754227-26-4Relevant articles and documents
Structure-Function Studies of Artemisia tridentata Farnesyl Diphosphate Synthase and Chrysanthemyl Diphosphate Synthase by Site-Directed Mutagenesis and Morphogenesis
Lee, J. Scott,Pan, Jian-Jung,Ramamoorthy, Gurusankar,Poulter, C. Dale
supporting information, p. 14556 - 14567 (2017/10/24)
The amino acid sequences of farnesyl diphosphate synthase (FPPase) and chrysanthemyl diphosphate synthase (CPPase) from Artemisia tridentata ssp. Spiciformis, minus their chloroplast targeting regions, are 71% identical and 90% similar. FPPase efficiently and selectively synthesizes the "regular" sesquiterpenoid farnesyl diphosphate (FPP) by coupling isopentenyl diphosphate (IPP) to dimethylallyl diphosphate (DMAPP) and then to geranyl diphosphate (GPP). In contrast, CPPase is an inefficient promiscuous enzyme, which synthesizes the "irregular" monoterpenes chrysanthemyl diphosphate (CPP), lavandulyl diphosphate (LPP), and trace quantities of maconelliyl diphosphate (MPP) from two molecules of DMAPP, and couples IPP to DMAPP to give GPP. A. tridentata FPPase and CPPase belong to the chain elongation protein family (PF00348), a subgroup of the terpenoid synthase superfamily (CL0613) whose members have a characteristic α terpene synthase α-helical fold. The active sites of A. tridentata FPPase and CPPase are located within a six-helix bundle containing amino acids 53 to 241. The two enzymes were metamorphosed into one another by sequentially replacing the loops and helices of the six-helix bundle from enzyme with those from the other. Chain elongation was the dominant activity during the N-terminal to C-terminal metamorphosis of FPPase to CPPase, with product selectivity gradually switching from FPP to GPP, until replacement of the final α-helix, whereupon cyclopropanation and branching activity competed with chain elongation. During the corresponding metamorphosis of CPPase to FPPase, cyclopropanation and branching activities were lost upon replacement of the first helix in the six-helix bundle. Mutations of active site residues in CPPase to the corresponding amino acids in FPPase enhanced chain-elongation activity, while similar mutations in the active site of FPPase failed to significantly promote formation of significant amounts of irregular monoterpenes. Our results indicate that CPPase, a promiscuous enzyme, is more plastic toward acquiring new activities, whereas FPPase is more resistant. Mutations of residues outside of the α terpene synthase fold are important for acquisition of FPPase activity for synthesis of CPP, LPP, and MPP.
A common mechanism for branching, cyclopropanation, and cyclobutanation reactions in the isoprenoid biosynthetic pathway
Thulasiram, Hirekodathakallu V.,Erickson, Hans K.,Poulter, C. Dale
, p. 1966 - 1971 (2008/09/18)
Four reactions - chain elongation, cyclopropanation, branching, and cyclobutanation - are used in nature to join isoprenoid units for construction of the carbon skeletons for over 55 000 naturally occurring isoprenoid compounds. Those molecules produced by chain elongation have head-to-tail (regular) carbon skeletons, while those from cyclopropanation, branching, or cyclobutanation have non-head-to-tail (irregular) skeletons. Although wild type enzymes have not been identified for the branching and cyclobutanation reactions, chimeric proteins constructed from farnesyl diphosphate synthase (chain elongation) and chrysanthemyl diphosphate synthase (cyclopropanation) catalyze all four of the known isoprenoid coupling reactions to give a mixture of geranyl diphosphate (chain elongation), chrysanthemyl diphosphate (cyclopropanation), lavandulyl diphosphate (branching), and maconelliyl and planococcyl diphosphate (cyclobutanation). Replacement of the hydrogen atoms at C1 or C2 or hydrogen atoms in the methyl groups of dimethylallyl diphosphate by deuterium alters the distribution of the cyclopropanation, branching, and cyclobutanation products through primary and secondary kinetic isotope effects on the partitioning steps of common carbocationic intermediates. These experiments establish the sequence in which the intermediates are formed and indicate that enzyme-mediated control of the carbocationic rearrangement and elimination steps determines the distribution of products.
Chiral synthesis of maconelliol: A novel cyclobutanoid terpene alcohol from pink hibiscus mealybug, Maconellicoccus hirsutus
Zhang, Aijun,Nie, Junying,Khrimian, Ashot
, p. 9401 - 9403 (2007/10/03)
The chiral synthesis of maconelliol, [2,2-dimethyl-3-(1-methylethylidene) cyclobutyl] methanol, the alcohol moiety of the major sex pheromone component isolated from the pink hibiscus mealybug, Maconellicoccus hirsutus, is described. The compound was synthesized in six steps from alpha-pinene and the key step is dehydration of 5 to 7 through the intermediate 6. The absolute configuration of the naturally occurring maconelliol was determined as R.
