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The eunicellane diterpenoids are a unique family of natural products seen in marine organisms, plants, and bacteria. We used a series of biochemical, bioinformatics, and theoretical experiments to investigate the mechanism of the first diterpene synthase known to form the eunicellane skeleton. Deuterium labeling studies and quantum chemical calculations support that Bnd4, from Streptomyces sp. (CL12‐4), forms the 6,10‐bicyclic skeleton through a 1,10‐cyclization, 1,3‐hydride shift, and 1,14‐cyclization cascade. Bnd4 also demonstrated sesquiterpene cyclase activity and the ability to prenylate small molecules. Bnd4 possesses a unique D94NxxxD motif and mutation experiments confirmed an absolute requirement for D94 as well as E169. [ABSTRACT FROM AUTHOR]

The eunicellane diterpenoids are a unique family of natural products seen in marine organisms, plants, and bacteria. We used a series of biochemical, bioinformatics, and theoretical experiments to investigate the mechanism of the first diterpene synthase known to form the eunicellane skeleton. Deuterium labeling studies and quantum chemical calculations support that Bnd4, from Streptomyces sp. (CL12‐4), forms the 6,10‐bicyclic skeleton through a 1,10‐cyclization, 1,3‐hydride shift, and 1,14‐cyclization cascade. Bnd4 also demonstrated sesquiterpene cyclase activity and the ability to prenylate small molecules. Bnd4 possesses a unique D94NxxxD motif and mutation experiments confirmed an absolute requirement for D94 as well as E169. [ABSTRACT FROM AUTHOR]

A new bicyclic diterpenoid, benditerpenoic acid, was isolated from soil‐dwelling Streptomyces sp. (CL12‐4). We sequenced the bacterial genome, identified the responsible biosynthetic gene cluster, verified the function of the terpene synthase, and heterologously produced the core diterpene. Comparative bioinformatics indicated this Streptomyces strain is phylogenetically unique and possesses nine terpene synthases. The absolute configurations of the new trans‐fused bicyclo[8.4.0]tetradecanes were achieved by extensive spectroscopic analyses, including Mosher's analysis, J‐based coupling analysis, and computations based on sparse NMR‐derived experimental restraints. Interestingly, benditerpenoic acid exists in two distinct ring‐flipped bicyclic conformations with a rotational barrier of ≈16 kcal mol−1 in solution. The diterpenes exhibit moderate antibacterial activity against Gram‐positive bacteria including methicillin and multi‐drug resistant Staphylococcus aureus. This is a rare example of an eunicellane‐type diterpenoid from bacteria and the first identification of a diterpene synthase and biosynthetic gene cluster responsible for the construction of the eunicellane scaffold. [ABSTRACT FROM AUTHOR]

Ein neues bicyclisches Diterpenoid, Benditerpensäure, wurde aus einem im Erdreich vorkommenden Streptomyceten‐Stamm (CL12‐4) isoliert. Wir sequenzierten das Bakteriengenom, identifizierten den verantwortlichen Biosynthesegencluster, verifizierten die Funktion der Terpensynthase und produzierten heterolog das Diterpenoid‐Grundgerüst. Vergleichende Bioinformatik zeigte, dass dieser Streptomyceten‐Stamm phylogenetisch einzigartig ist und neun Terpensynthasen besitzt. Die absoluten Konfigurationen der neuen trans‐fusionierten Bicyclo[8.4.0]tetradecane wurden durch umfangreiche spektroskopische Analysen erreicht, einschließlich Moshers Analyse, NMR‐basierter Kopplungsanalyse, sowie DFT Berechnungen auf Basis von experimentellen NMR Parametern. Interessanterweise liegt Benditerpensäure in Lösung in zwei Ringkonformationen vor. Die Rotationsbarriere beträgt ca. 16 kcal mol−1. Die Diterpenoide zeigen mäßige antibakterielle Aktivität gegen Gram‐positive Bakterien, einschließlich Methicillin‐resistenten und multiresistenten Staphylococcus aureus. Hier präsentieren wir die erste Isolierung eines bakteriellen Eunicellan‐Diterpenoids und die Identifizierung der Diterpensynthase und des Biosynthesegenclusters, der für den Aufbau des bakteriellen Eunicellan‐Gerüsts verantwortlich ist. [ABSTRACT FROM AUTHOR]

Lysine decarboxylation is the first biosynthetic step of Huperzine A (HupA). Six cDNAs encoding lysine decarboxylases (LDCs) were cloned from Huperzia serrata by degenerate PCR and rapid amplification of cDNA ends (RACE). One HsLDC isoform was functionally characterized as lysine decarboxylase. The HsLDC exhibited greatest catalytic efficiency ( k cat / K m , 2.11 s −1 mM −1 ) toward L-lysine in vitro among all reported plant-LDCs. Moreover, transient expression of the HsLDC in tobacco leaves specifically increased cadaverine content from zero to 0.75 mg per gram of dry mass. Additionally, a convenient and reliable method used to detect the two catalytic products was developed. With the novel method, the enzymatic products of HsLDC and HsCAO, namely cadaverine and 5-aminopentanal, respectively, were detected simultaneously both in assay with purified enzymes and in transgenic tobacco leaves. This work not only provides direct evidence of the first two-step in biosynthetic pathway of HupA in Huperzia serrata and paves the way for further elucidation of the pathway, but also enables engineering heterologous production of HupA. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) X protein (HBx) has been determined to play a crucial role in the replication and transcription of HBV, and its biological functions mainly depend on the interaction with other host proteins. This study aims at screening the proteins that bind to the key functional domain of HBx by integrated proteomics. Proteins that specifically bind to the transactivation domain of HBx were selected by comparing interactors of full-length HBx and HBx-D5 truncation determined by glutathione-S-transferase (GST) pull-down assay combined with mass spectrometry (MS). The function of HBx interactor Pin1 in HBV replication was further investigated by in vitro experiments. In this study, a total of 189 proteins were identified from HepG2 cells that specifically bind to the transactivation domain of HBx by GST pull-down and subsequent MS. After gene ontology (GO) analysis, Pin1 was selected as the protein with the highest score in the largest cluster functioning in protein binding, and also classified into the cluster of proteins with the function of structural molecule activity, which is of great potential to be involved in HBV life cycle. The interaction between Pin1 and HBx has been further confirmed by Ni2+-NTA pulldown assay, co-immunoprecipitation, and immunofluorescence microscopy. HBsAg and HBeAg levels significantly decreased in Pin1 expression inhibited HepG2.2.15 cells. Besides, the inhibition of Pin1 expression in HepG2 cells impeded the restored replication of HBx-deficient HBV repaired by ectopic HBx expression. In conclusion, our study identified Pin1 as an interactor binds to the transactivation domain of HBx, and suggested the potential association between Pin1 and the function of HBx in HBV replication. [ABSTRACT FROM AUTHOR]

Covering: up to mid-2020 Terpenoids, also called isoprenoids, are the largest and most structurally diverse family of natural products. Found in all domains of life, there are over 80 000 known compounds. The majority of characterized terpenoids, which include some of the most well known, pharmaceutically relevant, and commercially valuable natural products, are produced by plants and fungi. Comparatively, terpenoids of bacterial origin are rare. This is counter-intuitive to the fact that recent microbial genomics revealed that almost all bacteria have the biosynthetic potential to create the C5 building blocks necessary for terpenoid biosynthesis. In this review, we catalogue terpenoids produced by bacteria. We collected 1062 natural products, consisting of both primary and secondary metabolites, and classified them into two major families and 55 distinct subfamilies. To highlight the structural and chemical space of bacterial terpenoids, we discuss their structures, biosynthesis, and biological activities. Although the bacterial terpenome is relatively small, it presents a fascinating dichotomy for future research. Similarities between bacterial and non-bacterial terpenoids and their biosynthetic pathways provides alternative model systems for detailed characterization while the abundance of novel skeletons, biosynthetic pathways, and bioactivies presents new opportunities for drug discovery, genome mining, and enzymology. [ABSTRACT FROM AUTHOR]

Plants can synthesize a wide range of terpenoids in response to various environmental cues. However, the specific regulatory mechanisms governing terpenoid biosynthesis at the cellular level remain largely elusive. In this study, we employed single-cell RNA sequencing to comprehensively characterize the transcriptome profile of cotton leaves and established a hierarchical transcriptional network regulating cell-specific terpenoid production. We observed substantial expression levels of genes associated with the biosynthesis of both volatile terpenes (such as β-caryophyllene and β-myrcene) and non-volatile gossypol-type terpenoids in secretory glandular cells. Moreover, two novel transcription factors, namely GoHSFA4a and GoNAC42, are identified to function downstream of the Gossypium PIGMENT GLAND FORMATION genes. Both transcription factors could directly regulate the expression of terpenoid biosynthetic genes in secretory glandular cells in response to developmental and environmental stimuli. For convenient retrieval of the single-cell RNA sequencing data generated in this study, we developed a user-friendly web server. Our findings not only offer valuable insights into the precise regulation of terpenoid biosynthesis genes in cotton leaves but also provide potential targets for cotton breeding endeavors. This study provides a comprehensive analysis of the transcriptome profile of cotton leaves, uncovering a hierarchical transcriptional network that regulates cell-specific terpenoid production in response to developmental and environmental stimuli. The findings offer valuable insights into terpenoid biosynthesis in cotton, and the accompanying scRNA-seq datasets and web server serves as a useful resource for future cotton research and breeding. [ABSTRACT FROM AUTHOR]

Natural products have been playing an indispensable role in drug discovery. However, it seems that the golden period of discovering new compounds has passed since the first antibiotic–penicillin. With the development of genome sequencing, it has been found that marine fungi contain various biosynthetic gene clusters (BGCs), which are silent under standard laboratory conditions. Therefore, it might be envisioned that once these BGCs are expressed, a large quantity of new secondary metabolites with biological activities could be generated. This paper reviewed several activation techniques implemented from 2020 to 2022, including epigenetics regulation, co-culture, precursor feeding, heterologous expression, and changing fermentation parameters to activate silent BGCs of marine fungi. We also described the diversity and bioactivities of these newly discovered uncommon marine fungi-derived compounds based on the classification of activation techniques, facilitating research groups focusing on natural products to enhance discovering efficiency. [Display omitted] [ABSTRACT FROM AUTHOR]