Search Results (4)

Background: Gentiana crassicaulis Duthie ex Burk., a key species used in traditional Chinese medicine for treating rheumatic pain and stroke, contains iridoids as its primary active component. However, the biosynthetic mechanisms underlying iridoid production are not fully understood. Methods: This study focused on iridoid biosynthesis during the germination of G. crassicaulis seeds, integrating metabolomic and transcriptomic analyses to uncover the underlying pathways and key candidate genes. Results: 196,132 unigenes and 10 iridoid compounds were identified through RNA-seq and ultra performance liquid chromatography-quadrupole time of flight-mass spectrometer (UPLC-Q-TOF-MS), respectively. The intersection of results from Pearson correlation analysis and weighted gene co-expression network analysis (WGCNA) revealed a significant correlation between 26 genes and iridoid levels, suggesting their potential role in the iridoid metabolism. Notably, six highly expressed candidate genes (DL7H, SLS, CYP76, CYP72A2, CYP84A1, and 13-LOX3) and five iridoids (loganic acid, sweroside, swertiamarin, gentiopicroside, and 6′-O-β-D-glucosyl-gentiopicroside) responded to methyl jasmonate stimulation in G. crassicaulis seedlings. Conclusions: by combining the known functions of candidate gene families, It is hypothesized that the CYP716 and LOX families exert indirect influences on iridoid metabolism, while the CYP71, CYP81, CYP72, CYP76, CYP710 families, 2OG-FeII family, and the glucosyltransferase family are likely to play direct roles in the biosynthetic transformations of the five iridoids. This study provides a theoretical basis for further functional gene validation and metabolic engineering aimed at enhancing iridoid production. The insights gained could lead to improved iridoid production efficiency in medicinal plants, ultimately benefiting the quality and efficacy of medicinal materials. Full article

Pipecolic acid (Pip) and its derivative hydroxypipecolic acids, such as (2S,3R)-3-hydroxypipecolic acid (cis-3-L-HyPip), are components of many natural and synthetic bioactive molecules. Fe(II)/α-ketoglutaric acid (Fe(II)/2-OG)-dependent dioxygenases can catalyze the hydroxylation of pipecolic acid. However, the available enzymes with desired activity and selectivity are limited. Herein, we compare the possible candidates in the Fe(II)/2-OG-dependent dioxygenase family, and cis-P3H is selected for potentially catalyzing selective hydroxylation of L-Pip. cis-P3H was further engineered to increase its catalytic efficiency toward L-Pip. By analyzing the structural confirmation and residue composition in substrate-binding pocket, a “handlebar” mode of molecular interactions is proposed. Using molecular docking, virtual mutation analysis, and dynamic simulations, R97, E112, L57, and G282 were identified as the key residues for subsequent site-directed saturation mutagenesis of cis-P3H. Consequently, the variant R97M showed an increased catalytic efficiency toward L-Pip. In this study, the k_cat/K_m value of the positive mutant R97M was about 1.83-fold that of the wild type. The mutation R97M would break the salt bridge between R97 and L-Pip and weaken the positive-positive interaction between R97 and R95. Therefore, the force on the amino and carboxyl groups of L-Pip was lightly balanced, allowing the molecule to be stabilized in the active pocket. These results provide a potential way of improving cis-P3H catalytic activity through rational protein engineering. Full article

A variety of secondary metabolites contributing to plant growth are synthesized by bacterial nonribosomal peptide synthases (NRPSs). Among them, the NRPS biosynthesis of surfactin is regulated by the SrfA operon. To explore the molecular mechanism for the diversity of surfactins produced by bacteria within the genus Bacillus, we performed a genome-wide identification study focused on three critical genes of the SrfA operon—SrfAA, SrfAB and SrfAC—from 999 Bacillus genomes (belonging to 47 species). Gene family clustering indicated the three genes can be divided into 66 orthologous groups (gene families), of which a majority comprised members of multiple genes (e.g., OG0000009 had members of all three SrfAA, SrfAB and SrfAC genes), indicating high sequence similarity among the three genes. Phylogenetic analyses also found that none of the three genes formed monophyletic groups, but were usually arranged in a mixed manner, suggesting the close evolutionary relationship among the three genes. Considering the module structure of the three genes, we propose that self-duplication, especially tandem duplications, might have contributed to the initial establishment of the entire SrfA operon, and further gene fusion and recombination as well as accumulated mutations might have continuously shaped the different functional roles of SrfAA, SrfAB and SrfAC. Overall, this study provides novel insight into metabolic gene clusters and operon evolution in bacteria. Full article

In this article, we use Lehmann alternative-II to extend the odd generalized exponential family. The uniqueness of this family lies in the fact that this transformation has resulted in a multitude of inverted distribution families with important applications in actuarial field. We can characterize the density of the new family as a linear combination of generalised exponential distributions, which is useful for studying some of the family’s properties. Among the structural characteristics of this family that are being identified are explicit expressions for numerous types of moments, the quantile function, stress-strength reliability, generating function, Rényi entropy, stochastic ordering, and order statistics. The maximum likelihood methodology is often used to compute the new family’s parameters. To confirm that our results are converging with reduced mean square error and biases, we perform a simulation analysis of one of the special model, namely OGE2-Fréchet. Furthermore, its application using two actuarial data sets is achieved, favoring its superiority over other competitive models, especially in risk theory. Full article