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3WJO: Crystal Structure Of Octaprenyl Pyrophosphate Synthase From Escherichia Coli With Isopentenyl Pyrophosphate (ipp)
Crystal structures of ligand-bound octaprenyl pyrophosphate synthase from escherichia coli reveal the catalytic and chain-length determining mechanisms
Octaprenyl pyrophosphate synthase (OPPs) catalyzes consecutive condensation reactions of one allylic substrate farnesyl pyrophosphate (FPP) and five homoallylic substrate isopentenyl pyrophosphate (IPP) molecules to form a C40 long-chain product OPP, which serves as a side chain of ubiquinone and menaquinone. OPPs belongs to the trans-prenyltransferase class of proteins. The structures of OPPs from Escherichia coli were solved in the apo-form as well as in complexes with IPP and a FPP thio-analog, FsPP, at resolutions of 2.2 to 2.6 A, and revealed the detailed interactions between the ligands and enzyme. At the bottom of the active-site tunnel, M123 and M135 act in concert to form a wall which determines the final chain length. These results represent the first ligand-bound crystal structures of a long-chain trans-prenyltransferase and provide new information on the mechanisms of catalysis and product chain elongation. (c) Proteins 2014;. (c) 2014 Wiley Periodicals, Inc.