PMID: 30095206
Lee CC, Ko TP, Chen CT, Chan YT, Lo SY, Chang JY, Chen YW, Chung TF, Hsieh HJ, Hsiao CD, Wang AH
Crystal structure of PigA, a prolyl thioester-oxidizing enzyme in prodigiosin biosynthesis.
Chembiochem. 2018 Aug 10. doi: 10.1002/cbic.201800409.
Prodigiosin is an intensely red pigment comprising three pyrroles. The biosynthetic pathway includes a two-step proline oxidation catalyzed by PigA, using FAD as its cofactor. Here the enzyme is crystallized in apo-form and in complex with FAD and proline. As an acyl-CoA dehydrogenase (ACAD) family member, the protein folds into a beta-sheet flanked by two alpha-helical domains. PigA forms a tetramer, consistent with analytical ultracentrifugation results. FAD binds to PigA in a similar way to that in the other ACAD-family enzymes. The variable conformations of loop beta4-beta5 and helix alphaG correlate well with the structural flexibility required for substrate entrance to the Re side of FAD. Modeling with PigG, the acyl carrier protein, suggests a reasonable mode of interaction with PigA. The structure helps explain the proline oxidation mechanism, in which Glu244 plays a central role by abstracting the substrate protons. It also reveals a plausible pocket for oxygen binding to the Si side of FAD.