Bacterial transformation of lignin: key enzymes and high-value products

Lignin, a natural organic polymer that is recyclable and inexpensive, serves as one of the most abundant green resources in nature. With the increasing consumption of fossil fuels and the deterioration of the environment, the development and utilization of renewable resources have attracted considerable attention. Therefore, the effective and comprehensive utilization of lignin has become an important global research topic, with the goal of environmental protection and economic development. This review focused on the bacteria and enzymes that can bio-transform lignin, focusing on the main ways that lignin can be utilized to produce high-value chemical products. Bacillus has demonstrated the most prominent effect on lignin degradation, with 89% lignin degradation by Bacillus cereus. Furthermore, several bacterial enzymes were discussed that can act on lignin, with the main enzymes consisting of dye-decolorizing peroxidases and laccase. Finally, low-molecular-weight lignin compounds were converted into value-added products through specific reaction pathways. These bacteria and enzymes may become potential candidates for efficient lignin degradation in the future, providing a method for lignin high-value conversion. In addition, the bacterial metabolic pathways convert lignin-derived aromatics into intermediates through the "biological funnel", achieving the biosynthesis of value-added products. The utilization of this "biological funnel" of aromatic compounds may address the heterogeneous issue of the aromatic products obtained via lignin depolymerization. This may also simplify the separation of downstream target products and provide avenues for the commercial application of lignin conversion into high-value products.

The amino acid metabolomics signature of differentiating myocardial infarction from strangulation death in mice models

This study differentiates myocardial infarction (MI) and strangulation death (STR) from the perspective of amino acid metabolism. In this study, MI mice model via subcutaneous injection of isoproterenol and STR mice model by neck strangulation were constructed, and were randomly divided into control (CON), STR, mild MI (MMI), and severe MI (SMI) groups. The metabolomics profiles were obtained by liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics. Principal component analysis, partial least squares-discriminant analysis, volcano plots, and heatmap were used for discrepancy metabolomics analysis. Pathway enrichment analysis was performed and the expression of proteins related to metabolomics was detected using immunohistochemical and western blot methods. Differential metabolites and metabolite pathways were screened. In addition, we found the expression of PPM1K was significantly reduced in the MI group, but the expression of p-mTOR and p-S6K1 were significantly increased (all P < 0.05), especially in the SMI group (P < 0.01). The expression of Cyt-C was significantly increased in each group compared with the CON group, especially in the STR group (all P < 0.01), and the expression of AMPKα1 was significantly increased in the STR group (all P < 0.01). Our study for the first time revealed significant differences in amino acid metabolism between STR and MI.

Stable and efficient immobilization of bi-enzymatic NADPH cofactor recycling system under consecutive microwave irradiation

One of the challenges in biocatalysis is the development of stable and efficient bi-enzymatic cascades for bio-redox reactions coupled to the recycling of soluble cofactors. Aldo-keto reductase (LEK) and glucose dehydrogenase (GDH) can be utilized as the NADPH recycling system for economic and efficient biocatalysis of (R)-4-chloro-3-hydroxybutanoate ((R)-CHBE), an important chiral pharmaceutical intermediate. The LEK and GDH was efficiently co-immobilized in mesocellular siliceous foams (MCFs) under microwave irradiation (CoLG-MIA). while they were also co-immobilized by entrapment in calcium alginate without MIA as control (CoLG-CA). The relative activity of CoLG-MIA was increased to 140% compared with that of free LEK. The CoLG-MIA exhibited a wider range of pH and temperature stabilities compared with other preparations. The thermal, storage and batch operational stabilities of microwave-assisted immobilized LEK-GDH were also improved. The NADPH recycling system exhibited the potential as the stable and efficient catalyst for the industrial preparation of (R)-CHBE.

Newcastle Disease virus infection activates PI3K/Akt/mTOR and p38 MAPK/Mnk1 pathways to benefit viral mRNA translation via interaction of the viral NP protein and host eIF4E

Newcastle disease virus (NDV), a member of the Paramyxoviridae family, can activate PKR/eIF2α signaling cascade to shutoff host and facilitate viral mRNA translation during infection, however, the mechanism remains unclear. In this study, we revealed that NDV infection up-regulated host cap-dependent translation machinery by activating PI3K/Akt/mTOR and p38 MAPK/Mnk1 pathways. In addition, NDV infection induced p38 MAPK/Mnk1 signaling participated 4E-BP1 hyperphosphorylation for efficient viral protein synthesis when mTOR signaling is inhibited. Furthermore, NDV NP protein was found to be important for selective cap-dependent translation of viral mRNAs through binding to eIF4E during NDV infection. Taken together, NDV infection activated multiple signaling pathways for selective viral protein synthesis in infected cells, via interaction between viral NP protein and host translation machinery. Our results may help to design novel targets for therapeutic intervention against NDV infection and to understand the NDV anti-oncolytic mechanism.

Viruses are obligate intracellular parasites and have no protein translation machinry of their own. Therefore, viruses remain exclusively dependent on host translation machinery to ensure viral protein synthesis and progeny virion production during infection. We previous reported that Newcastle disease virus (NDV) shutoff host and facilitate viral mRNA translation by activating PKR/eIF2α signaling cascade. Here, we demonstrated that NDV infection up-regulated host cap-dependent translation machinery by activating PI3K/Akt/mTOR and p38 MAPK/Mnk1 pathways. Furthermore, NDV NP protein was found to be important for selective cap-dependent translation of viral mRNAs. Our findings highlight a new strategy how virus used host translation machinery for selective viral protein synthesis.

β-Elemene derivatives produced from SeO2-mediated oxidation reaction

Herein, we report the first access of β-elemene derivatives through the SeO₂-mediated oxidation reaction. Several new compounds were isolated through such a one-step reaction, and their structures were elucidated using various 2D-NMR techniques. This method provides easy access to multiple oxidative β-elemene derivatives in one single step and represents the first modifications on cyclohexyl ring of β-elemene. It is expected to open up the opportunity for future derivatization on cyclohexyl ring of β-elemene. The new compounds obtained above showed better anti-proliferation activities than β-elemene itself on several cancer cell lines. Among them, compound 17 shows the best activity in antiproliferation assays of A549 and U-87MG cell lines.