Two homologs of the diterpene synthase CotB2 from Streptomyces collinus (ScCotB2) and Streptomyces iakyrus (SiCotB2) were investigated for their products by in vitro incubations of the recombinant enzymes with geranylgeranyl pyrophosphate, followed by compound isolation and structure elucidation by NMR. ScCotB2 produced the new compound collinodiene, besides the canonical CotB2 product cyclooctat-9-en-7-ol, dolabella-3,7,18-triene and dolabella-3,7,12-triene, while SiCotB2 gave mainly cyclooctat-9-en-7-ol and only traces of dolabella-3,7,18-triene. The cyclisation mechanism towards the ScCotB2 products and their absolute configurations were investigated through isotopic labelling experiments.
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http://dx.doi.org/10.1002/chem.202302469 | DOI Listing |
J Biol Chem
December 2024
Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA 50011, USA.
The citrus scent arises from the volatile monoterpene limonene, whose cyclic nature can be viewed as a miniaturized form of the poly-cyclic sterol triterpenoids. In particular, as these rings are all formed from poly-isoprenyl precursors via carbocation cascades. However, the relevant reactions are initiated by distinct mechanisms, either lysis/ionization of an allylic diphosphate ester bond, as in limonene synthases, or protonation of a terminal olefin or epoxide, as in lanosterol synthases.
View Article and Find Full Text PDFBiochemistry
December 2024
Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, Hannover 30167, Germany.
Farnesyl pyrophosphate derivatives bearing an additional oxygen atom at position 5 proved to be very suitable for expanding the substrate promiscuity of sesquiterpene synthases (STSs) and the formation of new oxygenated terpenoids. Insertion of an oxygen atom in position 9, however, caused larger restraints that led to restricted acceptance by STSs. In order to reduce some of the proposed restrictions, two FPP-ether derivatives with altered substitution pattern around the terminal olefinic double bond were designed.
View Article and Find Full Text PDFYing Yong Sheng Tai Xue Bao
October 2024
College of Plant Protection, Shandong Agricultural University, Tai'an 271018, Shandong, China.
We investigated the effects of exogenous abscisic acid (ABA) on grain filling, starch accumulation, and endogenous hormones in maize (both the heat-tolerant maize variety Zhengdan 958 (ZD958) and the heat-sensitive variety Xianyu 335 (XY335)) under early post-anthesis high temperature stress by simulating high temperature stress for a period of 6 to 12 days post-anthesis in 2022 and 2023. There were three treatments: spraying water at ambient temperature as the control, spraying water at high temperature, and spraying ABA at high temperature. The results showed that early post-anthesis high temperature stress resulted in a significant reduction in grain weight and yield in maize, with XY335 showing a greater reduction than ZD958.
View Article and Find Full Text PDFJ Cell Mol Med
December 2024
Graduate Institute of Biomedical Sciences, Program for MD/PhD, Research Center for Cancer Biology, School of Medicine, China Medical University, Taichung, Taiwan.
Lipid reprogramming in carcinoma is reported to have a role in carcinogenesis, prognosis and therapy response. The lipid reprogramming could be contributed by either autonomous or nonautonomous resources. Since the nonautonomous lipid resources contributed by lipoproteins and their receptors have been reported in epithelial ovarian cancer (EOC), the impact of autonomous lipid metabolites was unknown.
View Article and Find Full Text PDFAn unusual family of bifunctional terpene synthases has been discovered in which both catalytic domains - a prenyltransferase and a cyclase - are connected by a long, flexible linker. These enzymes are unique to fungi and catalyze the first committed steps in the biosynthesis of complex terpenoid natural products: the prenyltransferase assembles 5-carbon precursors to form C geranylgeranyl diphosphate (GGPP), and the cyclase converts GGPP into a polycyclic hydrocarbon product. Weak domain-domain interactions as well as linker flexibility render these enzymes refractory to crystallization and challenge their visualization by cryo-EM.
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