Fig. 1 | Nature Communications

Fig. 1

From: Bacterially derived synthetic mimetics of mammalian oligomannose prime antibody responses that neutralize HIV infectivity

Fig. 1

Analogy between the carbohydrate backbone of R. radiobacter Rv3 LOS and the D1 arm of oligomannose and conceptual design of Rv3 oligosaccharide derivatives. a Chemical structure of the carbohydrate backbone of Rv3 LOS (top), highlighting the tetra-mannosyl sequence of units E-C-B-D (purple) that is analogous to the chemical structure of the D1 arm (green) of Man9 (bottom). The two sequences differ in the anomeric configuration of the first branched mannosyl unit, which is α in the Rv3 oligosaccharide (unit D) and β in oligomannose. b Complex of bnAb PGT128 (heavy chain: light blue, light chain: dark blue) and Man9 (green) (PDB 3TV3) with the crystallized fragment of the Rv3 oligosaccharide (purple) (PDB 4RBP) modeled into the PGT128-binding site using the D1 arm of Man9 as a guide. The modeling suggested that a mannosyl extension at position C4 or C6 of unit F might form a structural surrogate of the D3 arm. c Core pentasaccharide scaffold Man-(1 → 2)-Man-(1 → 2)-Man-(1 → 3)-[R-Man-(1 → 6)]-Man-(1 → Spacer), derived from the chemical structure of the crystallized Rv3 oligosaccharide fragment, designed to incorporate, based on modeling of the Rv3 oligosaccharide into the PGT128-binding site as in b, extensions at the side-chain mannose unit F at residues R (position C6) and R’ (position C4). Spacer = O(CH2)3NH2

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