Reducing the uncertainty in estimating soil microbial-derived carbon storage.

Soil organic carbon (SOC) is the largest carbon pool in terrestrial ecosystems and plays a crucial role in mitigating climate change and enhancing soil productivity. Microbial-derived carbon (MDC) is the main component of the persistent SOC pool. However, current formulas used to estimate the proportional contribution of MDC are plagued by uncertainties due to limited sample sizes and the neglect of bacterial group composition effects. Here, we compiled the comprehensive global dataset and employed machine learning approaches to refine our quantitative understanding of MDC contributions to total carbon storage. Our efforts resulted in a reduction in the relative standard errors in prevailing estimations by an average of 71% and minimized the effect of global variations in bacterial group compositions on estimating MDC. Our estimation indicates that MDC contributes approximately 758 Pg, representing approximately 40% of the global soil carbon stock. Our study updated the formulas of MDC estimation with improving the accuracy and preserving simplicity and practicality. Given the unique biochemistry and functioning of the MDC pool, our study has direct implications for modeling efforts and predicting the land-atmosphere carbon balance under current and future climate scenarios.

SIRT2 promotes base excision repair by transcriptionally activating OGG1 in an ATM/ATR-dependent manner.

Sirtuin 2 (SIRT2) regulates the maintenance of genome integrity by targeting pathways of DNA damage response and homologous recombination repair. However, whether and how SIRT2 promotes base excision repair (BER) remain to be determined. Here, we found that independent of its catalytic activity SIRT2 interacted with the critical glycosylase OGG1 to promote OGG1 recruitment to its own promoter upon oxidative stress, thereby enhancing OGG1 promoter activity and increasing BER efficiency. Further studies revealed that SIRT2 was phosphorylated on S46 and S53 by ATM/ATR upon oxidative stress, and SIRT2 phosphorylation enhanced the SIRT2-OGG1 interaction and mediated the stimulatory effect of SIRT2 on OGG1 promoter activity. We also characterized 37 cancer-derived SIRT2 mutants and found that 5 exhibited the loss of the stimulatory effects on OGG1 transcription. Together, our data reveal that SIRT2 acts as a tumor suppressor by promoting OGG1 transcription and increasing BER efficiency in an ATM/ATR-dependent manner.

Nek7 Protects Telomeres from Oxidative DNA Damage by Phosphorylation and Stabilization of TRF1.

Telomeric repeat binding factor 1 (TRF1) is essential to the maintenance of telomere chromatin structure and integrity. However, how telomere integrity is maintained, especially in response to damage, remains poorly understood. Here, we identify Nek7, a member of the Never in Mitosis Gene A (NIMA) kinase family, as a regulator of telomere integrity. Nek7 is recruited to telomeres and stabilizes TRF1 at telomeres after damage in an ATM activation-dependent manner. Nek7 deficiency leads to telomere aberrations, long-lasting γH2AX and 53BP1 foci, and augmented cell death upon oxidative telomeric DNA damage. Mechanistically, Nek7 interacts with and phosphorylates TRF1 on Ser114, which prevents TRF1 from binding to Fbx4, an Skp1-Cul1-F box E3 ligase subunit, thereby alleviating proteasomal degradation of TRF1, leading to a stable association of TRF1 with Tin2 to form a shelterin complex. Our data reveal a mechanism of efficient protection of telomeres from damage through Nek7-dependent stabilization of TRF1.

Palmitoylation is required for Sept8-204 and Sept5 to form vesicle-like structure and colocalize with synaptophysin.

Sept8 is a vesicle associated protein and there are two typical transcriptional variants (Sept8-204 and Sept8-201) expressed in mice brain. Interestingly, the coexpression of Sept8-204/Sept5 induces the formation of small sized vesicle-like structure, while that of the Sept8-201/Sept5 produces large puncta. Sept8 is previously shown to be palmitoylated. Here it was further revealed that protein palmitoylation is required for Sept8-204/Sept5 to maintain small sized vesicle-like structure and colocalize with synaptophysin, since either the expression of nonpalmitoylated Sept8-204 mutant (Sept8-204-3CA) or inhibiting Sept8-204 palmitoylation by 2-BP with Sept5 produces large puncta, which barely colocalizes with synaptophysin (SYP). Moreover, it was shown that the dynamic palmitoylation of Sept8-204 is controlled by ZDHHC17 and PPT1, loss of ZDHHC17 decreases Sept8-204 palmitoylation and induces large puncta, while loss of PPT1 increases Sept8-204 palmitoylation and induces small sized vesicle-like structure. Together, these findings suggest that palmitoylation is essential for the maintenance of the small sized vesicle-like structure for Sept8-204/Sept5, and may hint their important roles in synaptic functions.

PLK4 deubiquitination by Spata2-CYLD suppresses NEK7-mediated NLRP3 inflammasome activation at the centrosome.

The innate immune sensor NLRP3 assembles an inflammasome complex with NEK7 and ASC to activate caspase-1 and drive the maturation of proinflammatory cytokines IL-1ß and IL-18. NLRP3 inflammasome activity must be tightly controlled, as its over-activation is involved in the pathogenesis of inflammatory diseases. Here, we show that NLRP3 inflammasome activation is suppressed by a centrosomal protein Spata2. Spata2 deficiency enhances NLRP3 inflammasome activity both in the macrophages and in an animal model of peritonitis. Mechanistically, Spata2 recruits the deubiquitinase CYLD to the centrosome for deubiquitination of polo-like kinase 4 (PLK4), the master regulator of centrosome duplication. Deubiquitination of PLK4 facilitates its binding to and phosphorylation of NEK7 at Ser204. NEK7 phosphorylation in turn attenuates NEK7 and NLRP3 interaction, which is required for NLRP3 inflammasome activation. Pharmacological or shRNA-mediated inhibition of PLK4, or mutation of the NEK7 Ser204 phosphorylation site, augments NEK7 interaction with NLRP3 and causes increased NLRP3 inflammasome activation. Our study unravels a novel centrosomal regulatory pathway of inflammasome activation and may provide new therapeutic targets for the treatment of NLRP3-associated inflammatory diseases.

Photoswitchable Metal-Organic Framework as a Smart Nanoreactor for Ultraviolet Light-Enhanced Confined Catalysis.

Confined catalysis, where a chemical reaction is accommodated within a nanoscale host, provides an effective approach to control the pathways and outcomes of catalytic transformations. However, the confinement effect is typically limited to a fixed rate and/or selectivity once the nanohost is chosen. Herein, we developed a photoresponsive metal-organic framework (MOF) as a "smart" nanohost to realize ultraviolet (UV) light-enhanced confined catalysis of Knoevenagel condensation. Photoresponsive MOF of Zn-ADA was thus prepared by solvothermal strategy where azobenzene-4,4'-dicarboxylic acid (ADA) was used as the photoactive linker to coordinate with zinc nitrate. Characterization results suggested that UV light could decrease the pore size of Zn-ADA due to suppressed bending of the azobenzene-containing ADA linker in Zn-ADA. It enforced the proximity between substrates and catalytic groups within the confined space, and thus enhanced the confinement effect on Knoevenagel condensation. The UV light-enhanced confined catalysis enabled the translation of light stimulus into chemical signal, which may open up new control on the basis of the specific reaction field.

Nuclear cGAS suppresses DNA repair and promotes tumorigenesis.

Accurate repair of DNA double-stranded breaks by homologous recombination preserves genome integrity and inhibits tumorigenesis. Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that activates innate immunity by initiating the STING-IRF3-type I IFN signalling cascade1,2. Recognition of ruptured micronuclei by cGAS links genome instability to the innate immune response3,4, but the potential involvement of cGAS in DNA repair remains unknown. Here we demonstrate that cGAS inhibits homologous recombination in mouse and human models. DNA damage induces nuclear translocation of cGAS in a manner that is dependent on importin-α, and the phosphorylation of cGAS at tyrosine 215-mediated by B-lymphoid tyrosine kinase-facilitates the cytosolic retention of cGAS. In the nucleus, cGAS is recruited to double-stranded breaks and interacts with PARP1 via poly(ADP-ribose). The cGAS-PARP1 interaction impedes the formation of the PARP1-Timeless complex, and thereby suppresses homologous recombination. We show that knockdown of cGAS suppresses DNA damage and inhibits tumour growth both in vitro and in vivo. We conclude that nuclear cGAS suppresses homologous-recombination-mediated repair and promotes tumour growth, and that cGAS therefore represents a potential target for cancer prevention and therapy.

Enhanced remediation of real agricultural runoff in surface-flow constructed wetlands by coupling composite substrate-packed bio-balls, submerged plants and functional bacteria: Performance and mechanisms.

Import of agricultural runoff containing nutrients considerably contributes to eutrophication of receiving water bodies. Surface-flow constructed wetlands (SFCWs) are commonly applied for agricultural runoff purification, but the performance is usually unsatisfactory. In this study, suspended bio-balls filled with zeolite and iron-carbon (Fe-C) composite substrates, submerged macrophyte (Ceratophyllum demersum) and functional denitrifying bacteria were collectively added into SFCW microcosms to enhance the remediation efficiency for real agricultural runoff with high nutrient concentrations and low content of bioavailable organic matter. The bio-ball added SFCWs achieved notably higher pollutant removal efficiencies (21.1%, 80.2% and 47.5% for chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP), respectively) than the control (COD: 6.9%, TN: 64.4%, TP: 27.9%), because of the versatile functions of filling materials for pollutant removal. C. demersum plantation (COD: 44.2%, TN: 82.8% and TP: 53.7%) and functional bacteria inoculation (COD: 51.8%, TN: 85.8% and TP: 55.1%) further enhanced the efficiency of the SFCWs for agricultural runoff remediation. Bio-ball addition and C. demersum plantation significantly increased the humification degree and reduced the molecular weight of dissolved organic matter (DOM) in the agricultural runoff. Moreover, the two intensification measures also notably reduced organic and nitrogen contents in the wetland sediment. Remarkable distinction in bacterial community distribution patterns was observed in the SFCW sediment and filling substrates in bio-balls. Keystone genera including Clostridium_sensu_stricto_1 and Bacillus in the zeolite, Sphingomonas and Exiguobacterium in the Fe-C substrates and Sediminibacterium in the sediment might be critical for agricultural runoff remediation in the SFCW microcosms. The study highlights a high potential of the intensified SFCWs by these coupling measures for agricultural runoff remediation.

Clinical Diagnostic Value of Shear-Wave Elastography in Detecting Malignant Nipple Retraction.

OBJECTIVES: In recent years, the use of shear-wave elastography (SWE) as a diagnostic tool for detecting malignant breast lesions has shown promising results. This study aims to determine the clinical diagnostic value of SWE in detecting malignant nipple retraction. METHODS: Both US and SWE (Philips EPIQ7 system) were performed for 41 consecutive patients with nipple retraction (56 nipples). The mean, median, and maximum tissue elasticity values (in kilopascals) were determined for each nipple by using SWE. The sensitivity, specificity, and overall accuracy of each measurement was determined by using the surgical pathology results or clinical diagnosis as the gold standard. RESULTS: Of the 56 retracted nipples, 32 were due to benign lesions, and 24 were due to malignant lesions. No significant differences in dimensions or echo features were found between the benign and malignant groups. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the color Doppler flow imaging (CDFI) pattern were 63.89% (23/36), 95% (19/20), 95.83 (23/24), 59.38 (19/32), and 75% (42/56), respectively; the corresponding values for median elasticity on SWE were 88.46% (23/26), 96.67% (29/30), 95.83 (23/24), 90.63 (29/32), and 92.85 (52/56), respectively. CONCLUSIONS: The addition of SWE to conventional US could help differentiate benign from malignant lesions associated with nipple retraction.

The care needs of the elderly in China's elderly care institutions: a narrative synthesis.

China's population is ageing, affecting trends in social development and basic national conditions. More attention must be paid to the lack of care needs assessments for the elderly in China's pension institutions. This paper discusses a systematic evaluation of the care needs of the elderly in China's elderly care institutions. Literature was collected and synthesized after a search of the Web of Science, PubMed, and other databases for works published up to August 2021. Relevant content is proposed, including the name of the first author, publication date, study area, and sample size. Exactly 18 articles were included in the literature, documents that reported on a total of 7277 elderly people. The results showed a combined demand rate of primary care needs ≥50%. The top five needs included mental/psychological (76%), tranquillity/care (73%), living/environmental (71%), medical treatment (64%), and preventive healthcare (64%). The combined demand rate of secondary care needs was ≥50%. The top five needs included 79% for room/laundry/cleaning, 77% for psychological comfort and nursing, 73% for end-of-life care, 70% for disease diagnosis and treatment, and 69% for physical examination. The health needs of older people are diverse and focus mainly on mental/psychological, tranquility/care, living/environmental (71%), pharmacotherapy, and preventive healthcare.

Improving Interface Matching in MOF-on-MOF S-Scheme Heterojunction through π-π Conjugation for Boosting Photoelectric Response.

Accelerating the migration of interfacial carriers in a heterojunction is of paramount importance for driving high-performance photoelectric responses. However, the inferior contact area and large resistance at the interface limit the eventual photoelectric performance. Herein, we fabricated an S-scheme heterojunction involving a 2D/2D dual-metalloporphyrin metal-organic framework with metal-center-regulated CuTCPP(Cu)/CuTCPP(Fe) through electrostatic self-assembly. The ultrathin nanosheet-like architectures reduce the carrier migration distance, while the similar porphyrin backbones promote reasonable interface matching through π-π conjugation, thereby inhibiting the recombination of photogenerated carriers. Furthermore, the metal-center-regulated S-scheme band alignments create a giant built-in electric field, which provides a huge driving force for efficient carrier separation and migration. Coupling with the biomimetic catalytic activity of CuTCPP(Fe), the resultant heterojunction was utilized to construct photoelectrochemical uric acid biosensors. This work provides a general strategy to enhance photoelectric responses by engineering the interfacial structure of heterojunctions.

Pollution area identification, receptor model-oriented sources and probabilistic health hazards to prioritize control measures for heavy metal management in soil.

Identifying the primary source of heavy metals (HMs) pollution and the key pollutants is crucial for safeguarding eco-health and managing risks in industrial vicinity. For this purpose, this investigation was carried out to investigate the pollution area identification with soil static environmental capacity (QI), receptor model-oriented critical sources, and Monte Carlo simulation (MCS) based probabilistic environmental and human health hazards associated with HMs in agricultural soils of Narayanganj, Bangladesh. The average concentration of Cr, Ni, Cu, Cd, Pb, Co, Zn, and Mn were 98.67, 63.41, 37.39, 1.28, 23.93, 14.48, 125.08, and 467.45 mg/kg, respectively. The geoaccumulation index identified Cd as the dominant metal, indicating heavy to extreme contamination in soils. The QI revealed that over 99% of the areas were polluted for Ni and Cd with less uncertain regions whereas Cr showed a significant portion of areas with uncertain pollution status. The positive matrix factorization (PMF) model identified three major sources: agricultural (29%), vehicular emissions (25%), and industrial (46%). The probabilistic assessment of health hazards indicated that both carcinogenic and non-carcinogenic risks for adult male, adult female, and children were deemed unacceptable. Moreover, children faced a higher health hazard compared to adults. For adult male, adult female, and children, industrial operations contributed 48.4%, 42.7%, and 71.2% of the carcinogenic risks, respectively and these risks were associated with Ni and Cr as the main pollutants of concern. The study emphasizes valuable scientific insights for environmental managers to tackle soil pollution from HMs by effectively managing anthropogenic sources. It could aid in devising strategies for environmental remediation engineering and refining industry standards.

Anisotropic Dual S-Scheme Heterojunctions Mimic Natural Photosynthetic System for Boosting Photoelectric Response.

The design of heterojunctions that mimic natural photosynthetic systems holds great promise for enhancing photoelectric response. However, the limited interfacial space charge layer (SCL) often fails to provide sufficient driving force for the directional migration of inner charge carriers. Drawing inspiration from the electron transport chain (ETC) in natural photosynthesis system, we developed a novel anisotropic dual S-scheme heterojunction artificial photosynthetic system composed of Bi2O3-BiOBr-AgI for the first time, with Bi2O3 and AgI selectively distributed along the bicrystal facets of BiOBr. Compared to traditional semiconductors, the anisotropic carrier migration in BiOBr overcomes the recombination resulting from thermodynamic diffusion, thereby establishing a potential ETC for the directional migration of inner charge carriers. Importantly, this pioneering bioinspired design overcomes the limitations imposed by the limited distribution of SCL in heterojunctions, resulting in a remarkable 55-fold enhancement in photoelectric performance. Leveraging the etching of thiols on Ag-based materials, this dual S-scheme heterojunction is further employed in the construction of photoelectrochemical sensors for the detection of acetylcholinesterase and organophosphorus pesticides.

Horseradish Peroxidase Immobilized in Metal Aerogels Boosts Electron Transfer and an Interfacial Reaction for Photoelectrochemical Immunoassay.

Photoelectrochemical (PEC) enzymatic biosensors have attracted widespread attention for their specificity and sensitivity, but the charge migration between an enzyme and a semiconductor remains uncertain. In this work, horseradish peroxidase (HRP) was successfully immobilized on ionic liquid-functioned Cu@Cu2O (IL-Cu@Cu2O) aerogels to boost charge transfer and an interfacial redox reaction. The photogenerated electrons flow from the conduction band of Cu2O to HRP under the assistance of Cu and are subsequently captured by [Fe(CN)6]3- in the electrolyte, which boosts the PEC response. The improved interfacial catalytic ability after the immobilization of HRP is proved by the enhanced redox ability under light irradiation. Benefiting from the excellent PEC activity and catalysis reaction of IL-Cu@Cu2O@HRP, an immunoassay platform was constructed for sensing prostate-specific antigens, which presents a wide detection range and a low limit of detection. An in-depth understanding of the direct electronic communication between a photoactive material and an enzyme for boosted charge transfer and interfacial catalysis provides a new view for the design of advanced PEC sensing platforms.

Exploring the non-monotonic DNA capture behavior in a charged graphene nanopore.

Nanopore-based biomolecule detection has emerged as a promising and sought-after innovation, offering high throughput, rapidity, label-free analysis, and cost-effectiveness, with potential applications in personalized medicine. However, achieving efficient and tunable biomolecule capture into the nanopore remains a significant challenge. In this study, we employ all-atom molecular dynamics simulations to investigate the capture of double-stranded DNA (dsDNA) molecules into graphene nanopores with varying positive charges. We discover a non-monotonic relationship between the DNA capture rate and the charge of the graphene nanopore. Specifically, the capture rate initially decreases and then increases with an increase in nanopore charge. This behavior is primarily attributed to differences in the electrophoretic force, rather than the influence of electroosmosis or counterions. Furthermore, we also observe this non-monotonic trend in various ionic solutions, but not in ionless solutions. Our findings shed light on the design of novel DNA sequencing devices, offering valuable insights into enhancing biomolecule capture rates in nanopore-based sensing platforms.

Rational combination therapy for hepatocellular carcinoma with PARP1 and DNA-PK inhibitors.

Understanding differences in DNA double-strand break (DSB) repair between tumor and normal tissues would provide a rationale for developing DNA repair-targeted cancer therapy. Here, using knock-in mouse models for measuring the efficiency of two DSB repair pathways, homologous recombination (HR) and nonhomologous end-joining (NHEJ), we demonstrated that both pathways are up-regulated in hepatocellular carcinoma (HCC) compared with adjacent normal tissues due to altered expression of DNA repair factors, including PARP1 and DNA-PKcs. Surprisingly, inhibiting PARP1 with olaparib abrogated HR repair in HCC. Mechanistically, inhibiting PARP1 suppressed the clearance of nucleosomes at DNA damage sites by blocking the recruitment of ALC1 to DSB sites, thereby inhibiting RPA2 and RAD51 recruitment. Importantly, combining olaparib with NU7441, a DNA-PKcs inhibitor that blocks NHEJ in HCC, synergistically suppressed HCC growth in both mice and HCC patient-derived-xenograft models. Our results suggest the combined inhibition of both HR and NHEJ as a potential therapy for HCC.

Computed tomography radiomic features and clinical factors predicting the response to first transarterial chemoembolization in intermediate-stage hepatocellular carcinoma.

BACKGROUND: According to clinical practice guidelines, transarterial chemoembolization (TACE) is the standard treatment modality for patients with intermediate-stage hepatocellular carcinoma (HCC). Early prediction of treatment response can help patients choose a reasonable treatment plan. This study aimed to investigate the value of the radiomic-clinical model in predicting the efficacy of the first TACE treatment for HCC to prolong patient survival. METHODS: A total of 164 patients with HCC who underwent the first TACE from January 2017 to September 2021 were analyzed. The tumor response was assessed by modified response evaluation criteria in solid tumors (mRECIST), and the response of the first TACE to each session and its correlation with overall survival were evaluated. The radiomic signatures associated with the treatment response were identified by the least absolute shrinkage and selection operator (LASSO), and four machine learning models were built with different types of regions of interest (ROIs) (tumor and corresponding tissues) and the model with the best performance was selected. The predictive performance was assessed with receiver operating characteristic (ROC) curves and calibration curves. RESULTS: Of all the models, the random forest (RF) model with peritumor (+10 mm) radiomic signatures had the best performance [area under ROC curve (AUC) = 0.964 in the training cohort, AUC = 0.949 in the validation cohort]. The RF model was used to calculate the radiomic score (Rad-score), and the optimal cutoff value (0.34) was calculated according to the Youden's index. Patients were then divided into a high-risk group (Rad-score > 0.34) and a low-risk group (Rad-score ≤ 0.34), and a nomogram model was successfully established to predict treatment response. The predicted treatment response also allowed for significant discrimination of Kaplan-Meier curves. Multivariate Cox regression identified six independent prognostic factors for overall survival, including male [hazard ratio (HR) = 0.500, 95% confidence interval (CI): 0.260-0.962, P = 0.038], alpha-fetoprotein (HR = 1.003, 95% CI: 1.002-1.004, P < 0.001), alanine aminotransferase (HR = 1.003, 95% CI: 1.001-1.005, P = 0.025), performance status (HR = 2.400, 95% CI: 1.200-4.800, P = 0.013), the number of TACE sessions (HR = 0.870, 95% CI: 0.780-0.970, P = 0.012) and Rad-score (HR = 3.480, 95% CI: 1.416-8.552, P = 0.007). CONCLUSIONS: The radiomic signatures and clinical factors can be well-used to predict the response of HCC patients to the first TACE and may help identify the patients most likely to benefit from TACE.

Exploring the impact of emissions trading schemes on income inequality between urban and rural areas.

While the Paris Agreement and 2030 Agenda for Sustainable Development are the two most important global governance agendas, in practice they have been implemented in isolation. This calls for the need to focus on the potential policy synergies between emission reduction policies and Sustainable Development Goals (SDGs). This paper therefore aims to explore whether the emissions trading scheme (ETS) policy-one of the most effective ways to fulfill the target determined by the Paris Agreement, would facilitate reducing income inequality (SDG10). By combining a difference-in-difference estimation and propensity score matching technique based on a balanced panel dataset for 31 Chinese provinces from 2010 to 2018, we quantify the impact of ETS policy on income inequality between urban and rural areas in China. The results demonstrate that compared with the regions without ETS, the Theil index between rural and urban areas with ETS decreased by 0.018 on average in China. In addition, the ETS would perform better in regions with low urbanization level and high coal dependence. Hence it is vital to speed up the establishment of a unified ETS market in China. This is particularly true for inner underdeveloped regions in China. These findings proven to be robust according to a series of tests challenge the view that SDG 10 has the least relevance to climate action and suggest rethinking the effectiveness and applicability of ETS. Therefore, our research can not only serve as a reference for the development of ETS in China and elsewhere, but also inform decision makers who are seeking for policy synergies between the Paris Agreement and SDGs.

Contribution of small-scale farmers to global food security: a meta-analysis.

In this study, the impacts of small-scale farmers on food security enhancement were estimated in three dimensions of food availability, food access and food utilization. In the current study, a systematic review and meta-analysis have been performed to synthesize results from 75 original articles. It includes the pooling of data that quantitatively investigate whether or not causal links characterized in the original articles remain valid across a broader scope of the literature. The findings show that farmers who are small-scale in natural/physical capital would lead to higher median food production and agricultural productivity, compared with small-scale farmers in financial capital, at about 19% and 15%, respectively. Meta-regression results indicate that small-scale farmers in natural/physical capital have significantly positive effects on the average agricultural productivity, food income and biofortification. By contrast, farmers who are small-scale in financial capital have negative effects on food security. The influential role of these small-scale farmers should also be considered since food insecurity leads to socio-economic implications. Therefore, it is recommended to cultivate higher value crops, to participate in various income-generating activities such as fisheries and forestry, and to pay agricultural credits. The effect of the size of small-scale farmers on global food security is very useful for policymakers to plan for a world without hunger. © 2022 Society of Chemical Industry.

Glycosyltransferase-Related Protein GtrA Is Essential for Localization of Type IX Secretion System Cargo Protein Cellulase Cel9A and Affects Cellulose Degradation in Cytophaga hutchinsonii.

The Gram-negative bacterium Cytophaga hutchinsonii digests cellulose through a novel cellulose degradation mechanism. It possesses the lately characterized type IX secretion system (T9SS). We recently discovered that N-glycosylation of the C-terminal domain (CTD) of a hypothetical T9SS substrate protein in the periplasmic space of C. hutchinsonii affects protein secretion and localization. In this study, green fluorescent protein (GFP)-CTDCel9A recombinant protein was found with increased molecular weight in the periplasm of C. hutchinsonii. Site-directed mutagenesis studies on the CTD of cellulase Cel9A demonstrated that asparagine residue 900 in the D-X-N-X-S motif is important for the processing of the recombinant protein. We found that the glycosyltransferase-related protein GtrA (CHU_0012) located in the cytoplasm of C. hutchinsonii is essential for outer membrane localization of the recombinant protein. The deletion of gtrA decreased the abundance of the outer membrane proteins and affected cellulose degradation by C. hutchinsonii. This study provided a link between the glycosylation system and cellulose degradation in C. hutchinsonii. IMPORTANCE N-Glycosylation systems are generally limited to some pathogenic bacteria in prokaryotes. The disruption of the N-glycosylation pathway is related to adherence, invasion, colonization, and other phenotypic characteristics. We recently found that the cellulolytic bacterium Cytophaga hutchinsonii also has an N-glycosylation system. The cellulose degradation mechanism of C. hutchinsonii is novel and mysterious; cellulases and other proteins on the cell surface are involved in utilizing cellulose. In this study, we identified an asparagine residue in the C-terminal domain of cellulase Cel9A that is necessary for the processing of the T9SS cargo protein. Moreover, the glycosyltransferase-related protein GtrA is essential for the localization of the GFP-CTDCel9A recombinant protein. Deletion of gtrA affected cellulose degradation and the abundance of outer membrane proteins. This study enriched the understanding of the N-glycosylation system in C. hutchinsonii and provided a link between N-glycosylation and cellulose degradation, which also expanded the role of the N-glycosylation system in bacteria.