Saturation mutagenesis on Tyr205 of the cyclic dipeptide C2-prenyltransferase FtmPT1 results in mutants with strongly increased C3-prenylating activity

New prenylated indole-benzodiazepine-2,5-diones with α-glucosidase inhibitory activities from the mangrove-derived Aspergillus spinosus

Mangrove-derived fungi have been demonstrated to be promising source of structurally diverse and widely active secondary metabolites. During our search for new bioactive compounds, eight new indole-benzodiazepine-2,5-dione derivatives asperdinones A-H (1-8) and two known congeners (9 and 10) were isolated from the culture extracts of the mangrove-derived fungus Aspergillus spinosus WHUF0344 guided by one strain many compounds (OSMAC) and the heteronuclear 1H, 13C single-quantum coherence (HSQC) based small molecule accurate recognition technology (SMART) strategies. The structures and absolute configurations of the new compounds were elucidated by detailed spectroscopic analyze and electronic circular dichroism (ECD) calculations. The putative biosynthetic pathway of these compounds was proposed. Compounds 1-10 were evaluated for their antibacterial and α-glucosidase inhibitory activities. None of compounds showed antibacterial activity. Compounds 2-6 and 8 exhibited moderate inhibitory effects against α-glucosidase with IC50 values in the range of 24.65-312.25 μM. Besides, both 3 and 4 inhibited α-glucosidase variedly. Furthermore, the molecular docking study showed that compounds 2-4 were perfectly docking into the active sites of α-glucosidase. This study not only enriched the chemical diversity of secondary metabolites from the mangrove-derived fungi, but also provided potential hit compounds for further development of α-glucosidase inhibitors.

Structural insights into the diverse prenylating capabilities of DMATS prenyltransferases

Covering: 2009 up to August 2023Prenyltransferases (PTs) are involved in the primary and the secondary metabolism of plants, bacteria, and fungi, and they are key enzymes in the biosynthesis of many clinically relevant natural products (NPs). The continued biochemical and structural characterization of the soluble dimethylallyl tryptophan synthase (DMATS) PTs over the past two decades have revealed the significant promise that these enzymes hold as biocatalysts for the chemoenzymatic synthesis of novel drug leads. This is a comprehensive review of DMATSs describing the structure-function relationships that have shaped the mechanistic underpinnings of these enzymes, as well as the application of this knowledge to the engineering of DMATSs. We summarize the key findings and lessons learned from these studies over the past 14 years (2009-2023). In addition, we identify current gaps in our understanding of these fascinating enzymes.

Bioinspired Brønsted Acid-Promoted Regioselective Tryptophan Isoprenylations

Tryptophan-containing isoprenoid indole alkaloid natural products are well known for their intricate structural architectures and significant biological activities. Nature employs dimethylallyl tryptophan synthases (DMATSs) or aromatic indole prenyltransferases (iPTs) to catalyze regio- and stereoselective prenylation of l-Trp. Regioselective synthetic routes that isoprenylate cyclo-Trp-Trp in a 2,5-diketopiperazine (DKP) core, in a desymmetrizing manner, are nonexistent and are highly desirable. Herein, we present an elaborate report on Brønsted acid-promoted regioselective tryptophan isoprenylation strategy, applicable to both the monomeric amino acid and its dimeric l-Trp DKP. This report outlines a method that regio- and stereoselectively increases sp3 centers of a privileged bioactive core. We report on conditions involving screening of Brønsted acids, their conjugate base as salt, solvent, temperature, and various substrates with diverse side chains. Furthermore, we extensively delineate effects on regio- and stereoselection of isoprenylation and their stereochemical confirmation via NMR experiments. Regioselectively, the C3-position undergoes normal-isoprenylation or benzylation and forms exo-ring-fused pyrroloindolines selectively. Through appropriate prenyl group migrations, we report access to the bioactive tryprostatin alkaloids, and by C3-normal-farnesylation, we access anticancer drimentines as direct targets of this method. The optimized strategy affords iso-tryprostatin B-type products and predrimentine C with 58 and 55% yields, respectively. The current work has several similarities to biosynthesis, such as-reactions can be performed on unprotected substrates, conditions that enable Brønsted acid promotion, and they are easy to perform under ambient conditions, without the need for stoichiometric levels of any transition metal or expensive ligands.

Microbial soluble aromatic prenyltransferases for engineered biosynthesis

Prenyltransferase (PTase) enzymes play crucial roles in natural product biosynthesis by transferring isoprene unit(s) to target substrates, thereby generating prenylated compounds. The prenylation step leads to a diverse group of natural products with improved membrane affinity and enhanced bioactivity, as compared to the non-prenylated forms. The last two decades have witnessed increasing studies on the identification, characterization, enzyme engineering, and synthetic biology of microbial PTase family enzymes. We herein summarize several examples of microbial soluble aromatic PTases for chemoenzymatic syntheses of unnatural novel prenylated compounds.

Enzymatic studies on aromatic prenyltransferases

Aromatic prenyltransferases (PTases), including ABBA-type and dimethylallyl tryptophan synthase (DMATS)-type enzymes from bacteria and fungi, play important role for diversification of the natural products and improvement of the biological activities. For a decade, the characterization of enzymes and enzymatic synthesis of prenylated compounds by using ABBA-type and DMATS-type PTases have been demonstrated. Here, I introduce several examples of the studies on chemoenzymatic synthesis of unnatural prenylated compounds and the enzyme engineering of ABBA-type and DMATS-type PTases.