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1.
Nature ; 584(7821): 475-478, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32494008

RESUMEN

The endoplasmic reticulum (ER) membrane complex (EMC) cooperates with the Sec61 translocon to co-translationally insert a transmembrane helix (TMH) of many multi-pass integral membrane proteins into the ER membrane, and it is also responsible for inserting the TMH of some tail-anchored proteins1-3. How EMC accomplishes this feat has been unclear. Here we report the first, to our knowledge, cryo-electron microscopy structure of the eukaryotic EMC. We found that the Saccharomyces cerevisiae EMC contains eight subunits (Emc1-6, Emc7 and Emc10), has a large lumenal region and a smaller cytosolic region, and has a transmembrane region formed by Emc4, Emc5 and Emc6 plus the transmembrane domains of Emc1 and Emc3. We identified a five-TMH fold centred around Emc3 that resembles the prokaryotic YidC insertase and that delineates a largely hydrophilic client protein pocket. The transmembrane domain of Emc4 tilts away from the main transmembrane region of EMC and is partially mobile. Mutational studies demonstrated that the flexibility of Emc4 and the hydrophilicity of the client pocket are required for EMC function. The EMC structure reveals notable evolutionary conservation with the prokaryotic insertases4,5, suggests that eukaryotic TMH insertion involves a similar mechanism, and provides a framework for detailed understanding of membrane insertion for numerous eukaryotic integral membrane proteins and tail-anchored proteins.


Asunto(s)
Microscopía por Crioelectrón , Retículo Endoplásmico/enzimología , Membranas Intracelulares/enzimología , Complejos Multiproteicos/química , Complejos Multiproteicos/ultraestructura , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/ultraestructura , Saccharomyces cerevisiae , Sitios de Unión , Retículo Endoplásmico/química , Retículo Endoplásmico/ultraestructura , Evolución Molecular , Interacciones Hidrofóbicas e Hidrofílicas , Membranas Intracelulares/química , Membranas Intracelulares/ultraestructura , Modelos Moleculares , Complejos Multiproteicos/genética , Complejos Multiproteicos/metabolismo , Mutación , Dominios Proteicos , Subunidades de Proteína/química , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/ultraestructura , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Especificidad por Sustrato
2.
Brief Bioinform ; 25(1)2023 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-38171931

RESUMEN

The advancement of single-cell sequencing technology has smoothed the ability to do biological studies at the cellular level. Nevertheless, single-cell RNA sequencing (scRNA-seq) data presents several obstacles due to the considerable heterogeneity, sparsity and complexity. Although many machine-learning models have been devised to tackle these difficulties, there is still a need to enhance their efficiency and accuracy. Current deep learning methods often fail to fully exploit the intrinsic interconnections within cells, resulting in unsatisfactory results. Given these obstacles, we propose a unique approach for analyzing scRNA-seq data called scMPN. This methodology integrates multi-layer perceptron and graph neural network, including attention network, to execute gene imputation and cell clustering tasks. In order to evaluate the gene imputation performance of scMPN, several metrics like cosine similarity, median L1 distance and root mean square error are used. These metrics are utilized to compare the efficacy of scMPN with other existing approaches. This research utilizes criteria such as adjusted mutual information, normalized mutual information and integrity score to assess the efficacy of cell clustering across different approaches. The superiority of scMPN over current single-cell data processing techniques in cell clustering and gene imputation investigations is shown by the experimental findings obtained from four datasets with gold-standard cell labels. This observation demonstrates the efficacy of our suggested methodology in using deep learning methodologies to enhance the interpretation of scRNA-seq data.


Asunto(s)
Benchmarking , Análisis de Expresión Génica de una Sola Célula , Análisis por Conglomerados , Análisis de Datos , Redes Neurales de la Computación , Análisis de Secuencia de ARN , Perfilación de la Expresión Génica
3.
Subcell Biochem ; 104: 383-408, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38963493

RESUMEN

Oxidoreductases facilitating electron transfer between molecules are pivotal in metabolic pathways. Flavin-based electron bifurcation (FBEB), a recently discovered energy coupling mechanism in oxidoreductases, enables the reversible division of electron pairs into two acceptors, bridging exergonic and otherwise unfeasible endergonic reactions. This chapter explores the four distinct FBEB complex families and highlights a decade of structural insights into FBEB complexes. In this chapter, we discuss the architecture, electron transfer routes, and conformational changes across all FBEB families, revealing the structural foundation that facilitate these remarkable functions.


Asunto(s)
Flavinas , Transporte de Electrón , Flavinas/metabolismo , Flavinas/química , Oxidorreductasas/metabolismo , Oxidorreductasas/química , Conformación Proteica , Modelos Moleculares , Oxidación-Reducción
4.
J Biol Chem ; 299(2): 102852, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36592926

RESUMEN

The Saccharomyces cerevisiae Yta7 is a chromatin remodeler harboring a histone-interacting bromodomain (BRD) and two AAA+ modules. It is not well understood how Yta7 recognizes the histone H3 tail to promote nucleosome disassembly for DNA replication or RNA transcription. By cryo-EM analysis, here we show that Yta7 assembles a three-tiered hexamer with a top BRD tier, a middle AAA1 tier, and a bottom AAA2 tier. Unexpectedly, the Yta7 BRD stabilizes a four-stranded ß-helix, termed BRD-interacting motif (BIM), of the largely disordered N-terminal region. The BIM motif is unique to the baker's yeast, and we show both BRD and BIM contribute to nucleosome recognition. We found that Yta7 binds both acetylated and nonacetylated H3 peptides but with a higher affinity for the unmodified peptide. This property is consistent with the absence of key residues of canonical BRDs involved in acetylated peptide recognition and the role of Yta7 in general nucleosome remodeling. Interestingly, the BRD tier exists in a spiral and a flat-ring form on top of the Yta7 AAA+ hexamer. The spiral is likely in a nucleosome-searching mode because the bottom BRD blocks the entry to the AAA+ chamber. The flat ring may be in a nucleosome disassembly state because the entry is unblocked and the H3 peptide has entered the AAA+ chamber and is stabilized by the AAA1 pore loops 1 and 2. Indeed, we show that the BRD tier is a flat ring when bound to the nucleosome. Overall, our study sheds light on the nucleosome disassembly by Yta7.


Asunto(s)
Proteínas que Contienen Bromodominio , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Adenosina Trifosfatasas/metabolismo , Proteínas que Contienen Bromodominio/química , Proteínas que Contienen Bromodominio/genética , Proteínas que Contienen Bromodominio/metabolismo , Ensamble y Desensamble de Cromatina , Proteínas Cromosómicas no Histona/metabolismo , Histonas/metabolismo , Nucleosomas/metabolismo , Conformación Proteica en Lámina beta , Multimerización de Proteína , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
5.
Small ; 20(9): e2308273, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37849032

RESUMEN

Aqueous zinc-ion batteries (AZIBs) face challenges in achieving high energy density compared to conventional lithium-ion batteries (LIBs). The lower operating voltage and excessive Zn metal as anode pose constraints on the overall energy storage capacity of these batteries. An effective approach is to reduce the thickness of the Zn metal anode and control its mass appropriately. However, under the condition of using a thin Zn anode, the performance of AZIBs is often unsatisfactory. Through experiments and computational simulations, the electrode structural change and the formation of dead Zn as the primary reasons for the failure of batteries under a high Zn utilization rate are identified. Based on this understanding, a universal synergistic strategy that combines Cu foil current collectors and electrolyte additives to maintain the structural and thermodynamic stability of the Zn anode under a high Zn utilization rate (ZUR) is proposed. Specifically, the Cu current collectors can ensure that the Zn anode structure remains intact based on the spontaneous filling effect, while the additives can suppress parasitic side reactions at the interface. Ultimately, the symmetric cell demonstrates a cycling duration of 900 h at a 70% ZU, confirming the effectiveness of this strategy.

6.
Small ; 20(9): e2306945, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37863806

RESUMEN

The Sabatier principle defines the essential criteria for an ideal catalyst in heterogeneous catalysis, while reaching the Sabatier optimum is still challenging in catalyst design. Herein, an elegant strategy is described to reach the Sabatier optimum of Ni electrocatalyst in CO2 reduction reaction (CO2 RR) by atomically Zn doping. The incorporation of 3% Zn single atom into Ni lattice leads to the moderate degrade of d-band center via Ni-Zn electronic coupling, which balances the bonding strengths of *COOH and *CO, resulting in a relative low energy barrier for CO2 activation while not being substantially poisoned by CO. Consequently, NiZn0.03 /C exhibits unique catalytic activity (jCO >100 mA cm-2 at -0.6 V), wide potential range for selective CO production (FECO >90% from -0.65 to -1.15 V), and outstanding long-term stability (FECO >90% during 85 h electrolysis at -0.85 V). The results provide valuable insights for the rational fabrication of superior non-noble bimetallic electrocatalysts in CO2 electroreduction.

7.
J Transl Med ; 22(1): 613, 2024 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-38956649

RESUMEN

BACKGROUND: CD19-targeted chimeric antigen receptor T (CAR-T) cell therapy stands out as a revolutionary intervention, exhibiting remarkable remission rates in patients with refractory/relapsed (R/R) B-cell malignancies. However, the potential side effects of therapy, particularly cytokine release syndrome (CRS) and infections, pose significant challenges due to their overlapping clinical features. Promptly distinguishing between CRS and infection post CD19 target CAR-T cell infusion (CTI) remains a clinical dilemma. Our study aimed to analyze the incidence of infections and identify key indicators for early infection detection in febrile patients within 30 days post-CTI for B-cell malignancies. METHODS: In this retrospective cohort study, a cohort of 104 consecutive patients with R/R B-cell malignancies who underwent CAR-T therapy was reviewed. Clinical data including age, gender, CRS, ICANS, treatment history, infection incidence, and treatment responses were collected. Serum biomarkers procalcitonin (PCT), interleukin-6 (IL-6), and C-reactive protein (CRP) levels were analyzed using chemiluminescent assays. Statistical analyses employed Pearson's Chi-square test, t-test, Mann-Whitney U-test, Kaplan-Meier survival analysis, Cox proportional hazards regression model, Spearman rank correlation, and receiver operating characteristic (ROC) curve analysis to evaluate diagnostic accuracy and develop predictive models through multivariate logistic regression. RESULTS: In this study, 38 patients (36.5%) experienced infections (30 bacterial, 5 fungal, and 3 viral) within the first 30 days of CAR T-cell infusion. In general, bacterial, fungal, and viral infections were detected at a median of 7, 8, and 9 days, respectively, after CAR T-cell infusion. Prior allogeneic hematopoietic cell transplantation (HCT) was an independent risk factor for infection (Hazard Ratio [HR]: 4.432 [1.262-15.565], P = 0.020). Furthermore, CRS was an independent risk factor for both infection ((HR: 2.903 [1.577-5.345], P < 0.001) and severe infection (9.040 [2.256-36.232], P < 0.001). Serum PCT, IL-6, and CRP were valuable in early infection prediction post-CAR-T therapy, particularly PCT with the highest area under the ROC curve (AUC) of 0.897. A diagnostic model incorporating PCT and CRP demonstrated an AUC of 0.903 with sensitivity and specificity above 83%. For severe infections, a model including CRS severity and PCT showed an exceptional AUC of 0.991 with perfect sensitivity and high specificity. Based on the aforementioned analysis, we proposed a workflow for the rapid identification of early infection during CAR-T cell therapy. CONCLUSIONS: CRS and prior allogeneic HCT are independent infection risk factors post-CTI in febrile B-cell malignancy patients. Our identification of novel models using PCT and CRP for predicting infection, and PCT and CRS for predicting severe infection, offers potential to guide therapeutic decisions and enhance the efficacy of CAR-T cell therapy in the future.


Asunto(s)
Antígenos CD19 , Fiebre , Inmunoterapia Adoptiva , Humanos , Femenino , Masculino , Persona de Mediana Edad , Inmunoterapia Adoptiva/métodos , Adulto , Antígenos CD19/metabolismo , Infecciones/sangre , Anciano , Curva ROC , Adulto Joven , Estudios Retrospectivos
8.
Langmuir ; 40(22): 11684-11694, 2024 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-38781129

RESUMEN

The exceptional hydrophobicity and antifouling properties of polydimethylsiloxane (PDMS) composites have attracted extensive interest as a result of low surface energy. However, PDMS composites are hardly bound by common primers, greatly limiting their practical applications. To address this issue, an EPMS/VTMS (EV) primer synthesized by hydrolytic polycondensation of 3-[(2,3)-epoxypropoxypropyl]methyldiethoxysilane (EPMS) and vinyltrimethoxysilane (VTMS) in acidic conditions is proposed. Interestingly, the EV primer exhibits exceptional reactivity, self-healing capabilities, and strong adhesion to various substrates, including metals, plastics, and glass. The bonding aluminum plates are easily debonded by immersion in water without any residue left. Subsequently, the EV primer has been applied to the interface between silicone leather and the PDMS composite. Results show that the bonding strength for the silicone leather coated with the EV/PDMS composite is 16 times higher than that of the silicone leather modified with the PDMS composite. Meanwhile, the modified silicone leather exhibits impressive antifouling performance, including aqueous and oily stains, appreciable breathability, and excellent wear resistance, even if suffering from 20 000 cycles of abrasion. These excellent advantages for the modified silicone leather should be attributable to the synergistic effect of the EV primer and the PDMS composite. These findings pave the way to develop an ecofriendly debonding primer for PDMS composites, greatly facilitating applications of silicone leather.

9.
Rapid Commun Mass Spectrom ; 38(1): e9662, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38073199

RESUMEN

RATIONALE: Tetrandrine, the Q-marker in Stephaniae Tetrandrae Radix, was proven to present an obvious antitumor effect. Until now, the metabolism and antitumor mechanism of tetrandrine have not been fully elucidated. METHODS: The metabolites of tetrandrine in rats were profiled using ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry. The potential antitumor mechanism of tetrandrine in vivo was predicted using network pharmacology. RESULTS: A total of 30 metabolites were characterized in rats after ingestion of tetrandrine (10 mg/kg), including 0 in plasma, 7 in urine, 11 in feces, 9 in liver, 8 in spleen, 4 in lung, 5 in kidney, 5 in heart, and 4 in brain. This study was the first to show the metabolic processes demethylation, hydroxylation, and carbonylation in tetrandrine. The pharmacology network results showed that tetrandrine and its metabolites could regulate AKT1, TNF, MMP9, MMP2, PAK1, and so on by involving in proteoglycan tumor pathway, PI3K-Akt signaling pathway, tumor pathway, MAPK signaling pathway, and Rap1 signaling pathway. CONCLUSIONS: The metabolism features of tetrandrine and its potential antitumor mechanism were summarized, providing data for further pharmacological validation.


Asunto(s)
Medicamentos Herbarios Chinos , Neoplasias , Ratas , Animales , Fosfatidilinositol 3-Quinasas , Farmacología en Red , Cromatografía Líquida de Alta Presión/métodos , Medicamentos Herbarios Chinos/farmacología , Medicamentos Herbarios Chinos/química
10.
Inorg Chem ; 63(3): 1537-1542, 2024 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-38181068

RESUMEN

The cleavage of inert C-H bonds in methane at room temperature and the subsequent conversion into value-added products are quite challenging. Herein, the reactivity of boron-doped cobalt oxide cluster cations CoBO2+ toward methane under thermal collision conditions was studied by mass spectrometry experiments and quantum-chemical calculations. In this reaction, one H atom and the CH3 unit of methane were transformed separately to generate the product metaboric acid (HBO2) and one CoCH3+ ion, respectively. Theoretical calculations strongly suggest that a catalytic cycle can be completed by the recovery of CoBO2+ through the reaction of CoCH3+ with sodium perborate (NaBO3), and this reaction generates sodium methoxide (CH3ONa) as the other value-added product. This study shows that boron-doped cobalt oxide species are highly reactive to facilitate thermal methane transformation and may open a way to develop more effective approaches for methane (CH4) activation and conversion under mild conditions.

11.
Methods ; 211: 48-60, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36804214

RESUMEN

Single-cell RNA sequencing (scRNA-seq) data scale surges with high-throughput sequencing technology development. However, although single-cell data analysis is a powerful tool, various issues have been reported, such as sequencing sparsity and complex differential patterns in gene expression. Statistical or traditional machine learning methods are inefficient, and the accuracy needs to be improved. The methods based on deep learning can not directly process non-Euclidean spatial data, such as cell diagrams. In this study, we have developed graph autoencoders and graph attention network for scRNA-seq analysis based on a directed graph neural network named scDGAE. Directed graph neural networks cannot only retain the connection properties of the directed graph but also expand the receptive field of the convolution operation. Cosine similarity, median L1 distance, and root-mean-squared error are used to measure the gene imputation performance of different methods with scDGAE. Furthermore, adjusted mutual information, normalized mutual information, completeness score, and Silhouette coefficient score are used to measure the cell clustering performance of different methods with scDGAE. Experiment results show that the scDGAE model achieves promising performance in gene imputation and cell clustering prediction on four scRNA-seq data sets with gold-standard cell labels. Furthermore, it is a robust framework that can be applied to general scRNA-Seq analyses.


Asunto(s)
Redes Neurales de la Computación , Análisis de Expresión Génica de una Sola Célula , Análisis de Secuencia de ARN/métodos , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Análisis de la Célula Individual/métodos , Análisis de Datos , Análisis por Conglomerados , Perfilación de la Expresión Génica/métodos
12.
Phys Chem Chem Phys ; 26(5): 3912-3919, 2024 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-38230689

RESUMEN

N2 adsorption is a prerequisite for activation and transformation. Time-of-flight mass spectrometry experiments show that the Nb2C6H4+ cation, resulting from the gas-phase reaction of Nb2+ with C6H6, is more favorable for N2 adsorption than Nb+ and Nb2+ cations. Density functional theory calculations reveal the effect of the ortho-C6H4 ligand on N2 adsorption. In Nb2C6H4+, interactions between the Nb-4d and C-2p orbitals enable the Nb2+ cation to form coordination bonds with the ortho-C6H4 ligand. Although the ortho-C6H4 ligand in Nb2C6H4+ is not directly involved in the reaction, its presence increases the polarity of the cluster and brings the highest occupied molecular orbital (HOMO) closer to the lowest occupied molecular orbital (LUMO) of N2, thereby increasing the N2 adsorption energy, which effectively facilitates N2 adsorption and activation. This study provides fundamental insights into the mechanisms of N2 adsorption in "transition metal-organic ligand" systems.

13.
J Phys Chem A ; 128(2): 449-455, 2024 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-38174707

RESUMEN

Nitrogen (N2) activation at room temperature has long been a great challenge. Therefore, the rational design of reactive species to adsorb N2, which is a prerequisite for cleavage of the strong N≡N triple bond in industrial and biological processes, is highly desirable and meaningful. Herein, the N2 adsorption process is controlled by regulating the types and numbers of organic ligands, and the organic ligands are produced through the reactions of Ir+ with methane and ethane. CH4 molecules dissociate on the Ir+ cations to form Ir(CH2)1,2+. The reaction of Ir+ with C2H6 can generate HIrC2H3+, which is different from the structure of Ir(CH2)2+ obtained from Ir+/CH4. The reactivity order of N2 adsorption is Ir(CH2)2+ > HIrC2H3+ ≫ HIrCH+ ≈ Ir+ (almost inert under similar reaction conditions), indicating that different organic ligand structures affect reactivity dramatically. The main reason for this interesting reactivity difference is that the lowest unoccupied molecular orbital (LUMO) level of Ir(CH2)2+ is much closer to the highest occupied molecular orbital (HOMO) level of N2 than those of the other three systems. This study provides new insights into the adsorption of N2 on metal-organic ligand species, in which the organic ligand dominates the reactivity, and it discovers new clues in designing effective transition metal carbine species for N2 activation.

14.
Mol Cell ; 64(1): 79-91, 2016 10 06.
Artículo en Inglés | MEDLINE | ID: mdl-27666591

RESUMEN

CENP-A is a centromere-specific histone 3 variant essential for centromere specification. CENP-A partially replaces canonical histone H3 at the centromeres. How the particular CENP-A/H3 ratio at centromeres is precisely maintained is unknown. It also remains unclear how CENP-A is excluded from non-centromeric chromatin. Here, we identify Ccp1, an uncharacterized NAP family protein in fission yeast that antagonizes CENP-A loading at both centromeric and non-centromeric regions. Like the CENP-A loading factor HJURP, Ccp1 interacts with CENP-A and is recruited to centromeres at the end of mitosis in a Mis16-dependent manner. These data indicate that factors with opposing CENP-A loading activities are recruited to centromeres. Furthermore, Ccp1 also cooperates with H2A.Z to evict CENP-A assembled in euchromatin. Structural analyses indicate that Ccp1 forms a homodimer that is required for its anti-CENP-A loading activity. Our study establishes mechanisms for maintenance of CENP-A homeostasis at centromeres and the prevention of ectopic assembly of centromeres.


Asunto(s)
Carboxipeptidasas/genética , Proteínas Portadoras/genética , Proteínas Cromosómicas no Histona/genética , Eucromatina/química , Regulación Fúngica de la Expresión Génica , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/genética , Sitios de Unión , Carboxipeptidasas/química , Carboxipeptidasas/metabolismo , Proteínas Portadoras/química , Proteínas Portadoras/metabolismo , Centrómero/química , Centrómero/metabolismo , Centrómero/ultraestructura , Ensamble y Desensamble de Cromatina , Proteínas Cromosómicas no Histona/química , Proteínas Cromosómicas no Histona/metabolismo , Eucromatina/metabolismo , Eucromatina/ultraestructura , Histonas/química , Histonas/genética , Histonas/metabolismo , Mitosis , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Schizosaccharomyces/metabolismo , Schizosaccharomyces/ultraestructura , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/metabolismo , Transducción de Señal
15.
Nucleic Acids Res ; 50(D1): D471-D479, 2022 01 07.
Artículo en Inglés | MEDLINE | ID: mdl-34788852

RESUMEN

Protein post-translational modifications (PTMs) play an important role in different cellular processes. In view of the importance of PTMs in cellular functions and the massive data accumulated by the rapid development of mass spectrometry (MS)-based proteomics, this paper presents an update of dbPTM with over 2 777 000 PTM substrate sites obtained from existing databases and manual curation of literature, of which more than 2 235 000 entries are experimentally verified. This update has manually curated over 42 new modification types that were not included in the previous version. Due to the increasing number of studies on the mechanism of PTMs in the past few years, a great deal of upstream regulatory proteins of PTM substrate sites have been revealed. The updated dbPTM thus collates regulatory information from databases and literature, and merges them into a protein-protein interaction network. To enhance the understanding of the association between PTMs and molecular functions/cellular processes, the functional annotations of PTMs are curated and integrated into the database. In addition, the existing PTM-related resources, including annotation databases and prediction tools are also renewed. Overall, in this update, we would like to provide users with the most abundant data and comprehensive annotations on PTMs of proteins. The updated dbPTM is now freely accessible at https://awi.cuhk.edu.cn/dbPTM/.


Asunto(s)
Bases de Datos de Proteínas , Redes Reguladoras de Genes , Procesamiento Proteico-Postraduccional , Proteínas/metabolismo , Programas Informáticos , Animales , Arabidopsis/genética , Arabidopsis/metabolismo , Bacterias/genética , Bacterias/metabolismo , Humanos , Internet , Ratones , Modelos Moleculares , Anotación de Secuencia Molecular , Unión Proteica , Conformación Proteica , Mapeo de Interacción de Proteínas , Proteínas/química , Proteínas/genética , Ratas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
16.
Proc Natl Acad Sci U S A ; 118(2)2021 01 12.
Artículo en Inglés | MEDLINE | ID: mdl-33372143

RESUMEN

The electron-transferring flavoprotein-menaquinone oxidoreductase ABCX (EtfABCX), also known as FixABCX for its role in nitrogen-fixing organisms, is a member of a family of electron-transferring flavoproteins that catalyze electron bifurcation. EtfABCX enables endergonic reduction of ferredoxin (E°' ∼-450 mV) using NADH (E°' -320 mV) as the electron donor by coupling this reaction to the exergonic reduction of menaquinone (E°' -80 mV). Here we report the 2.9 Å structure of EtfABCX, a membrane-associated flavin-based electron bifurcation (FBEB) complex, from a thermophilic bacterium. EtfABCX forms a superdimer with two membrane-associated EtfCs at the dimer interface that contain two bound menaquinones. The structure reveals that, in contrast to previous predictions, the low-potential electrons bifurcated from EtfAB are most likely directly transferred to ferredoxin, while high-potential electrons reduce the quinone via two [4Fe-4S] clusters in EtfX. Surprisingly, EtfX shares remarkable structural similarity with mammalian [4Fe-4S] cluster-containing ETF ubiquinone oxidoreductase (ETF-QO), suggesting an unexpected evolutionary link between bifurcating and nonbifurcating systems. Based on this structure and spectroscopic studies of a closely related EtfABCX, we propose a detailed mechanism of the catalytic cycle and the accompanying structural changes in this membrane-associated FBEB system.


Asunto(s)
Flavoproteínas Transportadoras de Electrones/metabolismo , Quinona Reductasas/metabolismo , Quinona Reductasas/ultraestructura , Proteínas Bacterianas/metabolismo , Catálisis , Microscopía por Crioelectrón/métodos , Transporte de Electrón , Electrones , Ferredoxinas/metabolismo , Flavinas/metabolismo , Flavoproteínas/metabolismo , Proteínas Hierro-Azufre/metabolismo , Modelos Moleculares , NAD/metabolismo , Fijación del Nitrógeno/fisiología , Oxidación-Reducción , Pyrococcus furiosus/metabolismo , Quinona Reductasas/fisiología , Vitamina K 2/metabolismo
17.
Angew Chem Int Ed Engl ; 63(27): e202320014, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38598078

RESUMEN

Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen-containing molecules. Here, we report the sustainable production of amino acids from biomass-derived hydroxy acids with high activity under visible-light irradiation and mild conditions, using atomic ruthenium-promoted cadmium sulfide (Ru1/CdS). On a metal basis, the optimized Ru1/CdS exhibits a maximal alanine formation rate of 26.0 molAla ⋅ gRu -1 ⋅ h-1, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru1/CdS to the facilitated charge separation and O-H bond dissociation of the α-hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique "double activation" mechanism of both the CH-OH and CH3-CH-OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.


Asunto(s)
Aminoácidos , Biomasa , Compuestos de Cadmio , Rutenio , Sulfuros , Sulfuros/química , Rutenio/química , Compuestos de Cadmio/química , Catálisis , Aminoácidos/química , Procesos Fotoquímicos , Teoría Funcional de la Densidad , Luz
18.
Angew Chem Int Ed Engl ; 63(13): e202316791, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38308859

RESUMEN

Heparin and heparan sulfate (HS) are naturally occurring mammalian glycosaminoglycans, and their synthetic and semi-synthetic mimetics have attracted significant interest as potential therapeutics. However, understanding the mechanism of action by which HS, heparin, and HS mimetics have a biological effect is difficult due to their highly charged nature, broad protein interactomes, and variable structures. To address this, a library of novel single-entity dendritic mimetics conjugated to BODIPY, Fluorine-19 (19 F), and biotin was synthesized for imaging and localization studies. The novel dendritic scaffold allowed for the conjugation of labeling moieties without reducing the number of sulfated capping groups, thereby better mimicking the multivalent nature of HS-protein interactions. The 19 F labeled mimetics were assessed in phantom studies and were detected at concentrations as low as 5 mM. Flow cytometric studies using a fluorescently labeled mimetic showed that the compound associated with immune cells from tumors more readily than splenic counterparts and was directed to endosomal-lysosomal compartments within immune cells and cancer cells. Furthermore, the fluorescently labeled mimetic entered the central nervous system and was detectable in brain-infiltrating immune cells 24 hours after treatment. Here, we report the enabling methodology for rapidly preparing various labeled HS mimetics and molecular probes with diverse potential therapeutic applications.


Asunto(s)
Biotina , Compuestos de Boro , Heparitina Sulfato , Animales , Heparitina Sulfato/química , Glicosaminoglicanos/metabolismo , Heparina/metabolismo , Mamíferos/metabolismo
19.
Apoptosis ; 28(1-2): 124-135, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36241947

RESUMEN

The Notch signaling pathway is related to endothelial dysfunction in coronary atherosclerosis. Our objective was to explore the role of Notch signaling in coronary microvascular dysfunction (CMD). CMD models were constructed by sodium laurate injection in vivo and homocysteine (Hcy) stimulation in vitro. The binding ability of Notch Intracellular Domain (NICD)/H3K9Ac/GCN5 (General Control Non-derepressible 5) to Neuregulin-1 (Nrg-1) promoter was examined by chromatin immunoprecipitation. Immunofluorescence staining was conducted to detect CD31 positive cells, NICD localization, and co-localization of NICD and GCN5. Flow cytometry and Tunel staining were conducted to identify the apoptosis. Hematoxylin and eosin staining, quantitative real-time PCR, western blot, immunohistochemical staining, co-immunoprecipitation, and double luciferase report analysis were also conducted. Notch signaling pathway-related protein levels were decreased, levels of Nrg-1 and the phosphorylation of ErbB2 and ErbB4 were enhanced in CMD models. Interference with Nrg-1 further increased the apoptosis in Hcy-induced cardiac microvascular endothelial cells (CMECs). Meanwhile, the activation of the Notch signaling pathway increased the levels of Nrg-1 and the phosphorylation of ErbB2 and ErbB4, as well as inhibited the apoptosis induced by Hcy. Furthermore, NICD and histone acetyltransferase enzyme GCN5 could regulate Nrg-1 promoter activity by affecting the expression of acetylation-modified protein H3K9Ac. In addition, NICD also interacted with GCN5. In vivo results also confirmed that the activation of the Notch signal alleviated CMD. Notch signaling pathway regulates Nrg-1 level through synergistic interaction with GCN5, thereby mitigating CMD.


Asunto(s)
Células Endoteliales , Isquemia Miocárdica , Humanos , Células Endoteliales/metabolismo , Neurregulina-1/metabolismo , Neurregulina-1/farmacología , Código de Histonas , Apoptosis , Transducción de Señal , Receptor ErbB-4/metabolismo , Isquemia Miocárdica/metabolismo , Receptor Notch1
20.
BMC Cancer ; 23(1): 658, 2023 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-37452325

RESUMEN

BACKGROUND: Recurrences are the main reasons for unfavorable outcomes for patients with stage II colorectal cancer (CRC). To obtain a clear understanding of the high-risk factors, further investigation is warranted. The present study aimed to analyze the risk factors associated with postoperative recurrence in patients with stage II CRC. METHODS: Eligible patients with pathologically confirmed stage II CRC were enrolled in the study retrospectively based on a prospectively maintained database from April 2008 to March 2019. The Kaplan-Meier method were used to calculate the overall survival (OS) rate and the cumulative recurrence rate. Univariate and multivariable Cox regression analyses were performed to identify risk factors for recurrence. RESULTS: There were 2515 patients included, of whom 233 (9.3%) developed local or distant recurrence. Recurrence was associated with a significantly worse 5-year OS (45.4% vs. 95.5%, p < 0.0001). The 5-year cumulative recurrence rate was 13.0% in patients with stage II CRC. On multivariable Cox analysis, tumor size (Hazard Ratio (HR) [95% confidence interval (CI)] = 1.79[1.38, 2.33]), preoperative carbohydrate antigen (CA) 125 level (HR [95% CI] = 1.78[1.17, 2.70]), preoperative CA 199 level (HR [95% CI] = 1.56[1.09, 2.22]), and ulcerating tumor (HR [95% CI] = 1.61[1.19, 2.17]) were found to be associated with postoperative recurrence. Adjuvant chemotherapy was associated with a lower cumulative recurrence rate in patients with these risk factors (p = 0.00096). CONCLUSION: The tumor diameter, preoperative CA125 level, preoperative CA199 level, and an ulcerative tumor can predict postoperative recurrence in patients with stage II CRC, and postoperative chemotherapy could reduce the cumulative recurrence rate in patients with these high-risk factors.


Asunto(s)
Neoplasias Colorrectales , Humanos , Estadificación de Neoplasias , Pronóstico , Estudios Retrospectivos , Neoplasias Colorrectales/patología , Factores de Riesgo , Recurrencia Local de Neoplasia/patología
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