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1.
World J Microbiol Biotechnol ; 40(9): 267, 2024 Jul 15.
Article in English | MEDLINE | ID: mdl-39004689

ABSTRACT

As an efficient and safe industrial bacterium, Corynebacterium glutamicum has extensive application in amino acid production. However, it often faces oxidative stress induced by reactive oxygen species (ROS), leading to diminished production efficiency. To enhance the robustness of C. glutamicum, numerous studies have focused on elucidating its regulatory mechanisms under various stress conditions such as heat, acid, and sulfur stress. However, a comprehensive review of its defense mechanisms against oxidative stress is needed. This review offers an in-depth overview of the mechanisms C. glutamicum employs to manage oxidative stress. It covers both enzymatic and non-enzymatic systems, including antioxidant enzymes, regulatory protein families, sigma factors involved in transcription, and physiological redox reduction pathways. This review provides insights for advancing research on the antioxidant mechanisms of C. glutamicum and sheds light on its potential applications in industrial production.


Subject(s)
Antioxidants , Bacterial Proteins , Corynebacterium glutamicum , Gene Expression Regulation, Bacterial , Oxidation-Reduction , Oxidative Stress , Reactive Oxygen Species , Sigma Factor , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Antioxidants/metabolism , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Reactive Oxygen Species/metabolism , Sigma Factor/metabolism , Sigma Factor/genetics
2.
Molecules ; 29(12)2024 Jun 18.
Article in English | MEDLINE | ID: mdl-38930958

ABSTRACT

The phosphoenol pyruvate-oxaloacetate-pyruvate-derived amino acids (POP-AAs) comprise native intermediates in cellular metabolism, within which the phosphoenol pyruvate-oxaloacetate-pyruvate (POP) node is the switch point among the major metabolic pathways existing in most living organisms. POP-AAs have widespread applications in the nutrition, food, and pharmaceutical industries. These amino acids have been predominantly produced in Escherichia coli and Corynebacterium glutamicum through microbial fermentation. With the rapid increase in market requirements, along with the global food shortage situation, the industrial production capacity of these two bacteria has encountered two bottlenecks: low product conversion efficiency and high cost of raw materials. Aiming to push forward the update and upgrade of engineered strains with higher yield and productivity, this paper presents a comprehensive summarization of the fundamental strategy of metabolic engineering techniques around phosphoenol pyruvate-oxaloacetate-pyruvate node for POP-AA production, including L-tryptophan, L-tyrosine, L-phenylalanine, L-valine, L-lysine, L-threonine, and L-isoleucine. Novel heterologous routes and regulation methods regarding the carbon flux redistribution in the POP node and the formation of amino acids should be taken into consideration to improve POP-AA production to approach maximum theoretical values. Furthermore, an outlook for future strategies of low-cost feedstock and energy utilization for developing amino acid overproducers is proposed.


Subject(s)
Amino Acids , Metabolic Engineering , Metabolic Engineering/methods , Amino Acids/metabolism , Oxaloacetic Acid/metabolism , Escherichia coli/metabolism , Escherichia coli/genetics , Phosphoenolpyruvate/metabolism , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Pyruvic Acid/metabolism , Metabolic Networks and Pathways , Fermentation
3.
PLoS Genet ; 20(6): e1011127, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38829907

ABSTRACT

The cell envelope fortifies bacterial cells against antibiotics and other insults. Species in the Mycobacteriales order have a complex envelope that includes an outer layer of mycolic acids called the mycomembrane (MM) and a cell wall composed of peptidoglycan and arabinogalactan. This envelope architecture is unique among bacteria and contributes significantly to the virulence of pathogenic Mycobacteriales like Mycobacterium tuberculosis. Characterization of pathways that govern envelope biogenesis in these organisms is therefore critical in understanding their biology and for identifying new antibiotic targets. To better understand MM biogenesis, we developed a cell sorting-based screen for mutants defective in the surface exposure of a porin normally embedded in the MM of the model organism Corynebacterium glutamicum. The results revealed a requirement for the conserved σD envelope stress response in porin export and identified MarP as the site-1 protease, respectively, that activate the response by cleaving the membrane-embedded anti-sigma factor. A reporter system revealed that the σD pathway responds to defects in mycolic acid and arabinogalactan biosynthesis, suggesting that the stress response has the unusual property of being induced by activating signals that arise from defects in the assembly of two distinct envelope layers. Our results thus provide new insights into how C. glutamicum and related bacteria monitor envelope integrity and suggest a potential role for members of the σD regulon in protein export to the MM.


Subject(s)
Cell Membrane , Cell Wall , Corynebacterium glutamicum , Mycolic Acids , Sigma Factor , Cell Wall/metabolism , Cell Wall/genetics , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/metabolism , Mycolic Acids/metabolism , Sigma Factor/metabolism , Sigma Factor/genetics , Cell Membrane/metabolism , Stress, Physiological , Porins/metabolism , Porins/genetics , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Galactans/metabolism , Gene Expression Regulation, Bacterial , Peptidoglycan/metabolism
4.
Sheng Wu Gong Cheng Xue Bao ; 40(6): 1711-1727, 2024 Jun 25.
Article in Chinese | MEDLINE | ID: mdl-38914487

ABSTRACT

Amino acids as the building blocks of proteins are widely applied in food, medicine, feed, and chemical industries. Amino acid production by microbial cell factories from renewable resources is praised for the environmental friendliness, mild reaction conditions, and high product purity, which helps to achieve the goal of carbon neutrality. Researchers have employed the methods of metabolic engineering and synthetic biology to engineer Escherichia coli and Corynebacterium glutamicum and optimized the culture conditions to construct the microbial cell factories with high performance for producing branched chain amino acids, amino acids of the aspartic acid and glutamic acid families, and aromatic amino acids. We review the engineering process of microbial cell factories for high production of amino acids, in the hope of providing a reference for the creation of high-performance microbial cell factories.


Subject(s)
Amino Acids , Corynebacterium glutamicum , Escherichia coli , Metabolic Engineering , Metabolic Engineering/methods , Amino Acids/biosynthesis , Amino Acids/metabolism , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Escherichia coli/metabolism , Escherichia coli/genetics , Synthetic Biology , Industrial Microbiology
5.
PLoS One ; 19(5): e0299588, 2024.
Article in English | MEDLINE | ID: mdl-38718091

ABSTRACT

Corynebacterium glutamicum is a non-pathogenic species of the Corynebacteriaceae family. It has been broadly used in industrial biotechnology for the production of valuable products. Though it is widely accepted at the industrial level, knowledge about the genomic diversity of the strains is limited. Here, we investigated the comparative genomic features of the strains and pan-genomic characteristics. We also observed phylogenetic relationships among the strains based on average nucleotide identity (ANI). We found diversity between strains at the genomic and pan-genomic levels. Less than one-third of the C. glutamicum pan-genome consists of core genes and soft-core genes. Whereas, a large number of strain-specific genes covered about half of the total pan-genome. Besides, C. glutamicum pan-genome is open and expanding, which indicates the possible addition of new gene families to the pan-genome. We also investigated the distribution of biosynthetic gene clusters (BGCs) among the strains. We discovered slight variations of BGCs at the strain level. Several BGCs with the potential to express novel bioactive secondary metabolites have been identified. Therefore, by utilizing the characteristic advantages of C. glutamicum, different strains can be potential applicants for natural drug discovery.


Subject(s)
Corynebacterium glutamicum , Genetic Variation , Genome, Bacterial , Phylogeny , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/metabolism , Multigene Family , Genomics/methods
6.
J Agric Food Chem ; 72(23): 13186-13195, 2024 Jun 12.
Article in English | MEDLINE | ID: mdl-38814711

ABSTRACT

Ketopantoate hydroxymethyltransferase (KPHMT) plays a pivotal role in d-pantothenic acid biosynthesis. Most KPHMTs are homodecamers with low thermal stability, posing challenges for protein engineering and limiting output enhancement. Previously, a high-enzyme activity KPHMT mutant (K25A/E189S) from Corynebacterium glutamicum was screened as mother strain (M0). Building upon this strain, our study focused on interface engineering modifications, employing a multifaceted approach including integrating folding-free energy calculation, B-factor analysis, and conserved site analysis. Preliminary screening led to the selection of five mutants in the interface─E106S, E98T, E98N, S247I, and S247D─showing improved thermal stability, culminating in the double-site mutant M8 (M0-E98N/S247D). M8 exhibited a T1/2 value of 288.79 min at 50 °C, showing a 3.29-fold increase compared to M0. Meanwhile, the Tm value of M8 was elevated from 53.2 to 59.6 °C. Investigations of structural and molecular dynamics simulations revealed alterations in surface electrostatic charge distribution and the formation of increased hydrogen bonds between subunits, contributing to enhanced thermal stability. This investigation corroborates the efficacy of interface engineering modifications in bolstering KPHMT stability while showing its potential for positively impacting industrial d-pantothenic acid synthesis.


Subject(s)
Bacterial Proteins , Corynebacterium glutamicum , Enzyme Stability , Protein Engineering , Corynebacterium glutamicum/enzymology , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Molecular Dynamics Simulation , Kinetics , Hot Temperature
7.
Microb Cell Fact ; 23(1): 147, 2024 May 23.
Article in English | MEDLINE | ID: mdl-38783320

ABSTRACT

Aminopyrrolnitrin (APRN), a natural halogenated phenylpyrrole derivative (HPD), has strong antifungal and antiparasitic activities. Additionally, it showed 2.8-fold increased photostability compared to pyrrolnitrin, a commercially available HPD with antimicrobial activity. For microbial production of APRN, we first engineered anthranilate phosphoribosyltransferase encoded by trpD from Corynebacterium glutamicum, resulting in a TrpDA162D mutation that exhibits feedback-resistant against L-tryptophan and higher substrate affinity compared to wild-type TrpD. Plasmid-borne expression of trpDA162D in C. glutamicum TP851 strain with two copies of trpDA162D in the genome led to the production of 3.1 g/L L-tryptophan in flask culture. Subsequent step for L-tryptophan chlorination into 7-chloro-L-tryptophan was achieved by introducing diverse sources of genes encoding tryptophan 7-halogenase (PrnA or RebH) and flavin reductase (Fre, PrnF, or RebF). The combined expression of prnA from Serratia grimesii or Serratia plymuthica with flavin reductase gene from Escherichia coli, Pseudomonas fluorescens, or Lechevalieria aerocolonigenes yielded higher production of 7-chloro-L-tryptophan in comparison to other sets of two-component systems. In the next step, production of putative monodechloroaminopyrrolnitrin (MDAP) from 7-chloro-L-tryptophan was achieved through the expression of prnB encoding MDAP synthase from S. plymuthica or P. fluorescens. Finally, an artificial APRN biosynthetic pathway was constructed by simultaneously expressing genes coding for tryptophan 7-halogenase, flavin reductase, MDAP synthase, and MDAP halogenase (PrnC) from different microbial sources within the L-tryptophan-producing TP851 strain. As prnC from S. grimesii or S. plymuthica was introduced into the host strain, which carried plasmids expressing prnA from S. plymuthica, fre from E. coli, and prnB from S. plymuthica, APN3639 and APN3638 accumulated 29.5 mg/L and 28.1 mg/L of APRN in the culture broth. This study represents the first report on the fermentative APRN production by metabolically engineered C. glutamicum.


Subject(s)
Corynebacterium glutamicum , Metabolic Engineering , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Metabolic Engineering/methods , Pyrrolnitrin/biosynthesis , Pyrrolnitrin/metabolism , Fermentation , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Tryptophan/biosynthesis , Tryptophan/metabolism , Escherichia coli/genetics , Escherichia coli/metabolism , Oxidoreductases
8.
J Chem Inf Model ; 64(10): 4250-4262, 2024 May 27.
Article in English | MEDLINE | ID: mdl-38701175

ABSTRACT

The microbial enzyme diaminopimelate epimerase (DapF), a vital enzyme in the lysine biosynthetic pathway, catalyzes the conversion of L, L-diaminopimelate (L, L-DAP) to D, L-diaminopimelate (D, L-DAP) using a catalytic cysteine dyad with one cysteine in thiol state and another in thiolate. Under oxidizing conditions, the catalytic cysteines of apo DapF form a disulfide bond that alters the structure and function of DapF. Given its potential as a target for antimicrobial resistance treatments, understanding DapF's functional dynamics is imperative. In the present work, we employ microsecond-scale all-atom molecular dynamics simulations of product-bound DapF and apo-DapF under oxidized and reduced conditions. We employ a polarized charge model for the ligand and the active site residues, which was necessary to preserve the electrostatic environment in the active site and retain the ligand in the active site. The product-bound DapF and apo-DapF in oxidized and reduced conditions exhibit a closed, semi-open, and open conformation, respectively, as identified using the internal coordinates of the dimeric enzyme and the principal component analysis. The conformational switch is guided by the dynamic catalytic (DC) loop, loop II, and loop III movements in the active site. The time scale of the close-to-open conformational transition is estimated to be 0.8 µs through Markov state modeling (MSM) and transition path theory (TPT). The present study explains the role of various active site residues and loops in ligand binding and protein dynamics in the DapF enzyme under different redox conditions. Such information will be helpful in future inhibitor design studies targeting the DapF enzyme.


Subject(s)
Corynebacterium glutamicum , Markov Chains , Molecular Dynamics Simulation , Protein Conformation , Corynebacterium glutamicum/enzymology , Ligands , Amino Acid Isomerases/metabolism , Amino Acid Isomerases/chemistry , Catalytic Domain , Oxidation-Reduction
9.
Bioresour Technol ; 402: 130774, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38701983

ABSTRACT

Formate as an ideal mediator between the physicochemical and biological realms can be obtained from electrochemical reduction of CO2 and used to produce bio-chemicals. Yet, limitations arise when employing natural formate-utilizing microorganisms due to restricted product range and low biomass yield. This study presents a breakthrough: engineered Corynebacterium glutamicum strains (L2-L4) through modular engineering. L2 incorporates the formate-tetrahydrofolate cycle and reverse glycine cleavage pathway, L3 enhances NAD(P)H regeneration, and L4 reinforces metabolic flux. Metabolic modeling elucidates C1 assimilation, guiding strain optimization for co-fermentation of formate and glucose. Strain L4 achieves an OD600 of 0.5 and produces 0.6 g/L succinic acid. 13C-labeled formate confirms C1 assimilation, and further laboratory evolution yields 1.3 g/L succinic acid. This study showcases a successful model for biologically assimilating formate in C. glutamicum that could be applied in C1-based biotechnological production, ultimately forming a formate-based bioeconomy.


Subject(s)
Biomass , Corynebacterium glutamicum , Formates , Metabolic Engineering , Succinic Acid , Corynebacterium glutamicum/metabolism , Formates/metabolism , Metabolic Engineering/methods , Succinic Acid/metabolism , Fermentation , Models, Biological , Glucose/metabolism
10.
J Agric Food Chem ; 72(21): 12219-12228, 2024 May 29.
Article in English | MEDLINE | ID: mdl-38747135

ABSTRACT

Phycocyanobilin, an algae-originated light-harvesting pigment known for its antioxidant properties, has gained attention as it plays important roles in the food and medication industries and has surged in demand owing to its low-yield extraction from natural resources. In this study, engineered Corynebacterium glutamicum was developed to achieve high PCB production, and three strategies were proposed: reinforcement of the heme biosynthesis pathway with the introduction of two PCB-related enzymes, strengthening of the pentose phosphate pathway to generate an efficient cycle of NADPH, and fed-batch fermentation to maximize PCB production. Each approach increased PCB synthesis, and the final engineered strain successfully produced 78.19 mg/L in a flask and 259.63 mg/L in a 5 L bioreactor, representing the highest bacterial production of PCB reported to date, to our knowledge. The strategies applied in this study will be useful for the synthesis of PCB derivatives and can be applied in the food and pharmaceutical industries.


Subject(s)
Corynebacterium glutamicum , Metabolic Engineering , Phycobilins , Phycocyanin , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Phycocyanin/metabolism , Phycocyanin/genetics , Phycobilins/metabolism , Phycobilins/genetics , Fermentation , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Pentose Phosphate Pathway/genetics , Bioreactors/microbiology
11.
Molecules ; 29(10)2024 May 10.
Article in English | MEDLINE | ID: mdl-38792114

ABSTRACT

Flavonoids and stilbenoids, crucial secondary metabolites abundant in plants and fungi, display diverse biological and pharmaceutical activities, including potent antioxidant, anti-inflammatory, and antimicrobial effects. However, conventional production methods, such as chemical synthesis and plant extraction, face challenges in sustainability and yield. Hence, there is a notable shift towards biological production using microorganisms like Escherichia coli and yeast. Yet, the drawbacks of using E. coli and yeast as hosts for these compounds persist. For instance, yeast's complex glycosylation profile can lead to intricate protein production scenarios, including hyperglycosylation issues. Consequently, Corynebacterium glutamicum emerges as a promising alternative, given its adaptability and recent advances in metabolic engineering. Although extensively used in biotechnological applications, the potential production of flavonoid and stilbenoid in engineered C. glutamicum remains largely untapped compared to E. coli. This review explores the potential of metabolic engineering in C. glutamicum for biosynthesis, highlighting its versatility as a cell factory and assessing optimization strategies for these pathways. Additionally, various metabolic engineering methods, including genomic editing and biosensors, and cofactor regeneration are evaluated, with a focus on C. glutamicum. Through comprehensive discussion, the review offers insights into future perspectives in production, aiding researchers and industry professionals in the field.


Subject(s)
Corynebacterium glutamicum , Flavonoids , Metabolic Engineering , Stilbenes , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Metabolic Engineering/methods , Flavonoids/biosynthesis , Flavonoids/metabolism , Stilbenes/metabolism
12.
Curr Microbiol ; 81(6): 167, 2024 May 10.
Article in English | MEDLINE | ID: mdl-38727744

ABSTRACT

Diabetes mellitus represents a persistent metabolic condition marked by heightened levels of blood glucose, presenting a considerable worldwide health concern, and finding targeted treatment for it is a crucial priority for global health. Gram-positive aerobic bacteria, predominantly inhabiting water and soil, are known carriers of various enzyme-encoding genetic material, which includes the malic enzyme gene that plays a role in insulin secretion. Corynebacterium glutamicum bacteria (ATCC 21799) were acquired from the Pasteur Institute and confirmed using microbiological and molecular tests, including DNA extraction. After identification, gene purification and cloning of the maeB gene were performed using the TA Cloning method. Additionally, the enhancement of enzyme expression was assessed using the expression vector pET-28a, and validation of simulation results was monitored through a real-time PCR analysis. Based on previous studies, the malic enzyme plays a pivotal role in maintaining glucose homeostasis, and increased expression of this enzyme has been associated with enhanced insulin sensitivity. However, the production of malic enzyme has encountered numerous challenges and difficulties. This study successfully isolated the malic enzyme genes via Corynebacterium glutamicum and introduced them into Escherichia coli for high-yield production. According to the results, the optimum temperature for the activity of enzymes has been identified as 39 °C.


Subject(s)
Cloning, Molecular , Corynebacterium glutamicum , Escherichia coli , Malate Dehydrogenase , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cloning, Molecular/methods , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/enzymology , Diabetes Mellitus/genetics , Escherichia coli/genetics , Gene Expression , Malate Dehydrogenase/genetics , Malate Dehydrogenase/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Temperature
13.
World J Microbiol Biotechnol ; 40(5): 159, 2024 Apr 12.
Article in English | MEDLINE | ID: mdl-38607454

ABSTRACT

Gamma-aminobutyric acid (GABA) is a non-protein amino acid which is widely applied in agriculture and pharmaceutical additive industries. GABA is synthesized from glutamate through irreversible α-decarboxylation by glutamate decarboxylase. Recently, microbial synthesis has become an inevitable trend to produce GABA due to its sustainable characteristics. Therefore, reasonable microbial platform design and metabolic engineering strategies for improving production of GABA are arousing a considerable attraction. The strategies concentrate on microbial platform optimization, fermentation process optimization, rational metabolic engineering as key metabolic pathway modification, promoter optimization, site-directed mutagenesis, modular transporter engineering, and dynamic switch systems application. In this review, the microbial producers for GABA were summarized, including lactic acid bacteria, Corynebacterium glutamicum, and Escherichia coli, as well as the efficient strategies for optimizing them to improve the production of GABA.


Subject(s)
Corynebacterium glutamicum , gamma-Aminobutyric Acid , Agriculture , Corynebacterium glutamicum/genetics , Drug Industry , Engineering , Escherichia coli/genetics
14.
J Am Chem Soc ; 146(17): 12138-12154, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38635392

ABSTRACT

Protein lipidation dynamically controls protein localization and function within cellular membranes. A unique form of protein O-fatty acylation in Corynebacterium, termed protein O-mycoloylation, involves the attachment of mycolic acids─unusually large and hydrophobic fatty acids─to serine residues of proteins in these organisms' outer mycomembrane. However, as with other forms of protein lipidation, the scope and functional consequences of protein O-mycoloylation are challenging to investigate due to the inherent difficulties of enriching and analyzing lipidated peptides. To facilitate the analysis of protein lipidation and enable the comprehensive profiling and site mapping of protein O-mycoloylation, we developed a chemical proteomics strategy integrating metabolic labeling, click chemistry, cleavable linkers, and a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method employing LC separation and complementary fragmentation methods tailored to the analysis of lipophilic, MS-labile O-acylated peptides. Using these tools in the model organism Corynebacterium glutamicum, we identified approximately 30 candidate O-mycoloylated proteins, including porins, mycoloyltransferases, secreted hydrolases, and other proteins with cell envelope-related functions─consistent with a role for O-mycoloylation in targeting proteins to the mycomembrane. Site mapping revealed that many of the proteins contained multiple spatially proximal modification sites, which occurred predominantly at serine residues surrounded by conformationally flexible peptide motifs. Overall, this study (i) discloses the putative protein O-mycoloylome for the first time, (ii) yields new insights into the undercharacterized proteome of the mycomembrane, which is a hallmark of important pathogens (e.g., Corynebacterium diphtheriae, Mycobacterium tuberculosis), and (iii) provides generally applicable chemical strategies for the proteomic analysis of protein lipidation.


Subject(s)
Bacterial Proteins , Corynebacterium glutamicum , Proteomics , Proteomics/methods , Bacterial Proteins/metabolism , Bacterial Proteins/chemistry , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/chemistry , Mycolic Acids/metabolism , Mycolic Acids/chemistry , Tandem Mass Spectrometry , Chromatography, Liquid , Acylation , Click Chemistry
15.
World J Microbiol Biotechnol ; 40(5): 154, 2024 Apr 03.
Article in English | MEDLINE | ID: mdl-38568465

ABSTRACT

D-chiro-inositol (DCI) is a potential drug for the treatment of type II diabetes and polycystic ovary syndrome. In order to effectively synthesize DCI in Corynebacterium glutamicum, the genes related to inositol catabolism in clusters iol1 and iol2 were knocked out in C. glutamicum SN01 to generate the chassis strain DCI-1. DCI-1 did not grow in and catabolize myo-inositol (MI). Subsequently, different exogenous and endogenous inosose isomerases were expressed in DCI-1 and their conversion ability of DCI from MI were compared. After fermentation, the strain DCI-7 co-expressing inosose isomerase IolI2 and inositol dehydrogenase IolG was identified as the optimal strain. Its DCI titer reached 3.21 g/L in the presence of 20 g/L MI. On this basis, the pH, temperature and MI concentration during whole-cell conversion of DCI by strain DCI-7 were optimized. Finally, the optimal condition that achieved the highest DCI titer of 6.96 g/L were obtained at pH 8.0, 37 °C and addition of 40 g/L MI. To our knowledge, it is the highest DCI titer ever reported.


Subject(s)
Corynebacterium glutamicum , Diabetes Mellitus, Type 2 , Inositol/analogs & derivatives , Female , Humans , Corynebacterium glutamicum/genetics , Metabolic Engineering
16.
J Microbiol Biotechnol ; 34(5): 1154-1163, 2024 May 28.
Article in English | MEDLINE | ID: mdl-38563097

ABSTRACT

Glucosylation is a well-known approach to improve the solubility, pharmacological, and biological properties of flavonoids, making flavonoid glucosides a target for large-scale biosynthesis. However, the low yield of products coupled with the requirement of expensive UDP-sugars limits the application of enzymatic systems for large-scale. C. glutamicum is a Gram-positive and generally regarded as safe (GRAS) bacteria frequently employed for the large-scale production of amino acids and bio-fuels. Due to the versatility of its cell factory system and its non-endotoxin producing properties, it has become an attractive system for the industrial-scale biosynthesis of alternate products. Here, we explored the cell factory of C. glutamicum for efficient glucosylation of flavonoids using apigenin as a model flavonoid, with the heterologous expression of a promiscuous glycosyltransferase, YdhE from Bacillus licheniformis and the endogenous overexpression of C. glutamicum genes galU1 encoding UDP-glucose pyrophosphorylase and pgm encoding phosphoglucomutase involved in the synthesis of UDP-glucose to create a C. glutamicum cell factory system capable of efficiently glucosylation apigenin with a high yield of glucosides production. Consequently, the production of various apigenin glucosides was controlled under different temperatures yielding almost 4.2 mM of APG1(apigenin-4'-O-ß-glucoside) at 25°C, and 0.6 mM of APG2 (apigenin-7-O-ß-glucoside), 1.7 mM of APG3 (apigenin-4',7-O-ß-diglucoside) and 2.1 mM of APG4 (apigenin-4',5-O-ß-diglucoside) after 40 h of incubation with the supplementation of 5 mM of apigenin and 37°C. The cost-effective developed system could be used to modify a wide range of plant secondary metabolites with increased pharmacokinetic activities on a large scale without the use of expensive UDP-sugars.


Subject(s)
Apigenin , Corynebacterium glutamicum , Glucosides , Metabolic Engineering , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/genetics , Apigenin/metabolism , Metabolic Engineering/methods , Glucosides/metabolism , Glucosides/biosynthesis , Glycosylation , Bacillus licheniformis/metabolism , Bacillus licheniformis/genetics , Bacillus licheniformis/enzymology , Uridine Diphosphate Glucose/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , UTP-Glucose-1-Phosphate Uridylyltransferase/metabolism , UTP-Glucose-1-Phosphate Uridylyltransferase/genetics , Glycosyltransferases/metabolism , Glycosyltransferases/genetics
17.
J Agric Food Chem ; 72(15): 8674-8683, 2024 Apr 17.
Article in English | MEDLINE | ID: mdl-38569079

ABSTRACT

The enhancement of intracellular glutamate synthesis in glutamate-independent poly-γ-glutamic acid (γ-PGA)-producing strains is an essential strategy for improving γ-PGA production. Bacillus tequilensis BL01ΔpgdSΔggtΔsucAΔgudB:P43-ppc-pyk-gdhA for the efficient synthesis of γ-PGA was constructed through expression of glutamate synthesis features of Corynebacterium glutamicum, which increased the titer of γ-PGA by 2.18-fold (3.24 ± 0.22 g/L) compared to that of B. tequilensis BL01ΔpgdSΔggtΔsucAΔgudB (1.02 ± 0.11 g/L). To further improve the titer of γ-PGA and decrease the production of byproducts, three enzymes (Ppc, Pyk, and AceE) were assembled to a complex using SpyTag/Catcher pairs. The results showed that the γ-PGA titer of the assembled strain was 31.31% higher than that of the unassembled strain. To further reduce the production cost, 25.73 ± 0.69 g/L γ-PGA with a productivity of 0.48 g/L/h was obtained from cheap molasses. This work provides new metabolic engineering strategies to improve the production of γ-PGA in B. tequilensis BL01. Furthermore, the engineered strain has great potential for the industrial production of γ-PGA from molasses.


Subject(s)
Bacillus , Corynebacterium glutamicum , Polyglutamic Acid/analogs & derivatives , Glutamic Acid/metabolism , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/metabolism
18.
Curr Opin Microbiol ; 79: 102478, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38653035

ABSTRACT

Members of the order Mycobacteriales are distinguished by a characteristic diderm cell envelope, setting them apart from other Actinobacteria species. In addition to the conventional peptidoglycan cell wall, these organisms feature an extra polysaccharide polymer composed of arabinose and galactose, termed arabinogalactan. The nonreducing ends of arabinose are covalently linked to mycolic acids (MAs), forming the immobile inner leaflet of the highly hydrophobic MA membrane. The contiguous outer leaflet of the MA membrane comprises trehalose mycolates and various lipid species. Similar to all actinobacteria, Mycobacteriales exhibit apical growth, facilitated by a polar localized elongasome complex. A septal cell envelope synthesis machinery, the divisome, builds instead of the cell wall structures during cytokinesis. In recent years, a growing body of knowledge has emerged regarding the cell wall synthesizing complexes of Mycobacteriales., focusing particularly on three model species: Corynebacterium glutamicum, Mycobacterium smegmatis, and Mycobacterium tuberculosis.


Subject(s)
Cell Wall , Galactans , Mycolic Acids , Cell Wall/metabolism , Mycolic Acids/metabolism , Galactans/metabolism , Peptidoglycan/metabolism , Mycobacterium tuberculosis/metabolism , Mycobacterium tuberculosis/genetics , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/growth & development , Corynebacterium glutamicum/genetics , Mycobacterium smegmatis/metabolism , Mycobacterium smegmatis/growth & development , Mycobacterium smegmatis/genetics , Arabinose/metabolism , Bacterial Proteins/metabolism , Bacterial Proteins/genetics
19.
Sci Rep ; 14(1): 8081, 2024 04 06.
Article in English | MEDLINE | ID: mdl-38582923

ABSTRACT

Astaxanthin, a versatile C40 carotenoid prized for its applications in food, cosmetics, and health, is a bright red pigment with powerful antioxidant properties. To enhance astaxanthin production in Corynebacterium glutamicum, we employed rational pathway engineering strategies, focused on improving precursor availability and optimizing terminal oxy-functionalized C40 carotenoid biosynthesis. Our efforts resulted in an increased astaxanthin precursor supply with 1.5-fold higher ß-carotene production with strain BETA6 (18 mg g-1 CDW). Further advancements in astaxanthin production were made by fine-tuning the expression of the ß-carotene hydroxylase gene crtZ and ß-carotene ketolase gene crtW, yielding a nearly fivefold increase in astaxanthin (strain ASTA**), with astaxanthin constituting 72% of total carotenoids. ASTA** was successfully transferred to a 2 L fed-batch fermentation with an enhanced titer of 103 mg L-1 astaxanthin with a volumetric productivity of 1.5 mg L-1 h-1. Based on this strain a pathway expansion was achieved towards glycosylated C40 carotenoids under heterologous expression of the glycosyltransferase gene crtX. To the best of our knowledge, this is the first time astaxanthin-ß-D-diglucoside was produced with C. glutamicum achieving high titers of microbial C40 glucosides of 39 mg L-1. This study showcases the potential of pathway engineering to unlock novel C40 carotenoid variants for diverse industrial applications.


Subject(s)
Carotenoids , Corynebacterium glutamicum , Carotenoids/metabolism , Corynebacterium glutamicum/genetics , Corynebacterium glutamicum/metabolism , Xanthophylls/metabolism , beta Carotene/metabolism , Metabolic Engineering/methods
20.
Int J Biol Macromol ; 267(Pt 2): 131415, 2024 May.
Article in English | MEDLINE | ID: mdl-38582485

ABSTRACT

The complete enzyme catalytic cycle includes substrate binding, chemical reaction and product release, in which different dynamic conformations are adopted. Due to the complex relationship among enzyme activity, stability and dynamics, the directed evolution of enzymes for improved activity or stability commonly leads to a trade-off in stability or activity. It hence remains a challenge to engineer an enzyme to have both enhanced activity and stability. Here, we have attempted to reconstruct the dynamics correlation network involved with active center to improve both activity and stability of a 2,3-butanediol dehydrogenase (2,3-BDH) by introducing inter-chain disulfide bonds. A computational strategy was first applied to evaluate the effect of introducing inter-chain disulfide bond on activity and stability of three 2,3-BDHs, and the N258C mutation of 2,3-BDH from Corynebacterium glutamicum (CgBDH) was proved to be effective in improving both activity and stability. In the results, CgBDH-N258C showed a different unfolding curve from the wild type, with two melting temperatures (Tm) of 68.3 °C and 50.8 °C, 19.7 °C and 2 °C higher than 48.6 °C of the wild type. Its half-life was also improved by 14.8-fold compared to the wild type. Catalytic efficiency (kcat/Km) of the mutant was increased by 7.9-fold toward native substrate diacetyl and 8.8-fold toward non-native substrate 2,5-hexanedione compared to the wild type. Molecular dynamics simulations revealed that an interaction network formed by Cys258, Arg162, Ala144 and the catalytic residues was reconstructed in the mutant and the dynamics change caused by the disulfide bond could be propagated through the interactions network. This improved the enzyme stability and activity by decreasing the flexibility and locking more "reactive" pose, respectively. Further construction of mutations including A144G showing a 44-fold improvement in catalytic efficiency toward meso-2,3-BD confirmed the role of modifying dynamics correlation network in tunning enzyme activity and selectivity. This study provided important insights into the relationship among dynamics, enzyme catalysis and stability, and will be useful in the designing new enzymes with co-evolution of stability, activity and selectivity.


Subject(s)
Alcohol Oxidoreductases , Corynebacterium glutamicum , Disulfides , Enzyme Stability , Molecular Dynamics Simulation , Alcohol Oxidoreductases/chemistry , Alcohol Oxidoreductases/genetics , Alcohol Oxidoreductases/metabolism , Disulfides/chemistry , Corynebacterium glutamicum/enzymology , Corynebacterium glutamicum/genetics , Mutation , Catalytic Domain , Kinetics , Protein Conformation , Protein Engineering/methods
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