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The largest living rodent, capybara, can efficiently depolymerize and utilize lignocellulosic biomass through microbial symbiotic mechanisms yet elusive. Herein, we elucidate the microbial community composition, enzymatic systems and metabolic pathways involved in the conversion of dietary fibers into short-chain fatty acids, a main energy source for the host. In this microbiota, the unconventional enzymatic machinery from Fibrobacteres seems to drive cellulose degradation, whereas a diverse set of carbohydrate-active enzymes from Bacteroidetes, organized in polysaccharide utilization loci, are accounted to tackle complex hemicelluloses typically found in gramineous and aquatic plants. Exploring the genetic potential of this community, we discover a glycoside hydrolase family of β-galactosidases (named as GH173), and a carbohydrate-binding module family (named as CBM89) involved in xylan binding that establishes an unprecedented three-dimensional fold among associated modules to carbohydrate-active enzymes. Together, these results demonstrate how the capybara gut microbiota orchestrates the depolymerization and utilization of plant fibers, representing an untapped reservoir of enzymatic mechanisms to overcome the lignocellulose recalcitrance, a central challenge toward a sustainable and bio-based economy.

Xylanolytic enzymes from glycoside hydrolase family 43 (GH43) are involved in the breakdown of hemicellulose, the second most abundant carbohydrate in plants. Here, we kinetically and mechanistically describe the non-reducing-end xylose-releasing exo-oligoxylanase activity and report the crystal structure of a native GH43 Michaelis complex with its substrate prior to hydrolysis. Two distinct calcium-stabilized conformations of the active site xylosyl unit are found, suggesting two alternative catalytic routes. These results are confirmed by QM/MM simulations that unveil the complete hydrolysis mechanism and identify two possible reaction pathways, involving different transition state conformations for the cleavage of xylooligosaccharides. Such catalytic conformational promiscuity in glycosidases is related to the open architecture of the active site and thus might be extended to other exo-acting enzymes. These findings expand the current general model of catalytic mechanism of glycosidases, a main reaction in nature, and impact on our understanding about their interaction with substrates and inhibitors. Family 43 glycoside hydrolases (GH43) are involved in the breakdown of hemicellulose. Functional, structural and computational characterization of a GH43 enzyme, including a snapshot of an active Michaelis complex, reveal the hydrolysis mechanism and suggest two possible reaction pathways.

β-glucosidases play a critical role among the enzymes in enzymatic cocktails designed for plant biomass deconstruction. By catalysing the breakdown of β-1, 4-glycosidic linkages, β-glucosidases produce free fermentable glucose and alleviate the inhibition of other cellulases by cellobiose during saccharification. Despite this benefit, most characterised fungal β-glucosidases show weak activity at high glucose concentrations, limiting enzymatic hydrolysis of plant biomass in industrial settings. In this study, structural analyses combined with site-directed mutagenesis efficiently improved the functional properties of a GH1 β-glucosidase highly expressed by Trichoderma harzianum (ThBgl) under biomass degradation conditions. The tailored enzyme displayed high glucose tolerance levels, confirming that glucose tolerance can be achieved by the substitution of two amino acids that act as gatekeepers, changing active-site accessibility and preventing product inhibition. Furthermore, the enhanced efficiency of the engineered enzyme in terms of the amount of glucose released and ethanol yield was confirmed by saccharification and simultaneous saccharification and fermentation experiments using a wide range of plant biomass feedstocks. Our results not only experimentally confirm the structural basis of glucose tolerance in GH1 β-glucosidases but also demonstrate a strategy to improve technologies for bioethanol production based on enzymatic hydrolysis.

Cancer cells normally develop the ability to rewire or reprogram themselves to become resistant to treatments that were previously effective. Despite progress in understanding drug resistance, knowledge gaps remain regarding the underlying biological causes of drug resistance and the design of cancer treatments to overcome it. So, resistance acquisition remains a major problem in cancer treatment. Targeted therapeutics are considered the next generation of cancer therapy because they overcome many limitations of traditional treatments. Numerous tumor cells overexpress several receptors that have a high binding affinity for hyaluronic acid (HA), while they are poorly expressed in normal body cells. HA and its derivatives have the advantage of being biocompatible and biodegradable and may be conjugated with a variety of drugs and drug carriers for developing various formulations as anticancer therapies such as micelles, nanogels, and inorganic nanoparticles. Due to their stability in blood circulation and predictable delivery patterns, enhanced tumor-selective drug accumulation, and decreased toxicity to normal tissues, tumor-targeting nanomaterial-based drug delivery systems have been shown to represent an efficacious approach for the treatment of cancer. In this review, we aim to provide an overview of some in vitro and in vivo studies related to the potential of HA as a ligand to develop targeted nanovehicles for future biomedical applications in cancer treatment.

Bilirubin, a breakdown product of heme, is normally glucuronidated and excreted by the liver into bile. Failure of this system can lead to a buildup of conjugated bilirubin in the blood, resulting in jaundice. Hyperbilirubinemia is an important clinical sign that needs to be investigated under a stepwise evaluation. Inherited non‐hemolytic conjugated hyperbilirubinemic conditions include Dubin‐Johnson syndrome (caused by mutations affecting ABCC2 gene) and Rotor syndrome (caused by the simultaneous presence of mutations in SLCO1B1 and SLCO1B3 genes). Although classically viewed as benign conditions requiring no treatment, they lately gained an increased interest since recent studies suggested that mutations in the responsible genes leading to hyperbilirubinemia, as well as minor genetic variants, may result in an increased susceptibility to drug toxicity. This article provides a comprehensive review on the pathophysiology of Dubin‐Johnson and Rotor syndromes, presenting the current knowledge concerning the molecular details and basis of these conditions.

Xyloglucans are highly substituted and recalcitrant polysaccharides found in the primary cell walls of vascular plants, acting as a barrier against pathogens. Here, we reveal that the diverse and economically relevant Xanthomonas bacteria are endowed with a xyloglucan depolymerization machinery that is linked to pathogenesis. Using the citrus canker pathogen as a model organism, we show that this system encompasses distinctive glycoside hydrolases, a modular xyloglucan acetylesterase and specific membrane transporters, demonstrating that plant-associated bacteria employ distinct molecular strategies from commensal gut bacteria to cope with xyloglucans. Notably, the sugars released by this system elicit the expression of several key virulence factors, including the type III secretion system, a membrane-embedded apparatus to deliver effector proteins into the host cells. Together, these findings shed light on the molecular mechanisms underpinning the intricate enzymatic machinery of Xanthomonas to depolymerize xyloglucans and uncover a role for this system in signaling pathways driving pathogenesis. Xyloglucans are polysaccharides found in plant cell walls. Here, the authors describe the xyloglucan depolymerization machinery of phytopathogenic Xanthomonas bacteria, and show that sugars released by this system induce the expression of key virulence factors driving pathogenesis.

Office workers are exposed to a range of occupational health risks, including prolonged sedentary behaviour, postural load, elevated heart rate, and noise, yet objective and continuous monitoring of these risk factors in workplace settings remains uncommon. This study aimed to co-design occupational health visualisations based on smartphone and smartwatch data, through a multi-stakeholder group of office workers and occupational health professionals. A generative co-design framework was applied, comprising a pre-design phase with a field study and questionnaire, a structured multi-stakeholder workshop, and a follow-up evaluation session. Thematic analysis of the workshop transcript yielded 17 occupational health themes, which were subsequently assessed for technical feasibility relative to the available sensing platform. Of the 27 discrete visualisation elements proposed across both groups, the majority were classified as directly addressable using smartphone and smartwatch sensor data. Visualisations covering physical activity, heart rate, environmental noise exposure, and postural load were implemented in Python using real-world data collected from office workers. The follow-up session provided qualitative confirmation that the developed visualisations were interpretable and aligned with the stakeholder expectations. The generative co-design framework proved well-suited to the occupational health visualisation context, enabling structured translation of stakeholder requirements into technically feasible and interpretable visualisation outputs.

Disulfide bonds are a key post-translational modification involved in protein folding, structural stability, and functional regulation. Here, we demonstrate that a glycoside hydrolase from the GH2 family undergoes reversible redox regulation through an intramolecular disulfide bond. The enzyme is inactive in its oxidized state and becomes active when reduced through a fully reversible process. Under oxidative conditions, multiple crystallographic and cryo-EM structures revealed a pronounced structural disorder in the active site, most prominent in the regulatory and catalytic loops, which disrupts the substrate binding site and, remarkably, the configuration of the acidic catalytic residues. Conversely, a high-resolution cryo-EM structure of the active (reduced) state unveiled a well-ordered active site with catalytic residues properly positioned for a classical Koshland retaining mechanism. This reversible order-disorder process based on a disulfide switch provides a mechanism for redox-dependent control of glycoside hydrolase activity, with potential implications for carbohydrate metabolism, microbial adaptation and biotechnological applications. Disulfide bonds act as dynamic redox switches that modulate protein function. Here, the authors reveal a glycoside hydrolase in which reversible disulfide formation remodels the active site to control catalysis.

Fatty acid peroxygenases have emerged as promising biocatalysts for hydrocarbon biosynthesis due to their ability to perform C-C scission, producing olefins - key building blocks for sustainable materials and fuels. These enzymes operate through non-canonical and complex mechanisms that yield a bifurcated chemoselectivity between hydroxylation and decarboxylation. In this study, we elucidate structural features in P450 decarboxylases that enable the catalysis of unsaturated substrates, expanding the mechanistic pathways for decarboxylation reaction. Combining X-ray crystallography, molecular dynamics simulations, and machine learning, we have identified intricate molecular rearrangements within the active site that enable the Cβ atom of the substrate to approach the heme iron, thereby promoting oleate decarboxylation. Furthermore, we demonstrate that the absence of the aromatic residue in the Phe-His-Arg triad preserves chemoselectivity for alkenes, providing a distinct perspective on the molecular determinants of decarboxylation activity. Ultimately, these findings enable the sustainable production of biohydrocarbons from industrial feedstocks. This study uncovers a distinct mechanistic pathway for bio-olefin production from industrial feedstocks by fatty acid peroxygenases through unconventional decarboxylation, paving the way for sustainable bio-based hydrocarbon production.