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1.
BMC Bioinformatics ; 22(1): 3, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407079

RESUMO

BACKGROUND: Hydrogen cross-feeding microbes form a functionally important subset of the human colonic microbiota. The three major hydrogenotrophic functional groups of the colon: sulphate-reducing bacteria (SRB), methanogens and reductive acetogens, have been linked to wide ranging impacts on host physiology, health and wellbeing. RESULTS: An existing mathematical model for microbial community growth and metabolism was combined with models for each of the three hydrogenotrophic functional groups. The model was further developed for application to the colonic environment via inclusion of responsive pH, host metabolite absorption and the inclusion of host mucins. Predictions of the model, using two existing metabolic parameter sets, were compared to experimental faecal culture datasets. Model accuracy varied between experiments and measured variables and was most successful in predicting the growth of high relative abundance functional groups, such as the Bacteroides, and short chain fatty acid (SCFA) production. Two versions of the colonic model were developed: one representing the colon with sequential compartments and one utilising a continuous spatial representation. When applied to the colonic environment, the model predicted pH dynamics within the ranges measured in vivo and SCFA ratios comparable to those in the literature. The continuous version of the model simulated relative abundances of microbial functional groups comparable to measured values, but predictions were sensitive to the metabolic parameter values used for each functional group. Sulphate availability was found to strongly influence hydrogenotroph activity in the continuous version of the model, correlating positively with SRB and sulphide concentration and negatively with methanogen concentration, but had no effect in the compartmentalised model version. CONCLUSIONS: Although the model predictions compared well to only some experimental measurements, the important features of the colon environment included make it a novel and useful contribution to modelling the colonic microbiota.


Assuntos
Bactérias/metabolismo , Colo , Microbioma Gastrointestinal , Hidrogênio/metabolismo , Colo/metabolismo , Colo/microbiologia , Humanos , Modelos Biológicos , Sulfetos/metabolismo
2.
PLoS One ; 15(10): e0237643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33064729

RESUMO

We previously reported that maternal cigarette smoke (CS) exposure resulted in impairment of central chemoreception and induced mitochondrial dysfunction in offspring parafacial respiratory group (pFRG), the kernel for mammalian central chemoreception. We also found that hydrogen sulfide (H2S) could attenuate maternal CS exposure-induced impairment of central chemoreception in the rat offspring in vivo. Mitochondrial ATP sensitive potassium (mitoKATP) channel has been reported to play a significant role in mitochondrial functions and protect against apoptosis in neurons. Thus, we hypothesize here that mitoKATP channel plays a role in the protective effects of H2S on neonatal central chemoreception in maternal CS-exposed rats. Our findings revealed that pretreatment with NaHS (donor of H2S, 22.4mM) reversed the central chemosensitivity decreased by maternal CS exposure, and also inhibited cell apoptosis in offspring pFRG, however, 5-HD (blocker of mitoKATP channels, 19mM) attenuated the protective effects of NaHS. In addition, NaHS declined pro-apoptotic proteins related to mitochondrial pathway apoptosis in CS rat offspring pFRG, such as Bax, Cytochrome C, caspase9 and caspase3. NaHS or 5-HD alone had no significant effect on above indexes. These results suggest that mitoKATP channels play an important role in the protective effect of H2S against impairment of central chemoreception via anti-apoptosis in pFRG of rat offspring exposed to maternal CS.


Assuntos
Células Quimiorreceptoras/efeitos dos fármacos , Fumar Cigarros/efeitos adversos , Sulfeto de Hidrogênio/metabolismo , Exposição Materna/efeitos adversos , Canais de Potássio/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Células Quimiorreceptoras/patologia , Células Quimiorreceptoras/fisiologia , Feminino , Bulbo/efeitos dos fármacos , Bulbo/patologia , Bulbo/fisiopatologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Substâncias Protetoras/metabolismo , Substâncias Protetoras/farmacologia , Ratos , Ratos Sprague-Dawley , Mecânica Respiratória/efeitos dos fármacos , Mecânica Respiratória/fisiologia , Sulfetos/metabolismo , Sulfetos/farmacologia
3.
Appl Environ Microbiol ; 86(22)2020 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-32917752

RESUMO

Heterotrophic bacteria actively participate in the biogeochemical cycle of sulfur on Earth. The heterotrophic bacterium Cupriavidus pinatubonensis JMP134 contains several enzymes involved in sulfur oxidation, but how these enzymes work together to oxidize sulfide in the bacterium has not been studied. Using gene-deletion and whole-cell assays, we determined that the bacterium uses sulfide:quinone oxidoreductase to oxidize sulfide to polysulfide, which is further oxidized to sulfite by persulfide dioxygenase. Sulfite spontaneously reacts with polysulfide to produce thiosulfate. The sulfur-oxidizing (Sox) system oxidizes thiosulfate to sulfate. Flavocytochrome c sulfide dehydrogenase enhances thiosulfate oxidation by the Sox system but couples with the Sox system for sulfide oxidation to sulfate in the absence of sulfide:quinone oxidoreductase. Thus, C. pinatubonensis JMP134 contains a main pathway and a contingent pathway for sulfide oxidation.IMPORTANCE We establish a new pathway of sulfide oxidation with thiosulfate as a key intermediate in Cupriavidus pinatubonensis JMP134. The bacterium mainly oxidizes sulfide by using sulfide:quinone oxidoreductase, persulfide dioxygenase, and the Sox system with thiosulfate as a key intermediate. Although the purified and reconstituted Sox system oxidizes sulfide, its rate of sulfide oxidation in C. pinatubonensis JMP134 is too low to be physiologically relevant. The findings reveal how these sulfur-oxidizing enzymes participate in sulfide oxidation in a single bacterium.


Assuntos
Proteínas de Bactérias/metabolismo , Cupriavidus/metabolismo , Sulfatos/metabolismo , Sulfetos/metabolismo , Redes e Vias Metabólicas , Oxirredução , Tiossulfatos/metabolismo
4.
Mol Genet Genomics ; 295(6): 1529-1535, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32894358

RESUMO

Lanthipeptides are a subgroup of ribosomally encoded and post-translationally modified peptides (RiPPs) which frequently possess potent biological activity. Here we provide the first comprehensive bioinformatic analysis of the lanthipeptide-producing capability of the Salinispora genus, a marine actinomycete. One hundred twenty-two Salinispora arenicola, tropica, and pacifica genomic sequences were analyzed for lanthipeptide gene clusters, and the resulting 182 clusters were divided into seven groups based on sequence similarities. Group boundaries were defined based on LanB and LanM sequences with greater than 80% similarity within groups. Of the seven groups, six are predicted to encode class I lanthipeptides while only one group is predicted to encode class II lanthipeptides. Leader and core peptides were predicted for each cluster along with the number of possible lanthionine bridges. Notably, all of the predicted products of these clusters would represent novel lanthipeptide scaffolds. Of the 122 Salinispora genomes analyzed in this study, 92% contained at least one lanthipeptide gene cluster suggesting that Salinispora is a rich, yet untapped, source of lanthipeptides.


Assuntos
Alanina/análogos & derivados , Proteínas de Bactérias/metabolismo , Genoma Bacteriano , Micromonosporaceae/metabolismo , Fragmentos de Peptídeos/metabolismo , Sulfetos/metabolismo , Alanina/isolamento & purificação , Alanina/metabolismo , Proteínas de Bactérias/genética , Genômica , Micromonosporaceae/genética , Micromonosporaceae/crescimento & desenvolvimento , Fragmentos de Peptídeos/isolamento & purificação , Sulfetos/isolamento & purificação
5.
Nat Commun ; 11(1): 4658, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938931

RESUMO

Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Água do Mar/química , Água do Mar/microbiologia , Compostos de Sulfônio/metabolismo , Bactérias/isolamento & purificação , Clorofila A/análise , Clorofila A/metabolismo , Genes Bacterianos , Sedimentos Geológicos/química , Pressão Hidrostática , Marinobacter/genética , Marinobacter/isolamento & purificação , Marinobacter/metabolismo , Metagenoma , Mutação , Oceanos e Mares , Prochlorococcus/genética , Prochlorococcus/isolamento & purificação , Prochlorococcus/metabolismo , RNA Ribossômico 16S , Sulfetos/análise , Sulfetos/metabolismo , Compostos de Sulfônio/análise , Synechococcus/genética , Synechococcus/isolamento & purificação , Synechococcus/metabolismo
6.
J Biosci Bioeng ; 130(6): 610-615, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32800812

RESUMO

Dimethyl trisulfide (DMTS) is one of the main components responsible for hineka, the aroma associated with deteriorated Japanese sake during storage. The molecule 1,2-dihydroxy-5-(methylsulfinyl)pentan-3-one (DMTS-P1) has been previously identified as a major precursor compound of DMTS. Furthermore, it had been suggested that the yeast methionine salvage pathway is involved in the production of DMTS-P1. In sake brewing tests, DMTS-P1 and the DMTS producing potential (DMTS-pp; DMTS amount of sake after accelerated storage) were significantly reduced in mde1 or mri1 strain, which lack genes of the methionine salvage pathway. Industrial use of the gene-disrupting strains may not be accepted in the Japanese food industry. In order to obtain mde1 or mri1 mutants, we established a method to screen 5'-methylthioadenosine (MTA) non-utilizing strains using minimum culture medium containing methionine or MTA by ethyl methanesulfonate (EMS) mutagenesis with methionine-auxotrophic sake yeast haploid. As expected, mde1 and mri1 mutants were identified among the obtained mutants by an established screening method. The obtained strains had poor fermentation ability in sake brewing tests, so back-crossing was performed on the mutants to obtain mde1 or mri1 homozygous mutants. These strains had improved brewing characteristics, and DMTS-P1 and the DMTS-pp of the produced sake were significantly lower than those of the parent strains. These strains are expected to contribute to improving the maintenance of sake quality during storage.


Assuntos
Bebidas Alcoólicas/microbiologia , Hibridização Genética , Mutagênese , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sulfetos/metabolismo , Fermentação , Haploidia , Odorantes/análise , Pentanonas/metabolismo
7.
Appl Environ Microbiol ; 86(18)2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32680873

RESUMO

Biomineralization of Cu has been shown to control contaminant dynamics and transport in soils. However, very little is known about the role that subsurface microorganisms may play in the biogeochemical cycling of Cu. In this study, we investigate the bioreduction of Cu(II) by the subsurface metal-reducing bacterium Geobacter sulfurreducens Rapid removal of Cu from solution was observed in cell suspensions of G. sulfurreducens when Cu(II) was supplied, while transmission electron microscopy (TEM) analyses showed the formation of electron-dense nanoparticles associated with the cell surface. Energy-dispersive X-ray spectroscopy (EDX) point analysis and EDX spectrum image maps revealed that the nanoparticles are rich in both Cu and S. This finding was confirmed by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses, which identified the nanoparticles as Cu2S. Biomineralization of CuxS nanoparticles in soils has been reported to enhance the colloidal transport of a number of contaminants, including Pb, Cd, and Hg. However, formation of these CuxS nanoparticles has only been observed under sulfate-reducing conditions and could not be repeated using isolates of implicated organisms. As G. sulfurreducens is unable to respire sulfate, and no reducible sulfur was supplied to the cells, these data suggest a novel mechanism for the biomineralization of Cu2S under anoxic conditions. The implications of these findings for the biogeochemical cycling of Cu and other metals as well as the green production of Cu catalysts are discussed.IMPORTANCE Dissimilatory metal-reducing bacteria are ubiquitous in soils and aquifers and are known to utilize a wide range of metals as terminal electron acceptors. These transformations play an important role in the biogeochemical cycling of metals in pristine and contaminated environments and can be harnessed for bioremediation and metal bioprocessing purposes. However, relatively little is known about their interactions with Cu. As a trace element that becomes toxic in excess, Cu can adversely affect soil biota and fertility. In addition, biomineralization of Cu nanoparticles has been reported to enhance the mobilization of other toxic metals. Here, we demonstrate that when supplied with acetate under anoxic conditions, the model metal-reducing bacterium Geobacter sulfurreducens can transform soluble Cu(II) to Cu2S nanoparticles. This study provides new insights into Cu biomineralization by microorganisms and suggests that contaminant mobilization enhanced by Cu biomineralization could be facilitated by Geobacter species and related organisms.


Assuntos
Biomineralização , Cobre/metabolismo , Geobacter/metabolismo , Nanopartículas Metálicas , Sulfetos/metabolismo
8.
World J Microbiol Biotechnol ; 36(6): 81, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32448917

RESUMO

This study evaluated the effect of three sulfate salt-based culture media on the reprecipitation of sulfur under the action of two types of bacterial inoculum, a pure strain of Acidithiobacillus ferrooxidans (ATCC 23270) and a consortium of this strain and Acidithiobacillus thiooxidans (ATCC 15494), in a biodesulfurization process for coal (particle size < 0.25 mm) from the 'La Guacamaya' mine (Puerto Libertador, Córdoba, Colombia). All of the experiments were periodically monitored, with measurements taken of pH, cell concentration, iron concentration, and pyrite oxidation. Additionally, mineralogical analyses were conducted on the initial and final coal samples, through scanning electron microscopy with an energy-dispersive X-ray spectrometer. The results showed that sulfate reprecipitation occurred primarily, and nearly entirely, during the first 3 days of the process. While all the treatments obtained high levels of mineral oxidation, the reprecipitation processes decreased in media with low concentrations of sulfate, leading to the higher final removal of inorganic sulfur. The bioassays revealed that after 15 days, the maximum pyrite oxidation (86%) and inorganic sulfur removal (53%) was obtained with the treatments using the Kos and McCready culture media. The bacteria evaluated were found to have a great ability to adapt to very simple culture media with minimal nutrient concentrations, and even with some nutrients absent (as in the case of magnesium).


Assuntos
Acidithiobacillus/crescimento & desenvolvimento , Crescimento Quimioautotrófico , Carvão Mineral/microbiologia , Meios de Cultura/química , Compostos de Enxofre/metabolismo , Acidithiobacillus/metabolismo , Biodegradação Ambiental , Ferro/metabolismo , Sulfatos/metabolismo , Sulfetos/metabolismo
9.
Sci Rep ; 10(1): 8264, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32427954

RESUMO

Sedimentary pyrite (FeS2) is commonly thought to be a product of microbial sulfate reduction and hence may preserve biosignatures. However, proof that microorganisms are involved in pyrite formation is still lacking as only metastable iron sulfides are usually obtained in laboratory cultures. Here we show the rapid formation of large pyrite spherules through the sulfidation of Fe(III)-phosphate (FP) in the presence of a consortium of sulfur- and sulfate-reducing bacteria (SRB), Desulfovibrio and Sulfurospirillum, enriched from ferruginous and phosphate-rich Lake Pavin water. In biomineralization experiments inoculated with this consortium, pyrite formation occurred within only 3 weeks, likely enhanced by the local enrichment of polysulfides around SRB cells. During this same time frame, abiotic reaction of FP with sulfide led to the formation of vivianite (Fe3(PO4)2·8H2O) and mackinawite (FeS) only. Our results suggest that rates of pyritization vs. vivianite formation are regulated by SRB activity at the cellular scale, which enhances phosphate release into the aqueous phase by increased efficiency of iron sulfide precipitation, and thus that these microorganisms strongly influence biological productivity and Fe, S and P cycles in the environment.


Assuntos
Campylobacteraceae/metabolismo , Desulfovibrio/metabolismo , Ferro/metabolismo , Lagos/microbiologia , Consórcios Microbianos , Sulfatos/metabolismo , Sulfetos/metabolismo , Enxofre/metabolismo , Campylobacteraceae/genética , Campylobacteraceae/isolamento & purificação , Desulfovibrio/genética , Desulfovibrio/isolamento & purificação , Oxirredução , Fosfatos/metabolismo
10.
J Agric Food Chem ; 68(16): 4650-4656, 2020 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-32233408

RESUMO

Methionol is a sulfur-containing aroma compound that contributes to the flavors of fermented foods. In this work, a novel method for methionol production was established using 3-methylthiopropionaldehyde (MMP) and alcohol dehydrogenase (ADH). First, expression of seven ADH genes was analyzed in yeast fermentation added with MMP. Only ADH4 displayed an evident increased expression in response to MMP. ADH4 was then overexpressed in Saccharomyces cerevisiae S288c and Escherichia coli BL21. The recombinant yeast strain S4 produced more methionol than control strain in MMP fermentation. Furthermore, 0.55 g/L 42 kDa Adh4p was prepared from E. coli by induced expression and purification. A fed-batch catalysis system was finally established to produce methionol from MMP by Adh4p. In 10 h of continuous catalysis, the conversion rate of MMP remained 80-95%, and a final yield of 0.2 g/L methionol was achieved. This work proposed a novel method for methionol production by enzymatic catalysis with a potential application prospect in industry.


Assuntos
Álcool Desidrogenase/genética , Aldeídos/metabolismo , Propanóis/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sulfetos/metabolismo , Álcool Desidrogenase/metabolismo , Aldeídos/química , Biocatálise , Escherichia coli/genética , Escherichia coli/metabolismo , Fermentação , Expressão Gênica , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
11.
Mar Environ Res ; 157: 104926, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32275508

RESUMO

Seasonal hypoxia/suboxia (at times anoxia) towards the end of Southwest monsoon (SWM; June to September) at the coastal time series site off Goa, West coast of India was found to influence the dynamics of phytoplankton biomass, community structure and production of climatically active gas, dimethylsulphide (DMS). In this diatom dominated study region, high DMS production in the subsurface waters during late SWM might possible be attributed to the stress experienced by micro- and macro-algae from the prevailing low oxygen subsurface waters through different pathways specifically believed to be via methylation pathway (see Schafer et al., 2010). Based on laboratory experiments, we hypothesize presence of floating seaweeds mostly Sargassum species washed from the shore to the study site to contribute sizably to DMS production in the water column as they sink and degrade during the senescence phase. However, we are yet to address its loss/emission processes across the oxic-hypoxic boundary of seasonal (and permanent) oxygen minimum zone of the northern Indian Ocean, which is important from the viewpoint of global climate change.


Assuntos
Monitoramento Ambiental , Fitoplâncton , Sulfetos/metabolismo , Biomassa , Eutrofização , Índia , Oceano Índico , Oxigênio , Sargassum , Estações do Ano , Água do Mar
12.
Chemosphere ; 253: 126637, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278910

RESUMO

A kinetic study was carried out in a sequencing batch reactor (SBR) (125 mg NH4+-N/L) inoculated with a physiologically stable nitrifying sludge not previously acclimated to sulfur compounds and fed at different initial sulfide concentrations (2.5-20.0 mg HS--S/L). Up to 10.0 mg HS--S/L, the nitrifying process kept stable and complete, reaching an ammonium consumption efficiency (ENH4+) of 100% and a nitrate yield (YNO3-) of 0.95 ± 0.03 mg NO3--N/mg NH4+-N consumed. At 15.0 and 20.0 mg HS--S/L, after an initial alteration in the nitrite oxidizing process, the YNO2- was decreasing throughout the cycles and the YNO3- increasing, obtaining in the last cycle at 20.0 mg HS--S/L, an ENH4+ of 100%, a YNO2- of zero, and a YNO3- of 0.80 mg NO3--N/mg NH4+-N consumed. At the end of the period at 20.0 mg HS--S/L, the specific rates of ammonium consumption and nitrate formation were 15 and 55% lower than their respective values in the control period without sulfide addition, showing that the sludge had a better metabolic adaptation for ammonium oxidizing activity than for nitrite oxidizing activity. The sludge acquired a higher sulfide oxidation capacity along the cycles. Bacterial population dynamics assessment indicated that the ammonium oxidizing bacteria (AOB) community was more diverse and stable than the nitrite oxidizing bacteria (NOB) community. The use of consortia with a previously stabilized nitrifying activity in SBR may constitute an alternative for eliminating simultaneously ammonium by nitrification and sulfide by sulfide oxidation and be implemented for the treatment of wastewater with ammonium and sulfide.


Assuntos
Compostos de Amônio/metabolismo , Sulfetos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Bactérias/metabolismo , Reatores Biológicos/microbiologia , Cinética , Nitratos/metabolismo , Nitrificação , Nitritos/metabolismo , Oxirredução , Dinâmica Populacional , Esgotos/microbiologia , Compostos de Enxofre/metabolismo , Águas Residuárias
13.
ISME J ; 14(6): 1508-1519, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32152390

RESUMO

The majority of anaerobic biogeochemical cycling occurs within marine sediments. To understand these processes, quantifying the distribution of active cells and gross metabolic activity is essential. We present an isotope model rooted in thermodynamics to draw quantitative links between cell-specific sulfate reduction rates and active sedimentary cell abundances. This model is calibrated using data from a series of continuous culture experiments with two strains of sulfate reducing bacteria (freshwater bacterium Desulfovibrio vulgaris strain Hildenborough, and marine bacterium Desulfovibrio alaskensis strain G-20) grown on lactate across a range of metabolic rates and ambient sulfate concentrations. We use a combination of experimental sulfate oxygen isotope data and nonlinear regression fitting tools to solve for unknown kinetic, step-specific oxygen isotope effects. This approach enables identification of key isotopic reactions within the metabolic pathway, and defines a new, calibrated framework for understanding oxygen isotope variability in sulfate. This approach is then combined with porewater sulfate/sulfide concentration data and diagenetic modeling to reproduce measured 18O/16O in porewater sulfate. From here, we infer cell-specific sulfate reduction rates and predict abundance of active cells of sulfate reducing bacteria, the result of which is consistent with direct biological measurements.


Assuntos
Desulfovibrio/metabolismo , Isótopos de Oxigênio , Sulfatos/metabolismo , Bactérias/metabolismo , Oxirredução , Sulfetos/metabolismo , Óxidos de Enxofre/metabolismo
14.
Arterioscler Thromb Vasc Biol ; 40(4): 874-884, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32131614

RESUMO

Hydrogen sulfide has emerged as an important gaseous signaling molecule and a regulator of critical biological processes. However, the physiological significance of hydrogen sulfide metabolites such as persulfides, polysulfides, and other reactive sulfur species (RSS) has only recently been appreciated. Emerging evidence suggests that these RSS molecules may have similar or divergent regulatory roles compared with hydrogen sulfide in various biological activities. However, the chemical nature of persulfides and polysulfides is complex and remains poorly understood within cardiovascular and other pathophysiological conditions. Recent reports suggest that RSS can be produced endogenously, with different forms having unique chemical properties and biological implications involving diverse cellular responses such as protein biosynthesis, cell-cell barrier functions, and mitochondrial bioenergetics. Enzymes of the transsulfuration pathway, CBS (cystathionine beta-synthase) and CSE (cystathionine gamma-lyase), may also produce RSS metabolites besides hydrogen sulfide. Moreover, CARSs (cysteinyl-tRNA synthetase) are also able to generate protein persulfides via cysteine persulfide (CysSSH) incorporation into nascently formed polypeptides suggesting a new biologically relevant amino acid. This brief review discusses the biochemical nature and potential roles of RSS, associated oxidative stress redox signaling, and future research opportunities in cardiovascular disease.


Assuntos
Doenças Cardiovasculares/metabolismo , Sulfeto de Hidrogênio/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Disponibilidade Biológica , Doenças Cardiovasculares/fisiopatologia , Cistationina gama-Liase/genética , Humanos , Óxidos de Nitrogênio/metabolismo , Oxirredução , Polimorfismo Genético , Sulfetos/metabolismo , Remodelação Vascular
15.
Anal Chim Acta ; 1106: 115-125, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32145839

RESUMO

Two-dimentional layered WS2 nanosheets with rich active edge exhibit intrinsic peroxidase-mimic activity, which make them an ideal material for sensor design. However, there is still lack of research on the catalysis and regulation mechanisms of the layered WS2 nanosheets as well as their application in the detection of hazardous substances. Herein, the regulatory effect of Pb(II) on the peroxidase-mimic activity of the layered WS2 nanosheets was firstly investigated, which enable us to construct a novel and facile colorimetric sensor for ultrasensitive and selective detection of Pb(II). To improve the performance of colorimetric sensor, some important parameters like buffer conditions, substrates and temperature have been investigated. Under the optimal conditions, the catalytic kinetics of layered WS2 nanosheets were extensively investigated. The peroxidase-mimic catalytic reaction was proved to be the "ping pong" mechanism, and the regulatory effect of Pb(II) on layered WS2 nanosheets was agreed with noncompetitive inhibition. The absorbance variation of colorimetric sensor is proportionally related to the concentration of heavy metals, which enable us to easily distinguish whether Pb(II) exceeds the permissible level in less than 20 min even by the naked eyes. The limit of detection (LOD) and the limit of quantification (LOQ) of the proposed colorimetric sensor for Pb(II) were determined as low as 4 µg L-1 and 13.3 µg L-1, and displays excellent selectivity against other competitive metal ions. Moreover, the further studies also validate the applicability of colorimetric sensor in several actual samples, indicating that our strategy may has prospective applications for Pb(II) detection in environment and biological samples.


Assuntos
Colorimetria , Poluentes Ambientais/análise , Chumbo/análise , Nanoestruturas/química , Peroxidase/metabolismo , Sulfetos/metabolismo , Compostos de Tungstênio/metabolismo , Animais , Biocatálise , Monitoramento Ambiental , Poluentes Ambientais/metabolismo , Peixes , Radical Hidroxila/análise , Chumbo/metabolismo , Tamanho da Partícula , Peroxidase/química , Sulfetos/química , Propriedades de Superfície , Compostos de Tungstênio/química
16.
Plant Cell ; 32(4): 1000-1017, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32024687

RESUMO

Hydrogen sulfide (H2S) is a gaseous signaling molecule that regulates diverse cellular signaling pathways through persulfidation, which involves the post-translational modification of specific Cys residues to form persulfides. However, the mechanisms that underlie this important redox-based modification remain poorly understood in higher plants. We have, therefore, analyzed how protein persulfidation acts as a specific and reversible signaling mechanism during the abscisic acid (ABA) response in Arabidopsis (Arabidopsis thaliana). Here we show that ABA stimulates the persulfidation of l-CYSTEINE DESULFHYDRASE1, an important endogenous H2S enzyme, at Cys44 and Cys205 in a redox-dependent manner. Moreover, sustainable H2S accumulation drives persulfidation of the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG PROTEIN D (RBOHD) at Cys825 and Cys890, enhancing its ability to produce reactive oxygen species. Physiologically, s-persulfidation-induced RBOHD activity is relevant to ABA-induced stomatal closure. Together, these processes form a negative feedback loop that fine-tunes guard cell redox homeostasis and ABA signaling. These findings not only expand our current knowledge of H2S function in the context of guard cell ABA signaling, but also demonstrate the presence of a rapid signal integration mechanism involving specific and reversible redox-based post-translational modifications that occur in response to changing environmental conditions.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Cistationina gama-Liase/metabolismo , NADPH Oxidases/metabolismo , Estômatos de Plantas/citologia , Transdução de Sinais , Sulfetos/metabolismo , Cisteína/metabolismo , Sulfeto de Hidrogênio/metabolismo , Modelos Biológicos , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
17.
Curr Microbiol ; 77(6): 1070-1080, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32036394

RESUMO

Exploring the effects of nitrate ions (NO3-) on the bio-oxidation of Fe2+ and pyrite will help reveal the actual mechanism of acid mine drainage (AMD) production. Long period shaking flask experiments were carried out in order to assess the effect of NO3- on the Acidithiobacillus ferrooxidans LX5 (A. ferrooxidans LX5)-mediated bio-oxidation of Fe2+ and pyrite. In Fe2+ bio-oxidation systems, A. ferrooxidans LX5 had stronger Fe2+ oxidation capabilities in a NO3--loaded solution than in a NO3--free solution after 24 days, and the Fe2+ bio-oxidation capacity of A. ferrooxidans LX5 acclimatized in solutions containing low concentrations (8.2-32.9 mmol/L) of NO3- was greater than when it was acclimatized in high NO3- concentration solutions (49.4-65.8 mmol/L). In pyrite bio-oxidation systems, in comparison with the system without NO3-, pyrite bio-oxidation efficiency was significantly increased when the NO3- concentration in the system was 8.2-16.5 mmol/L, and that the pyrite bio-oxidation efficiency in the system containing 8.2 mmol/L of NO3- was greater than that for the system with 16.5 mmol/L of NO3-. The pyrite bio-oxidation efficiency was inhibited when the NO3- concentration was above 32.9 mmol/L. The results from this study can be used to reveal the actual control behavior of NO3- on AMD production.


Assuntos
Acidithiobacillus/efeitos dos fármacos , Compostos Ferrosos/metabolismo , Íons/metabolismo , Ferro/metabolismo , Nitratos/farmacologia , Sulfetos/metabolismo , Aclimatação , Acidithiobacillus/metabolismo , Acidithiobacillus/ultraestrutura , Ácidos/metabolismo , Biodegradação Ambiental , Poluentes Ambientais/metabolismo , Concentração de Íons de Hidrogênio , Mineração , Oxirredução
18.
Biotechnol Lett ; 42(6): 957-964, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32100159

RESUMO

OBJECTIVE: This study aims to investigate the attachment of Acidithiobacillus ferrooxidans to pyrite in two different environments: fresh and saline water (water with 35 g/L of NaCl or 0.6 M). Adsorption isotherms were analyzed using the Langmuir and Freundlich models. Saline water is water with 35 g/L of NaCl (0.6 M), which is the concentration of NaCl in seawater. The use of raw seawater in mining is becoming relevant in leaching and flotation process. At the same time the use of microorganisms in both processes is gaining attention. For this reason, it is important to study the behavior of adherence of microorganisms to minerals in saline aqueous environments, similar to seawater. RESULTS: The bacteria showed a higher level of attachment to pyrite in fresh water than in saline water. The Langmuir model fitted better the experimental data obtained in fresh water than in saline water with a coefficient of determination (R2) of 0.85 and 0.61 for fresh and saline water, respectively. CONCLUSIONS: This suggests that the bacteria tend to adhere more as a monolayer in fresh than in saline water in the early stage of adhesion.


Assuntos
Acidithiobacillus/metabolismo , Água Doce , Ferro/metabolismo , Modelos Químicos , Águas Salinas , Sulfetos/metabolismo , Acidithiobacillus/química , Adsorção , Água Doce/química , Água Doce/microbiologia , Ferro/química , Cinética , Sulfetos/química
19.
Sci Rep ; 10(1): 2418, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-32051465

RESUMO

We conducted pot experiments to assess the bioavailability of cadmium (Cd) in contaminated rhizosphere soil and accumulation in rice organs in response to nitrogen (N) supply ((NH4)2SO4, NH4NO3, NH4Cl). The results showed that the concentration of bioavailable Cd in rice rhizosphere soil was (NH4)2SO4 treatment > NH4Cl treatment > NH4NO3 treatment at the same level of N application and growth period; the Cd concentration in rice roots was (NH4)2SO4 treatment > NH4NO3 treatment > NH4Cl treatment; and the Cd concentration in rice straw was NH4NO3 treatment > NH4Cl. The Cd concentration in rice roots, straws, and seeds at the maturity stage was (NH4)2SO4 treatment > NH4Cl treatment. With the same N fertilizer, excessive N promoted Cd accumulation in rice at later growth stages. This suggested that sulfate (SO42-) influenced Cd concentration in rice. NH4Cl application maintained a low Cd level in different rice organs with the same N level. This confirmed that NH4Cl is a safe N source for rice planting in polymetallic sulfide mining areas. The study concludes that appropriate NH4Cl levels for Cd-contaminated paddy soil with high-S-content could obtain rice grains with Cd concentrations below the food safety standards (0.2 or 0.4 mg·kg-1).


Assuntos
Cádmio/metabolismo , Nitrogênio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Biotransformação , Cádmio/análise , Fertilizantes/análise , Mineração , Nitrogênio/análise , Oryza/crescimento & desenvolvimento , Rizosfera , Solo/química , Poluentes do Solo/análise , Sulfatos/análise , Sulfatos/metabolismo , Sulfetos/análise , Sulfetos/metabolismo
20.
Essays Biochem ; 64(1): 155-168, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-32016341

RESUMO

Persulfides (RSSH/RSS-) can be formed in protein and non-protein thiols (RSH) through several different pathways, some of which are dependent on hydrogen sulfide (H2S/HS-). In addition to their roles in biosynthetic processes, persulfides are possible transducers of physiological effects of H2S through the modification of critical cysteines. Persulfides have a very rich biological chemistry that is currently under investigation. They are more nucleophilic and acidic than thiols and, unlike thiols, they can also be electrophilic. They are especially good one-electron reductants. Methods to detect their formation are under continuous development. In this minireview we describe the pathways of formation of persulfides, their biochemical properties and the techniques available for their detection, and we discuss the possible implications of their formation in biological systems.


Assuntos
Proteínas/metabolismo , Sulfetos/metabolismo , Animais , Humanos , Sulfeto de Hidrogênio/química , Proteínas/análise , Proteínas/química , Proteômica , Compostos de Sulfidrila/química , Sulfetos/análise , Sulfetos/química
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