Bioscience, Biotechnology, and Biochemistry最新文献

Selaginellin A (Sela A), a derivative from Selaginella tamariscina, exerts antitriple-negative breast cancer effects in MDA-MB-231 cells. Proteomic profiling identified 1136 differentially expressed proteins after Sela A treatment, predominantly downregulated (n = 889). Enrichment analyses revealed that Sela A significantly downregulated pathways critical for DNA repair, replication, and cell cycle progression, while upregulating ribosomal biogenesis and protein processing. Mechanistically, Sela A acts as a PTP1B inhibitor (IC50 = 7.4 μm), binding key residues (PHE-182, GLU-186). This inhibition activates the mechanistic target of rapamycin complex 1 (mTOR). Consequently, mTOR activation stimulates ribosomal synthesis but concurrently triggers a p70S6K-mediated negative feedback loop, degrading IRS1. IRS1 loss suppresses Akt signaling, reducing expression of cell cycle proteins and inducing G1-phase arrest. Thus, Sela A may block MDA-MB-231 cell proliferation via PTP1B inhibition driving mTOR/IRS1/Akt dysregulation.

Glucagon dysregulation is a hallmark of type 2 diabetes mellitus (T2DM), yet its early hepatic effects remain unclear. Here, we demonstrate that glucagon-induced gluconeogenesis is markedly enhanced in primary hepatocytes from prediabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a well-established model of human T2DM. Compared to control LETO rats, OLETF hepatocytes showed significantly higher glucagon-stimulated expression of gluconeogenic genes (Pepck, G6pase, and Fbp1) at both mRNA and protein levels, along with elevated glucose production. Notably, mRNA decay analysis revealed prolonged half-lives of gluconeogenic transcripts in OLETF hepatocytes, indicating enhanced mRNA stability as a novel mechanism contributing to increased hepatic glucose output. These findings highlight aberrant glucagon responsiveness and posttranscriptional regulation as potential predisposing factors in genetically susceptible models prior to the onset of overt metabolic abnormality, which may be of interest for preventive or therapeutic strategies for controlling fasting hyperglycemia.

Kimoto seed mash is a traditional fermentation starter used in sake brewing that contains sufficient lactic acid produced by various lactic acid bacteria (LAB). To determine the factors influencing their community, we investigated the actively operating LAB species in addition to brewing and chemical components in the early and middle periods over different brewing years in the same sake brewery. The results showed that the composition and changes in the LAB species and amino acid profiles varied annually. Furthermore, reproduction of changes in the LAB community using a modified synthetic medium demonstrated the dependency of certain LAB strains on specific amino acids. Notably, we found that the behaviors of cocci such as Leuconostoc citreum, Lactococcus raffinolactis, Leuconostoc suionicum, and Pediococcus pentosaceus were affected by tryptophan or tyrosine requirements for each species. The metabolic activities of some LAB species were also reflected in the organic acid profile of kimoto seed mash.

Antimycin A (AA) is a widely used inhibitor to study photosynthesis and respiration. In photosynthesis, it is commonly used to inhibit a pathway of cyclic electron flow around photosystem I (CEF-PSI), but has also been reported to affect photosystem II (PSII), not involved in CEF-PSI. Although concerns have been raised about AA's specificity, its impact on PSII activity remains unclear. AA3 was recently proposed as a more specific inhibitor of the same CEF-PSI pathway. In the mitochondrial respiratory chain, AA inhibits complex III, like myxothiazol. Here, we investigated the direct effects of AA, AA3, and myxothiazol on PSII activity and linear photosynthetic electron transport using isolated plant PSII and thylakoid membranes. AA, but neither AA3 nor myxothiazol, directly suppressed PSII activity and linear electron transport. Furthermore, the extent of AA's effects was batch-dependent. Thus, we propose using AA3 to inhibit CEF-PSI, and myxothiazol to inhibit complex III, instead of AA.

We isolated 23 soil bacterial strains tolerating methaneseleninic acid (MSeA), an oxidized organoselenium metabolite. Among them, Pseudomonas sp. M10 exhibited the highest MSeA tolerance and converted MSeA into volatile dimethyldiselenide, consistent with a redox-driven, nonenzymatic process. This is the first report of bacterially mediated MSeA volatilization, revealing a previously unrecognized microbial contribution to selenium flux between terrestrial and atmospheric compartments.

Selenium is an essential trace element in many organisms but becomes toxic at elevated concentrations. At moderately increased, non-lethal levels, selenite triggers both selenium utilization and stress responses in microorganisms. However, the thresholds of such responses in archaea remain poorly understood. Here, we investigated the effects of elevated yet non-inhibitory concentrations of selenite on growth and gene expression in the methanogenic archaeon Methanococcus maripaludis JJ. We observed no significant impact on growth rate or cell yield, even at 100 µm selenite. RNA sequencing and reverse transcription-quantitative polymerase chain reaction analyses revealed differential expression of genes involved in methanogenesis and transport systems, which may contribute to maintaining growth under elevated selenite. Our findings suggest that the transcriptional response to selenite in M. maripaludis is initiated at low concentrations (eg <1 µm) and remains saturated across a hundredfold range (up to 100 µm), without inducing stress responses or impairing growth.

Matcha, a Japanese powdered green tea, enhances Drosophila resistance to oxidative stress. Transcriptome analysis shows activation of detoxification and antioxidant pathways, likely driven by caffeine-catechin synergy. Unlike green tea catechins, matcha did not extend lifespan under high-protein diets, underscoring complex physiological effects and validating Drosophila as a nutrigenomic model.

Zinc and iron are essential trace elements indispensable for life in all organisms. However, even when these metals are sufficiently supplied to cells, the disruption of their proper distribution among intracellular organelles can lead to various diseases. ZIP13, a member of the Zrt-, Irt-like protein (ZIP) transporters that is localized to the endoplasmic reticulum (ER) and Golgi apparatus, was originally identified as an intracellular zinc transporter, but was recently shown to also transport iron ions. The dysfunction of ZIP13 disrupts metal distribution in the ER and Golgi apparatus, thereby impairing the homeostasis and function of various tissues. In this review, we summarize current understanding of ZIP13 biology, highlight its dual roles in zinc and iron transport, and discuss future perspectives on how ZIP13 research may provide new insights into the mechanisms underlying diseases associated with dysregulated intracellular metal homeostasis.

This mini-review highlights the emerging agricultural applications of iron oxides, the primary form of iron and one of the most abundant elements on Earth. Rice yield is strongly influenced by soil nitrogen fertility, which is supported by biological nitrogen fixation. Using soil metatranscriptomic analysis and isolation-cultivation experiments, we recently discovered iron-reducing Deltaproteobacteria as the predominant but previously overlooked drivers of nitrogen fixation in paddy soil. As these bacteria utilize Fe3+ as an electron acceptor during anaerobic respiration, we hypothesized that amending soils with Fe3+-rich iron oxides would enhance their nitrogen-fixing activity. Laboratory and field experiments confirmed that applying iron oxides with low crystallinity significantly stimulated the diazotrophic activity of iron-reducing bacteria, enabling reduced nitrogen fertilizer input in rice cultivation, with a reduced nitrogen burden to the environment. Recognition of iron-reducing diazotrophs has opened a new research frontier: using metals, particularly crystalline forms of iron oxides, in sustainable agricultural systems.

Biomineral proteins play critical roles in controlling the polymorph, orientation, and morphology of calcium carbonate (CaCO3) in mollusk shells. Many of these proteins are intrinsically disordered and contain low-complexity regions (IDPs). Structural and functional analyses of IDPs are highly challenging because of their structural flexibility. This mini review highlights recent research elucidating the conformational changes and mineral-binding mechanisms of two representative biomineral proteins from Pinctada fucata: Pif 80, which promotes tablet-shaped aragonite formation in the nacreous layer, and LMP, which facilitates the organization of aragonite nanofibers in the hinge ligament. Using solution nuclear magnetic resonance (NMR) in combination with CaCO3 dispersive particles (DPs), we characterized structural transitions in short repeat peptides derived from these proteins. These findings provide insight into the molecular mechanisms underlying organic-inorganic interactions during biomineralization and offer principles for designing bioinspired materials with controllable mineralization properties.