Substrate geometry controls the cyclization cascade in multiproduct terpene synthases from Zea mays.
Multiproduct terpene synthases TPS4-B73 and TPS5-Delprim from maize (Zea mays) catalyze the conversion of farnesyl diphosphate (FDP) and geranyl diphosphate (GDP) into a complex mixture of sesquiterpenes and monoterpenes, respectively. Various isotopic and geometric isomers of natural substrates like (2Z)-[2-(2)H]- and [2,4,4,9,9,9-(2)H6]-(GDP) and (2Z,6E)-[2-(2)H]- and [2,4,4,13,13,13-(2)H6]-(FDP) were synthesized analogous to presumptive reaction intermediates. On incubation with labeled (2Z) substrates, TPS4 and TPS5 showed much lower kinetic isotope effects than the labeled (2E) substrates. Interestingly, the products arising from the deuterated (2Z)-precursors revealed a distinct preference for cyclic products and exhibited an enhanced turnover on comparison with natural (2E)-substrates. This increase in the efficiency due to (2Z) configuration emphasizes the rate limiting effect of the initial (2E) → (2Z) isomerization step in the reaction cascade of the multiproduct terpene synthases. Apart from turnover advantages, these results suggest that substrate geometry can be used as a tool to optimize the biosynthetic reaction cascade towards valuable cyclic terpenoids.
Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, D-07745 Jena, Germany. boland@ice.mpg.de.
Abith
A
Vattekkatte
Nathalie
N
Gatto
Tobias G
TG
Köllner
Jörg
J
Degenhardt
Jonathan
J
Gershenzon
Wilhelm
W
Boland
D019883:Alkyl and Aryl Transferases / Q000378:metabolism*; D003500:Cyclization; D011756:Diphosphates / Q000737:chemistry / Q000378:metabolism; D004224:Diterpenes / Q000737:chemistry / Q000378:metabolism; D039821:Monoterpenes / Q000737:chemistry / Q000378:metabolism*; D011106:Polyisoprenyl Phosphates / Q000737:chemistry / Q000378:metabolism; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D003313:Zea mays / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism
D011756:Diphosphates; D004224:Diterpenes; D039821:Monoterpenes; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; C511282:geranyl diphosphate; C004808:farnesyl pyrophosphate; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase