Stabilization of the reaction intermediate eudesmane cation (3) through interaction with Trp 334 during catalysis by aristolochene synthase from Penicillium roqueforti was investigated by site-directed incorporation of proteinogenic and non-canonical aromatic amino acids. The amount of germacrene A (2) generated by the mutant enzymes served as a measure of the stabilization of 3. 2 is a neutral intermediate, from which 3 is formed during PR-AS catalysis by protonation of the C6,C7 double bond. The replacement of Trp 334 with para-substituted phenylalanines of increasing electron-withdrawing properties led to a progressive accumulation of 2 that showed a good correlation with the interaction energies of simple cations such as Na(+) with substituted benzenes. These results provide compelling evidence for the stabilizing role played by Trp 334 in aristolochene synthase catalysis for the energetically demanding transformation of 2 to 3.
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http://dx.doi.org/10.1021/ja205927u | DOI Listing |
Biochemistry
February 2024
Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75080, United States.
Inferring the historical and biophysical causes of diversity within protein families is a complex puzzle. A key to unraveling this problem is characterizing the rugged topography of sequence-function adaptive landscapes. Using biochemical data from a 2 = 512 combinatorial library of tobacco 5--aristolochene synthase (TEAS) mutants engineered to make the native major product of Egyptian henbane premnaspirodiene synthase (HPS) and a complementary 512 mutant HPS library, we address the question of how product specificity is controlled.
View Article and Find Full Text PDFChembiochem
November 2022
Natur- und Wirkstoffchemie, Leibniz-Institut für Pflanzenbiochemie, Weinberg 3, 06120, Halle/Saale, Germany.
Two terpene cyclases were used as biocatalytic tool, namely, limonene synthase from Cannabis sativa (CLS) and 5-epi-aristolochene synthase (TEAS) from Nicotiana tabacum. They showed significant substrate flexibility towards non-natural prenyl diphosphates to form novel terpenoids, including core oxa- and thia-heterocycles and alkyne-modified terpenoids. We elucidated the structures of five novel monoterpene-analogues and a known sesquiterpene-analogue.
View Article and Find Full Text PDFJ Agric Food Chem
May 2022
State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, Frontiers Science Center for Materiobiology and Dynamic Chemistry, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Org Biomol Chem
August 2021
State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, PR China.
The exquisite chemodiversity of terpenoids is the product of the large diverse terpene synthase (TPS) superfamily. Here, by using structural and phylogenetic analyses and site-directed mutagenesis, we identified a residue (Cys440 in Nicotiana tabacum 5-epi-aristolochene synthase) proximal to an ion-binding motif common to all TPSs and named the preNSE/DTE residue, which determines the product specificity of sesquiterpene synthases from different plant species. In sesquiterpene synthases catalyzing 1,10-cyclization (1,10-cyclases) of farnesyl diphosphate, mutation of the residue in both specific and promiscuous 1,10-cyclases from different lineages leads to the accumulation of monocyclic germacrene A-11-ol, which is "short-circuited" from complex cyclization cascades, suggesting a key role of this residue in generating the first common intermediate of 1,10-cyclization.
View Article and Find Full Text PDFOrg Lett
April 2021
Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, 30167 Hannover, Germany.
The sesquiterpene cyclases pentalenene synthase (PenA) and two Δ-protoilludene synthases Omp6 and Omp7 convert a FPP ether into several new tetrahydrofurano terpenoids, one of which is also formed as the main product by the sesquiterpene cyclase BcBOT2. Thus, PenA, Omp6/7, and BcBOT2 follow closely related catalytic pathways and induce similar folding of their diphosphate substrates despite low levels of amino acid sequence similarity. Some of the new terpenoids show pronounced olfactoric properties.
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