International Journal of Biological Macromolecules最新文献

Thiocyanate dehydrogenase (TcDH) plays a pivotal role in the decomposition of thiocyanate in some sulfur-oxidizing bacteria. Here we report the assembly mechanism of the unique three-copper center (Cu1, Cu2 and Cu3) of TcDH in vitro. Using EPR, we established the sequence of copper incorporation into the active center: copper ions are first incorporated in parallel into Cu1 and Cu2 sites, and finally into Cu3 site. TcDH shows high affinities for both Cu(II) (K_D values for three sites range from 2.0 × 10^-12 to 3.8 × 10^-17 M) and Cu(I) (average K_D values of three sites are 1.0 × 10^-13 M). The process of assembling the TcDH copper center, and thus acquiring the enzyme catalytic activity, is kinetically fast with Cu(I) (~min) ions but extremely slow with Cu(II) (~hours), which correlates with the rate of Cu(II) incorporation into the protein. The inactivation of TcDH due to removal of copper from the active site is kinetically slow due to the low accessibility of the copper center. This phenomenon appears to act as an adaptation mechanism that prevents unwanted loss of copper in vivo due to interaction with the higher-affinity copper binders. Based on the slow incorporation of Cu(II) into the TcDH active center in vitro, we suggest that it is Cu(I) that is involved in the process of assembling of TcDH copper center in vivo.

Inorganic pyrophosphatases (PPases) catalyze the hydrolysis of inorganic pyrophosphate (PPi) into orthophosphate (Pi) in the presence of magnesium ions, thereby driving diverse biosynthetic processes. They have been widely applied in in vitro transcription, PCR, and sequencing platforms. Mechanism of family I PPases has been well established, experimental validation of the functional indispensability of conserved catalytic residues in thermophilic archaeal PPases remains limited. In this study, we characterized a thermostable PPase from the archaeon Thermococcus litoralis (TliPPase) through enzymatic assays, phylogenetic analysis, structural modeling, and site-directed mutagenesis. TliPPase retained robust activity under alkaline and high-temperature conditions and effectively relieved PPi accumulation-induced inhibition in PCR systems. Mutational analysis demonstrated that Tyr56, Asp71, and Asp103 are indispensable for enzymatic activity, consistent with their established functional importance in family I PPases. Together, these findings validate the conserved catalytic architecture of a thermophilic PPase and provide a foundation for future studies and engineering of thermophilic PPases.

Diabetes is a metabolic disorder that significantly impacts human health, with 25% of patients suffering from diabetic ulcers. Chronic persistent inflammation is one of the primary factors impeding wound healing in diabetes. As a recently identified adipocytokine, omentin-1 (also known as intelectin-1, ITLN1) demonstrates significant expression levels in the omentum, subcutaneous adipose tissue, and vascular endothelium, exhibiting potent anti-inflammatory characteristics. Emerging evidence indicates that this adipokine plays a crucial protective role in multiple inflammatory disorders, particularly in the pathogenesis of atherosclerosis, osteoarthritis, and inflammatory bowel disease. However, its therapeutic potential in diabetic wound healing remains unclear. Our experimental data demonstrated a marked downregulation of omentin-1 expression in cutaneous tissues obtained from the Streptozotocin (STZ)-induced diabetic murine model. Local administration of recombinant omentin-1 improved efferocytosis in impaired macrophages within the wound bed and promoted macrophage phenotypic switching to the reparative M2 phenotype, thereby attenuating inflammatory responses and accelerating wound healing in diabetic mice. Further mechanistic studies revealed that omentin-1 enhanced the expression of the key efferocytosis receptor MERTK (mer proto-oncogene tyrosine kinase) in diabetic wounds and facilitated macrophage efferocytosis through modulation of the downstream SRC/PI3K/Akt signaling cascade. Additionally, omentin-1 facilitated the polarization of macrophages toward the M2 phenotype and attenuated the inflammatory responses induced by lipopolysaccharide (LPS). The findings of this study indicate that omentin-1 suggests its potential as a candidate for developing novel adjunctive therapies for chronic non-healing diabetic wounds.

Fish epizootic ulcerative syndrome (EUS) caused by resistant strains of Pseudomonas aeruginosa (P. aeruginosa) presents a significant challenge. The present research objective was to synthesize dual biopolymer engineered aluminium ferrite (AlFeO₃) nanostructures (NSs) doped with polyacrylic acid (PAA), as stabilizing agent, and chitosan, bioactive dopant, (CS/PAA-AlFeO₃) to address the catalytic reduction of rhodamine B (RhB) dye and resistance challenge in Ctenopharyngodon idella (Grass carp) affected by EUS as not previously reported for AlFeO₃ based systems. The maximum catalytic degradation rates towards RhB in basic and neutral media were 76.1% and 82.7% for PAA-AlFeO₃, respectively. For antibacterial assessment, the impeded tissues from the gills and pancreas of clinically affected Grass carp, averaging 120 ± 2 g in weight and 20 ± 3 cm in length, were retrieved and inoculated into nutrient broth following overnight incubation. The susceptibility of unique isolates to specific antibiotics was assessed using the disc diffusion method on Mueller-Hinton agar. The in-vitro antibacterial potential of the synthesized CS/PAA-AlFeO₃ NSs was assessed at concentrations of 500 μg/50 μl and 1000 μg/50 μl against resistant P. aeruginosa utilizing the agar well diffusion method. The synthesized 4 wt% CS/PAA-AlFeO₃ NSs demonstrated significant (P < 0.05) bactericidal efficacy, with an inhibition zone of 5.15 ± 0.02 mm against resistant P. aeruginosa. Molecular docking elucidated the bactericidal mechanism of CS/PAA-AlFeO₃ by emphasizing their inhibitory effect on DNA gyrase in P. aeruginosa. The outcomes suggested that synthesized NSs are promising candidates, warranting further investigations to manage resistant bacterial infections in aquaculture and to reduce RhB.

The incidence of obesity and colorectal cancer (CRC) is rising annually. Obesity, particularly visceral obesity, poses a serious health threat, yet the association of obesity with CRC progression, as well as the role of visceral obesity, remains debated. This study analyzed 394 CRC patients and revealed that both high body mass index (BMI) and visceral fat area (VFA) correlated with poor prognosis, with VFA being an independent risk factor. RNA sequencing and TCGA analysis showed that methyltransferase-like protein 27 (METTL27) was overexpressed in CRC tissues from patients with obesity (especially visceral obesity), and was associated with poor prognosis. Mechanistically, METTL27 activates the PPARD/CPT1A axis in an FABP5-dependent manner to promote CRC cell proliferation, migration, and invasion. Lipid metabolomics identified visceral obesity-specific fatty acids. In vitro, treatment with adipose tissue-conditioned medium (ACM) or visceral obesity-associated fatty acids induced lipid droplets accumulation and enhanced METTL27/FABP5/PPARD/CPT1A signaling, exacerbating CRC malignancy. This study is the first to elucidate METTL27's biological function, identifying it as a key upstream partner of FABP5, delineating its regulation of the FABP5/PPARD/CPT1A axis and its role in driving CRC progression in the context of visceral obesity, thereby providing new directions for therapeutic targets in CRC patients with visceral obesity.

Camellia oleifera Abel (commonly abbreviated as COA), a species of the Camellia genus, is a woody oil-bearing tree endemic to China. It has been cultivated and utilized in China for over 2300 years. COA possesses both medicinal and edible value. In recent years, most of the biological research on COA has focused on the development and breeding of new varieties, and the research on economic value has focused on the extraction of high-quality camellia oil. Research on Camellia oleifera Abel polysaccharides (COAPs) remains relatively limited. This paper systematically evaluates the composition, extraction methods, biological activity, and application prospects of COAPs to enhance their quality, stability, safety, and reliability. It specifically examines the impact of different extraction processes on polysaccharide structure. Furthermore, it elucidates the intrinsic relationship between molecular structure and biological function. By summarizing the structure-activity relationship of polysaccharides from different parts of COA, this review lays a scientific foundation for their function-oriented production and application.

Hydrogels are promising candidates for soft, skin-conformable strain sensors in wearable electronics and personalized health monitoring devices, yet simultaneously achieving high mechanical robustness, stable conductivity, strong adhesion, and antibacterial activity remains challenging. Here, we report a multifunctional poly(vinyl alcohol) (PVA) hydrogel strain sensor reinforced by polydopamine/silver-decorated cellulose nanofibrils (PDA@CNF-Ag) prepared via freeze-thaw process. The synthesized PDA@CNF-Ag is uniformly dispersed within the PVA matrix, forming a mechanically percolated three-dimensional network that reinforces the hydrogel and establishes efficient conductive pathways. Consequently, the PVA-PDA/CNF-Ag-0.5 hydrogel exhibits a conductivity of 17 mS·m^-1, a stretchability of 536%, and a tensile strength of 60 kPa. As a strain sensor, it shows high sensitivity (GF = 2.1), stable signal responses over 300 cycles, and reliable detection of both large and subtle human motions, together with strong, repeatable adhesion and robust antibacterial activity. This bio-based conductive hydrogel offers a robust platform for human-motion monitoring in next-generation wearable electronics.

Cryogels are macroporous polymeric materials with significant potential in biomedical and environmental applications due to their elasticity, interconnected porosity, and structural resilience. However, cryogels composed solely of chitosan, a biopolymer valued for its biocompatibility, biodegradability, and antibacterial properties, suffer from mechanical instability. To address this limitation, we synthesized and characterized cryogels based on chitosan and its blends with gelatin (CH-G) and compared the results with those of chitosan-silk fibroin (CH-SF) cryogel and chitosan‑sodium alginate (CH-SA) cryogel. Cryogel particles were prepared via the inverse Leidenfrost (iLF) effect, and glutaraldehyde was employed as a cross-linking agent. By combining chitosan's structural backbone with gelatin's flexibility and biocompatibility, and stabilizing the network using glutaraldehyde crosslinking, we achieved cryogels with enhanced elasticity and a relatively high surface area compared to other cryogel systems (2.03 m²/g). Scanning electron microscopy (SEM) revealed a compact fibrous interconnected network, and nitrogen adsorption isotherms further confirmed the mesoporosity. Overall, these results demonstrate how polymer blending can be utilized to enhance the mechanical properties of cryogels for targeted functional applications.

Iron (Fe) toxicity is a major abiotic stress that compromises crop productivity and quality, yet the underlying molecular mechanisms in medicinal plants like ginseng (Panax ginseng C.A. Meyer) remain poorly elucidated. Here, the core transcription factor PgbHLH149 was identified as being up-regulated by exogenous silicon (Si) and acted as a key regulatory factor in response to Fe toxicity in ginseng. Overexpression of PgbHLH149 in both Arabidopsis and ginseng significantly enhanced Fe stress tolerance through a dual mechanism: 1) modulating elemental homeostasis by reducing Fe accumulation and promoting the uptake of beneficial elements (Ca, Mg, Si); and 2) activating the antioxidant system, thereby increasing enzyme activities (SOD, POD, CAT, APX) and diminishing reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Furthermore, yeast two-hybrid screening revealed that PgbHLH149 interacts with a serine/threonine protein kinase (STPK1) and a fellow transcription factor (bHLH74). And bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the in vivo interaction between PgbHLH149 and STPK1 in the nucleus. LC-MS/MS analysis further identified phosphorylation of PgbHLH149 at serine-133 by STPK1, indicating post-translational regulation. Under silicon conditions, PgbHLH149 forms a regulatory "STPK1-PgbHLH149-bHLH74" module, which may achieve Fe detoxification by synchronizing elemental homeostasis and antioxidant defense system. Our findings unveiled a novel transcriptional regulatory network for Fe stress tolerance in ginseng, providing crucial molecular targets for breeding rust-resistant varieties and advancing soil remediation strategies in Fe-contaminated soils.