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2.
Nat Commun ; 15(1): 1591, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38383540

RESUMEN

CO2 fixation plays a key role to make biobased production cost competitive. Here, we use 3-hydroxypropionic acid (3-HP) to showcase how CO2 fixation enables approaching theoretical-yield production. Using genome-scale metabolic models to calculate the production envelope, we demonstrate that the provision of bicarbonate, formed from CO2, restricts previous attempts for high yield production of 3-HP. We thus develop multiple strategies for bicarbonate uptake, including the identification of Sul1 as a potential bicarbonate transporter, domain swapping of malonyl-CoA reductase, identification of Esbp6 as a potential 3-HP exporter, and deletion of Uga1 to prevent 3-HP degradation. The combined rational engineering increases 3-HP production from 0.14 g/L to 11.25 g/L in shake flask using 20 g/L glucose, approaching the maximum theoretical yield with concurrent biomass formation. The engineered yeast forms the basis for commercialization of bio-acrylic acid, while our CO2 fixation strategies pave the way for CO2 being used as the sole carbon source.


Asunto(s)
Carbono , Ácido Láctico/análogos & derivados , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Bicarbonatos/metabolismo , Ingeniería Metabólica
3.
Small ; : e2310465, 2024 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-38366001

RESUMEN

The modification of metal oxides with noble metals is one of the most effective means of improving gas-sensing performance of chemiresistors, but it is often accompanied by unintended side effects such as sensor resistance increases up to unmeasurable levels. Herein, a carbonization-oxidation method is demonstrated using ultrasonic spray pyrolysis technique to realize platinum (Pt) single atom (SA) substitutional doping into SnO2 (named PtSA-SnO2 ). The substitutional doping strategy can obviously enhance gas-sensing properties, and meanwhile decrease sensor resistance by two orders of magnitude (decreased from ≈850 to ≈2 MΩ), which are attributed to the tuning of band gap and fermi-level position, efficient single atom catalysis, and the raising of adsorption capability of formaldehyde, as validated by the state-of-the-art characterizations, such as spherical aberration-corrected scanning transmission electron microscopy (Cs -corrected STEM), in situ diffuse reflectance infrared Fourier transformed spectra (in situ DRIFT), CO temperature-programmed reduction (CO-TPR), and theoretical calculations. As a proof of concept, the developed PtSA-SnO2 sensor shows humidity-independent (30-70% relative humidity) gas-sensing performance in the selective detection of formaldehyde with high response, distinguishable selectivity (8< Sformaldehyde /Sinterferant <14), and ultra-low detection limit (10 ppb). This work presents a generalized and facile method to design high-performance metal oxides for chemical sensing of volatile organic compounds (VOCs).

4.
IEEE Trans Cybern ; PP2024 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-38349837

RESUMEN

Deep reinforcement learning (DRL) is a powerful tool for learning from interactions within a stationary environment where state transition and reward distributions remain constant throughout the process. Addressing the practical but challenging nonstationary environments with time-varying state transition or reward function changes during the interactions, ingenious solutions are essential for the stability and robustness of DRL agents. A key assumption to cope with nonstationary environments is that the change points between the previous and the new environments are known beforehand. Unfortunately, this assumption is impractical in many cases, such as outdoor robots and online recommendations. To address this problem, this article presents a robust DRL algorithm for nonstationary environments with unknown change points. The algorithm actively detects change points by monitoring the joint distribution of states and actions. A detection boosted, gradient-constrained optimization method then adapts the training of the current policy with the supporting knowledge of formerly well-trained policies. The previous policies and experience help the current policy adapt rapidly to environmental changes. Experiments show that the proposed method accumulates the highest reward among several alternatives and is the fastest to adapt to new environments. This work has compelling potential for increasing the environmental suitability of intelligent agents, such as drones, autonomous vehicles, and underwater robots.

5.
Virol J ; 21(1): 4, 2024 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-38178220

RESUMEN

BACKGROUND: Cross-species transmission of zoonotic IAVs to humans is potentially widespread and lethal, posing a great threat to human health, and their cross-species transmission mechanism has attracted much attention. miRNAs have been shown to be involved in the regulation of IAVs infection and immunity, however, few studies have focused on the molecular mechanisms underlying miRNAs and mRNAs expression after IAVs cross-species infection. METHODS: We used tree shrews, a close relative of primates, as a model and used RNA-Seq and bioinformatics tools to analyze the expression profiles of DEMs and DEGs in the nasal turbinate tissue at different time points after the newly emerged swine influenza A virus SW2783 cross-species infection with tree shrews, and miRNA-mRNA interaction maps were constructed and verified by RT-qPCR, miRNA transfection and luciferase reporter assay. RESULTS: 14 DEMs were screened based on functional analysis and interaction map, miR-760-3p, miR-449b-2, miR-30e-3p, and miR-429 were involved in the signal transduction process of replication and proliferation after infection, miR-324-3p, miR-1301-1, miR-103-1, miR-134-5p, miR-29a, miR-31, miR-16b, miR-34a, and miR-125b participate in negative feedback regulation of genes related to the immune function of the body to activate the antiviral immune response, and miR-106b-3p may be related to the cross-species infection potential of SW2783, and the expression level of these miRNAs varies in different days after infection. CONCLUSIONS: The miRNA regulatory networks were constructed and 14 DEMs were identified, some of them can affect the replication and proliferation of viruses by regulating signal transduction, while others can play an antiviral role by regulating the immune response. It indicates that abnormal expression of miRNAs plays a crucial role in the regulation of cross-species IAVs infection, which lays a solid foundation for further exploration of the molecular regulatory mechanism of miRNAs in IAVs cross-species infection and anti-influenza virus targets.


Asunto(s)
MicroARNs , Animales , Humanos , Porcinos , MicroARNs/genética , MicroARNs/metabolismo , Subtipo H3N2 del Virus de la Influenza A/genética , Tupaia , Perfilación de la Expresión Génica , Tupaiidae/genética , Musarañas , ARN Mensajero
6.
Anal Chem ; 95(44): 16089-16097, 2023 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-37883656

RESUMEN

Thanks to its ease, speed, and sensitivity, CRISPR-based nucleic acid detection has been increasingly explored for molecular diagnostics. However, one of its major limitations is lack of multiplexing capability because the detection relies on the trans-cleavage activity of the Cas protein, which necessitates the use of multiple orthogonal Cas proteins for multiplex detection. Here we report the development of a multiplexed CRISPR-based nucleic acid detection system with single-nucleotide resolution using a single Cas protein (Cas12a). This method, termed as CRISPR-TMSD, integrates the toehold-mediated strand displacement (TMSD) reaction, and the cis-cleavage activity of the Cas protein and multiplexed detection are achieved using a single Cas protein owing to the use of target-specific reporters. A set of computational simulation toolkits was used to design the TMSD reporter, allowing for highly sensitive and specific identification of target sequences. In combination with the recombinase polymerase amplification (RPA), the detection limit can reach as low as 1 copy/µL. As proof of concept, CRISPR-TMSD was subsequently used to detect an oncogenic gene and SARS-CoV-2 RNA with a single-nucleotide resolution. This work represents a conceptually new strategy for designing a CRISPR-based diagnostic system and has great potential to expand the application of CRISPR-based diagnostics.


Asunto(s)
Nucleotidiltransferasas , ARN Viral , Simulación por Computador , Nucleótidos , Recombinasas , Técnicas de Amplificación de Ácido Nucleico , Sistemas CRISPR-Cas
7.
Nat Commun ; 14(1): 4267, 2023 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-37460548

RESUMEN

Synthetic biology requires efficient systems that support the well-coordinated co-expression of multiple genes. Here, we discover a 9-bp nucleotide sequence that enables efficient polycistronic gene expression in yeasts and filamentous fungi. Coupling polycistronic expression to multiplexed, markerless, CRISPR/Cas9-based genome editing, we develop a strategy termed HACKing (Highly efficient and Accessible system by CracKing genes into the genome) for the assembly of multigene pathways. HACKing allows the expression level of each enzyme to be precalibrated by linking their translation to those of host proteins with predetermined abundances under the desired fermentation conditions. We validate HACKing by rapidly constructing highly efficient Saccharomyces cerevisiae cell factories that express 13 biosynthetic genes, and produce model endogenous (1,090.41 ± 80.92 mg L-1 squalene) or heterologous (1.04 ± 0.02 mg L-1 mogrol) terpenoid products. Thus, HACKing addresses the need of synthetic biology for predictability, simplicity, scalability, and speed upon fungal pathway engineering for valuable metabolites.


Asunto(s)
Sistemas CRISPR-Cas , Edición Génica , Saccharomyces cerevisiae/genética , Hongos/genética
8.
Biotechnol Biofuels Bioprod ; 16(1): 64, 2023 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-37031180

RESUMEN

BACKGROUND: With unique physiochemical environments in subcellular organelles, there has been growing interest in harnessing yeast organelles for bioproduct synthesis. Among these organelles, the yeast mitochondrion has been found to be an attractive compartment for production of terpenoids and branched-chain alcohols, which could be credited to the abundant supply of acetyl-CoA, ATP and cofactors. In this study we explored the mitochondrial potential for production of 3-hydroxypropionate (3-HP) and performed the cofactor engineering and flux control at the acetyl-CoA node to maximize 3-HP synthesis. RESULTS: Metabolic modeling suggested that the mitochondrion serves as a more suitable compartment for 3-HP synthesis via the malonyl-CoA pathway than the cytosol, due to the opportunity to obtain a higher maximum yield and a lower oxygen consumption. With the malonyl-CoA reductase (MCR) targeted into the mitochondria, the 3-HP production increased to 0.27 g/L compared with 0.09 g/L with MCR expressed in the cytosol. With enhanced expression of dissected MCR enzymes, the titer reached to 4.42 g/L, comparable to the highest titer achieved in the cytosol so far. Then, the mitochondrial NADPH supply was optimized by overexpressing POS5 and IDP1, which resulted in an increase in the 3-HP titer to 5.11 g/L. Furthermore, with induced expression of an ACC1 mutant in the mitochondria, the final 3-HP production reached 6.16 g/L in shake flask fermentations. The constructed strain was then evaluated in fed-batch fermentations, and produced 71.09 g/L 3-HP with a productivity of 0.71 g/L/h and a yield on glucose of 0.23 g/g. CONCLUSIONS: In this study, the yeast mitochondrion is reported as an attractive compartment for 3-HP production. The final 3-HP titer of 71.09 g/L with a productivity of 0.71 g/L/h was achieved in fed-batch fermentations, representing the highest titer reported for Saccharomyces cerevisiae so far, that demonstrated the potential of recruiting the yeast mitochondria for further development of cell factories.

9.
Cell ; 186(4): 748-763.e15, 2023 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-36758548

RESUMEN

Although many prokaryotes have glycolysis alternatives, it's considered as the only energy-generating glucose catabolic pathway in eukaryotes. Here, we managed to create a hybrid-glycolysis yeast. Subsequently, we identified an inositol pyrophosphatase encoded by OCA5 that could regulate glycolysis and respiration by adjusting 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP7) levels. 5-InsP7 levels could regulate the expression of genes involved in glycolysis and respiration, representing a global mechanism that could sense ATP levels and regulate central carbon metabolism. The hybrid-glycolysis yeast did not produce ethanol during growth under excess glucose and could produce 2.68 g/L free fatty acids, which is the highest reported production in shake flask of Saccharomyces cerevisiae. This study demonstrated the significance of hybrid-glycolysis yeast and determined Oca5 as an inositol pyrophosphatase controlling the balance between glycolysis and respiration, which may shed light on the role of inositol pyrophosphates in regulating eukaryotic metabolism.


Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Difosfatos/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Fosfatos de Inositol/genética , Fosfatos de Inositol/metabolismo , Glucólisis/genética , Respiración , Pirofosfatasas/metabolismo , Glucosa/metabolismo
10.
Proc Natl Acad Sci U S A ; 120(5): e2215575120, 2023 01 31.
Artículo en Inglés | MEDLINE | ID: mdl-36696445

RESUMEN

Chloroplast division involves the coordination of protein complexes from the stroma to the cytosol. The Min system of chloroplasts includes multiple stromal proteins that regulate the positioning of the division site. The outer envelope protein PLASTID DIVISION1 (PDV1) was previously reported to recruit the cytosolic chloroplast division protein ACCUMULATION AND REPLICATION OF CHLOROPLAST5 (ARC5). However, we show here that PDV1 is also important for the stability of the inner envelope chloroplast division protein PARALOG OF ARC6 (PARC6), a component of the Min system. We solved the structure of both the C-terminal domain of PARC6 and its complex with the C terminus of PDV1. The formation of an intramolecular disulfide bond within PARC6 under oxidized conditions prevents its interaction with PDV1. Interestingly, this disulfide bond can be reduced by light in planta, thus promoting PDV1-PARC6 interaction and chloroplast division. Interaction with PDV1 can induce the dimerization of PARC6, which is important for chloroplast division. Magnesium ions, whose concentration in chloroplasts increases upon light exposure, also promote the PARC6 dimerization. This study highlights the multilayer regulation of the PDV1-PARC6 interaction as well as chloroplast division.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Plastidios/metabolismo , Cloroplastos/metabolismo , Disulfuros/metabolismo , Dinaminas/metabolismo
11.
Virus Res ; 324: 199027, 2023 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-36543317

RESUMEN

Animal influenza viruses can spread across species and pose a fatal threat to human health due to the high pathogenicity and mortality. Animal models are crucial for studying cross-species infection and the pathogenesis of influenza viruses. Tupaia belangeri (tree shrew) has been emerging as an animal model for multiple human virus infections recently because of the close genetic relationship and phylogeny with humans. So far, tree shrew has been reported to be susceptible to human influenza virus subtype H1N1, avian influenza viruses subtype H9N2, subtype H5N1, and subtype H7N9. However, the pathogenicity, infection, and immunity of swine and land avian influenza viruses with low pathogenicity and the potential to jump to humans remain largely unexplored in the tree shrew model. Previously, our team has successfully isolated the newly emerging swine influenza virus subtype H3N2 (A/Swine/GX/NS2783/2010, SW2783) and avian influenza virus subtype H6N6 (A/CK/ZZ/346/2014, ZZ346). In this study, we observed the pathogenicity, immune characteristics, and cross-species infection potential ability of SW2783 and ZZ346 strains in tree shrew model with 50% tissue culture infective dose (TCID50), hematoxylin and eosin (HE) staining, immunohistochemistry (IHC), real-time quantitative PCR (qRT-PCR) and other experimental methods. Both animal-borne influenza viruses had a strong ability on tissue infection in the turbinate and the trachea of tree shrews in vitro, in which SW2783 showed stronger replication ability than in ZZ346. SW2783 and ZZ346 both showed pathogenic ability with infected tree shrews model in vivo without prior adaptive culture, which mainly happened in the upper respiratory tract. However, the infection ability was weak, the clinical symptoms were mild, and the histopathological changes in the respiratory tract were relatively light. Furthermore, innate immune responses and adaptive immunity were observed in the tree shrew model after the infection of SW2783 and ZZ346 strains. We observed that the unadapted SW2783 and ZZ346 virus could transmit among tree shrews by direct contact. We also observed that SW2783 virus could transmit from tree shrews to guinea pigs. These results indicated that both animal-borne influenza viruses could induce similar pathogenicity and immune response to those caused by human-common influenza viruses. Tree shrews may be an excellent animal model for studying the interaction between the influenza virus and the host and the cross-species infection mechanism of the animal influenza virus.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A , Subtipo H5N1 del Virus de la Influenza A , Subtipo H7N9 del Virus de la Influenza A , Subtipo H9N2 del Virus de la Influenza A , Gripe Humana , Infecciones por Orthomyxoviridae , Humanos , Animales , Cobayas , Tupaia , Tupaiidae , Subtipo H3N2 del Virus de la Influenza A , Virulencia , Musarañas , Tráquea/patología , Replicación Viral
12.
Folia Microbiol (Praha) ; 68(2): 207-217, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36201138

RESUMEN

During yeast dough fermentation, such as the high-sucrose bread-making process, the yeast cells are subjected to considerable osmotic stress, resulting in poor outcomes. Invertase is important for catalyzing the irreversible hydrolysis of sucrose to free glucose and fructose, and decreasing the catalytic activity of the invertase may reduce the glucose osmotic stress on the yeast. In this study, we performed structural design and site-directed mutagenesis (SDM) on the Saccharomyces cerevisiae invertase (ScInV) in an Escherichia coli expression system to study the catalytic activity of ScInV mutants in vitro. In addition, we generated the same mutation sites in the yeast endogenous genome and tested their invertase activity in yeast and dough fermentation ability. Our results indicated that appropriately reduced invertase activity of yeast ScInV can enhance dough fermentation activity under high-sucrose conditions by 52%. Our systems have greatly accelerated the engineering of yeast endogenous enzymes both in vitro and in yeast, and shed light on future metabolic engineering of yeast.


Asunto(s)
Saccharomyces cerevisiae , beta-Fructofuranosidasa , Saccharomyces cerevisiae/metabolismo , Fermentación , beta-Fructofuranosidasa/genética , beta-Fructofuranosidasa/metabolismo , Sacarosa/metabolismo , Glucosa/metabolismo , Ingeniería de Proteínas
13.
Bioresour Bioprocess ; 10(1): 33, 2023 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-38647598

RESUMEN

The 3-Hydroxypropionic acid (3-HP) pathway is one of the six known natural carbon fixation pathways, in which the carbon species used is bicarbonate. It has been considered to be the most suitable pathway for aerobic CO2 fixation among the six natural carbon fixation pathways. Mesaconate is a high value-added derivative in the 3-HP pathway and can be used as a co-monomer to produce fire-retardant materials and hydrogels. In this study, we use mesaconate as a reporting compound to evaluate the construction and optimization of the sub-part of the 3-HP pathway in Saccharomyces cerevisiae. Combined with fine-tuning of the malonyl-CoA reductase (MCR-C and MCR-N) expression level and optimization of 3-Hydroxypropionyl-CoA synthase, the 3-HP sub-pathway was optimized using glucose or ethanol as the substrate, with the productions of mesaconate reaching 90.78 and 61.2 mg/L, respectively.

14.
J Nat Prod ; 85(12): 2723-2730, 2022 12 23.
Artículo en Inglés | MEDLINE | ID: mdl-36414326

RESUMEN

Spiromaterpenes are a group of rare tropone-containing sesquiterpenes with antineuroinflammatory activity. Herein, we elucidate their biosynthetic pathway in a deep-sea-derived Spiromastix sp. fungus by heterologous expression, biochemical characterization, and incubation experiments. The sesquiterpene cyclase SptA was first characterized to catalyze the production of guaia-1(5),6-diene, and a multifunctional cytochrome P450 catalyzed the tropone ring formation. These results provide important clues for the rational mining of bioactive guaiane-type sesquiterpenes and expand the repertoire of P450 activities to synthesize unique building blocks of natural products.


Asunto(s)
Sesquiterpenos , Sesquiterpenos/química , Sistema Enzimático del Citocromo P-450/metabolismo , Hongos/metabolismo , Sesquiterpenos de Guayano
15.
Bioresour Technol ; 364: 128095, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36220528

RESUMEN

The intensifying impact of green-house gas (GHG) emission on environment and climate change has attracted increasing attention, and biorefinery represents one of the most effective routes for reducing GHG emissions from human activities. However, this requires a shift for microbial fermentation from the current use of sugars to the use of biomass, and even better to the primary fixation of single carbon (C1) compounds. Here how microorganisms can be engineered for fixation and conversion of C1 compounds into metabolites that can serve as fuels and platform chemicals are reviewed. Meanwhile, key factors for utilization of these different pathways are discussed, followed by challenges and barriers for the development of C1-based biorefinery.

16.
Small ; 18(49): e2204356, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36310140

RESUMEN

Developing low-cost all-iron hybrid redox flow batteries (RFBs) presents a practical alternative to the high-cost all-vanadium RFBs and is deemed vital for grid-scale energy storage applications. However, the intrinsically poor Fe anode reversibility associated with the deposition and dissolution of metallic iron greatly limits the cycling performance and long-term stability of all-iron hybrid RFBs. Herein, a highly reversible and dendrite-free Fe anode is reported for all-iron RFBs through regulation of polar solvent dimethyl sulfoxide (DMSO) on FeCl2 anolyte, which simultaneously reshapes Fe2+ solvation structure and induces controllable oriented Fe deposition. Combining both experimental and theoretical analyses, the polar DMSO additives prove effective in replacing H2 O molecule from the primary solvation shell of Fe2+ cation via the Fe2+ -O (DMSO) bond and meanwhile induces a fine-grained Fe nucleation on the preferred Fe (110) plane, which are responsible for the minimized hydrogen evolution and dendrite-free Fe deposition that significantly enhance Fe anode reversibility. The all-iron RFB based on the proposed FeCl2 -DMSO anolyte demonstrates an excellent combination of peak power density of 134 mW cm-2 , high energy efficiency of 75% at 30 mA cm-2 , and high capacity retention of 98.6% over 200 cycles, which presents the best performance of all-iron RFBs among previously reported research.


Asunto(s)
Suministros de Energía Eléctrica , Hierro , Electrodos , Dimetilsulfóxido , Hidrógeno
17.
Synth Syst Biotechnol ; 7(4): 1034-1043, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35801089

RESUMEN

The respiro-fermentative metabolism in the yeast Saccharomyces cerevisiae, also called the Crabtree effect, results in lower energy efficiency and biomass yield which can impact yields of chemicals to be produced using this cell factory. Although it can be engineered to become Crabtree negative, the slow growth and glucose consumption rate limit its industrial application. Here the Crabtree effect in yeast can be alleviated by engineering the transcription factor Mth1 involved in glucose signaling and a subunit of the RNA polymerase II mediator complex Med2. It was found that the mutant with the MTH1 A81D&MED2*432Y allele could grow in glucose rich medium with a specific growth rate of 0.30 h-1, an ethanol yield of 0.10 g g-1, and a biomass yield of 0.21 g g-1, compared with a specific growth rate of 0.40 h-1, an ethanol yield of 0.46 g g-1, and a biomass yield of 0.11 g g-1 in the wild-type strain CEN.PK 113-5D. Transcriptome analysis revealed significant downregulation of the glycolytic process, as well as the upregulation of the TCA cycle and the electron transfer chain. Significant expression changes of several reporter transcription factors were also identified, which might explain the higher energy efficiencies in the engineered strain. We further demonstrated the potential of the engineered strain with the production of 3-hydroxypropionic acid at a titer of 2.04 g L-1, i.e., 5.4-fold higher than that of a reference strain, indicating that the alleviated glucose repression could enhance the supply of mitochondrial acetyl-CoA. These results suggested that the engineered strain could be used as an efficient cell factory for mitochondrial production of acetyl-CoA derived chemicals.

18.
Nat Commun ; 13(1): 4333, 2022 07 26.
Artículo en Inglés | MEDLINE | ID: mdl-35882877

RESUMEN

Toxin-antitoxin (TA) systems are ubiquitous genetic modules in bacteria and archaea. Here, we perform structural and biochemical characterization of the Legionella pneumophila effector Lpg2370, demonstrating that it is a Ser/Thr kinase. Together with two upstream genes, lpg2370 constitutes the tripartite HipBST TA. Notably, the toxin Lpg2370 (HipTLp) and the antitoxin Lpg2369 (HipSLp) correspond to the C-terminus and N-terminus of HipA from HipBA TA, respectively. By determining crystal structures of autophosphorylated HipTLp, its complex with AMP-PNP, and the structure of HipTLp-HipSLp complex, we identify residues in HipTLp critical for ATP binding and those contributing to its interactions with HipSLp. Structural analysis reveals that HipSLp binding induces a loop-to-helix shift in the P-loop of HipTLp, leading to the blockage of ATP binding and inhibition of the kinase activity. These findings establish the L. pneumophila effector Lpg2370 as the HipBST TA toxin and elucidate the molecular basis for HipT neutralization in HipBST TA.


Asunto(s)
Antitoxinas , Toxinas Bacterianas , Legionella pneumophila , Sistemas Toxina-Antitoxina , Adenosina Trifosfato , Antitoxinas/genética , Antitoxinas/metabolismo , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/metabolismo , Legionella pneumophila/genética , Legionella pneumophila/metabolismo , Sistemas Toxina-Antitoxina/genética
19.
ACS Synth Biol ; 11(6): 2163-2174, 2022 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-35677969

RESUMEN

Efficient utilization of both glucose and xylose, the two most abundant sugars in biomass hydrolysates, is one of the main objectives of biofermentation with lignocellulosic materials. The utilization of xylose is commonly inhibited by glucose, which is known as glucose catabolite repression (GCR). Here, we report a GCR-based dynamic control (GCR-DC) strategy aiming at better co-utilization of glucose and xylose, by decoupling the cell growth and biosynthesis of riboflavin as a product. Using the thermophilic strain Geobacillus thermoglucosidasius DSM 2542 as a host, we constructed additional riboflavin biosynthetic pathways that were activated by xylose but not glucose. The engineered strains showed a two-stage fermentation process. In the first stage, glucose was preferentially used for cell growth and no production of riboflavin was observed, while in the second stage where glucose was nearly depleted, xylose was effectively utilized for riboflavin biosynthesis. Using corn cob hydrolysate as a carbon source, the optimized riboflavin yields of strains DSM2542-DCall-MSS (full pathway dynamic control strategy) and DSM2542-DCrib (single-module dynamic control strategy) were 5.3- and 2.3-fold higher than that of the control strain DSM 2542 Rib-Gtg constitutively producing riboflavin, respectively. This GCR-DC strategy should also be applicable to the construction of cell factories that can efficiently use natural carbon sources with multiple sugar components for the production of high-value chemicals in future.


Asunto(s)
Glucosa , Xilosa , Bacillaceae , Carbono , Fermentación , Glucosa/metabolismo , Lignina , Riboflavina/metabolismo , Azúcares , Xilosa/metabolismo
20.
Sheng Wu Gong Cheng Xue Bao ; 38(4): 1527-1536, 2022 Apr 25.
Artículo en Chino | MEDLINE | ID: mdl-35470624

RESUMEN

Halomonas can grow on diverse carbon sources. As it can be used for unsterile fermentation under high-salt conditions, it has been applied as a chassis for next-generation industrial biotechnology. Short-chain volatile fatty acids, including acetate, propionate, and butyrate, can be prepared from biomass and are expected to be novel carbon sources for microbial fermentation. Halomonas sp. TD01 and TD08 were subjected to shaking culture with 10-50 g/L butyrate, and they were found to effectively synthesize poly-3-hydroxybutyrate with butyrate as the carbon source. The highest yield of poly-3-hydroxybutyrate was achieved at butyrate concentration of 20 g/L (9.12 g/L and 7.37 g/L, respectively). Butyrate at the concentration > 20 g/L inhibited cell growth, and the yield of poly-3-hydroxybutyrate decreased to < 4 g/L when butyrate concentration was 50 g/L. Moreover, Halomonas sp. TD08 can accumulate the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate by using propionate and butyrate as carbon sources. However, propionate was toxic to cells. To be specific, when 2 g/L propionate and 20 g/L butyrate were simultaneously provided, cell dry weight and polymer titer were 0.83 g/L and 0.15 g/L, respectively. The addition of glycerol significantly improved cell growth and boosted the copolymer titer to 3.95 g/L, with 3-hydroxyvalerate monomer content of 8.76 mol%. Short-chain volatile fatty acids would be promising carbon sources for the production of polyhydroxyalkanoates by Halomonas.


Asunto(s)
Halomonas , Polihidroxialcanoatos , Butiratos , Carbono , Ácidos Grasos Volátiles , Propionatos
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