Abstract In methionine biosynthesis, homoserine O-acylation is catalyzed by MetX together with its regulatory protein, MetW, in some bacteria. MetW interacts with MetX and regulates its enzymatic activity. Although this interaction and regulation are likely indispensable for efficient methionine biosynthesis, the specific regions of MetW crucial for these functions remain unidentified. Here, we characterize this system using MetW and MetX from Pseudomonas aeruginosa (PaMetW and PaMetX, respectively). We found that the N-terminal region of PaMetW and the C-terminal region of PaMetX are critical for their interaction. Additionally, the C-terminal region of PaMetW is essential for enhancing homoserine O-succinylation activity. Structural models predict that the PaMetW N-terminal region is located near the PaMetX C-terminal region and that the two terminal regions form an intermolecular parallel β-sheet. These results suggest that the N- and C-terminal regions of PaMetW play important roles in the interaction with PaMetX and enhancement of its enzymatic activity, respectively.
Abstract Equisetum arvense polysaccharides (EAP) represent promising functional nutrients with anti-obesity properties. Using a high fat diet (HFD)-induced obese aging mouse model, this study investigated the anti-obesity efficacy and underlying mechanisms of EAP from the perspective of intestinal microbiota and systemic metabolic networks. Histological assays, biochemical measurements, 16S rRNA gene sequencing, and untargeted metabolomics were adopted to comprehensively detect inflammatory factors, oxidative stress markers, lipid profiles, intestinal flora, and metabolites. The results demonstrated that EAP reduced body weight, alleviated lipid accumulation in hepatic and epididymal adipose tissues, restored lipid homeostasis, recovered the gut microbial diversity impaired by high-fat feeding, and modulated intestinal metabolites. In conclusion, EAP may represent a potential functional dietary ingredient for obesity management.
Abstract Plant growth-promoting bacteria are gaining significant attention as promising biofertilizers. However, the inconsistency between in vitro plant growth-promoting traits and actual field performance remains a challenge, driven partly by a limited understanding of in situ colonization. This study characterized the colonization patterns of Citrobacter sedlakii CESi7, a novel plant growth-promoting bacterium, isolated from oil palm waste compost, during Brassica rapa cultivation. The in situ behavior of CESi7 was observed in both sterilized medium and non-sterilized soil using fluorescence in situ hybridization with a strain-targeting probe. The results revealed that CESi7 can establish both epiphytic and endophytic populations that transiently colonize roots. In a sterilized medium, CESi7 was widely distributed throughout the root tissues. Conversely, in non-sterilized soil, the bacterium formed dense aggregates specifically at the root tips. This study provides direct microscopic evidence of the colonization strategy of CESi7, offering crucial insights for its development as an effective biofertilizer.
Abstract During extracellular glutamate overproduction in Corynebacterium glutamicum, an increase in metabolic flux toward glutamate synthesis occurs without an increase in the transcriptional or translational levels of relevant enzymes, suggesting the involvement of unprecedented post-translational regulatory mechanisms. Here, we investigated the relationship of enzyme condensation with the metabolic shifts that lead to glutamate overproduction. We systematically analyzed the subcellular localization of enzymes involved in glutamate overproduction using fluorescent protein tagging to identify enzyme condensates in C. glutamicum. Our analyses revealed punctate localization, suggesting condensate formation for glyceraldehyde 3-phosphate dehydrogenase, enolase, pyruvate carboxylase, citrate synthase, pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase (ODH) complexes, and the intrinsic ODH inhibitor OdhI. Notably, enolase frequently formed condensates under glutamate-producing conditions, without changes in protein abundance. Our findings provide key insights into the intracellular dynamics of central carbon metabolic enzymes and offer a novel perspective on the mechanisms underlying glutamate overproduction in C. glutamicum.
Abstract We examined the effects of fibroblast growth factor (FGF)21 on re-epithelialization during wound healing. Wound closure and re-epithelialization were significantly delayed in FGF21 KO mice. For the in vitro assay, the FGF21-induced keratinocyte migration was reversed by extracellular signal-regulated kinase (ERK) inhibitors. These results suggest that FGF21 promotes re-epithelialization via the ERK pathways.
