Interaction of PqqE and PqqD in the pyrroloquinoline quinone (PQQ) biosynthetic pathway links PqqD to the radical SAM superfamilyThis article is part of the 'Enzymes and Proteins' web-theme issue for ChemComm.Electronic supplementary information (ESI) available: Experimental protocols. See DOI: 10.1039/c0cc00968g

pqqD is one of six genes required for PQQ production in Klebsiella pneumoniae. Herein, we demonstrate that PqqD interacts specifically with the radical SAM enzyme PqqE, causing a perturbation in the electronic environment around the [4Fe-4S] + clusters. This interaction redirects the role for PqqD in PQQ biosynthesis. Data are presented that show PqqD interacting with PqqE.