structure bearing 4-O-acetylated Neu5Ac (probe 6), nor to the α2,6-linked sialyl analogs of 3SL and 3SLN (probes 77 and 81) or the α2,8-linked disialyl analog of 3SL (probe 104). A 3SLN analog with a β1,3 linkage between Gal and GlcNAc (probe 27) did not elicit a signal. In addition, ganglioside sequences that are branched at the Gal residue (e.g. probes 67 and 72) were not recognized. Taken together, glycan microarray analysis shows that binding to 3SL/3SLN is specific for defined linkages between each disaccharide, and only select modifications of individual sugar moieties can be tolerated.

Bottom Line: High-resolution crystal structures of the LPyV capsid protein VP1 alone and in complex with the trisaccharide ligands 3'-sialyllactose and 3'-sialyl-N-acetyl-lactosamine (3SL and 3SLN, respectively) show essentially identical interactions.Our analysis provides a structural basis for the observed specificity of LPyV for linear glycan motifs terminating in α2,3-linked sialic acid, and links the different tropisms of known LPyV strains to the receptor binding site.It also serves as a useful template for understanding the ligand-binding properties and serological crossreactivity of HPyV9.

View Article: PubMed Central - PubMed

Affiliation: Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany.

ABSTRACT
B-Lymphotropic Polyomavirus (LPyV) serves as a paradigm of virus receptor binding and tropism, and is the closest relative of the recently discovered Human Polyomavirus 9 (HPyV9). LPyV infection depends on sialic acid on host cells, but the molecular interactions underlying LPyV-receptor binding were unknown. We find by glycan array screening that LPyV specifically recognizes a linear carbohydrate motif that contains α2,3-linked sialic acid. High-resolution crystal structures of the LPyV capsid protein VP1 alone and in complex with the trisaccharide ligands 3'-sialyllactose and 3'-sialyl-N-acetyl-lactosamine (3SL and 3SLN, respectively) show essentially identical interactions. Most contacts are contributed by the sialic acid moiety, which is almost entirely buried in a narrow, preformed cleft at the outer surface of the capsid. The recessed nature of the binding site on VP1 and the nature of the observed glycan interactions differ from those of related polyomaviruses and most other sialic acid-binding viruses, which bind sialic acid in shallow, more exposed grooves. Despite their different modes for recognition, the sialic acid binding sites of LPyV and SV40 are half-conserved, hinting at an evolutionary strategy for diversification of binding sites. Our analysis provides a structural basis for the observed specificity of LPyV for linear glycan motifs terminating in α2,3-linked sialic acid, and links the different tropisms of known LPyV strains to the receptor binding site. It also serves as a useful template for understanding the ligand-binding properties and serological crossreactivity of HPyV9.

Show MeSH
Related in: MedlinePlus