TY - JOUR T1 - Structural basis of ligand selectivity by a bacterial adhesin lectin involved in multi- species biofilm formation JF - bioRxiv DO - 10.1101/2020.11.18.389155 SP - 2020.11.18.389155 AU - Shuaiqi Guo AU - Tyler D.R. Vance AU - Hossein Zahiri AU - Robert Eves AU - Corey Stevens AU - Jan-Hendrik Hehemann AU - Silvia Vidal-Melgosa AU - Peter L. Davies Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/11/18/2020.11.18.389155.abstract N2 - Carbohydrate recognition by lectins governs critical host-microbe interactions. MpPA14 lectin is a domain of a 1.5-MDa adhesin responsible for a symbiotic bacterium-diatom interaction in Antarctica. Here we show MpPA14 binds various monosaccharides, with L-fucose and N-acetyl glucosamine being the strongest ligands (Kd ~ 150 μM). High-resolution structures of MpPA14 with 15 different sugars bound elucidated the molecular basis for the lectin’s apparent binding promiscuity but underlying selectivity. MpPA14 mediates strong Ca2+-dependent interactions with the 3, 4 diols of L-fucopyranose and glucopyranoses, and binds other sugars via their specific minor isomers. Thus, MpPA14 only binds polysaccharides like branched glucans and fucoidans with these free end-groups. Consistent with our findings, adhesion of MpPA14 to diatom cells was selectively blocked by L-fucose, but not by N-acetyl galactosamine. With MpPA14 lectin homologs present in adhesins of several pathogens, our work gives insight into an anti-adhesion strategy to block infection via ligand-based antagonists.Competing Interest StatementThe authors have declared no competing interest. ER -