Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Onoceroids are a rare family of triterpenes. One representative onoceroid is ambrein, which is the main component of ambergris used as a traditional medicine. We have previously identified the onoceroid synthase, BmeTC, in Bacillus megaterium and succeeded in creating ambrein synthase by introducing mutations into BmeTC. Owing to the structural similarity of ambrein to vitamin D, a molecule with diverse biological activities, we hypothesized that some of the activities of ambergris may be induced by the binding of ambrein to the vitamin D receptor (VDR). We demonstrated the VDR binding ability of ambrein. By comparing the structure–activity relationships of triterpenes with both the VDR affinity and osteoclastic differentiation-promoting activity, we observed that the activity of ambrein was not induced via the VDR. Therefore, some of the activities of ambergris, but not all, can be attributed to its VDR interaction. Additionally, six unnatural onoceroids were synthesized using the BmeTC reactions, and these compounds exhibited higher VDR affinity than that of ambrein. Enzymatic syntheses of onoceroid libraries will be valuable in creating a variety of bioactive compounds beyond ambergris.

DOI： 10.1038/s41598-024-52013-7

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Other Link： https://www.nature.com/articles/s41598-024-52013-7

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

DOI： 10.1039/D4SC01381F

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Language：English  

DOI： 10.1016/bs.mie.2024.03.017

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Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Isoprenoids with reduced Z,E‐mixed prenyl groups are found in various organisms. To date, only polyprenol reductases (PR‐Dol) involved in dolichol biosynthesis have been identified as enzymes capable of reducing Z,E‐mixed prenyl groups. Although C₃₅‐isoprenoids with reduced Z,E‐mixed prenyl groups are found in mycobacteria, Z,E‐mixed heptaprenyl reductase (HepR) remains unidentified. In the present study, the identification and functional analysis of HepR was performed. No PR‐Dol homolog gene was detected in the genome of Mycolicibacterium vanbaalenii. However, a homolog of geranylgeranyl reductase (GGR), which reacts with an all‐E prenyl group as a substrate, was encoded in the genome; thus, we analyzed it as a HepR candidate. In vitro enzymatic assay and in vivo gene suppression analysis identified the GGR homolog as HepR and revealed that HepR catalyzes the reduction of ω‐ and E‐ prenyl units in Z,E‐mixed heptaprenyl diphosphates, and C₃₅‐isoprenoids are mainly biosynthesized using E,E,E‐geranylgeranyl diphosphate as a precursor. Thus, it was demonstrated that the Z,E‐mixed prenyl reductase family exists in the GGR homologs. To the best of our knowledge, this is the first identification of a new type of Z,E‐mixed prenyl reductase with no sequence homology to PR‐Dol. The substrate specificity of HepR significantly differed from that of GGR, suggesting that it is a new enzyme. HepR homologs are widely distributed in mycobacterial genomes, and lipid analysis suggests that many strains, including pathogenic species, produce HepR metabolites. The discovery of this new enzyme will promote further research on Z,E‐mixed isoprenoids.

DOI： 10.1111/febs.16412

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/febs.16412

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Comprehensive functional analyses of E‐isoprenyl diphosphate synthases (E‐IDSs) from nonpathogenic Mycobacterium vanbaalenii have been performed. Mv0992 and Mv1577 represent a nonaprenyl diphosphate (E‐C₄₅) synthase and a geranylgeranyl diphosphate (E‐C₂₀) synthase, respectively. Although Mv3536 was identified as an E‐C₂₀ synthase using a single enzyme, co‐incubation of Mv3536 and Z‐IDSs (Mv4662 and Mv3822) strongly suggested it releases an intermediate geranyl diphosphate (E‐C₁₀) during a continuous condensation reaction. Mv0992 and Mv3536 functions differed from those of the previously reported pathogenic Mycobacterium tuberculosis homologues Rv0562 and Rv2173, respectively. Re‐analysis of Rv0562 and Rv2173 demonstrated that their functions were similar to those of Mv0992 and Mv3536 (Rv0562: E‐C₄₅ synthase; Rv2173: E‐C_10–15 synthase). The newly proposed functions of Rv0562 and Rv2173 would be in the biosynthesis of menaquinone and glycosyl carrier lipids essential for growth. Furthermore, a reduced allylic diphosphate could be used as the Z‐IDS of the Mv3822 substrate, thereby introducing a potentially novel pathway of cyclic sesquarterpene biosynthesis.

DOI： 10.1002/cbic.202000235

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/cbic.202000235

J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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