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Recent advances in methodology have made phosphopeptide analysis a tractable problem for many proteomics researchers. There are now a wide variety of robust and accessible enrichment strategies to generate phosphoproteomes while free or inexpensive software tools for quantitation and site localization have simplified phosphoproteome analysis workflow tremendously. As a research group under the Association for Biomolecular Resource Facilities umbrella, the Proteomics Standards Research Group has worked to develop a multipathway phosphopeptide standard based on a mixture of heavy-labeled phosphopeptides designed to enable researchers to rapidly develop assays. This mixture contains 131 mass spectrometry vetted phosphopeptides specifically chosen to cover as many known biologically interesting phosphosites as possible from seven different signaling networks: AMPK signaling, death and apoptosis signaling, ErbB signaling, insulin/insulin-like growth factor-1 signaling, mTOR signaling, PI3K/AKT signaling, and stress (p38/SAPK/JNK) signaling. Here, we describe a characterization of this mixture spiked into a HeLa tryptic digest stimulated with both epidermal growth factor and insulin-like growth factor-1 to activate the MAPK and PI3K/AKT/mTOR pathways. We further demonstrate a comparison of phosphoproteomic profiling of HeLa performed independently in five labs using this phosphopeptide mixture with data-independent acquisition. Despite different experimental and instrumentation processes, we found that labs could produce reproducible, harmonized datasets by reporting measurements as ratios to the standard, while intensity measurements showed lower consistency between labs even after normalization. Our results suggest that widely available, biologically relevant phosphopeptide standards can act as a quantitative "yardstick" across laboratories and sample preparations enabling experimental designs larger than a single laboratory can perform. Raw data files are publicly available in the MassIVE dataset MSV000090564.
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Fosfopeptídeos , Proteínas Proto-Oncogênicas c-akt , Fosforilação , Fosfopeptídeos/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Fosfoproteínas/metabolismoRESUMO
Doping lanthanide ions is an efficient method to modify the optical properties of lead-free double-perovskite halides. However, most lanthanide-doped double perovskites show a low luminescence efficiency and require a high excitation energy. Here, we have successfully prepared a series of Ho3+-doped Cs2NaBiCl6 microcrystals through a simple hydrothermal method and obtained strong characteristic emissions of Ho3+ at 492 and 657 nm under low-energy excitation (449 nm). After codoping Mn2+, apart from the characteristic emissions from Ho3+ under 450 nm wavelength excitation, the orangish-red luminescence consisting of the emission band centered at 591 nm from Mn2+ and a sharp emission peak at 657 nm from Ho3+ is obtained under 355 nm UV light excitation. Photoluminescence (PL) emission and excitation spectra, along with the PL decay curves, confirm the existence of an energy-transfer channel from Cs2NaBiCl6 to Mn2+ and then from Mn2+ to Ho3+. The enhanced absorption efficiency (10.5 â 70.7%) suggests that the codoping of Mn2+ overcomes the low absorption efficiency caused by f-f forbidden transitions of Ho3+. Finally, the diverse luminescent performance within the Cs2NaBiCl6:Ho3+, Mn2+ phosphor is realized by altering the excitation wavelength, thereby enabling its application in warm-white-light-emitting diodes and plant growth in this work.
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OBJECTIVE: To investigate the risk factors for delayed postoperative bleeding after endoscopic submucosal dissection (ESD) in patients with gastric precancerous lesions and to construct a risk prediction model. METHODS: This retrospective analysis included clinical data from patients with gastric precancerous lesions who underwent ESD at Wuhan University People's Hospital between November 2016 and June 2022. An XGBoost model was built to predict delayed bleeding after ESD using risk factors identified by univariable and multivariate logistic regression analysis. The model was evaluated using receiver operating characteristic curves (ROC), and SHapely Additive exPlanations (SHAP) analysis was used to interpret the model. RESULTS: Seven factors were statistically associated with delayed postoperative bleeding in gastric precancerous lesions after ESD: age, low-grade intraepithelial neoplasia, hypertension, lesion size ≥ 40 mm, operative time ≥ 120 min, female, and nonuse of hemoclips. A risk prediction model was established. In the training cohort, the model achieved an AUC of 0.97 (0.96-0.98), a sensitivity of 0.90, a specificity of 0.94, and an F1 score of 0.91. In the validation cohort, the AUC was 0.94(0.90-0.98), with a sensitivity of 0.85, a specificity of 0.89, and an F1 score of 0.85. In the test cohort, the AUC was 0.94 (0.89-0.99), the sensitivity was 0.80, the specificity was 0.92, and the F1 score was 0.84, indicating strong predictive capability. CONCLUSION: In this study, an XGBoost prediction model for assessing the risk of delayed postoperative bleeding after ESD in patients with gastric precancerous lesions was developed and validated. This model can be applied in clinical practice to effectively predict the risk of post-ESD bleeding for individual patients.
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Ressecção Endoscópica de Mucosa , Hemorragia Pós-Operatória , Lesões Pré-Cancerosas , Neoplasias Gástricas , Humanos , Feminino , Masculino , Neoplasias Gástricas/cirurgia , Pessoa de Meia-Idade , Estudos Retrospectivos , Lesões Pré-Cancerosas/cirurgia , Ressecção Endoscópica de Mucosa/efeitos adversos , Hemorragia Pós-Operatória/etiologia , Hemorragia Pós-Operatória/epidemiologia , Medição de Risco/métodos , Fatores de Risco , Idoso , Curva ROCRESUMO
Metallo-supramolecular cages have garnered tremendous attention for their diverse yet molecular-level precision structures. However, physical properties of these supramolecular ensembles, which are of potential significance in molecular electronics, remain largely unexplored. We herein constructed a series of octahedral metallo-cages and cage-fullerene complexes with notably enhanced structural stability. As such, we could systematically evaluate the electrical conductivity of these ensembles at both single-molecule level and aggregated bulk state (as well-defined films). Our findings reveal that counteranions and fullerene guests play a pivotal role in determining the electrical conductivity of aggregated state, while such effects are less significant for single-molecule conductance. Both counteranions and fullerenes effectively tune the electronic structures and packing density of metallo-supramolecular assemblies, and facilitate efficient charge transfer between the cage hosts and fullerenes, resulting in a notable one order of magnitude increase in electrical conductivity of the aggregated state.
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The activating receptor natural killer group 2D (NKG2D) expressed by Natural killer (NK) cells functions as a "master-switch" in governing the awakening status of NK cells. The NKG2D-mediated cytotoxicity has been declared to be related with the expression levels of NKG2D ligands (NKG2DLs) expressed on tumor cells. Therefore, selective induction of NKG2DLs could be a reliable approach to enhance the efficacy of NK cell-mediated immunotherapy. Our existing study demonstrated that Ciclopirox Olamine (CPX), an off-patent antifungal agent, effectively elevated the expression of NKG2DLs on leukemia cells and sensitized leukemia cells to NK-cell mediated cytolysis. Induction of ROS production and AKT phosphorylation by CPX is essential for the up-regulation of NKG2DLs expressions. Inhibition of AKT by using AKT inhibitor MK2206 decreased both NKG2DLs expressions and NK cell cytotoxicity. These data indicated that increased sensitivity of CPX-treated leukemia cells to NK cell cytolysis was attributed to higher NKG2DLs expressions, resulting from activated AKT signaling pathway. Our findings support the ongoing development of CPX as an anti-tumor agent and suggest its promising immunotherapeutic value in the medication of leukemia.
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Leucemia , Proteínas Proto-Oncogênicas c-akt , Humanos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ciclopirox/farmacologia , Ciclopirox/metabolismo , Subfamília K de Receptores Semelhantes a Lectina de Células NK/metabolismo , Células Matadoras Naturais/metabolismo , Transdução de Sinais , Leucemia/tratamento farmacológico , Leucemia/metabolismo , Linhagem Celular TumoralRESUMO
Excessive fluoride intake can cause dental fluorosis during teeth development and growth. However, the mechanisms underlying fluoride-induced enamel damage are still not fully elucidated. Previously, we observed fluoride-induced autophagy in ameloblasts, but the effects of fluoride on autophagy flux in ameloblasts remain unclear. Hence, this study aimed to clarify the effects of fluoride and rapamycin, an autophagy activator, on autophagy flux in ameloblasts. This in vitro study used the murine ameloblast-derived cell line LS8. Cells were treated with different concentrations of sodium fluoride (NaF) to evaluate NaF-induced cytotoxicity. Using transmission electron microscopy, we observed an increase in the number of autophagosomes with increasing fluoride concentrations. Western blot analyses showed increases in microtubule-associated protein 1 light chain 3 (LC3) and SQSTM1 (p62) expression after NaF treatment and an increase in LC3II expression after bafilomycin A1 administration. Together with changes in RFP-GFP-LC3 lentivirus expression, this demonstrated that fluoride impaired autophagy flux. Furthermore, we evaluated whether rapamycin can alleviate fluoride-induced cytotoxicity by restoring autophagy flux. Compared to the NaF-treated group, LS8 cells cotreated with NaF and rapamycin grew considerably better and had significantly decreased p62 expression. Taken together, these data suggest that fluoride-induced impaired autophagosome degradation may damage ameloblasts. This provides experimental in vitro evidence and an explanation for the observed NaF-induced toxicity of ameloblasts. Rapamycin probably alleviates this impairment by decreasing the expression of p62, thereby preventing autophagy defects.
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Ameloblastos , Fluoretos , Camundongos , Animais , Ameloblastos/metabolismo , Fluoretos/toxicidade , Sirolimo/farmacologia , Autofagia , Fluoreto de Sódio/toxicidadeRESUMO
Colorectal cancer stem cells (CCSCs) are implicated in colorectal tumor initiation, invasion, recurrence and treatment resistance, so elucidation of the mechanism underlying the cancer stem cells induction and development of drugs targeting CCSCs are vital for cancer treatment. Growing evidence shows that dysregulated deubiquitinase (DUBs) expression is frequently associated with stemness and maintenance of cancer stem cells (CSCs). In the current study, we found that upregulation of USP47 is associated with tumorigenesis and poor prognosis in clinical patients with colorectal cancer (CRC). Besides, USP47 was highly expressed in CCSCs enriched by serum-free culture. Further investigation showed that USP47 is closely involved in the maintenance of the stemness of CCSCs. USP47 silencing reduces proliferation and migration of colorectal cancer cells and suppresses the self-renewal of CCSCs by downregulating the expression of cancer stem cell markers, including CD44, CD133, CD166, OCT4 and NANOG. Furthermore, we identified Parthenolide (PTL), a natural sesquiterpene lactone, as a novel USP47 inhibitor. PTL diminishes CCSCs self-renewal and induces apoptosis of CCSCs. Taken together, our ï¬ndings highlighted a novel DUB involved in the modulation of CCSCs stemness and the potential of PTL in the CRC treatment by targeting CCSCs as the USP47 inhibitor.
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Neoplasias Colorretais/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Sesquiterpenos/farmacologia , Ubiquitina Tiolesterase/metabolismo , Apoptose/efeitos dos fármacos , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Inativação Gênica , Humanos , Células-Tronco Neoplásicas/efeitos dos fármacos , Prognóstico , Ligação Proteica/efeitos dos fármacos , Ubiquitina Tiolesterase/genética , Proteases Específicas de Ubiquitina , Regulação para Cima/efeitos dos fármacosRESUMO
Cancer has always been one of the most common malignant diseases in the world. Therefore, there is an urgent need to find potent agents with selective antitumor activity against cancer cells. It has been reported that antimicrobial peptides (AMPs) can selectively target tumor cells. In this study, we focused on the anti-tumor activity and mechanism of Brevinin-1RL1, a cationic α-helical AMP isolated from frog Rana limnocharis skin secretions. We found that Brevinin-1RL1 preferentially inhibits tumor cells rather than non-tumor cells with slight hemolytic activity. Cell viability assay demonstrated the intermolecular disulfide bridge contributes to the inhibitory activity of the peptide as the antitumor activity was abolished when the disulfide bridge reduced. Further mechanism studies revealed that both necrosis and apoptosis are involved in Brevinin-1RL1 mediated tumor cells death. Moreover, Brevinin-1RL1 induced extrinsic and mitochondria intrinsic apoptosis is caspases dependent, as the pan-caspase inhibitor z-VAD-FMK rescued Brevinin-1RL1 induced tumor cell proliferative inhibition. Immunohistology staining showed Brevinin-1RL1 mainly aggregated on the surface of the tumor cells. These results together suggested that Brevinin-1RL1 preferentially converges on the cancer cells to trigger necrosis and caspase-dependent apoptosis and Brevinin-1RL1 could be considered as a pharmacological candidate for further development as anti-cancer agent.
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Apoptose , Proteínas Citotóxicas Formadoras de Poros/farmacologia , Ranidae/metabolismo , Pele/química , Sequência de Aminoácidos , Animais , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Linhagem Celular Tumoral , Hemólise/efeitos dos fármacos , Concentração Inibidora 50 , Peso Molecular , Necrose , Proteínas Citotóxicas Formadoras de Poros/síntese química , Proteínas Citotóxicas Formadoras de Poros/química , Proteínas Citotóxicas Formadoras de Poros/isolamento & purificação , Agregados Proteicos/efeitos dos fármacosRESUMO
Proteomics by mass spectrometry (MS) allows for the identification of amino acid/peptide sequences in complex mixtures. Peptide analysis and quantitation enables screening of protein biomarkers and targeted protein biomarker analysis for clinical applications. Whereas miniature mass spectrometers have primarily demonstrated point-of-care analyses with simple procedures aiming at drugs and lipids, it would be interesting to explore their potential in analyzing proteins and peptides. In this work, we adapted a miniature MS instrument for peptide analysis. A mass range as wide as 100-2000 m/z was achieved for obtaining peptide spectra using this instrument with dual linear ion traps. MS2 and MS3 can be performed to analyze a wide range of peptides. The parameters of pressure, electric potentials, and solution conditions were optimized to analyze peptides with molecular weights between 900 and 1800 Da. The amino acid sequences were identified using both beam-type and in-trap collision-induced dissociation, and the results were comparable to those obtained by a commercial quadrupole time-of-flight mass spectrometer. With product ion monitoring scan mode, peptide quantitation was performed with a limit of detection of 20 nM achieved for the Met peptide. The method developed has also been applied to the analysis of the trypsin-digested cell lysate of SKBR3 cells with a low expression level of the Met gene.
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Peptídeos , Proteômica , Sequência de Aminoácidos , Espectrometria de Massas , ProteínasRESUMO
The contact of heterogeneous materials with different atomic structures and concentrations becomes omnipresent in modern materials. The differences across the interface introduce various gradients that could alter thermodynamic and kinetic behaviors of the materials. Here, we report a spontaneous melting of the interface formed by a crystalline metal and an amorphous solid at the temperature below their respective equilibrium melting temperatures. The transformation can even become continuous with disappearance of all known features of the first-order melting transition. We show that the change in the nature of melting in the interface region is caused by random disordering induced by interdiffusing atomic elements or impurities in the crystalline phase and the presence of a strong concentration gradient constrained by the sample geometry.
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Biotin labeling in combination with mass spectrometry has been widely applied in large-scale biological studies, such as determination of protein partners, protein subcellular localization, and protein post-translational modifications. Previous studies have shown that immunoaffinity enrichment is a better method than streptavidin/avidin purification for site-specific studies of biotinylated molecules. In this study, we made a crucial improvement to the elution phase of the immunoaffinity enrichment step for biotinylated peptides, which involves the addition of a highly organic solvent, and developed a monoclonal anti-biotin antibody that improved the identification number for biotinylated peptides. We then demonstrated its application in the characterization of protein interaction sites for the ß2 adrenergic receptor (ß2AR) by proximity labeling in living cells. Our research provides an improved and reproducible immunoaffinity enrichment method for site-specific biotin-related research.
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Human blood is a window of physiology and disease. Examination of biomarkers in blood is a common clinical procedure, which can be informative in diagnosis and prognosis of diseases, and in evaluating treatment effectiveness. There is still a huge demand on new blood biomarkers and assays for precision medicine nowadays, therefore plasma/serum proteomics has attracted increasing attention in recent years. How to effectively proceed with the biomarker discovery and clinical diagnostic assay development is a question raised to researchers who are interested in this area. In this review, we comprehensively introduce the background and advancement of technologies for blood proteomics, with a focus on mass spectrometry (MS). Analyzing existing blood biomarkers and newly-built diagnostic assays based on MS can shed light on developing new biomarkers and analytical methods. We summarize various protein analytes in plasma/serum which include total proteome, protein post-translational modifications, and extracellular vesicles, focusing on their corresponding sample preparation methods for MS analysis. We propose screening multiple protein analytes in the same set of blood samples in order to increase success rate for biomarker discovery. We also review the trends of MS techniques for blood tests including sample preparation automation, and further provide our perspectives on their future directions.
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Biomarcadores , Proteínas Sanguíneas , Espectrometria de Massas , Proteômica , Humanos , Proteômica/métodos , Biomarcadores/sangue , Espectrometria de Massas/métodos , Proteínas Sanguíneas/análise , Proteoma/análise , Processamento de Proteína Pós-Traducional , Vesículas Extracelulares/química , Vesículas Extracelulares/metabolismo , Plasma/químicaRESUMO
The aberrant activation of the Wnt/ß-catenin signaling pathway is closely associated with the development of various carcinomas, especially colorectal cancers (CRCs), where adenomatous colorectal polyposis (APC) mutations are the most frequently observed, which limits the anti-tumor efficiency of inhibitors targeting the upstream of Wnt/ß-catenin pathway. The anti-tumor activity of the naturally occurring alkaloid cepharanthine (CEP) extracted from the plant Stephania cepharantha Hayata has been reported in various types of tumors. We previously observed that its derivatives inhibited the Wnt/ß-catenin signaling in liver cancer; however, the specific mechanism remains unknown. In this study, we confirmed CEP can effectively inhibit APC-mutant CRC cell lines (SW480, SW620, LoVo) through disturbing of the Wnt/ß-catenin signaling and elucidated the underlying mechanisms. Here, we demonstrate that CEP attenuates the Wnt/ß-catenin signaling by decreasing the ß-catenin, subsequently impeding the proliferation of APC-mutant CRCs. Moreover, CEP induced ß-catenin transcription inhibition rather than the instability of ß-catenin protein and mRNA contributes to reduction of ß-catenin. Taken together, our findings identify CEP as the first ß-catenin transcriptional inhibitor in the modulation of Wnt/ß-catenin signaling and indicate CEP as a potential therapeutic option for the treatment of APC-mutated CRCs.
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To elucidate the role of post-translational modifications (PTMs) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein's structure and virulence, we generated a high-resolution map of 87 PTMs using liquid chromatography with tandem mass spectrometry data on the extracted spike protein from SARS-CoV-2 virions and then reconstituted its structure heterogeneity caused by PTMs. Nonetheless, Alphafold2, a high-accuracy artificial intelligence tool to perform protein structure prediction, relies solely on primary amino acid sequence, whereas the impact of PTM, which often modulates critical protein structure and function, is much ignored. To overcome this challenge, we proposed the mutagenesis approach-an in silico, site-directed amino acid substitution to mimic the influence of PTMs on protein structure due to altered physicochemical properties in the post-translationally modified amino acids-and then reconstituted the spike protein's structure from the substituted sequences by Alphafold2. For the first time, the proposed method revealed predicted protein structures resulting from PTMs, a problem that Alphafold2 has yet to address. As an example, we performed computational analyses of the interaction of the post-translationally modified spike protein with its host factors such as angiotensin-converting enzyme 2 to illuminate binding affinity. Mechanistically, this study suggested the structural analysis of post-translationally modified protein via mutagenesis and deep learning. To summarize, the reconstructed spike protein structures showed that specific PTMs can be used to modulate host factor binding, guide antibody design, and pave the way for new therapeutic targets. The code and Supplementary Materials are freely available at https://github.com/LTZHKUSTGZ/SARS-CoV-2-spike-protein-PTM.
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Background: Individuals of domestic migrant populations in China (specifically, migration that is economically driven) often face difficulties in social integration. They are suffering from discrimination and unfair treatment in work and life, which do harm to their physical/mental health and Subjective Well-Being (SWB). Methods: The current study utilized a stratified sampling survey in the Yangtze River Delta region of China, in October and November 2022. Six hundred and eleven useful self-reported questionnaires were collected. Questionnaires include questions about social integration, social capital, physical/mental health, and SWB; Bootstrapping method was used to test the mediating effect of physical health and mental health. Multiple hierarchical regression was used to test the moderating effect of social capital. Results: Social integration had positive impact on the SWB (r = 0.523, p < 0.01). Bootstrap analysis showed that physical health and mental health partially mediated the correlation between social integration and SWB of Floating Population with a mediation effect of 0.149 and 0.192. Social capital can positively moderate the relationship between two pair of variables: social integration and SWB (ß = 0.152, t = 4.42, p < 0.001), physical health and SWB (ß = 0.148, t = 4.39, p < 0.01). However, social capital does not play a significant moderating role in the association between the effect of mental health on SWB (ß = 0.032, t = 0.973, p > 0.05). Conclusion: This study proved a significant correlation between social integration and SWB of Floating Population, with physical/mental health playing a mediating role. Enhancing the social integration of floating population and keeping healthy physically and mentally are key to improving their SWB.
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Análise de Mediação , Saúde Mental , Humanos , Nível de Saúde , Integração Social , China/epidemiologiaRESUMO
Perfluorocarbon nanodroplets (PFCnDs) are sub-micrometer emulsions composed of a surfactant-encased perfluorocarbon (PFC) liquid and can be formulated to transiently vaporize through optical stimulation. However, the factors governing repeated optical droplet vaporization (ODV) have not been investigated. In this study, we employ high-frame-rate ultrasound (US) to characterize the ODV thresholds of various formulations and imaging parameters and identify those that exhibit low vaporization thresholds and repeatable vaporization. We observe a phenomenon termed "preconditioning", where initial laser pulses generate reduced US contrast that appears linked with an increase in nanodroplet size. Variation in laser pulse repetition frequency is found not to change the vaporization threshold, suggesting that "preconditioning" is not related to residual heat. Surfactants (bovine serum albumin, lipids, and zonyl) impact the vaporization threshold and imaging lifetime, with lipid shells demonstrating the best performance with relatively low thresholds (21.6 ± 3.7 mJ/cm2) and long lifetimes (t1/2 = 104 ± 21.5 pulses at 75 mJ/cm2). Physiological stiffness does not affect the ODV threshold and may enhance nanodroplet stability. Furthermore, PFC critical temperatures are found to correlate with vaporization thresholds. These observations enhance our understanding of ODV behavior and pave the way for improved nanodroplet performance in biomedical applications.
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Molecules that covalently engage target proteins are widely used as activity-based probes and covalent drugs. The performance of these covalent inhibitors is, however, often compromised by the paradox of efficacy and risk, which demands a balance between reactivity and selectivity. The challenge is more evident when targeting protein-protein interactions owing to their low ligandability and undefined reactivity. Here we report sulfur(VI) fluoride exchange (SuFEx) in vitro selection, a general platform for high-throughput discovery of covalent inhibitors from trillions of SuFEx-modified oligonucleotides. With SuFEx in vitro selection, we identified covalent inhibitors that cross-link distinct residues of the SARS-CoV-2 spike protein at its protein-protein interaction interface with the human angiotensin-converting enzyme 2. A separate suite of covalent inhibitors was isolated for the human complement C5 protein. In both cases, we observed a clear disconnection between binding affinity and cross-linking reactivity, indicating that direct search for the aimed reactivity-as enabled by SuFEx in vitro selection-is vital for discovering covalent inhibitors of high selectivity and potency.
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Fluoretos , Enxofre , Humanos , Fluoretos/farmacologia , Fluoretos/química , Enxofre/química , Glicoproteína da Espícula de Coronavírus , ProteínasRESUMO
Photophysical properties of benzil (1,2-diphenylethane-1,2-dione) and its derivatives in the crystal state have recently attracted much attention. However, the study of substituted benzils has mostly been limited to para-substituted derivatives, which did not induce a significant effect on the emission wavelength compared to pristine benzil. The effects of ortho- and meta-substituents on the photophysical properties in the crystal state have not been investigated so far. Our recently developed organocatalytic pinacol coupling of substituted benzaldehydes allowed us to prepare various ortho-, meta-, and para-substituted benzil derivatives and to investigate their luminescence properties. Ortho- and meta-substituents affected the electronic states of benzils in the crystal state, resulting in differences in their luminescence properties. The luminescence wavelength and type, i.e., phosphorescence or fluorescence, were altered by these substituents. Fast self-recovering phosphorescence-to-phosphorescence mechanochromism by the para-CF3 substituent at room temperature was also discovered.
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Indigo is an important pigment widely used in industries of food, cosmetics, and textile. In this work, the styrene monooxygenase StyAB from Pseudomonas putida was co-expressed with the tryptophanase TnaA and the chaperone groES-groEL in Escherichia coli for indigo production. Over-expression of the gene styAB endowed the recombinant E. coli AB with the capacity of indigo biosynthesis from indole and tryptophan. Tryptophan fermentation in E. coli AB generated about five times more indigo than that from indole, and the maximum 530 mg/L of indigo was obtained from 1.2 mg/mL of tryptophan. The gene TnaA was then co-expressed with styAB, and the tryptophanase activity significantly increased in the recombinant E. coli ABT. However, TnaA expression led to a decrease in the activity of StyAB and indigo yield in E. coli ABT. Furthermore, the plasmid pGro7 harboring groES-groEL was introduced into E. coli AB, which obviously promoted the activity of StyAB and accelerated indigo biosynthesis in the recombinant E. coli ABP. In addition, the maximum yield of indigo was further increased to 550 mg/L from 1.2 mg/mL of tryptophan in E. coli ABP. The genetic manipulation strategy proposed in this work could provide new insights into construction of indigo biosynthesis cell factory for industrial production.
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Amino acid metabolism could exert regulatory effects on Monascus pigments (MPs) biosynthesis. In this work, MPs biosynthesis regulated by methionine and S-adenosylmethionine (SAM) was investigated in Monascus purpureus RP2. The results indicated that the addition of methionine in fermentation significantly reduced MPs production by 60-70%, and it induced a higher expression of SAM synthetase Mon2A2272 and consequently led to SAM accumulation. However, the addition of SAM in fermentation promoted MPs production by a maximum of 35%, while over-expression of the gene Mon2A2272 led to a decrease in MPs yield, suggesting that SAM synthetase and SAM were likely to play different regulatory roles in MPs biosynthesis. Furthermore, the gene transcription profile indicated that SAM synthetase expression led to a higher expression of the transcriptional regulatory protein of the MPs biosynthesis gene cluster, while the addition of SAM gave rise to a higher expression of MPs biosynthesis activator and the global regulator LaeA, which probably accounted for changes in MPs production and the mycelium colony morphology of M. purpureus RP2 triggered by methionine and SAM. This work proposed a possible regulation mechanism of MPs biosynthesis by SAM metabolism from methionine. The findings provided a new perspective for a deep understanding of MPs biosynthesis regulation in M. purpureus.