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PloS One 2024Glycerol dehydrogenase (GDH) catalyzes glycerol oxidation to dihydroxyacetone in a NAD+-dependent manner. As an initiator of the oxidative pathway of glycerol...
Glycerol dehydrogenase (GDH) catalyzes glycerol oxidation to dihydroxyacetone in a NAD+-dependent manner. As an initiator of the oxidative pathway of glycerol metabolism, a variety of functional and structural studies of GDH have been conducted previously. Structural studies revealed intriguing features of GDH, like the flexible β-hairpin and its significance. Another commonly reported structural feature is the enzyme's octameric oligomerization, though its structural details and functional significance remained unclear. Here, with a newly reported GDH structure, complexed with both NAD+ and glycerol, we analyzed the octamerization of GDH. Structural analyses revealed that octamerization reduces the structural dynamics of the N-domain, which contributes to more consistently maintaining a distance required for catalysis between the cofactor and substrate. This suggests that octamerization may play a key role in increasing the likelihood of the enzyme reaction by maintaining the ligands in an appropriate configuration for catalysis. These findings expand our understanding of the structure of GDH and its relation to the enzyme's activity.
Topics: NAD; Glycerol; Sugar Alcohol Dehydrogenases; Oxidation-Reduction; Glutamate Dehydrogenase
PubMed: 38483875
DOI: 10.1371/journal.pone.0300541 -
PLoS Pathogens Feb 2024The bacterial determinants that facilitate Mycobacterium tuberculosis (Mtb) adaptation to the human host environment are poorly characterized. We have sought to decipher...
The bacterial determinants that facilitate Mycobacterium tuberculosis (Mtb) adaptation to the human host environment are poorly characterized. We have sought to decipher the pressures facing the bacterium in vivo by assessing Mtb genes that are under positive selection in clinical isolates. One of the strongest targets of selection in the Mtb genome is lldD2, which encodes a quinone-dependent L-lactate dehydrogenase (LldD2) that catalyzes the oxidation of lactate to pyruvate. Lactate accumulation is a salient feature of the intracellular environment during infection and lldD2 is essential for Mtb growth in macrophages. We determined the extent of lldD2 variation across a set of global clinical isolates and defined how prevalent mutations modulate Mtb fitness. We show the stepwise nature of lldD2 evolution that occurs as a result of ongoing lldD2 selection in the background of ancestral lineage-defining mutations and demonstrate that the genetic evolution of lldD2 additively augments Mtb growth in lactate. Using quinone-dependent antibiotic susceptibility as a functional reporter, we also find that the evolved lldD2 mutations functionally increase the quinone-dependent activity of LldD2. Using 13C-lactate metabolic flux tracing, we find that lldD2 is necessary for robust incorporation of lactate into central carbon metabolism. In the absence of lldD2, label preferentially accumulates in dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P) and is associated with a discernible growth defect, providing experimental evidence for accrued lactate toxicity via the deleterious buildup of sugar phosphates. The evolved lldD2 variants increase lactate incorporation to pyruvate while altering triose phosphate flux, suggesting both an anaplerotic and detoxification benefit to lldD2 evolution. We further show that the mycobacterial cell is transcriptionally sensitive to the changes associated with altered lldD2 activity which affect the expression of genes involved in cell wall lipid metabolism and the ESX- 1 virulence system. Together, these data illustrate a multifunctional role of LldD2 that provides context for the selective advantage of lldD2 mutations in adapting to host stress.
Topics: Humans; Mycobacterium tuberculosis; L-Lactate Dehydrogenase; Lactic Acid; Pyruvates; Quinones; Phosphates
PubMed: 38422159
DOI: 10.1371/journal.ppat.1012050 -
Journal of Traditional Chinese Medicine... Oct 2023To examine the effects of moxibustion on myocardial injury and myocardial metabolomics in rats with rheumatoid arthritis (RA) based on the transforming growth factor...
OBJECTIVE
To examine the effects of moxibustion on myocardial injury and myocardial metabolomics in rats with rheumatoid arthritis (RA) based on the transforming growth factor beta1 (TGF-β1)/Smads signaling pathway.
METHODS
One hundred rats were treated with saline [normal control (NC) group] or complete Freund's adjuvant (CFA) by right plantar injection for the RA model group, and the latter were randomly divided into 4 groups. Tripterygium wilfordii polyglycoside tablets (, TPT) have anti-inflammatory and are widely used in the clinical treatment of RA, therefore serving as a positive control group. Three days post injection rats were given TPT tablet (TPT group), acupuncture therapy (APT group), and moxibustion treatment (MOX group) for 15 consecutive days, while NC group and model group were equally grasped and fixed and received normal saline. Rat joint swelling scores and arthritis index (AI) were evaluated in each group before the CFA challenge, therapy and after receiving therapy. Myocardial ultrastructure was observed by electron microscope. Enzyme-linked immunosorbent assay was used to detect cardiac troponin I (cTnI) levels in rat myocardial tissue. Quantitative reverse transcription polymerase chain reaction and Western blotting analysis were used to measure the mRNA and protein levels of TGF-β signaling molecules including TGF-β1, Smad2, Smad3, Smad4, and Smad7. Myocardial metabolomics was analyzed using gas chromatography-mass spectrometer.
RESULTS
Compared with model group, RA model rats receiving TPT, acupuncture, or moxibustion therapy all showed reduced joint swelling scores and AI (all 0.01) and improved myocardial damage, whereas rats treated with moxibustion were found to be more marked. Consistently, the expressions of cTnI, TGF-β1, Smad2, Smad3, and Smad4 were found to be elevated in model rat group in contrast to NC rats and were significantly downregulated in TPT, APT and MOX group when compared with model group, while the levels of Smad7 showed the opposite result (all 0.01). Moreover, the dissection of metabolomics suggested a novel metabolite biomarker panel including D-Xylulose 5-phosphate, dihydroxyacetone phosphate, arachidonic acid, etc was defined and implicated in amino acid, glucose, and fatty acid metabolic processes as revealed by principal component analysis and partial least squares discriminant analysis.
CONCLUSION
Moxibustion prevents RA-induced inflammatory response and offers potent therapeutic effects on myocardial dysfunctions. The protective effects might be associated with its role in TGF-β1 inactivation and metabolic reprogramming.
Topics: Rats; Animals; Transforming Growth Factor beta1; Moxibustion; Signal Transduction; Drugs, Chinese Herbal; Arthritis, Rheumatoid
PubMed: 37946481
DOI: 10.19852/j.cnki.jtcm.20230802.005 -
Molecules (Basel, Switzerland) Jun 2024The strain LMG 1385 was used for the bioconversion of crude glycerol to dihydroxyacetone. The suitability of fed-batch cultures for the production of dihydroxyacetone...
The strain LMG 1385 was used for the bioconversion of crude glycerol to dihydroxyacetone. The suitability of fed-batch cultures for the production of dihydroxyacetone was determined, and the influence of the pH of the culture medium and the initial concentration of glycerol on maximizing the concentration of dihydroxyacetone and on the yield and speed of obtaining dihydroxyacetone by bioconversion was examined. The feeding strategy of the substrate (crude glycerol) during the process was based on measuring the dissolved oxygen tension of the culture medium. The highest concentration of dihydroxyacetone P = 175.8 g·L and the highest yield Y = 94.3% were obtained when the initial concentration of crude glycerol was S = 70.0 g·L and the pH of the substrate was maintained during the process at level 5.0.
Topics: Gluconobacter oxydans; Dihydroxyacetone; Glycerol; Batch Cell Culture Techniques; Culture Media; Hydrogen-Ion Concentration; Fermentation
PubMed: 38930996
DOI: 10.3390/molecules29122932 -
Chemical Research in Toxicology Sep 2023Aerosol formation and production yields from 11 carbonyls (carbonyl concentration per aerosol mass unit) were investigated (1) from a fourth-generation (4th gen)...
Carbonyls and Aerosol Mass Generation from Vaping Nicotine Salt Solutions Using Fourth- and Third-Generation E-Cigarette Devices: Effects of Coil Resistance, Coil Age, and Coil Metal Material.
Aerosol formation and production yields from 11 carbonyls (carbonyl concentration per aerosol mass unit) were investigated (1) from a fourth-generation (4th gen) e-cigarette device at different coil resistances and coil age (0-5000 puffs) using unflavored e-liquid with 2% benzoic acid nicotine salt, (2) between a sub-ohm third-generation (3rd gen) tank mod at 0.12 Ω and a 4th gen pod at 1.2 Ω using e-liquid with nicotine salt, together with nicotine yield, and (3) from 3rd gen coils of different metals (stainless steel, kanthal, nichrome) using e-liquid with freebase nicotine. Coil resistance had an inverse relationship with coil temperature, and coil temperature was directly proportional to aerosol mass formation. Trends in carbonyl yields depended on carbonyl formation mechanisms. Carbonyls produced primarily from thermal degradation chemistry (e.g., formaldehyde, acetaldehyde, acrolein, propionaldehyde) increased per aerosol mass with higher coil resistances, despite lower coil temperature. Carbonyls produced primarily from chemistry initiated by reactive oxygen species (ROS) (e.g., hydroxyacetone, dihydroxyacetone, methylglyoxal, glycolaldehyde, lactaldehyde) showed the opposite trend. Coil age did not alter coil temperature nor aerosol mass formation but had a significant effect on carbonyl formation. Thermal carbonyls were formed optimally at 500 puffs in our study and then declined to a baseline, whereas ROS-derived carbonyls showed a slow rise to a maximum trend with coil aging. The 3rd gen versus 4th gen device comparison mirrored the trends in coil resistance. Nicotine yields per aerosol mass were consistent between 3rd and 4th gen devices. Coil material did not significantly alter aerosol formation nor carbonyl yield when adjusted for wattage. This work shows that sub-ohm coils may not necessarily produce higher carbonyl yields even when they produce more aerosol mass. Furthermore, carbonyl formation is dynamic and not generalizable during the coil's lifetime. Finally, studies that compare data across different e-cigarette devices, coil age, and coil anatomy should account for the aerosol chemistry trends that depend on these parameters.
PubMed: 37698991
DOI: 10.1021/acs.chemrestox.3c00172 -
Scientific Reports Dec 2023Nowadays, dealing with the growing chemical and energy demands is important without compromising the environment. So, this work studies photocatalytic glycerol...
Nowadays, dealing with the growing chemical and energy demands is important without compromising the environment. So, this work studies photocatalytic glycerol conversion (as biomass derivativ feedstock) into value-added products using an eco-friendly synthesized catalyst. Graphene quantum dots (GQDs) were prepared from available/cheap precursors like glucose via the hydrothermal method and used as a support for TiO. TiO/GQDs were characterized via different analytical techniques, revealing very small particle sizes of ~ 3-6 nm with a large surface area of ~ 253 m/g and a band gap of ~ 2.6 eV. The prepared photocatalyst shows good efficiency during photocatalytic glycerol conversion to dihydroxyacetone (DHA). Different reaction conditions were tested: reaction time, catalyst amount, presence of oxidant (HO), and biphasic media (aqueous/organic phases). Comparing a monophasic (HO) photoreactor with a biphasic reactor containing 90% organic phase (ethyl acetate) and 10% aqueous phase (HO and/or HO) indicates that the presence of HO increases glycerol conversion and liquid selectivity to reach 57% and 91%, respectively after 120 min. However, it still suffers a low DHA/GA ratio (2.7). On the other hand, using a biphasic reactor in the presence of an HO oxidant increases the DHA/GA ratio to ~ 6.6, which was not reached in previous research. The formation of HO/HO as micro-reactors dispersed in the ethyl acetate phase increased the average light intensity effect of the glycerol/photocatalyst system in the micro-reactors. Unlike previous work, this work presents a facile way to prepare eco-friendly/cheap (noble metal free) photocatalysts for glycerol conversion to ultrapure DHA using a biphasic photoreactor.
PubMed: 38071356
DOI: 10.1038/s41598-023-48781-3 -
Cureus Oct 2023The skin, hair, and nails can all present with yellow discoloration secondary to exogenous etiologies. Xanthoderma, yellow discoloration of the skin, can occur not only...
The skin, hair, and nails can all present with yellow discoloration secondary to exogenous etiologies. Xanthoderma, yellow discoloration of the skin, can occur not only from exogenous sources secondary to topical contact with various substances but also from endogenous causes such as diseases from the liver and kidney, or oral medications. A 64-year-old man developed asymptomatic, yellow staining of his distal left forearm, hand, and fingertips. He was not receiving antimalarials, did not have hepatic or renal dysfunction, and had not applied any sunless tanning solutions to his skin. Prior to the appearance of his xanthoderma, he had been tending to a tomato plant in his yard; the yellow staining appeared on the areas of his left upper extremity that had contacted the stems and leaves of the tomato plant. Within two days, the yellow skin discoloration resolved spontaneously after several washings of the affected areas with soap and water. Tomato plants have trichomes that appear as hair-like structures on the stems and produce an oily substance; the trichomes not only produce the scent of the plant, but also provide protection from cold, drought, disease, and pests. Initially, when the oily substance contacts the skin, the skin appears yellow; subsequently, the skin may become black. The skin that has been stained by a tomato plant is referred to as "tomato skin" (TOMASK). In addition to reviewing the etiology of exogenous xanthoderma, this paper also summarizes the causes of exogenous yellow hair and yellow nails. Exogenous yellowing of the skin can result from various topical causes. Common topical etiologies of xanthoderma include not only contact with tomato plants, but also sunless tanning solutions (that contain dihydroxyacetone) and tobacco (that not only causes yellow staining of the white hair on men's upper lip referred to as "smoker's mustache", but also yellow staining of the nail plate and fingertips used to hold the cigarette or cigar). In summary, tomato plant-associated xanthoderma is a benign exogenous etiology of yellow staining of the skin which eventually resolves after several washings of the affected sites with soap and water.
PubMed: 38021483
DOI: 10.7759/cureus.47218 -
Plant Biotechnology Journal Mar 2024Heat stress causes dysfunction of the carbon-assimilation metabolism. As a member of Calvin-Benson-Bassham (CBB) cycle, the chloroplast triose phosphate isomerases (TPI)...
Heat stress causes dysfunction of the carbon-assimilation metabolism. As a member of Calvin-Benson-Bassham (CBB) cycle, the chloroplast triose phosphate isomerases (TPI) catalyse the interconversion of glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). The tomato (Solanum lycopersicum) genome contains two individual SlTPI genes, Solyc10g054870 and Solyc01g111120, which encode the chloroplast-located proteins SlTPI1 and SlTPI2, respectively. The tpi1 and tpi2 single mutants had no visible phenotypes, but the leaves of their double mutant lines tpi1tpi2 had obviously reduced TPI activity and displayed chlorotic variegation, dysplasic chloroplasts and lower carbon-assimilation efficiency. In addition to altering carbon metabolism, proteomic data showed that the loss of both SlTPI1 and SlTPI2 severely affected photosystem proteins, reducing photosynthetic capacity. None of these phenotypes was evident in the tpi1 or tpi2 single mutants, suggesting that SlTPI1 and SlTPI2 are functionally redundant. However, the two proteins differed in their responses to heat stress; the protein encoded by the heat-induced SlTPI2 showed a higher level of thermotolerance than that encoded by the heat-suppressed SlTPI1. Notably, heat-induced transcription factors, SlWRKY21 and SlHSFA2/7, which negatively regulated SlTPI1 expression and positively regulated SlTPI2 expression, respectively. Our findings thus reveal that SlTPI1 and SlTPI2 have different thermostabilities and expression patterns in response to heat stress, which have the potential to be applied in thermotolerance strategies in crops.
Topics: Triose-Phosphate Isomerase; Solanum lycopersicum; Proteomics; Photosynthesis; Plastids; Protein Isoforms; Carbon
PubMed: 37878418
DOI: 10.1111/pbi.14212 -
BioRxiv : the Preprint Server For... Oct 2023The bacterial determinants that facilitate (Mtb) adaptation to the human host environment are poorly characterized. We have sought to decipher the pressures facing the...
The bacterial determinants that facilitate (Mtb) adaptation to the human host environment are poorly characterized. We have sought to decipher the pressures facing the bacterium by assessing Mtb genes that are under positive selection in clinical isolates. One of the strongest targets of selection in the Mtb genome is , which encodes a quinone-dependent L-lactate dehydrogenase (LldD2) that catalyzes the oxidation of lactate to pyruvate. Lactate accumulation is a salient feature of the intracellular environment during infection and is essential for Mtb growth in macrophages. We determined the extent of variation across a set of global clinical isolates and defined how prevalent mutations modulates Mtb fitness. We show the stepwise nature of evolution that occurs as a result of ongoing selection in the background of ancestral lineage defining mutations and demonstrate that the genetic evolution of additively augments Mtb growth in lactate. Using quinone-dependent antibiotic susceptibility as a functional reporter, we also find that the evolved mutations functionally increase the quinone-dependent activity of LldD2. Using C-lactate metabolic flux tracing, we find that is necessary for robust incorporation of lactate into central carbon metabolism. In the absence of , label preferentially accumulates in methylglyoxal precursors dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P) and is associated with a discernible growth defect, providing experimental evidence for accumulated lactate toxicity via a methylglyoxal pathway that has been proposed previously. The evolved variants increase lactate incorporation to pyruvate but also alter flux in the methylglyoxal pathway, suggesting both an anaplerotic and detoxification benefit to evolution. We further show that the mycobacterial cell is transcriptionally sensitive to the changes associated with altered activity which affect the expression of genes involved in cell wall lipid metabolism and the ESX-1 virulence system. Together, these data illustrate a multifunctional role of LldD2 that provide context for the selective advantage of mutations in adapting to host stress.
PubMed: 37873410
DOI: 10.1101/2023.10.09.561592 -
BioRxiv : the Preprint Server For... Aug 2023All organisms utilize -adenosyl-l-methionine (SAM) as a key co-substrate for methylation of biological molecules, synthesis of polyamines, and radical SAM reactions....
All organisms utilize -adenosyl-l-methionine (SAM) as a key co-substrate for methylation of biological molecules, synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as -adenosyl-l-homocysteine (SAH), 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). One of the most prevalent pathways found in bacteria for the metabolism of MTA and 5dAdo is the DHAP shunt, which converts these compounds into dihydroxyacetone phosphate (DHAP) and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Here we show that in Extraintestinal Pathogenic (ExPEC), the DHAP shunt serves none of these roles in any significant capacity, but rather physiologically functions as an assimilation pathway for use of MTA and 5dAdo as growth substrates. This is further supported by the observation that when MTA is the substrate for the ExPEC DHAP shunt, the sulfur components is not significantly recycled back to methionine, but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. While the pathway is active both aerobically and anaerobically, it only supports aerobic ExPEC growth, suggesting that it primarily functions in oxygenic extraintestinal environments like blood and urine versus the predominantly anoxic gut. This reveals a heretofore overlooked role of the DHAP shunt in carbon assimilation and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt.
PubMed: 37609188
DOI: 10.1101/2023.08.10.552779