Diterpene cyclases from bacteria and basidiomycete fungi are seldom studied. Here, we presented the identification and verification of EriG, a member of the UbiA superfamily, as the enzyme responsible for the cyclization of the cyathane skeleton in the mushroom Hericium erinaceum. Genome mining using the EriG protein sequence as a probe led to the discovery of a new family of ubiquitous UbiA-related diterpene cyclases in bacteria and fungi. We successfully characterized seven new diterpene cyclases from bacteria or basidiomycete fungi with the help of an engineered Escherichia coli strain and determined the structures of their corresponding products. A new diterpene with an unusual skeleton was generated during this process. The discovery of this new family of diterpene cyclases provides new insight into the UbiA superfamily.

Twelve putative sesquiterpene synthases genes were found in clades along with enzymes with 1,6-, 1,10-, and 1,11-cyclase activities in the genome of Flammulina velutipes. Chemistry investigation of F. velutipes led to the identification of two seco-cuparane sesquiterpenes, flammufuranone A (1) and B (2); 13 new sesquiterpenes with nor-eudesmane, spiroaxane, cadinane, and cuparane skeletons (3-14, 16); as well as two new ergosterol derivatives (17 and 18). Sesquiterpenes (3-14) derived from 1,10-cyclizing enzyme were first reported from this mushroom. The absolute configurations in 1 (3R,7S) and 2 (3R,7R) were assigned by electronic circular dichroism (ECD) calculation. The absolute configuration in 3 was confirmed by X-ray diffraction analysis. The absolute configurations in the 1,2-diol moiety of 13, and in the 1,3-diol moiety of 17 and 18 were determined using Snatzke's method. Among these compounds, 3, 5, 13, and 14 were found to inhibit the HMG-CoA reductase with IC of 114.7, 77.6, 55.5, and 87.1 μM, respectively. Compounds 5, 6, 7, 10, 13, and 14 showed DPP-4 inhibitory activity with IC of 75.9, 83.7, 70.9, 79.7, 80.5, and 74.8 μM, respectively. The biosynthesis for sesquiterpenes in F. velutipes was also discussed.

Ten new ergosteroids, gloeophyllins A-J (1-10), have been isolated from the solid cultures of Gloeophyllum abietinum. The absolute configurations of 1, 2, and 9 were determined by X-ray crystallographic analysis. Compound 1 has a rare C-nor-D-homosteroid skeleton. Compound 9 possesses an unusual ergostane skeleton having a 10-oxabicyclo [4.3.1] decane moiety replacing 6/5 fused C/D rings. Compound 10 represents the first ergosteroid featuring the cleavage of a C8-C14 bond. The cytotoxicity of 1-10 was tested against the human cancer cell lines K562 and HCT116. The biosynthetic pathway for 1-10 is postulated.

One new perhydrobenzannulated 5,5-spiroketal sesquiterpene, pleurospiroketal F (1), as well as six new modified bisabolene sesquiterpenes pleurotins A-F (2-7) were isolated from solid-state fermentation of Pleurotus citrinopileatus. The structures of compounds 1-7 were determined by NMR and MS spectroscopic analysis. The absolute configuration of 1 was determined by X-ray diffraction analysis, while the absolute configurations of 3-7 were assigned using the in situ dimolybdenum circular dichroism method and circular dichroism data comparison. Protein tyrosine phosphatase 1B plays a crucial role as a negative regulator of the insulin-dependent signal cascades. Therefore, the protein tyrosine phosphatase 1B inhibitor can be used for treating type 2 diabetes mellitus and obesity. Compounds 2 and 6 showed moderate inhibitory effects on protein tyrosine phosphatase 1B with IC50 s of 32.1 µM and 30.5 µM, respectively. The kinetic study confirmed compound 2 to be a noncompetitive inhibitor. Compounds 1-7 did not show cytotoxic activity against cancer cell lines (IC50 > 50 µM).

A rare fungal hopane-type triterpenoid glycoside fumihopaside A was identified by genome mining in combination with HPLC−MS/MS in Aspergillus f umigatus. Combining genetic deletions in A. f umigatus with heterologous reconstitutions in Aspergillus nidulans of the afum gene cluster, we identified one fungal squalene hopane cyclase AfumA charging the cyclization of the hopene skeleton, one cytochrome P450, and one UDP-glycosyltransferase. Bioassays indicated that fumihopaside A plays important roles in protecting A. f umigatus against heat or ultraviolet stress.

Diterpene cyclases from bacteria and basidiomycete fungi are seldom studied. Here,wepresented the identification and verification of EriG,amember of the UbiA superfamily,as the enzyme responsible for the cyclization of the cyathane skeleton in the mushroom Hericium erinaceum. Genome mining using the EriG protein sequence as ap robe led to the discovery of anew family of ubiquitous UbiA-related diterpene cyclases in bacteria and fungi. We successfully characterized seven new diterpene cyclases from bacteria or basidiomycete fungi with the help of an engineered Escherichia coli strain and determined the structures of their corresponding products.A new diterpene with an unusual skeleton was generated during this process.T he discovery of this new family of diterpene cyclases provides new insight into the UbiA superfamily.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.

No abstract

No abstract