Discovery of a Bacterial Hydrazine Transferase That Constructs the N-Aminolactam Pharmacophore in Albofungin Biosynthesis.

Structural motifs containing nitrogen-nitrogen (N-N) bonds are prevalent in a large number of clinical drugs and bioactive natural products. Hydrazine (NH) serves as a widely utilized building block for the preparation of these N-N-containing molecules in organic synthesis. Despite its common use in chemical processes, no enzyme has been identified to catalyze the incorporation of free hydrazine in natural product biosynthesis.

Nitric oxide synthase-guided genome mining identifies a cytochrome P450 enzyme for olefin nitration in bacterial specialized metabolism.

The biological signaling molecule nitric oxide (NO) has recently emerged as a metabolic precursor for the creation of microbial natural products with diversified structures and biological activities. Within the biosynthetic gene clusters (BGCs) of these compounds, genes associated with NO production pathways have been pinpointed. In this study, we employ a nitric oxide synthase (NOS)-guided genome mining strategy for the targeted discovery of NO-derived bacterial natural products and NO-utilizing biocatalysts.

Conserved Enzymatic Cascade for Bacterial Azoxy Biosynthesis.

Azoxy compounds exhibit a wide array of biological activities and possess distinctive chemical properties. Although there has been considerable interest in the biosynthetic mechanisms of azoxy metabolites, the enzymatic basis responsible for azoxy bond formation has remained largely enigmatic. In this study, we unveil the enzyme cascade that constructs the azoxy bond in valanimycin biosynthesis.

Hydroxytryptophan biosynthesis by a family of heme-dependent enzymes in bacteria.

Hydroxytryptophan serves as a chemical precursor to a variety of bioactive specialized metabolites, including the human neurotransmitter serotonin and the hormone melatonin. Although the human and animal routes to hydroxytryptophan have been known for decades, how bacteria catalyze tryptophan indole hydroxylation remains a mystery. Here we report a class of tryptophan hydroxylases that are involved in various bacterial metabolic pathways.

Effects of moderate drought extension on bacterial network structure in the rhizosphere soil of in semi-arid grasslands.

Introduction: Grasslands are home to complex bacterial communities whose dynamic interactions play a crucial role in organic matter and nutrient cycling. However, there is limited understanding regarding the impact of changes in rainfall amount and the duration of dry intervals on bacterial interactions.

Methods: To assess the impact of changes in precipitation volume and dry intervals on bacterial co-occurrence networks, we carried out precipitation manipulation experiments in the Eastern Eurasian Steppe of China.

Targeted genome mining for microbial antitumor agents acting through DNA intercalation.

Microbial natural products have been one of the most important sources for drug development. In the current postgenomic era, sequence-driven approaches for natural product discovery are becoming increasingly popular. Here, we develop an effective genome mining strategy for the targeted discovery of microbial metabolites with antitumor activities.

Heterologous Reconstitution of Toxoflavin Biosynthesis Reveals Key Pathway Intermediates and a Cofactor-Independent Oxidase.

Bacterial azapteridine-containing phytotoxin toxoflavin is a causal agent of rice grain rot. Here, we heterologously reconstitute toxoflavin biosynthesis in and identify key pathway intermediates, including the hitherto unknown ribityl-dedimethyl-toxoflavin. Furthermore, we characterized a cofactorless oxidase that converts ribityl-dedimethyl-toxoflavin to ribose and dedimethyl-toxoflavin, the latter of which then undergoes stepwise methylations to form toxoflavin.

Decreased precipitation reduced the complexity and stability of bacterial co-occurrence patterns in a semiarid grassland.

Introduction: Grasslands harbor complex bacterial communities, whose dynamic interactions are considered critical for organic matter and nutrient cycling. However, less is known about how changes in precipitation impact bacterial interactions.

Methods: We conducted precipitation manipulation experiments in the Eastern Eurasian Steppe in China and constructed co-occurrence networks for bacterial communities.

Ligninolytic characteristics of cultivated in cotton stalk media.

Biodelignification is widely regarded as a low-efficiency process because it is usually slow and difficult to control. To improve its efficiency and understand its mechanism, the present study analyzed the delignification characteristics of grown on a cotton stalk medium. The results demonstrated that all strains of can selectively degrade the cotton stalk lignin.

Functional Characterization of Laccase Isozyme (PoLcc1) from the Edible Mushroom Involved in Lignin Degradation in Cotton Straw.

Fungal laccases play important roles in the degradation of lignocellulose. In this study, the laccase producing cotton straw medium for was optimized by single-factor and orthogonal experiments, and to investigate the role of gene, one of the laccase-encoding genes, in the degradation of cotton straw lignin, an overexpression strain of gene was constructed, which was analyzed for the characteristics of lignin degradation. The results demonstrated that the culture conditions with the highest lignin degradation efficiency of the were the cotton straw particle size of 0.

Molecular basis of enzymatic nitrogen-nitrogen formation by a family of zinc-binding cupin enzymes.

Molecules with a nitrogen-nitrogen (N-N) bond in their structures exhibit various biological activities and other unique properties. A few microbial proteins are recently emerging as dedicated N-N bond forming enzymes in natural product biosynthesis. However, the details of these biochemical processes remain largely unknown.

Enzymatic Tailoring in Luzopeptin Biosynthesis Involves Cytochrome P450-Mediated Carbon-Nitrogen Bond Desaturation for Hydrazone Formation.

Luzopeptins and related decadepsipeptides are bisintercalator nonribosomal peptides featuring rare acyl-substituted tetrahydropyridazine-3-carboxylic acid (Thp) subunits that are critical to their biological activities. Herein, we reconstitute the biosynthetic tailoring pathway in luzopeptin A biosynthesis through in vivo genetic and in vitro biochemical approaches. Significantly, we revealed a multitasking cytochrome P450 enzyme that catalyzes four consecutive oxidations including the highly unusual carbon-nitrogen bond desaturation, forming the hydrazone-bearing 4-OH-Thp residues.

Nitric oxide as a source for bacterial triazole biosynthesis.

The heterocycle 1,2,3-triazole is among the most versatile chemical scaffolds and has been widely used in diverse fields. However, how nature creates this nitrogen-rich ring system remains unknown. Here, we report the biosynthetic route to the triazole-bearing antimetabolite 8-azaguanine.

The Biosynthetic Gene Cluster of Pyrazomycin-A C-Nucleoside Antibiotic with a Rare Pyrazole Moiety.

Pyrazomycin is a rare C-nucleoside antibiotic containing a naturally occurring pyrazole ring, the biosynthetic origin of which has remained obscure for decades. In this study we report the identification of the gene cluster responsible for pyrazomycin biosynthesis in Streptomyces candidus NRRL 3601, revealing that the StrR-family regulator PyrR is the cluster-situated transcriptional activator governing pyrazomycin biosynthesis. Furthermore, our results from in vivo reconstitution and stable-isotope feeding experiments provide support for the hypothesis that PyrN is a new nitrogen-nitrogen bond-forming enzyme that catalyzes the linkage of the ϵ-NH nitrogen atom of l-N -OH-lysine and the α-NH nitrogen atom of l-glutamic acid.

Convergent biosynthetic transformations to a bacterial specialized metabolite.

Microbes produce specialized metabolites to thrive in their natural habitats. However, it is rare that a given specialized metabolite is biosynthesized via pathways with distinct intermediates and enzymes. Here, we show that the core assembly mechanism of the antibiotic indolmycin in marine gram-negative Pseudoalteromonas luteoviolacea is distinct from its counterpart in terrestrial gram-positive Streptomyces species, with a molecule that is a shunt product in the Streptomyces pathway employed as a biosynthetic substrate for a novel metal-independent N-demethylindolmycin synthase in the P.

New phenanthrene and 9, 10-dihydrophenanthrene derivatives from the stems of Dendrobium officinale with their cytotoxic activities.

Two new phenanthrene and 9, 10-dihydrophenanthrene derivatives (1-2) with six known congeners (3-8) were isolated from the extraction of stems of Dendrobium officinale. Compounds 1 and 2 were based on carbon skeleton in which phenanthrene and 9, 10-dihydrophenanthrene moiety were linked with a phenylpropane unit through a dioxane bridge, respectively. Their structures were determined by comprehensive NMR spectroscopic data, the absolute configuration of new compounds were determined by comparing their experimental and calculated ECD for the first time.

An HPLC method for simultaneous quantitative determination of seven secoiridoid glucosides separated from the roots of Ilex pubescens.

A simple and specific high-performance liquid chromatographic method has been developed and validated to simultaneously determine seven secoiridoid glucosides for the first time. Three of them were separated from the ethanolic extract of the roots of Ilex pubescens for the first time, namely nuezhenide A, ligusides B and oleonuezhenide. In quantitative analysis, all of the calibration curves showed good linear regression (r > 0.

Two new compounds from the roots of Ilex pubescens and their cytotoxic activity.

A new phenylethanoid, 1-O-β-D-(4-hydroxyphenyl)-ethyl-6-O-vanilloyl-glucopyranoside (1), and a new furofuran lignan, (7R,7'R,7''S,8S,8'S,8''R)-4', 4''-dihydroxy-3,3',3'',5-tetramethoxy-7,9':7'9-diepoxy-4,8''-oxy-8,8'-sesquineolignan-7'',9''-diol (2), along with five known compounds (3-7) were isolated from the roots of Ilex pubescens. Their chemical structures were elucidated on the basis of extensive spectroscopic analysis, including UV, IR, MS, and NMR experiments. In addition, compounds 2-7 were evaluated in vitro for their cytotoxic effects on human HeLa cells; among them, compounds 2, 3, 6, and 7 showed cytotoxic activity against HeLa cells in the test.

Cell surface proteomics analysis indicates a neural lineage bias of rat bone marrow mesenchymal stromal cells.

Mesenchymal stromal cells (MSCs) are one of the most intensively studied stem cell types with application aims. However, the molecular characterisation and the relationship between the molecular characterisation and functional properties of MSCs are largely unknown. In this study, we purified the surface proteins from rat bone marrow MSCs (rBMMSCs) and characterised their surface proteome by LC-MS/MS.

Taurine postponed the replicative senescence of rat bone marrow-derived multipotent stromal cells in vitro.

The aging of many mammalian tissues is associated with replicative decline in somatic stem cells. Postponing this decline is a direct way of anti-aging. Bone marrow-derived multipotent stromal cells (BMSCs) hold promise for an increasing list of therapeutic uses due to their multilineage potential.