Fig. 2 Crystal structures and mannose binding of FimH variants in a tip-like setting. Crystal structures and mannose binding of FimH variants in a tip-like setting. (A) Reaction scheme of in vitro DSE reaction to produce tip-like FimGNteH complexes. (B) Representative SDS–polyacrylamide gel electrophoresis of purified FimGNteH variants either boiled (not labeled) or not boiled (NB). (C) Enzyme-linked immunosorbent assay (ELISA) measuring binding of FimGNteH variant complexes to surface-coated glycoproteins, which include secretory IgA (sIgA), Tamm-Horsfall protein (THP), collagen IV, and laminin. (D) Crystal structures of FimGNteH A62S [Protein Data Bank (PDB) ID 5JQI, left] and FimGNteH A27V/V163A (PDB ID 5JR4, right) depicted as ribbons. These structures are overlaid on previously solved crystal structures of FimH in a FimCFFGH complex (3JWN) and FimCH complex (1KLF), respectively. Conformations are labeled accordingly. FimHLD, linker, and FimHPD are colored as in (A), the insertion loop (residues 109 to 124) is colored purple, and FimGNte is colored gray. (E) FimHLD-FimHPD interface in FimGNteH A62S (left) and FimGNteH A27V/V163A (right). Contacts between residues are indicated as black dotted lines. (F) Structural alignment of FimGNteH A27V/V163A (colored blue) to FimHLD of mannose-bound FimCH (colored white). Residue side chains and mannose in green are depicted as sticks. Contacts between mannose and FimH are indicated as black dotted lines. Vasilios Kalas et al. Sci Adv 2017;3:e1601944 Published by AAAS