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1.
ACS Nano ; 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39088752

RESUMO

Utilizing the ubiquitous fog in nature to create decentralized energy-harvesting devices, free from geographical and hydrological constraints, presents an opportunity to foster sustainable power generation. Extracting electrical energy from fog relies heavily on fog-digesting performance. Improving the efficiency of fogwater utilization remains a formidable challenge for existing fogwater energy-harvesting technologies. Inspired by the water-harvesting behavior of Tillandsia leaves, a smart lanceolate surface is developed to harvest triboelectric energy by rapidly digesting fog. Such a surface exhibits capabilities in fog management, encompassing precise fog capture, transportation, and critical droplet separation. Specifically, fog droplets condense at hydrophilic sites of acylated cellulose ester, subsequently migrating toward the rear under Laplace pressure, thereby producing energy as they traverse through the tail end. Such architecture yields a brief voltage restoration period (with an average of 9.36 s), can rush the capacitor to 11.59 V within 20 s, and achieves a water-digestion rate of up to 71.05 kg/m2 h. This biomimetic approach enhances the water-digestion efficacy of the atmospheric water energy apparatus and offers perspectives on mitigating deficiencies in power resources.

2.
Nat Commun ; 15(1): 5737, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38982157

RESUMO

Exploring the promiscuity of native enzymes presents a promising strategy for expanding their synthetic applications, particularly for catalyzing challenging reactions in non-native contexts. In this study, we explore the promiscuous potential of old yellow enzymes (OYEs) to facilitate the Morita-Baylis-Hillman reaction (MBH reaction), leveraging substrate similarities between MBH reaction and reduction reaction. Using mass spectrometry and spectroscopic techniques, we confirm promiscuity of GkOYE in both MBH and reduction reactions. By blocking H- and H+ transfer pathways, we engineer GkOYE.8, which loses its reduction ability but enhances its MBH activity. The structural basis of MBH reaction catalyzed by GkOYE.8 is obtained through mutation studies and kinetic simulations. Furthermore, enantiocomplementary mutants GkOYE.11 and GkOYE.13 are obtained by directed evolution, exhibiting the ability to accept various aromatic aldehydes and alkenes as substrates. This study demonstrates the potential of leveraging substrate similarities to unlock enzyme functionalities, enabling the catalysis of new-to-nature reactions.


Assuntos
Biocatálise , Especificidade por Substrato , Cinética , Aldeídos/metabolismo , Aldeídos/química , Catálise , Mutação , Alcenos/metabolismo , Alcenos/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Engenharia de Proteínas
3.
Appl Environ Microbiol ; : e0096824, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39082808

RESUMO

Hyperosmotic stress tolerance is crucial for Saccharomyces cerevisiae in producing value-added products from renewable feedstock. The limited understanding of its tolerance mechanism has impeded the application of these microbial cell factories. Previous studies have shown that Med3 plays a role in hyperosmotic stress in S. cerevisiae. However, the specific function of Med3 in hyperosmotic stress tolerance remains unclear. In this study, we showed that the deletion of the mediator Med3 impairs S. cerevisiae growth under hyperosmotic stress. Phenotypic analyses and yeast two-hybrid assays revealed that Med3 interacts with the transcription factor Stb5 to regulate the expression of the genes gnd1 and ald6, which are involved in NADPH production under hyperosmotic stress conditions. The deletion of med3 resulted in a decrease in intracellular NADPH content, leading to increased oxidative stress and elevated levels of intracellular reactive oxygen species under hyperosmotic stress, thereby impacting bud formation. These findings highlight the significant role of Med3 as a regulator in maintaining NADPH generation and redox homeostasis in S. cerevisiae during hyperosmotic stress.IMPORTANCEHyperosmotic stress tolerance in the host strain is a significant challenge for fermentation performance in industrial production. In this study, we showed that the S. cerevisiae mediator Med3 is essential for yeast growth under hyperosmotic conditions. Med3 interacts with the transcription factor Stb5 to regulate the expression of genes involved in the NADPH-generation system during hyperosmotic stress. Adequate NADPH ensures the timely removal of excess reactive oxygen species and supports bud formation under these conditions. This work highlights the crucial role of Med3 as a regulator in maintaining NADPH generation and redox homeostasis in S. cerevisiae during hyperosmotic stress.

4.
ACS Synth Biol ; 13(6): 1879-1892, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38847341

RESUMO

Aromatic d-amino acids (d-AAs) play a pivotal role as important chiral building blocks and key intermediates in fine chemical and drug synthesis. Meso-diaminopimelate dehydrogenase (DAPDH) serves as an excellent biocatalyst in the synthesis of d-AAs and their derivatives. However, its strict substrate specificity and the lack of efficient engineering methods have hindered its widespread application. Therefore, this study aims to elucidate the catalytic mechanism underlying DAPDH from Proteus vulgaris (PvDAPDH) through the examination of its crystallographic structure, computational simulations of potential energies and molecular dynamics simulations, and site-directed mutagenesis. Mechanism-guided computational design showed that the optimal mutant PvDAPDH-M3 increased specific activity and catalytic efficiency (kcat/Km) for aromatic keto acids up to 124-fold and 92.4-fold, respectively, compared to that of the wild type. Additionally, it expanded the substrate scope to 10 aromatic keto acid substrates. Finally, six high-value-added aromatic d-AAs and their derivatives were synthesized using a one-pot three-enzyme cascade reaction, exhibiting a good conversion rate ranging from 32 to 84% and excellent stereoselectivity (enantiomeric excess >99%). These findings provide a potential synthetic pathway for the green industrial production of aromatic d-AAs.


Assuntos
Aminoácido Oxirredutases , Aminoácidos Aromáticos , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Aminoácido Oxirredutases/metabolismo , Aminoácido Oxirredutases/genética , Aminoácido Oxirredutases/química , Especificidade por Substrato , Aminoácidos Aromáticos/metabolismo , Aminoácidos Aromáticos/biossíntese , Proteus vulgaris/enzimologia , Proteus vulgaris/genética , Biocatálise , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química
5.
Med Sci Monit ; 30: e943972, 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38907516

RESUMO

BACKGROUND Simethicone can improve bowel preparation quality, but the optimal timing of oral simethicone before colonoscopy has not been determined. This study aimed to explore the effect of the time interval between oral simethicone and the start of colonoscopy (S-C) on bowel preparation quality. MATERIAL AND METHODS A total of 364 patients undergoing colonoscopy at our department from August 1, 2021 to November 30, 2021 were included in the training cohort, and 420 consecutive patients from December 15, 2021 to January 31, 2022 comprised the validation cohort. They were classified into short and long S-C groups according to the median S-C. Bowel preparation quality evaluated by the Boston Bowel Preparation Scale was compared between the 2 groups. Logistic regression analyses were performed to explore the correlation between S-C and bowel preparation quality, and we explored the effect of run-way time and time of starting colonoscopy on bowel preparation quality. RESULTS In the training cohort, 182 and 182 patients were classified into the short and long S-C groups, respectively; in the validation cohort, 210 and 210 patients were classified into the 2 groups, respectively. In the 2 cohorts, the short S-C group had a significantly higher rate of adequate/excellent bowel preparation than the long S-C group. Logistic regression analyses showed that shorter S-C, shorter run-way time, and colonoscopy in the morning were all correlated with adequate/excellent bowel preparation. CONCLUSIONS Bowel preparation quality may be affected by S-C, run-way time, and time of starting colonoscopy. S-C shortening should be given equal importance as run-way time shortening.


Assuntos
Catárticos , Colonoscopia , Simeticone , Humanos , Colonoscopia/métodos , Masculino , Feminino , Simeticone/administração & dosagem , Pessoa de Meia-Idade , Catárticos/administração & dosagem , Administração Oral , Idoso , Adulto , Fatores de Tempo
6.
Nano Lett ; 24(25): 7809-7818, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38874576

RESUMO

Noncontact sensing technology serves as a pivotal medium for seamless data acquisition and intelligent perception in the era of the Internet of Things (IoT), bringing innovative interactive experiences to wearable human-machine interaction perception networks. However, the pervasive limitations of current noncontact sensing devices posed by harsh environmental conditions hinder the precision and stability of signals. In this study, the triboelectric nanopaper prepared by a phase-directed assembly strategy is presented, which possesses low charge transfer mobility (1618 cm2 V-1 s-1) and exceptional high-temperature stability. Wearable self-powered noncontact sensors constructed from triboelectric nanopaper operate stably under high temperatures (200 °C). Furthermore, a temperature warning system for workers in hazardous environments is demonstrated, capable of nonintrusively identifying harmful thermal stimuli and detecting motion status. This research not only establishes a technological foundation for accurate and stable noncontact sensing under high temperatures but also promotes the sustainable intelligent development of wearable IoT devices under extreme environments.

7.
Toxicol Appl Pharmacol ; 489: 117012, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38906511

RESUMO

Keloid formation has been linked to abnormal fibroblast function, such as excessive proliferation and extracellular matrix (ECM) production. Serum deprivation protein response (SDPR) is a crucial regulator of cellular function under diverse pathological conditions, yet its role in keloid formation remains unknown. The current work investigated the function of SDPR in regulating the proliferation, motility, and ECM production of keloid fibroblasts (KFs), as well as to decipher the mechanisms involved. Analysis of RNA sequencing data from the GEO database demonstrated significant down-regulation of SDPR in KF compared to normal fibroblasts (NFs). This down-regulation was also observed in clinical keloid specimens and isolated KFs. Overexpression of SDPR suppressed the proliferation, motility, and ECM production of KFs, while depletion of SDPR exacerbated the enhancing impact of TGF-ß1 on the proliferation, motility, and ECM production of NFs. Mechanistic studies revealed that SDPR overexpression repressed TGF-ß/Smad signal cascade activation in KFs along with decreased levels of phosphorylated Samd2/3, while SDPR depletion exacerbated TGF-ß/Smad activation in TGF-ß1-stimulated NFs. SDPR overexpression also repressed ERK1/2 activation in KFs, while SDPR depletion exacerbated ERK1/2 activation in TGF-ß1-stimulated NFs. Inhibition of ERK1/2 abolished SDPR-depletion-induced TGF-ß1/Smad activation, cell proliferation, motility, and ECM production in NFs. In conclusion, SDPR represses the proliferation, motility, and ECM production in KFs by blocking the TGF-ß1/Smad pathway in an ERK1/2-dependent manner. The findings highlight the role of SDPR in regulating abnormal behaviors of fibroblasts associated with keloid formation and suggest it as a potential target for anti-keloid therapy development.


Assuntos
Movimento Celular , Proliferação de Células , Matriz Extracelular , Fibroblastos , Queloide , Sistema de Sinalização das MAP Quinases , Proteínas Smad , Fator de Crescimento Transformador beta1 , Humanos , Queloide/patologia , Queloide/metabolismo , Queloide/genética , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Proliferação de Células/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Fator de Crescimento Transformador beta1/metabolismo , Matriz Extracelular/metabolismo , Matriz Extracelular/efeitos dos fármacos , Proteínas Smad/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Transdução de Sinais , Células Cultivadas , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Masculino , Feminino , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Adulto
8.
Langmuir ; 40(28): 14555-14560, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38940619

RESUMO

Understanding the interaction between metal ions as catalytic centers and supramolecular scaffolds as chiral substrates plays an important role in developing chiral supramolecular catalysts with high enantioselectivity. Herein, we found that compared with l-norleucine chiral amphiphile (l-NorC16), l-methionine chiral amphiphile (l-MetC16) with the only heteroatom of S site difference in the hydrophilic group can form a similar supramolecular chiral nanoribbon (NR) with the bilayer structure through the self-assembly approach; yet, the interaction between the Cu(II) ion catalytic centers and supramolecular scaffolds is reinforced, favoring the chirality transfer and therefore enhancing their catalytic enantioselectivity of Diels-Alder reaction from 23% [l-NorC16-NR-Cu(II)] to 78% [l-MetC16-NR-Cu(II)]. Our work demonstrates a new strategy from the perspective of strengthening the metal ion-supramolecular scaffold interaction for the preparation of chiral supramolecular catalysts with good catalytic enantioselectivity.

9.
Pestic Biochem Physiol ; 202: 105953, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38879307

RESUMO

The brown planthopper (Nilaparvata lugens) is a major destructive rice pest in Asia. High levels of insecticide resistance have been frequently reported, and the G932C mutation in the chitin synthase 1 (CHS1) gene has been found to mediate buprofezin resistance. However, there has been no direct evidence to confirm the functional significance of the single G932C substitution mutation leading to buprofezin resistance in N. lugens. Here, we successfully constructed a knock-in homozygous strain (Nl-G932C) of N. lugens using CRISPR/Cas9 coupled with homology-directed repair (HDR). Compared with the background strain susceptible to buprofezin (Nl-SS), the knock-in strain (Nl-G932C) showed a 94.9-fold resistance to buprofezin. Furthermore, resistant strains (Nl-932C) isolated from the field exhibited a 2078.8-fold resistance to buprofezin, indicating that there are other mechanisms contributing to buprofezin resistance in the field. Inheritance analysis showed that the resistance trait is incomplete dominance. In addition, the Nl-G932C strain had a relative fitness of 0.33 with a substantially decreased survival rate, emergence rate, and fecundity. This study provided in vivo functional evidence for the causality of G932C substitution mutation of CHS1 with buprofezin resistance and valuable information for facilitating the development of resistance management strategies in N. lugens. This is the first example of using CRISPR/Cas9 gene-editing technology in a hemipteran insect to directly confirm the role of a candidate target site mutation in insecticide resistance.


Assuntos
Sistemas CRISPR-Cas , Quitina Sintase , Hemípteros , Resistência a Inseticidas , Inseticidas , Tiadiazinas , Animais , Hemípteros/genética , Resistência a Inseticidas/genética , Tiadiazinas/farmacologia , Quitina Sintase/genética , Inseticidas/farmacologia , Mutação , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Técnicas de Introdução de Genes , Feminino , Masculino
10.
Phys Chem Chem Phys ; 26(25): 17599-17608, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38864183

RESUMO

We conducted a study on the trajectory-dependent threshold effects of proton stopping power in LiF nanosheets using time-dependent density functional theory non-adiabatically coupled to the molecular dynamics. This study covered protons with initial velocities in the range of 0.1-1.0 a.u., offering a vast amount of detailed information on the electronic structure during the stopping process with superior spatial and temporal resolution. Our results show that the impact parameters of incident protons play a crucial role in determining the threshold behavior of proton stopping power in LiF nanosheets. Most importantly, we found that close collisions do not exhibit a discernible threshold. In addition, the research results also revealed the time dependence of the number of electrons occupying the atomic orbitals of F and Li as protons pass through the nanosheets.

11.
Food Chem ; 457: 140165, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38936118

RESUMO

Para-hydroxybenzoic acid (PHBA) is extensively used as an additive in the food and cosmetics industries, significantly enhancing product shelf life and stability. While microbial fermentation offers an environment-friendly and sustainable method for producing PHBA, the titer and productivity are limited due to product toxicity and complex metabolic flux distributions. Here, we initially redesigned a L-phenylalanine-producing Escherichia coli by employing rational metabolic engineering strategies, resulting in the production of PHBA reached the highest reported level of 14.17 g/L. Subsequently, a novel accelerated evolution system was devised comprising deaminase, the alpha subunit of RNA polymerase, an uracil-DNA glycosylase inhibitor, and the PHBA-responsive promoter PyhcN. This system enabled us to obtain a mutant strain exhibiting a 47% increase in the half-inhibitory concentration (IC50) for PHBA within 15 days. Finally, the evolved strain achieved a production of 21.35 g/L PHBA in a 5-L fermenter, with a yield of 0.19 g/g glucose and a productivity rate of 0.44 g/L/h. This engineered strain emerges as a promising candidate for industrial production of PHBA through an eco-friendly approach.

12.
ACS Synth Biol ; 13(6): 1820-1830, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38767944

RESUMO

Cadaverine is a critical C5 monomer for the production of polyamides. Pyridoxal 5'-phosphate (PLP), as a crucial cofactor for the key enzyme lysine decarboxylase in the cadaverine biosynthesis pathway, has seen a persistent shortage, leading to limitations in cadaverine production. To address this issue, a dual-pathway strategy was implemented, synergistically enhancing both endogenous and heterologous PLP synthesis modules and resulting in improved PLP synthesis. Subsequently, a growth-stage-dependent molecular switch was introduced to balance the precursor competition between PLP synthesis and cell growth. Additionally, a PLP sensor-based negative feedback circuit was constructed by integrating a newly identified PLP-responsive promoter PygjH and an arabinose-regulated system, dynamically regulating the expression of the PLP synthetic genes and preventing excessive intracellular PLP accumulation. The optimal strain, L18, cultivated in the minimal medium AM1, demonstrated cadaverine production with a titer, yield, and productivity of 64.03 g/L, 0.23 g/g glucose, and 1.33 g/L/h, respectively. This represents the highest titer reported to date in engineered Escherichia coli by fed-batch fermentation in a minimal medium.


Assuntos
Cadaverina , Meios de Cultura , Escherichia coli , Engenharia Metabólica , Fosfato de Piridoxal , Cadaverina/metabolismo , Cadaverina/biossíntese , Fosfato de Piridoxal/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Engenharia Metabólica/métodos , Meios de Cultura/química , Regiões Promotoras Genéticas , Carboxiliases/genética , Carboxiliases/metabolismo
13.
J Neuroinflammation ; 21(1): 140, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38807233

RESUMO

BACKGROUND: Perihematomal edema (PHE) after post-intracerebral hemorrhage (ICH) has complex pathophysiological mechanisms that are poorly understood. The complicated immune response in the post-ICH brain constitutes a crucial component of PHE pathophysiology. In this study, we aimed to characterize the transcriptional profiles of immune cell populations in human PHE tissue and explore the microscopic differences between different types of immune cells. METHODS: 9 patients with basal ganglia intracerebral hemorrhage (hematoma volume 50-100 ml) were enrolled in this study. A multi-stage profile was developed, comprising Group1 (n = 3, 0-6 h post-ICH, G1), Group2 (n = 3, 6-24 h post-ICH, G2), and Group3 (n = 3, 24-48 h post-ICH, G3). A minimal quantity of edematous tissue surrounding the hematoma was preserved during hematoma evacuation. Single cell RNA sequencing (scRNA-seq) was used to map immune cell populations within comprehensively resected PHE samples collected from patients at different stages after ICH. RESULTS: We established, for the first time, a comprehensive landscape of diverse immune cell populations in human PHE tissue at a single-cell level. Our study identified 12 microglia subsets and 5 neutrophil subsets in human PHE tissue. What's more, we discovered that the secreted phosphoprotein-1 (SPP1) pathway served as the basis for self-communication between microglia subclusters during the progression of PHE. Additionally, we traced the trajectory branches of different neutrophil subtypes. Finally, we also demonstrated that microglia-produced osteopontin (OPN) could regulate the immune environment in PHE tissue by interacting with CD44-positive cells. CONCLUSIONS: As a result of our research, we have gained valuable insight into the immune-microenvironment within PHE tissue, which could potentially be used to develop novel treatment modalities for ICH.


Assuntos
Edema Encefálico , Hemorragia Cerebral , Progressão da Doença , Análise de Sequência de RNA , Análise de Célula Única , Humanos , Edema Encefálico/imunologia , Edema Encefálico/patologia , Edema Encefálico/genética , Edema Encefálico/metabolismo , Edema Encefálico/etiologia , Hemorragia Cerebral/imunologia , Hemorragia Cerebral/patologia , Hemorragia Cerebral/genética , Masculino , Feminino , Pessoa de Meia-Idade , Análise de Sequência de RNA/métodos , Idoso , Hematoma/patologia , Hematoma/imunologia , Hematoma/genética
14.
Chembiochem ; 25(11): e202400142, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38742957

RESUMO

The widespread attention towards 1,4-butanediol (BDO) as a key chemical raw material stems from its potential in producing biodegradable plastics. However, the efficiency of its biosynthesis via current bioprocesses is limited. In this study, a dual-pathway approach for 1,4-BDO production from succinic acid was developed. Specifically, a double-enzyme catalytic pathway involving carboxylic acid reductase and ethanol dehydrogenase was proposed. Optimization of the expression levels of the pathway enzymes led to a significant 318 % increase in 1,4-BDO titer. Additionally, the rate-limiting enzyme MmCAR was engineered to enhance the kcat/KM values by 50 % and increase 1,4-BDO titer by 46.7 %. To address cofactor supply limitations, an NADPH and ATP cycling system was established, resulting in a 48.9 % increase in 1,4-BDO production. Ultimately, after 48 hours, 1,4-BDO titers reached 201 mg/L and 1555 mg/L in shake flask and 5 L fermenter, respectively. This work represents a significant advancement in 1,4-BDO synthesis from succinic acid, with potential applications in the organic chemical and food industries.


Assuntos
Butileno Glicóis , Escherichia coli , Ácido Succínico , Butileno Glicóis/metabolismo , Butileno Glicóis/química , Ácido Succínico/metabolismo , Ácido Succínico/química , Escherichia coli/metabolismo , Escherichia coli/genética , Biocatálise , Álcool Desidrogenase/metabolismo , Oxirredutases/metabolismo , Oxirredutases/genética , Fermentação
15.
ACS Synth Biol ; 13(6): 1621-1632, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38758631

RESUMO

Microbial synthetic epigenetics offers significant opportunities for the design of synthetic biology tools by leveraging reversible gene control mechanisms without altering DNA sequences. However, limited understanding and a lack of technologies for thorough analysis of the mechanisms behind epigenetic modifications have hampered their utilization in biotechnological applications. In this review, we explore advancements in developing epigenetic-based synthetic gene regulatory tools at both transcriptional and post-transcriptional levels. Furthermore, we examine strategies developed to construct epigenetic-based circuits that provide controllable and stable gene regulation, aiming to boost the performance of microbial chassis cells. Finally, we discuss the current challenges and perspectives in the development of synthetic epigenetic tools.


Assuntos
Epigênese Genética , Biologia Sintética , Biologia Sintética/métodos , Epigênese Genética/genética , Bactérias/genética , Redes Reguladoras de Genes/genética , Biotecnologia/métodos
16.
J Agric Food Chem ; 72(19): 11029-11040, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38699920

RESUMO

l-Phenylalanine (l-Phe) is widely used in the food and pharmaceutical industries. However, the biosynthesis of l-Phe using Escherichia coli remains challenging due to its lower tolerance to high concentration of l-Phe. In this study, to efficiently synthesize l-Phe, the l-Phe biosynthetic pathway was reconstructed by expressing the heterologous genes aroK1, aroL1, and pheA1, along with the native genes aroA, aroC, and tyrB in the shikimate-producing strain E. coli SA09, resulting in the engineered strain E. coli PHE03. Subsequently, adaptive evolution was conducted on E. coli PHE03 to enhance its tolerance to high concentrations of l-Phe, resulting in the strain E. coli PHE04, which reduced the cell mortality to 36.2% after 48 h of fermentation. To elucidate the potential mechanisms, transcriptional profiling was conducted, revealing MarA, a DNA-binding transcriptional dual regulator, as playing a crucial role in enhancing cell membrane integrity and fluidity for improving cell tolerance to high concentrations of l-Phe. Finally, the titer, yield, and productivity of l-Phe with E. coli PHE05 overexpressing marA were increased to 80.48 g/L, 0.27 g/g glucose, and 1.68 g/L/h in a 5-L fed-batch fermentation, respectively.


Assuntos
Escherichia coli , Fermentação , Engenharia Metabólica , Fenilalanina , Escherichia coli/genética , Escherichia coli/metabolismo , Fenilalanina/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Vias Biossintéticas
17.
Angew Chem Int Ed Engl ; 63(32): e202406060, 2024 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-38789390

RESUMO

The hydroxylation of remote C(sp3)-H bonds in aliphatic amino acids yields crucial precursors for the synthesis of high-value compounds. However, accurate regulation of the regioselectivity of remote C(sp3)-H bonds hydroxylation in aliphatic amino acids continues to be a common challenge in chemosynthesis and biosynthesis. In this study, the Fe(II)/α-ketoglutarate-dependent dioxygenase from Bacillus subtilis (BlAH) was mined and found to catalyze hydroxylation at the γ and δ sites of aliphatic amino acids. Crystal structure analysis, molecular dynamics simulations, and quantum chemical calculations revealed that regioselectivity was regulated by the spatial effect of BlAH. Based on these results, the spatial effect of BlAH was reconstructed to stabilize the transition state at the δ site of aliphatic amino acids, thereby successfully reversing the γ site regioselectivity to the δ site. For example, the regioselectivity of L-Homoleucine (5 a) was reversed from the γ site (1 : 12) to the δ site (>99 : 1). The present study not only expands the toolbox of biocatalysts for the regioselective functionalization of remote C(sp3)-H bonds, but also provides a theoretical guidance for the precision-driven modification of similarly remote C(sp3)-H bonds in complex molecules.


Assuntos
Aminoácidos , Bacillus subtilis , Dioxigenases , Ácidos Cetoglutáricos , Hidroxilação , Bacillus subtilis/enzimologia , Dioxigenases/metabolismo , Dioxigenases/química , Ácidos Cetoglutáricos/metabolismo , Ácidos Cetoglutáricos/química , Aminoácidos/química , Aminoácidos/metabolismo , Estereoisomerismo , Compostos Ferrosos/química , Compostos Ferrosos/metabolismo , Simulação de Dinâmica Molecular
18.
Enzyme Microb Technol ; 178: 110448, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38657401

RESUMO

D-allulose is a naturally occurring rare sugar and beneficial to human health. However, the efficient biosynthesis of D-allulose remains a challenge. Here, we mined a new D-tagatose 3-epimerase from Kroppenstedtia eburnean (KeDt3e) with high catalytic efficiency. Initially, crucial factors contributing to the low conversion of KeDt3e were identified through crystal structure analysis, density functional theory calculations (DFT), and molecular dynamics (MD) simulations. Subsequently, based on the mechanism, combining restructuring the flexible region, proline substitution based onconsensus sequence analysis, introducing disulfide bonds, and grafting properties, and reshaping the active center, the optimal mutant M5 of KeDt3e was obtained with enhanced thermostability and activity. The optimal mutant M5 exhibited an enzyme activity of 130.8 U/mg, representing a 1.2-fold increase; Tm value increased from 52.7 °C to 71.2 °C; and half-life at 55 °C extended to 273.7 min, representing a 58.2-fold improvement, and the detailed mechanism of performance improvement was analyzed. Finally, by screening the ribosome-binding site (RBS) of the optimal mutant M5 recombinant bacterium (G01), the engineered strain G08 with higher expression levels was obtained. The engineered strain G08 catalyzed 500 g/L D-fructose to produce 172.4 g/L D-allulose, with a conversion of 34.4% in 0.5 h and productivity of 344.8 g/L/h on a 1 L scale. This study presents a promising approach for industrial-scale production of D-allulose.


Assuntos
Carboidratos Epimerases , Estabilidade Enzimática , Hexoses , Hexoses/metabolismo , Carboidratos Epimerases/genética , Carboidratos Epimerases/metabolismo , Carboidratos Epimerases/química , Simulação de Dinâmica Molecular , Frutose/metabolismo , Cinética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Especificidade por Substrato , Engenharia de Proteínas , Racemases e Epimerases/metabolismo , Racemases e Epimerases/genética , Racemases e Epimerases/química
19.
Biotechnol Bioeng ; 121(7): 2147-2162, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38666765

RESUMO

P-coumaric acid (p-CA), a pant metabolite with antioxidant and anti-inflammatory activity, is extensively utilized in biomedicine, food, and cosmetics industry. In this study, a synthetic pathway (PAL) for p-CA was designed, integrating three enzymes (AtPAL2, AtC4H, AtATR2) into a higher l-phenylalanine-producing strain Escherichia coli PHE05. However, the lower soluble expression and activity of AtC4H in the PAL pathway was a bottleneck for increasing p-CA titers. To overcome this limitation, the soluble expression of AtC4H was enhanced through N-terminal modifications. And an optimal mutant, AtC4HL373T/G211H, which exhibited a 4.3-fold higher kcat/Km value compared to the wild type, was developed. In addition, metabolic engineering strategies were employed to increase the intracellular NADPH pool. Overexpression of ppnk in engineered E. coli PHCA20 led to a 13.9-folds, 1.3-folds, and 29.1% in NADPH content, the NADPH/NADP+ ratio and p-CA titer, respectively. These optimizations significantly enhance p-CA production, in a 5-L fermenter using fed-batch fermentation, the p-CA titer, yield and productivity of engineered strain E. coli PHCA20 were 3.09 g/L, 20.01 mg/g glucose, and 49.05 mg/L/h, respectively. The results presented here provide a novel way to efficiently produce the plant metabolites using an industrial strain.


Assuntos
Ácidos Cumáricos , Escherichia coli , Glucose , Engenharia Metabólica , Propionatos , Escherichia coli/genética , Escherichia coli/metabolismo , Ácidos Cumáricos/metabolismo , Engenharia Metabólica/métodos , Glucose/metabolismo , Propionatos/metabolismo
20.
Chem Commun (Camb) ; 60(34): 4569-4572, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38572692

RESUMO

L/D-Phenylglycine amphiphiles and metal ions with peroxidase-like activity self-assembled into chiral nanoribbons, which act as efficient chiral supramolecular nanozymes for catalyzing the 3,4-dihydroxy-L/D-phenylalanine (L/D-DOPA) oxidation reactions. The catalytic efficiency and enantioselectivity are dominated by the chirality transfer and the synergistic effect between the metal ions and chiral nanoribbons.

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