Aromatic prenyltransferases (aPTases) transfer prenyl moieties from isoprenoid donors to various aromatic acceptors, some of which have the rare property of extreme enzymatic promiscuity toward both a variety of prenyl donors and a large diversity of acceptors. In this study, we discovered a new aPTase, AtaPT, from Aspergillus terreus that exhibits unprecedented promiscuity toward diverse aromatic acceptors and prenyl donors and also yields products with a range of prenylation patterns. Systematic crystallographic studies revealed various discrete conformations for ligand binding with donor-dependent acceptor specificity and multiple binding sites within a spacious hydrophobic substrate-binding pocket. Further structure-guided mutagenesis of active sites at the substrate-binding pocket is responsible for altering the specificity and promiscuity toward substrates and the diversity of product prenylations. Our study reveals the molecular mechanism underlying the promiscuity of AtaPT and suggests an efficient protein engineering strategy to generate new prenylated derivatives in drug discovery applications.

No abstract

Three new sesquiterpenoids trichoacorenols B-C and cyclonerodiol B (1-3), along with three known ones (4-6), were isolated from the mangrove plant endophytic fungus Trichoderma sp. Xy24 using various column chromatography techniques. The structures of these compounds were determined on the basis of extensive spectroscopic data analyses. Compounds 1, 2, 4, and 5 were four acorane sesquiterpenes, 3 and 6 were two monocyclic sesquiterpenediols. Compounds 3 and 5 exhibited significant neural anti-inflammatory activity by inhibiting LPS-induced NO production in BV2 cells with the inhibitory rates of 75.0% and 39.2% at 0.1 μM, respectively, which are more potent than curcumin, a positive control with the inhibitory rate of 21.1% at 0.1 μM.

Epimedium is used in traditional Chinese medicine and contains flavonol glycosides that exhibit multiple biological activities. These bioactive flavonol glycosides usually have a rhamnose moiety at the 3-OH position of prenylflavonols, such as icariin (9), baohuoside I (1a) and baohuoside II (2a). However, to date, no rhamnosyltransferase has been reported to catalyze the 3-O-rhamnosylation of prenylflavonols. In this article, a flavonol rhamnosyltransferase, EpPF3RT, was identified from E. pseudowushanense B. L. Guo. The recombinant enzyme regiospecifically transfers a rhamnose moiety to 8-prenylkaempferol (1) and anhydroicaritin (2) at the 3-OH position to form baohuoside II (1a) and baohuoside I (2a) in vitro. In addition, a UDP-rhamnose synthase gene, EpRhS, from E. pseudowushanense was functionally characterized and used to produce the UDP-rhamnose sugar donor. Furthermore, an engineered Escherichia coli strain containing EpPF3RT and EpRhS was established to produce baohuoside II (1a) from whole cells. These studies indicate the significant potential of an enzymatic approach for the rhamnosylation of bioactive flavonoids in Epimedium plants and will provide a promising alternative for producing bioactive rhamnosylated flavonoids combined with other genes/enzymes by synthetic biology.