title: Crystal structures of ligand-bound octaprenyl pyrophosphate synthase from Escherichia coli reveal the catalytic and chain-length determining mechanisms.
abstract: 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 2.2-2.6 Å, 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.
authors.affiliation: Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Han
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Chen
authors.forename: Chih-Jung
authors.initials: CJ
authors.lastname: Kuo
authors.forename: Chun-Hsiang
authors.initials: CH
authors.lastname: Huang
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zheng
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhu
authors.forename: Xinxin
authors.initials: X
authors.lastname: Feng
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.forename: Eric
authors.initials: E
authors.lastname: Oldfield
authors.forename: Andrew H-J
authors.initials: AH
authors.lastname: Wang
authors.forename: Po-Huang
authors.initials: PH
authors.lastname: Liang
authors.forename: Rey-Ting
authors.initials: RT
authors.lastname: Guo
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Ma
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry*; D000595:Amino Acid Sequence; D055162:Biocatalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011106:Polyisoprenyl Phosphates; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012717:Sesquiterpenes; D013379:Substrate Specificity
chemical_list: D008024:Ligands; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; C004808:farnesyl pyrophosphate; D019883:Alkyl and Aryl Transferases; C048987:octaprenyl pyrophosphate synthetase
keywords: crystal structure; prenyltransferase; product chain length; site-directed mutagenesis