Crystal structure of TAS1 KS.
A, the overall structure of TAS1 KS (PDB ID: 6KOG). B, superposed structure of TAS1 KS (gold) and canonical type I PKS KS domain (purple, 6DEBS module 5 KS, PDB ID: 2HG4). C, the enlarged substrate-binding pocket of the superposed structure of TAS1 KS and 6DEBS module 5 KS domain. The side chains of catalytic triad and Ser-324 of TAS1 KS are shown as stick models.