Conformational differences between ZmPDC, ApPDC and GdPDC. A) Superposition of ZmPDC (orange), ApPDC (pink) and GdPDC (green) monomers emphasizing two regions where their conformations differ. Deviating regions are shown as stick models, conserved regions as ribbon diagrams. They extend from T341 to T352 and N499 to D503. Left insert: linker region, right insert: Interactions of Tyr502 B) An alignment of ScPDC (1QPD, yellow), ZmPDC (1ZPD, orange) and GdPDC (4COK, green) showing conserved residues, Arg221, Cys221, Tyr157 and Leu156 on either side of the cleft between PYR and R-domains. Arg221 is conserved but adopts a different conformation in ScPDC compared to ZmPDC and GdPDC. Tyr157 is unique to ScPDC, replaced by Leu156 in the bacterial homologues. Bacterial enzymes lack Cys221, involved in substrate induced allosteric activation in ScPDC C) Conformational change brought about by ThDP cofactor binding. Left to right: apo-ZmPDC (2WVH, pink), ZmPDC, TPU (2WVG, orange) and GdPDC, ThDP (4COK, green).