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1.
Beilstein J Org Chem ; 20: 692-700, 2024.
Article in English | MEDLINE | ID: mdl-38590537

ABSTRACT

The soil bacterial genus Variovorax produce distinct photoreactive siderophores that may play a crucial role in the iron cycle within the rhizosphere. This study focused on exploring the natural products of the soil-isolated Variovorax sp. H002, leading to the isolation of variochelins A-E (1-5), a series of lipohexapeptide siderophores. NMR and MS/MS analyses revealed that these siderophores share a common core structure - a linear hexapeptide with ß-hydroxyaspartate and hydroxamate functional groups, serving in iron-binding coordination. Three new variochelins C-E (3-5) were characterized by varied fatty acyl groups at their N-termini; notably, 4 and 5 represent the first variochelins with N-terminal unsaturated fatty acyl groups. Furthermore, the variochelin biosynthetic gene cluster was identified through draft genome sequencing and gene knockout experiments. Compounds 1-5 exhibited antimicrobial activities against Gram-negative bacteria, including several soil-isolated plant pathogens.

3.
Chem Pharm Bull (Tokyo) ; 72(1): 80-85, 2024.
Article in English | MEDLINE | ID: mdl-38233135

ABSTRACT

Five new viridogriseins B-F were isolated from Streptomyces niveoruber, along with viridogrisein and griseoviridin which belong to streptogramin family antibiotics. A combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and the advanced Marfey's method elucidated the structures of viridogriseins B-F, each featuring distinct constituent amino acids. Consistent with other streptogramin family antibiotics, these viridogrisein analogs exhibited potent antibacterial activity against Staphylococcus aureus. Furthermore, equimolar mixtures of each viridogrisein analog and griseoviridin inhibited the growth of S. aureus more potently than each analog treatment alone. Finally, an in vitro functional analysis of SgvY, encoded in the viridogrisein biosynthetic gene cluster, revealed that SgvY detoxifies viridogrisein against S. aureus by linearization. Considering that viridogrisein is not autotoxic to S. niveoruber, SgvY likely contributes to the self-resistance system against viridogrisein in S. niveoruber.


Subject(s)
Anti-Bacterial Agents , Depsipeptides , Macrolides , Streptogramins , Streptomyces , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/metabolism , Staphylococcus aureus , Chromatography, Liquid , Tandem Mass Spectrometry , Microbial Sensitivity Tests
4.
Angew Chem Int Ed Engl ; 62(42): e202307304, 2023 Oct 16.
Article in English | MEDLINE | ID: mdl-37449463

ABSTRACT

Most bacterial biosynthetic gene clusters (BGCs) are "silent BGCs" that are expressed poorly or not at all under normal culture conditions. However, silent BGCs, even in part, may be conditionally expressed in response to external stimuli in the original bacterial habitats. The growing knowledge of bacterial membrane vesicles (MVs) suggests that they could be promising imitators of the exogenous stimulants, especially given their functions as signaling mediators in bacterial cell-to-cell communication. Therefore, we envisioned that MVs added to bacterial cultures could activate diverse silent BGCs. Herein, we employed Burkholderia multivorans MVs, which induced silent metabolites in a wide range of bacteria in Actinobacteria, Bacteroidetes and Proteobacteria phyla. A mechanistic analysis of MV-induced metabolite production in Xenorhabdus innexi suggested that the B. multivorans MVs activate silent metabolite production by inhibiting quorum sensing in X. innexi. In turn, the X. innexi MVs carrying some MV-induced peptides suppressed the growth of B. multivorans, highlighting the interspecies communication between B. multivorans and X. innexi through MV exchange.

5.
Sci Rep ; 13(1): 5203, 2023 03 30.
Article in English | MEDLINE | ID: mdl-36997629

ABSTRACT

Systemic inflammation underlies the association between obesity and nonalcoholic fatty liver disease (NAFLD). Here, we investigated functional changes in leukocytes' mitochondria in obese individuals and their associations with NAFLD. We analyzed 14 obese male Japanese university students whose body mass index was > 30 kg/m2 and 15 healthy age- and sex-matched lean university students as controls. We observed that the mitochondrial oxidative phosphorylation (OXPHOS) capacity with complex I + II-linked substrates in peripheral blood mononuclear cells (PBMCs), which was measured using a high-resolution respirometry, was significantly higher in the obese group versus the controls. The PBMCs' mitochondrial complex IV capacity was also higher in the obese subjects. All of the obese subjects had hepatic steatosis defined by a fatty liver index (FLI) score ≥ 60, and there was a positive correlation between their FLI scores and their PBMCs' mitochondrial OXPHOS capacity. The increased PBMCs' mitochondrial OXPHOS capacity was associated with insulin resistance, systemic inflammation, and higher serum levels of interleukin-6 in the entire series of subjects. Our results suggest that the mitochondrial respiratory capacity is increased in the PBMCs at the early stage of obesity, and the enhanced PBMCs' mitochondrial oxidative metabolism is associated with hepatic steatosis in obese young adults.


Subject(s)
Insulin Resistance , Non-alcoholic Fatty Liver Disease , Humans , Male , Young Adult , Non-alcoholic Fatty Liver Disease/metabolism , Leukocytes, Mononuclear/metabolism , Obesity/metabolism , Mitochondria/metabolism , Inflammation/metabolism , Oxidative Stress , Liver/metabolism
6.
ACS Appl Mater Interfaces ; 14(31): 35978-35984, 2022 Aug 10.
Article in English | MEDLINE | ID: mdl-35894872

ABSTRACT

Redox-active organic molecules are promising candidates for next-generation electrode materials. Nevertheless, finding low-molecular-weight organic materials with a long cycle life remains a crucial challenge. Herein, we demonstrate the application of tetrathiafulvalene and its vinyl analogue bearing triphenylamines as long-cycle-life electrodes for lithium-ion batteries (LIBs). These molecules were successfully synthesized using palladium-catalyzed C-H arylation. Electrochemical analysis revealed that a polymer formed on the electrode. LIBs comprising these molecules exhibited noteworthy charge-discharge properties with a long cycle life (the capacity after 100 cycles was greater than 90% of the discharge capacity in the third cycle) and a high utilization ratio (approximately 100%). "In-cell" polymerization during the first charge process is considered to contribute to the effect. This study indicates new avenues for the creation of organic materials for rechargeable batteries.

7.
Mol Psychiatry ; 27(9): 3822-3832, 2022 09.
Article in English | MEDLINE | ID: mdl-35618888

ABSTRACT

Several lines of evidence suggest that stress induces the neurovascular dysfunction associated with increased blood-brain barrier (BBB) permeability, which could be an important pathology linking stress and psychiatric disorders, including major depressive disorder (MDD). However, the detailed mechanism resulting in BBB dysfunction associated in the pathophysiology of MDD still remains unclear. Herein, we demonstrate the role of vascular endothelial growth factor (VEGF), a key mediator of vascular angiogenesis and BBB permeability, in stress-induced BBB dysfunction and depressive-like behavior development. We implemented an animal model of depression, chronic restraint stress (RS) in BALB/c mice, and found that the BBB permeability was significantly increased in chronically stressed mice. Immunohistochemical and electron microscopic observations revealed that increased BBB permeability was associated with both paracellular and transcellular barrier alterations in the brain endothelial cells. Pharmacological inhibition of VEGF receptor 2 (VEGFR2) using a specific monoclonal antibody (DC101) prevented chronic RS-induced BBB permeability and anhedonic behavior. Considered together, these results indicate that VEGF/VEGFR2 plays a crucial role in the pathogenesis of depression by increasing the BBB permeability, and suggest that VEGFR2 inhibition could be a potential therapeutic strategy for the MDD subtype associated with BBB dysfunction.


Subject(s)
Brain Diseases , Depressive Disorder, Major , Animals , Mice , Blood-Brain Barrier/metabolism , Vascular Endothelial Growth Factor A/metabolism , Endothelial Cells/metabolism , Depressive Disorder, Major/metabolism , Depression , Brain Diseases/pathology , Mice, Inbred BALB C , Capillary Permeability/physiology
8.
BMC Nephrol ; 23(1): 7, 2022 01 03.
Article in English | MEDLINE | ID: mdl-34979979

ABSTRACT

BACKGROUND: Sedentary behavior and decreased physical activity are associated with reduced kidney function, yet most evidence is based on self-reported physical activity. This study investigated the association between accelerometer-based physical activity level and kidney function in a general Japanese population. METHODS: A cross-sectional study was conducted in 440 community-dwelling Japanese participants, aged 35-79 years. Time (min/d) was assessed for the following types of physical activity: sedentary behavior, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Kidney function was assessed using estimated glomerular filtration rate (eGFR). A linear regression model was employed to calculate the ß coefficient of eGFR for a 60-min/d increase in sedentary behavior and LPA and a 10-min/d increase in MVPA. A logistic regression model was used to calculate the odds ratio for low eGFR (< 60 versus ≥60 mL/min/1.73m2) for a 60-min/d or 10-min/d increase in each physical activity type. RESULTS: MVPA time and eGFR were positively associated in both men and women, after adjusting for age, body mass index, and other clinical characteristics (Men: ß, 0.91; P = 0.021; Women: ß, 0.70; P = 0.034). In women, sedentary behavior and eGFR were inversely associated after adjusting for the same factors (ß, - 1.06; P = 0.048). The odds ratio (95% confidence interval) for low eGFR associated with a 60-min increase in sedentary behavior was 1.65 (1.07-2.55) after adjusting for the same factors in women. CONCLUSION: Longer sedentary behavior and shorter MVPA time were associated with lower kidney function in the Japanese population.


Subject(s)
Exercise/physiology , Kidney/physiology , Accelerometry , Adult , Aged , Cross-Sectional Studies , Glomerular Filtration Rate , Humans , Independent Living , Japan , Kidney/physiopathology , Male , Middle Aged , Regression Analysis , Renal Insufficiency, Chronic/physiopathology , Risk Factors , Sedentary Behavior
9.
J Nephrol ; 35(3): 1033-1040, 2022 04.
Article in English | MEDLINE | ID: mdl-34757576

ABSTRACT

BACKGROUND: Cystogenesis in polycystic kidney disease (PKD) is likely accelerated by various renal insults, including crystal deposition, that activate renal tubule obstruction and dilation. We developed a capsule-based device that can be applied to cystic kidneys to restrict tubular lumen dilatation and cyst expansion. METHODS: Kidney capsule devices were designed from computed tomography images of wild-type and Cy/+ rats. Capsule devices were surgically implanted on kidneys in six surgical sessions over a period of 14 months in 7 wild-type rats of 6.5-8 weeks (3 sham operations, 2 right, 2 left) and 6 Cy/+ rats of 6.5 weeks (2 sham, 3 left, 1 bilateral). After surgery, the rats were followed for 5.4-12.4 weeks' growth and sacrificed to retrieve the kidneys. During the follow-up, serum creatinine was measured and retrieved kidneys were weighed. Histological analysis including cystic area measurement and immunohistochemistry was performed. RESULTS: Morphometric capsule devices were configured and developed by an image processing technique and produced using a 3D printer. Encapsulated Cy/+ kidneys (n = 5; mean weight 3.64 g) were consistently smaller in size (by 21-36%; p < 0.001) than unencapsulated Cy/+ kidneys (n = 7; mean weight 5.52 g). Encapsulated Cy/+ kidneys (mean %cyst area: 29.4%) showed smaller histological cystic area (by 28-58%; p < 0.001) than unencapsulated Cy/+ kidneys (mean %cyst area 48.6%). Cell proliferation and macrophages were also markedly reduced in encapsulated Cy/+ kidneys, compared to unencapsulated Cy/+ kidneys. CONCLUSIONS: We report a pilot feasibility study for the application of a novel morphometric 3D capsule device to the Cy/+ rat model showing restricted kidney volume expansion on polycystic kidney disease progression.


Subject(s)
Cysts , Polycystic Kidney Diseases , Animals , Cell Proliferation , Cysts/pathology , Disease Models, Animal , Feasibility Studies , Humans , Kidney/pathology , Polycystic Kidney Diseases/pathology , Rats
10.
J Nutr Sci Vitaminol (Tokyo) ; 67(4): 243-248, 2021.
Article in English | MEDLINE | ID: mdl-34470999

ABSTRACT

Daily fat and sugar intake has increased in Japan, while total energy intake has decreased. However, the number of type 2 diabetes mellitus patients has increased, and this often causes renal injury characterized by autophagic vacuoles. Although many studies with comparisons of high fat or sugar versus a normal macronutrient balanced diet have been reported, there are few studies that equalized calorie intake and body weights. In the current study, AIN93M diets (CONT group) with matching energy content with lard derived high saturated fat (LARD group), soybean oil derived unsaturated fat (SOY OIL group) and sucrose (SUCROSE group) were provided to compare their effects on renal morphology in streptozotocin-injected CD-1 mice without causing obesity. The number of renal tubular vacuoles was higher in SUCROSE and slightly higher in LARD compared with CONT mice, and was higher in LARD and SUCROSE compared with SOY OIL mice. Most of those vacuoles were LAMP1-positive, a marker of lysosomal autophagy. These results suggest that despite identical energy contents, diets with high sucrose or saturated fat compared to unsaturated fat may aggravate lysosomal renal injury in a non-obese, streptozotocin-induced model of diabetes mellitus.


Subject(s)
Diabetes Mellitus, Type 2 , Sucrose , Animals , Diet , Dietary Fats , Humans , Kidney , Lysosomes , Mice , Streptozocin , Sucrose/adverse effects
11.
Chem Rec ; 21(12): 3520-3531, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34086402

ABSTRACT

Tetrathiafulvalene (TTF) and its analogs are fascinating molecules in materials science based on their excellent electron-donating abilities. This personal account describes recent advances in the synthesis of TTF analogs for functional materials via the palladium-catalyzed modification of peripheries of TTF analogs. We first consider three types of molecules: fluorophore-TTF hybrid molecules, multi-redox systems, and an organic ligand for metal-organic frameworks. These molecules were successfully synthesized via Stille coupling or palladium-catalyzed direct C-H arylation and their structural, electrochemical, and optical properties were clarified. Subsequently, phosphorus-substituted TTF analogs were successfully synthesized for future applications of redox-active phosphine ligands for metal catalysts. The development of these molecules can significantly affect the advancement of chemical science.


Subject(s)
Heterocyclic Compounds , Catalysis , Ligands , Palladium
12.
J Nat Prod ; 84(4): 986-992, 2021 04 23.
Article in English | MEDLINE | ID: mdl-33646775

ABSTRACT

An antifungal metabolite, designated amphiol (1), was isolated from the culture broth of the fungus Pseudogymnoascus sp. PF1464. It exists as a mixture of inseparable tautomers, an acetal form and a keto form. The chemical structure was determined by spectroscopic analyses and chemical derivatization. Amphiol (1) showed antifungal but not antibacterial activities, while yeast mutant cells lacking ergosterol biosynthetic genes were less sensitive, implying a fungal specific, membrane-related mechanism of action.


Subject(s)
Antifungal Agents/pharmacology , Ascomycota/chemistry , Pigments, Biological/pharmacology , Antifungal Agents/isolation & purification , Ascomycota/classification , Aspergillus fumigatus/drug effects , Candida albicans/drug effects , Japan , Molecular Structure , Pigments, Biological/isolation & purification , Soil Microbiology
13.
Fujita Med J ; 7(2): 41-49, 2021.
Article in English | MEDLINE | ID: mdl-35111543

ABSTRACT

OBJECTIVES: Proximal stoma creation in neonates results in growth failure and distal intestinal atrophy. "Recycling stool" consists of stool injection from the proximal limb to the distal limb of a stoma. Because this method may prevent distal bowel atrophy and increase body weight, we investigated the effects of recycling stool upon distal intestinal mucosa by generating an ileostomy model in rats. METHODS: An ileostomy was created 5 cm proximal to the cecum in male Wistar/ST rats. Discharged stool or saline was injected into the distal limb, twice per day for 7 days. The intestinal adaptation was assessed by measuring the villus height and counting goblet cell number. Proliferation and apoptosis were analyzed by Ki67 and TUNEL immunostaining. RESULTS: The ratios of the height of the distal villi (D) to the that of proximal villi (P) were 0.97 (median [range] of D and P length: 421 [240-729] µm and 436 [294-638] µm, P<0.05) in the stool-injected group and 0.81 in the saline-injected group (442 [315-641] µm and 548 [236-776] µm, P<0.05). Compared with the saline-injected group, the stool-injected group showed elevated numbers of goblet cells (3.6 [2.0-7.6] vs. 4.9 [2.4-7.5] cells/100-µm villus length) and Ki67-positive cells (26.8% [13.8%-35.4%] vs. 40.1% [31.2%-45.7%]), along with a reduced number of apoptotic cells (5.0 [2.0-14.0] vs. 4.0 [1.0-9.0] cells/100-µm villus length). CONCLUSIONS: Recycling stool prevented distal intestinal atrophy; this experimental design may facilitate further studies concerning alternative methods to prevent intestinal atrophy and growth failure.

14.
J Epidemiol ; 31(10): 530-536, 2021 10 05.
Article in English | MEDLINE | ID: mdl-32779629

ABSTRACT

BACKGROUND: Previous research has established that women accumulate less moderate-to-vigorous physical activity (MVPA) than men. To date, however, little is known about the gender differences in device-based activity patterns of sedentary behavior (SB) and light-intensity physical activity (LPA). We aimed to compare time spent in SB and different intensities of physical activity taking into account of co-dependence of time use domains. METHODS: This cross-sectional study was conducted in Suttu town, Hokkaido, Japan. Data were analyzed from 634 Japanese adults (278 men, aged 19-92 years) who provided valid accelerometer (HJA-750C) data. Gender differences in activity behavior patterns were tested using multivariate analysis of covariance (MANCOVA) based on isometric log-ratio transformations of time use, adjusting for age. We also developed bootstrap percentile confidence intervals (CI) to support the interpretation of which behavior differed between genders. RESULTS: Overall, participants had percent time spent in SB, LPA, MVPA during wearing time (mean, 14.8 hours) corresponding to 53.9%, 41.7%, and 4.4% of wearing time, respectively. Activity behavior patterns differed significantly between genders after controlling for time spent in all activities. Women spent relatively 13.3% (95% CI, 9.9-15.9%) less time in SB and 19.8% (95% CI, 14.9-24.6%) more time in LPA compared to men. The difference of time spent in MVPA was not statistically significant. CONCLUSIONS: In contrast with previous studies, our findings suggest that Japanese women are more physically active than men when all intensities of activities are considered. Given the health benefits of LPA, evaluating only MVPA may disproportionately underestimate the level of physical activity of women.


Subject(s)
Exercise , Sedentary Behavior , Accelerometry , Adult , Aged , Aged, 80 and over , Cross-Sectional Studies , Female , Humans , Japan , Male , Middle Aged , Sex Factors , Time Factors , Young Adult
15.
ACS Chem Biol ; 15(10): 2766-2774, 2020 10 16.
Article in English | MEDLINE | ID: mdl-32808751

ABSTRACT

The products of most secondary metabolite biosynthetic gene clusters (BGCs) have yet to be discovered, in part due to low expression levels in laboratory cultures. Reporter-guided mutant selection (RGMS) has recently been developed for this purpose: a mutant library is generated and screened, using genetic reporters to a chosen BGC, to select transcriptionally active mutants that then enable the characterization of the "cryptic" metabolite. The requirement for genetic reporters limits the approach to a single pathway within genetically tractable microorganisms. Herein, we utilize untargeted metabolomics in conjunction with transposon mutagenesis to provide a global read-out of secondary metabolism across large numbers of mutants. We employ self-organizing map analytics and imaging mass spectrometry to identify and characterize seven cryptic metabolites from mutant libraries of two different Burkholderia species. Applications of the methodologies reported can expand our understanding of the products and regulation of cryptic BGCs across phylogenetically diverse bacteria.


Subject(s)
Biological Products/analysis , Metabolome , Burkholderia/chemistry , Burkholderia/genetics , DNA Transposable Elements , Mass Spectrometry , Metabolomics/methods , Multigene Family , Mutagenesis , Secondary Metabolism/genetics
16.
Beilstein J Org Chem ; 16: 974-981, 2020.
Article in English | MEDLINE | ID: mdl-32509028

ABSTRACT

Novel multistage redox tetrathiafulvalenes (TTFs) bearing 6-aryl-1,4-dithiafulvene moieties were synthesized by palladium-catalyzed direct C-H arylation. In the presence of a catalytic amount of Pd(OAc)2, P(t-Bu3)·HBF4, and an excess of Cs2CO3, the C-H arylation of TTF with several aryl bromides bearing 1,3-dithiol-2-ylidenes took place efficiently to produce the corresponding π-conjugated molecules. We also succeeded in the estimation of the oxidation potentials and number of electrons involved in each oxidation step of the obtained compounds by digital simulations.

17.
Parasitol Int ; 77: 102130, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32325118

ABSTRACT

The increasing Yezo sika deer (Cervus nippon yesoensis) population is creating a large problem. Yezo sika deer are an important blood meal source, and these deer contribute to the maintenance of tick populations. Theileria spp. infections in Yezo sika deer and T. orientalis infections in cows occur at high frequencies, and the same tick species infests both deer and cows. Therefore, a specific detection method to identify deer Theileria spp. is important. In this study, we establish a novel molecular detection method for identifying Theileria spp. from deer and tick samples using loop-mediated isothermal amplification (LAMP). This method targets a metalloprotease/cell division cycle protein gene homologue. Our LAMP protocol was able to detect deer Theileria and did not show cross reactivity with other closely related protozoan parasites, including T. orientalis. The LAMP method showed sensitivity and specificity equivalent to those of nested PCR performed on the same field samples from deer and ticks. These results demonstrate the applicability of LAMP to field surveys in which the detection of deer Theileria spp. is required. In conclusion, due to its simplicity, specificity, and reliability, we suggest our LAMP protocol as an appropriate method for routine surveys to detect Yezo sika deer and ticks infected with deer Theileria spp. parasites. Additionally, this LAMP method offers great promise as a useful tool to distinguish Yezo sika deer Theileria from related Theileria parasites present in livestock.


Subject(s)
DNA, Protozoan/genetics , Deer/parasitology , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Theileriasis/diagnosis , Animals , Japan/epidemiology , Phylogeny , RNA, Ribosomal, 18S/genetics , Reproducibility of Results , Sensitivity and Specificity , Sequence Analysis, DNA , Theileria/genetics , Theileriasis/epidemiology , Ticks/parasitology
18.
Article in English | MEDLINE | ID: mdl-32070493

ABSTRACT

Rodent models of chronic restraint stress (CRS) are often used as simple models of depressive disorder. However, these models of stress have been mainly developed in rats, and the behavioral phenotypes of CRS models are still controversial. In this study, we compared the physiological and behavioral responses of C57BL/6J (B6) and BALB/c mice, which are commonly used in genetic and behavioral studies, to CRS. In addition to measuring physiological parameters and the levels of corticosterone (a stress hormone) in response to stress, we also examined changes in the levels of testosterone (an anti-stress hormone), which have rarely been studied in stressed mice. The mice were exposed to CRS for 6 h a day for 21 days. In both B6 and BALB/c mice, CRS elicited several physiological stress responses, including decreased body weight gain and changes in the tissue weights of stress-related organs. Accumulated corticosterone in the hair was measured, and BALB/c mice had significantly greater levels than control mice and B6 mice after CRS. On the other hand, in the case of accumulated testosterone in the hair, both B6 mice and BALB/c mice showed significantly higher concentrations than control mice, but the degree of change was not different between the two strains. In the sucrose preference test, BALB/c mice, but not B6 mice, showed anhedonia-like behavior after CRS. However, neither strain showed depressive-like behavior in the forced swim or tail suspension test. Our results show that the physiological and behavioral stress responses of BALB/c mice are greater than those of B6 mice, although anti-stress responses to CRS are similar in both strains. This suggests that BALB/c mice are likely to be advantageous for use as a CRS-induced depression model.

19.
ChemSusChem ; 13(9): 2312-2320, 2020 May 08.
Article in English | MEDLINE | ID: mdl-32096607

ABSTRACT

Fused donor-acceptor triads composed of two tetrathiafulvalenes (TTFs) and benzoquinone (BQ; 1) or naphthoquinone (NQ; 2) were successfully synthesized. X-ray structure analysis of the bis(n-butylthio) derivative revealed that the molecules are stacked in a head-to-tail manner. The bis(n-hexylthio)-1 exhibited six-pairs of one-electron transfer waves in the cyclic voltammogram, corresponding to the formation of both reduction and oxidation states from -2 to +4. The unsubstituted and bis(methylthio) derivatives of 1 and 2 were active materials in positive electrodes for rechargeable batteries, several of which displayed energy densities exceeding 800 mWh g-1 . The bis(methylthio)-2 also functions as a positive electrode material for a rechargeable sodium-ion battery.

20.
mBio ; 11(1)2020 02 25.
Article in English | MEDLINE | ID: mdl-32098820

ABSTRACT

Low doses of antibiotics can trigger secondary metabolite biosynthesis in bacteria, but the underlying mechanisms are generally unknown. We sought to better understand this phenomenon by studying how the antibiotic trimethoprim activates the synthesis of the virulence factor malleilactone in Burkholderia thailandensis Using transcriptomics, quantitative multiplexed proteomics, and primary metabolomics, we systematically mapped the changes induced by trimethoprim. Surprisingly, even subinhibitory doses of the antibiotic resulted in broad transcriptional and translational alterations, with ∼8.5% of the transcriptome and ∼5% of the proteome up- or downregulated >4-fold. Follow-up studies with genetic-biochemical experiments showed that the induction of malleilactone synthesis can be sufficiently explained by the accumulation of methionine biosynthetic precursors, notably homoserine, as a result of inhibition of the folate pathway. Homoserine activated the malleilactone gene cluster via the transcriptional regulator MalR and gave rise to a secondary metabolome which was very similar to that generated by trimethoprim. Our work highlights the expansive changes that low-dose trimethoprim induces on bacterial physiology and provides insights into its stimulatory effect on secondary metabolism.IMPORTANCE The discovery of antibiotics ranks among the most significant accomplishments of the last century. Although the targets of nearly all clinical antibiotics are known, our understanding regarding their natural functions and the effects of subinhibitory concentrations is in its infancy. Stimulatory rather than inhibitory functions have been attributed to low-dose antibiotics. Among these, we previously found that antibiotics activate silent biosynthetic genes and thereby enhance the metabolic output of bacteria. The regulatory circuits underlying this phenomenon are unknown. We take a first step toward elucidating these circuits and show that low doses of trimethoprim (Tmp) have cell-wide effects on the saprophyte Burkholderia thailandensis Most importantly, inhibition of one-carbon metabolic processes by Tmp leads to an accumulation of homoserine, which induces the production of an otherwise silent cytotoxin via a LuxR-type transcriptional regulator. These results provide a starting point for uncovering the molecular basis of the hormetic effects of antibiotics.


Subject(s)
Anti-Bacterial Agents/pharmacology , Burkholderia/drug effects , Burkholderia/metabolism , Secondary Metabolism/drug effects , Bacterial Proteins , Biological Products/metabolism , Biosynthetic Pathways/drug effects , Biosynthetic Pathways/genetics , Burkholderia/genetics , Gene Expression Regulation, Bacterial/drug effects , Homoserine/metabolism , Lactones/chemistry , Lactones/metabolism , Multigene Family , Secondary Metabolism/genetics , Trimethoprim/pharmacology , Virulence Factors/metabolism
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