Fig. 5: Structural features of human FUTs.
From: Structure, function, and implications of fucosyltransferases in health and disease
a Superposition of the Michaelis complex (MC) of FUT9 (derived from the crystal structure, PDB: 8D0Q, shown in opaque red) with computational models of its α1,3/4-FUT isoenzymes (FUT3, cyan; FUT4, yellow; FUT5, hot pink; FUT6, green; FUT7, slate, all shown with transparency). Conserved disulfide bonds (top left) and the glycosylation site common to all FUT-isoenzymes (bottom left) are highlighted. (right panel) Key residues involved in acceptor recognition are shown, distinguishing between those conserved across FUT-isoenzymes and those specific to FUT9. b Representation of the MC of FUT8 (derived from the crystal structure, PDB: 6TKV), displaying the N-terminal coiled-coil domain (dark salmon), the catalytic domain (lime green), and the C-terminal SH3 domain (orange). Interdomain linkers are shown in navy, light blue, and the C-terminal loop in blue. (left panel) The conformational change of the mobile loops (loop 1 in red and loop 2 in purple) is shown in comparison to the apoenzyme (APO) form (PDB: 6DE0, pink). (right panel) Key interactions involved in substrate recognition are depicted. c Model of POFUT1 (violet), assembled from crystallographic structures (PDBs: 5UXH and 5KXH), with disordered loops in the binary complex highlighted in yellow. (right panel) The three-dimensional structure of the EGF domain (orange) is shown, featuring the fucosylation motif (gray), the three disulfide bonds, and the interaction interface with the enzyme (polar regions in blue and apolar regions in brown). The position of the acceptor Ser/Thr residue and the Asn involved in the proton shuttle are also indicated. d Model of POFUT2 (brick red), derived from crystallographic structures (PDBs: 4AP6 and 5FOE), highlighting its unique structural loop (yellow). On the right, the characteristic disulfide bonds of the TSR domain (lime) are shown, as well as the fucosylation motif (gray), the acceptor Ser/Thr residue, and the catalytic residue Glu54 (represented as sticks). Water molecules observed in the crystal structure (5FOE), displayed as sticks and in DOT surface format, reveal the hydrogen-bonding network that mediates substrate recognition.
