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1.
Chemosphere ; 262: 128361, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182109

RESUMO

Although Cd is threatening to the environment, animal, and human, the eco-friendly approach to mitigate the Cd-toxicity in alfalfa was barely studied. Therefore, this study aims at elucidating the role of S, a crucial macroelement, in alleviating Cd toxicity in alfalfa plants. The supplementation of S in Cd-stressed alfalfa reversed the detrimental effect on plant biomass, chlorophyll synthesis, and protein concentration. Interestingly, S surplus restored the photosynthetic kinetics, such as Fv/Fm, Pi_ABS, and Mo values in leaves of Cd-stressed alfalfa. Further, Cd-induced adverse effect on membrane stability, cell viability, and redox status was restored due to S under Cd stress. The exogenous S not only increased S status and the expression of sulfate transporters (MsSULRT1;2 and MsSULTR1;3), but also decreased the Cd concentration in the shoot by retaining elevated Cd in root tissue. Further analysis revealed the upregulation of MsGS (glutathione synthetase) and MsPCS1 (phytochelatin synthase) genes along with the increased concentration of glutathione and phytochelatin, predominantly in roots subjected to S surplus under Cd stress. The subcellular Cd analysis showed elevated Cd in the cell wall but not in the vacuole. It suggests that S-induced elevated glutathione enables the phytochelatin to bind with excess Cd leading to subcellular sequestration in the cell wall of roots. Also, S stimulates the S-metabolites and GR enzyme that coordinately counteracts Cd-induced oxidative damage. These findings can be utilized to popularize the application of S and to perform breeding/transgenic experiments to develop Cd-free forage crops.


Assuntos
Cádmio/toxicidade , Glutationa/metabolismo , Medicago sativa/fisiologia , Fitoquelatinas/metabolismo , Poluentes do Solo/toxicidade , Enxofre/toxicidade , Aminoaciltransferases , Cádmio/metabolismo , Parede Celular/metabolismo , Medicago sativa/metabolismo , Oxirredução , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo , Enxofre/metabolismo
2.
Nat Commun ; 11(1): 6310, 2020 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-33298951

RESUMO

Heme biosynthesis and iron-sulfur cluster (ISC) biogenesis are two major mammalian metabolic pathways that require iron. It has long been known that these two pathways interconnect, but the previously described interactions do not fully explain why heme biosynthesis depends on intact ISC biogenesis. Herein we identify a previously unrecognized connection between these two pathways through our discovery that human aminolevulinic acid dehydratase (ALAD), which catalyzes the second step of heme biosynthesis, is an Fe-S protein. We find that several highly conserved cysteines and an Ala306-Phe307-Arg308 motif of human ALAD are important for [Fe4S4] cluster acquisition and coordination. The enzymatic activity of human ALAD is greatly reduced upon loss of its Fe-S cluster, which results in reduced heme biosynthesis in human cells. As ALAD provides an early Fe-S-dependent checkpoint in the heme biosynthetic pathway, our findings help explain why heme biosynthesis depends on intact ISC biogenesis.


Assuntos
Heme/biossíntese , Proteínas com Ferro-Enxofre/metabolismo , Ferro/metabolismo , Sintase do Porfobilinogênio/metabolismo , Enxofre/metabolismo , Motivos de Aminoácidos , Vias Biossintéticas , Linhagem Celular , Coenzimas/metabolismo , Cisteína/metabolismo , Humanos , Proteínas com Ferro-Enxofre/genética , Sintase do Porfobilinogênio/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(47): 29629-29636, 2020 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-33168746

RESUMO

The unicellular green alga Chlamydomonas reinhardtii is capable of photosynthetic H2 production. H2 evolution occurs under anaerobic conditions and is difficult to sustain due to 1) competition between [FeFe]-hydrogenase (H2ase), the key enzyme responsible for H2 metabolism in algae, and the Calvin-Benson-Bassham (CBB) cycle for photosynthetic reductants and 2) inactivation of H2ase by O2 coevolved in photosynthesis. Recently, we achieved sustainable H2 photoproduction by shifting algae from continuous illumination to a train of short (1 s) light pulses, interrupted by longer (9 s) dark periods. This illumination regime prevents activation of the CBB cycle and redirects photosynthetic electrons to H2ase. Employing membrane-inlet mass spectrometry and [Formula: see text], we now present clear evidence that efficient H2 photoproduction in pulse-illuminated algae depends primarily on direct water biophotolysis, where water oxidation at the donor side of photosystem II (PSII) provides electrons for the reduction of protons by H2ase downstream of photosystem I. This occurs exclusively in the absence of CO2 fixation, while with the activation of the CBB cycle by longer (8 s) light pulses the H2 photoproduction ceases and instead a slow overall H2 uptake is observed. We also demonstrate that the loss of PSII activity in DCMU-treated algae or in PSII-deficient mutant cells can be partly compensated for by the indirect (PSII-independent) H2 photoproduction pathway, but only for a short (<1 h) period. Thus, PSII activity is indispensable for a sustained process, where it is responsible for more than 92% of the final H2 yield.


Assuntos
Clorófitas/metabolismo , Hidrogênio/metabolismo , Nutrientes/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Água/metabolismo , Chlamydomonas reinhardtii/metabolismo , Clorofila/metabolismo , Transporte de Elétrons/fisiologia , Elétrons , Hidrogenase/metabolismo , Oxigênio/metabolismo , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Enxofre/metabolismo
4.
Nat Commun ; 11(1): 5953, 2020 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-33230146

RESUMO

Modern day aerobic respiration in mitochondria involving complex I converts redox energy into chemical energy and likely evolved from a simple anaerobic system now represented by hydrogen gas-evolving hydrogenase (MBH) where protons are the terminal electron acceptor. Here we present the cryo-EM structure of an early ancestor in the evolution of complex I, the elemental sulfur (S0)-reducing reductase MBS. Three highly conserved protein loops linking cytoplasmic and membrane domains enable scalable energy conversion in all three complexes. MBS contains two proton pumps compared to one in MBH and likely conserves twice the energy. The structure also reveals evolutionary adaptations of MBH that enabled S0 reduction by MBS catalyzed by a site-differentiated iron-sulfur cluster without participation of protons or amino acid residues. This is the simplest mechanism proposed for reduction of inorganic or organic disulfides. It is of fundamental significance in the iron and sulfur-rich volcanic environments of early earth and possibly the origin of life. MBS provides a new perspective on the evolution of modern-day respiratory complexes and of catalysis by biological iron-sulfur clusters.


Assuntos
Proteínas com Ferro-Enxofre/química , Proteínas com Ferro-Enxofre/metabolismo , Oxirredutases/química , Oxirredutases/metabolismo , Enxofre/metabolismo , Catálise , Domínio Catalítico , Microscopia Crioeletrônica , Complexo I de Transporte de Elétrons/química , Complexo I de Transporte de Elétrons/metabolismo , Hidrogenase/química , Hidrogenase/metabolismo , Membranas Mitocondriais/enzimologia , Membranas Mitocondriais/metabolismo , Modelos Moleculares , Origem da Vida , Oxirredução , Bombas de Próton/química , Pyrococcus furiosus/química , Pyrococcus furiosus/enzimologia , Trocadores de Sódio-Hidrogênio/química
5.
Int J Syst Evol Microbiol ; 70(12): 6226-6234, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33112221

RESUMO

The genus Acidihalobacter has three validated species, Acidihalobacter ferrooxydans, Acidihalobacter prosperus and Acidihalobacter aeolinanus, all of which were isolated from Vulcano island, Italy. They are obligately chemolithotrophic, aerobic, acidophilic and halophilic in nature and use either ferrous iron or reduced sulphur as electron donors. Recently, a novel strain was isolated from an acidic, saline drain in the Yilgarn region of Western Australia. Strain F5T has an absolute requirement for sodium chloride (>5 mM) and is osmophilic, growing in elevated concentrations (>1 M) of magnesium sulphate. A defining feature of its physiology is its ability to catalyse the oxidative dissolution of the most abundant copper mineral, chalcopyrite, suggesting a potential role in biomining. Originally categorized as a strain of A. prosperus, 16S rRNA gene phylogeny and multiprotein phylogenies derived from clusters of orthologous proteins (COGS) of ribosomal protein families and universal protein families unambiguously demonstrate that strain F5T forms a well-supported separate branch as a sister clade to A. prosperus and is clearly distinguishable from A. ferrooxydans DSM 14175T and A. aeolinanus DSM14174T. Results of comparisons between strain F5T and the other Acidihalobacter species, using genome-based average nucleotide identity, average amino acid identity, correlation indices of tetra-nucleotide signatures (Tetra) and genome-to-genome distance (digital DNA-DNA hybridization), support the contention that strain F5T represents a novel species of the genus Acidihalobacter. It is proposed that strain F5T should be formally reclassified as Acidihalobacter yilgarnenesis F5T (=DSM 105917T=JCM 32255T).


Assuntos
Ectothiorhodospiraceae/classificação , Genoma Bacteriano , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , Cobre , DNA Bacteriano/genética , Ferro/metabolismo , Hibridização de Ácido Nucleico , Oxirredução , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Enxofre/metabolismo , Austrália Ocidental
6.
PLoS One ; 15(8): e0237998, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817691

RESUMO

Among the mineral nutrients that are required for plant metabolism, iron (Fe) and sulphur (S) play a central role as both elements are needed for the activity of several proteins involved in essential cellular processes. A combination of physiological, biochemical and molecular approaches was employed to investigate how S availability influences plant response to Fe deficiency, using the model plant Arabidopsis thaliana. We first observed that chlorosis symptom induced by Fe deficiency was less pronounced when S availability was scarce. We thus found that S deficiency inhibited the Fe deficiency induced expression of several genes associated with the maintenance of Fe homeostasis. This includes structural genes involved in Fe uptake (i.e. IRT1, FRO2, PDR9, NRAMP1) and transport (i.e. FRD3, NAS4) as well as a subset of their upstream regulators, namely BTS, PYE and the four clade Ib bHLH. Last, we found that the over accumulation of manganese (Mn) in response to Fe shortage was reduced under combined Fe and S deficiencies. These data suggest that S deficiency inhibits the Fe deficiency dependent induction of the Fe uptake machinery. This in turn limits the transport into the root and the plant body of potentially toxic divalent cations such as Mn and Zn, thus limiting the deleterious effect of Fe deprivation.


Assuntos
Arabidopsis/metabolismo , Ferro/deficiência , Enxofre/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Homeostase , Ferro/metabolismo , Transcrição Genética
7.
PLoS One ; 15(8): e0237884, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841243

RESUMO

The Solanum tuberosum plant specific insert (StPSI) has a defensive role in potato plants, with the requirements of acidic pH and anionic lipids. The StPSI contains a set of three highly conserved disulfide bonds that bridge the protein's helical domains. Removal of these bonds leads to enhanced membrane interactions. This work examined the effects of their sequential removal, both individually and in combination, using all-atom molecular dynamics to elucidate the role of disulfide linkages in maintaining overall protein tertiary structure. The tertiary structure was found to remain stable at both acidic (active) and neutral (inactive) pH despite the removal of disulfide linkages. The findings include how the dimer structure is stabilized and the impact on secondary structure on a residue-basis as a function of disulfide bond removal. The StPSI possesses an extensive network of inter-monomer hydrophobic interactions and intra-monomer hydrogen bonds, which is likely the key to the stability of the StPSI by stabilizing local secondary structure and the tertiary saposin-fold, leading to a robust association between monomers, regardless of the disulfide bond state. Removal of disulfide bonds did not significantly impact secondary structure, nor lead to quaternary structural changes. Instead, disulfide bond removal induces regions of amino acids with relatively higher or lower variation in secondary structure, relative to when all the disulfide bonds are intact. Although disulfide bonds are not required to preserve overall secondary structure, they may have an important role in maintaining a less plastic structure within plant cells in order to regulate membrane affinity or targeting.


Assuntos
Dissulfetos/metabolismo , Simulação de Dinâmica Molecular , Proteínas de Plantas/metabolismo , Saposinas/metabolismo , Solanum tuberosum/metabolismo , Cisteína/metabolismo , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Plantas/química , Multimerização Proteica , Estabilidade Proteica , Estrutura Secundária de Proteína , Sais/química , Enxofre/metabolismo
8.
Nat Commun ; 11(1): 4322, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859898

RESUMO

Gut microbial and metabolite alterations have been linked to the pathogenesis of inflammatory bowel diseases. Here we perform a multi-omics microbiome and metabolite analysis of a longitudinal cohort of Crohn's disease patients undergoing autologous hematopoietic stem cell transplantation, and investigational therapy that induces drug free remission in a subset of patients. Via comparison of patients who responded and maintained remission, responded but experienced disease relapse and patients who did not respond to therapy, we identify shared functional signatures that correlate with disease activity despite the variability of gut microbiota profiles at taxonomic level. These signatures reflect the disease state when transferred to gnotobiotic mice. Taken together, the integration of microbiome and metabolite profiles from human cohort and mice improves the predictive modelling of disease outcome, and allows the identification of a network of bacteria-metabolite interactions involving sulfur metabolism as a key mechanism linked to disease activity in Crohn's disease.


Assuntos
Doença de Crohn/metabolismo , Doença de Crohn/microbiologia , Microbioma Gastrointestinal/fisiologia , Enxofre/metabolismo , Adolescente , Adulto , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Doença de Crohn/tratamento farmacológico , Modelos Animais de Doenças , Fezes/microbiologia , Feminino , Transplante de Células-Tronco Hematopoéticas , Humanos , Interleucina-10/genética , Masculino , Metagenoma , Camundongos , Camundongos Knockout , RNA Ribossômico 16S/genética , Indução de Remissão , Adulto Jovem
9.
Biochim Biophys Acta Mol Cell Res ; 1867(11): 118829, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32822728

RESUMO

Biogenesis of iron-sulfur (FeS) clusters in an essential process in living organisms due to the critical role of FeS cluster proteins in myriad cell functions. During biogenesis of FeS clusters, multi-protein complexes are used to drive the mobilization and protection of reactive sulfur and iron intermediates, regulate assembly of various FeS clusters on an ATPase-dependent, multi-protein scaffold, and target nascent clusters to their downstream protein targets. The evolutionarily ancient sulfur formation (Suf) pathway for FeS cluster assembly is found in bacteria and archaea. In Escherichia coli, the Suf pathway functions as an emergency pathway under conditions of iron limitation or oxidative stress. In other pathogenic bacteria, such as Mycobacterium tuberculosis and Enterococcus faecalis, the Suf pathway is the sole source for FeS clusters and therefore is a potential target for the development of novel antibacterial compounds. Here we summarize the considerable progress that has been made in characterizing the first step of mobilization and protection of reactive sulfur carried out by the SufS-SufE or SufS-SufU complex, FeS cluster assembly on SufBC2D scaffold complexes, and the downstream trafficking of nascent FeS clusters to A-type carrier (ATC) proteins. Cell Biology of Metals III edited by Roland Lill and Mick Petris.


Assuntos
Evolução Molecular , Proteínas com Ferro-Enxofre/genética , Ferro/metabolismo , Enxofre/metabolismo , Adenosina Trifosfatases/genética , Enterococcus faecalis/genética , Enterococcus faecalis/patogenicidade , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas com Ferro-Enxofre/metabolismo , Liases/genética , Redes e Vias Metabólicas/genética , Família Multigênica/genética , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/patogenicidade
10.
Met Ions Life Sci ; 202020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32851828

RESUMO

Iron-sulfur clusters are ubiquitous protein cofactors composed of iron and inorganic sulfur. These cofactors are among the most ancient ones and may have contributed to the birth of life on Earth. Therefore, they are found even today in many enzymes central to metabolic processes like nitrogen fixation, respiration, and DNA processing and repair. Due to the toxicity associated with iron and sulfur ions, living organisms evolved dedicated machineries to synthetize and then transfer iron-sulfur clusters into client proteins. The iron-sulfur cluster (ISC) machinery is responsible for iron-sulfur cluster biogenesis in prokaryotes and in the mitochondrion of eukaryotes; the sulfur mobilization (SUF) machinery is present in prokaryotes and in the chloroplasts of plants; finally, the cytosolic iron-sulfur assembly (CIA) machinery is only present in the cytoplasm of eukaryotes. Genome analysis allowed the prediction of the proteins containing iron-sulfur clusters across a broad variety of living organisms, establishing links between the size and composition of iron-sulfur proteomes and the types of organisms that encode them. For example, the iron-sulfur proteomes of aerobes are generally smaller than those of anaerobes with similar genome size; furthermore, aerobes are enriched in [2Fe-2S] proteins compared to anaerobes, which predominantly use [4Fe-4S] proteins. This relates to the lower bioavailability of iron and the higher lability of [4Fe-4S] clusters within aerobic environments. Analogous considerations apply to humans, where the occurrence and functions of iron-sulfur proteins depend on the cellular compartment where they are localized. For example, an emerging primary role for nuclear iron-sulfur proteins is in DNA maintenance. Given their key functions in metabolism, dysfunctions of mutations in iron-sulfur proteins, or in proteins participating in iron-sulfur cluster biogenesis, are associated with serious human diseases.


Assuntos
Ferro/metabolismo , Enxofre/metabolismo , Humanos , Proteínas com Ferro-Enxofre/genética , Mitocôndrias/metabolismo
11.
Plant Physiol Biochem ; 155: 20-34, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32738579

RESUMO

Nitric oxide (NO) and hydrogen sulfide (H2S), versatile signaling molecules, play multiple roles in plant growth, physiological and biochemical processes under heavy metal stress. However, the mechanisms through which NO in association with endogenous H2S mediated hexavalent chromium Cr(VI) toxicity mitigation are still not fully understood. Therefore, we investigated the role of NO and H2S in sulfur (S)-assimilation and the effect of NO on endogenous H2S, and cysteine (Cys) biosynthesis and maintenance of cellular glutathione (GSH) pool in tomato seedlings under Cr(VI) stress. Cr(VI) toxicity caused an increase in reactive oxygen species (ROS; O2•- and H2O2) formation and activity of chlorophyll (Chl) degrading enzyme [Chlorophyllase (Chlase)] and decrease in seedlings growth attributes, Chl a and b content, and activity of Chl synthesizing enzyme [δ-aminolevulinic acid dehydratase (δ-ALAD)], gas exchange parameters, S-assimilation, and Cys and H2S metabolism. An increase in the content of glycinebetaine (GB), total soluble carbohydrates (TSCs) and total phenols (TPls), and decrease in DNA damage and ROS in NO treated seedlings conferred Cr(VI) toxicity tolerance. Under Cr(VI) toxicity conditions, the inclusion of H2S scavenger hypotaurine (HT) in growth medium containing NO validated the role of endogenous H2S in S-assimilation, H2S and Cys and GSH metabolism by withdrawing activity of enzymes involved in S-assimilation [adenosine 5-phosphosulfatereductase (APS-R), ATP-sulfurylase (ATP-S)], in the biosynthesis of H2S [L-cysteine desulfhydrase (L-CD) and D-cysteine desulfhydrase (D-CD)], Cys [O-acetylserin (thiol) lyase (OAST-L)], and GSH [glutamylcysteine synthetase (γ-GCS) and glutathione synthetase (GS)], and in antioxidant system. On the other hand, application of cPTIO [2-(4-32 carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], a NO scavenger and HT diminished the effect of NO on internal H2S levels, Cys and glutathione homeostasis, and S-assimilation, which resulted in poor immunity against oxidative stress induced by Cr(VI) toxicity. The obtained results postulate that NO-induced internal H2S conferred tolerance of tomato seedlings to Cr(VI) toxicity and maintained better photosynthesis process and plant growth.


Assuntos
Cromo/toxicidade , Sulfeto de Hidrogênio/metabolismo , Lycopersicon esculentum/efeitos dos fármacos , Óxido Nítrico/farmacologia , Enxofre/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Clorofila/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Plântula/efeitos dos fármacos
12.
Proc Natl Acad Sci U S A ; 117(36): 22402-22412, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839304

RESUMO

Multiple sclerosis (MS), an autoimmune disease of the central nervous system, generally starts as the relapsing remitting form (RRMS), but often shifts into secondary progressive MS (SPMS). SPMS represents a more advanced stage of MS, characterized by accumulating disabilities and refractoriness to medications. The aim of this study was to clarify the microbial and functional differences in gut microbiomes of the different stages of MS. Here, we compared gut microbiomes of patients with RRMS, SPMS, and two closely related disorders with healthy controls (HCs) by 16S rRNA gene and whole metagenomic sequencing data from fecal samples and by fecal metabolites. Each patient group had a number of species having significant changes in abundance in comparison with HCs, including short-chain fatty acid (SCFA)-producing bacteria reduced in MS. Changes in some species had close association with clinical severity of the patients. A marked reduction in butyrate and propionate biosynthesis and corresponding metabolic changes were confirmed in RRMS compared with HCs. Although bacterial composition analysis showed limited differences between the patient groups, metagenomic functional data disclosed an increase in microbial genes involved in DNA mismatch repair in SPMS as compared to RRMS. Together with an increased ratio of cysteine persulfide to cysteine in SPMS revealed by sulfur metabolomics, we postulate that excessive DNA oxidation could take place in the gut of SPMS. Thus, gut ecological and functional microenvironments were significantly altered in the different stages of MS. In particular, reduced SCFA biosynthesis in RRMS and elevated oxidative level in SPMS were characteristic.


Assuntos
Microbioma Gastrointestinal , Esclerose Múltipla Crônica Progressiva/microbiologia , Esclerose Múltipla Recidivante-Remitente/microbiologia , Adulto , Estudos de Casos e Controles , Cisteína/metabolismo , Ácidos Graxos Voláteis/metabolismo , Fezes/microbiologia , Feminino , Microbioma Gastrointestinal/genética , Microbioma Gastrointestinal/fisiologia , Humanos , Masculino , Metagenoma/genética , Esclerose Múltipla Crônica Progressiva/epidemiologia , Esclerose Múltipla Recidivante-Remitente/epidemiologia , Estresse Oxidativo/fisiologia , Enxofre/metabolismo
13.
J Dairy Sci ; 103(10): 8741-8749, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32747106

RESUMO

The aim of this study was to evaluate the concentrations of Ca, P, S, Mg, K, and Na, and their distribution in major fractions of donkey milk (i.e., fat, casein, whey proteins, and aqueous phase). Individual milk samples were collected by mechanical milking from 16 clinically healthy lactating donkeys. Milk yield per milking was recorded and milk gross composition, casein content, and pH were determined. Whole milk samples were centrifuged to separate fat and to obtain skim milk. Skim milk samples were ultracentrifuged to separate a sedimentable casein pellet and to obtain a supernatant whey (soluble) fraction, which was then ultrafiltered to obtain the aqueous phase of donkey milk. Whole milk and the processed samples were analyzed for the aforementioned elements by inductively coupled plasma-mass spectrometry. The concentration of elements associated with fat, casein, and whey proteins was then calculated. All the Na was present in the aqueous phase. The fat fraction in donkey milk carried very little or none of the investigated elements. The majority of Ca (62.9%) and P (53.1%) was associated with casein, and the rest of these elements was mostly present in the aqueous phase. The majority of Mg was present in the aqueous phase, but a relevant part (32.6%) was associated with the casein fraction. No K was associated with casein. On a molar basis, the ratio of colloidal Ca and P to casein (mmol/g of casein) was more than double the values reported in literature for cow milk. The correlation coefficient was negative between milk pH and P in the ultracentrifuged (r = -0.81) and ultrafiltered (aqueous) fraction (r = -0.66). Milk pH correlated positively with colloidal Ca (r = 0.59) and with the ratio of colloidal Ca to casein (mmol/g of casein; r = 0.68). Colloidal Ca and P were positively correlated (r = 0.64). These data suggest that the high ratio of colloidal Ca and P to donkey casein micelles is due to a larger amount of colloidal calcium phosphate bound to casein micelles compared with literature data on cow milk. The percentage of elements associated with whey proteins was less than 5% for Ca, P, and K, but Mg reached approximately 9% of total Mg. The majority of S (63.6%) was associated with whey proteins, and only one-fourth of this element was associated with casein, indicating a higher content of sulfur-containing amino acids in donkey whey proteins than in casein.


Assuntos
Cálcio/análise , Equidae , Magnésio/análise , Leite/química , Fósforo/análise , Potássio/análise , Sódio/análise , Animais , Fosfatos de Cálcio , Caseínas/química , Feminino , Concentração de Íons de Hidrogênio , Lactação , Micelas , Enxofre/metabolismo , Proteínas do Soro do Leite/análise
14.
Int J Syst Evol Microbiol ; 70(8): 4730-4738, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32697189

RESUMO

An obligately alkaliphilic, anaerobic, proteolytic bacterium was isolated from a sample of Tanatar III soda lake sediment (Altai region, Russia) and designated as strain Z-1701T. Cells of strain Z-1701T were short, straight, motile Gram-stain-positive rods. Growth of Z-1701T obligately depended on the presence of sodium carbonate. Strain Z-1701T could utilize various peptides mixtures, such as beef and yeast extracts, peptone, soytone, trypticase and tryptone, as well as such proteins as albumin, gelatin and sodium caseinate. It was able to grow oligotrophically with 0.02 g l-1 yeast extract as the sole energy and carbon source. Carbohydrates did not support the growth of strain Z-1701T. The main products released during the growth of strain Z-1701T on tryptone were formate, acetate and ammonium. Strain Z-1701T was able to reduce ferrihydrite, Fe(III)-EDTA, anthraquinone-2,6-disulfonate and elemental sulfur, using proteinaceous substrates as electron donors. In all cases the presence of the electron acceptor in the medium stimulated growth. The main cellular fatty acids were iso-C15 : 0, iso-C15 : 0 aldehyde, iso-C15 : 1 ω6, C16 : 0, iso-C17 : 0 aldehyde, C16 : 0 aldehyde and C14 : 0. The DNA G+C content of the isolate was 43.9 mol%. Phylogenetic analysis based on the concatenated alignment of 120 protein-marker sequences revealed that strain Z-1701T falls into a cluster with the genus Tindallia, family Clostridiaceae. 16S rRNA gene sequence identity between strain Z-1701T and Tindallia species were 88.3-89.75 %. On the basis of its phenotypic characteristics and phylogenetic position, the novel isolate is considered to be a representative of a novel genus and species for which the name Isachenkonia alkalipeptolytica gen. nov., sp. nov. is proposed, with Z-1701T (=JCM 32929Т=DSM 109060Т=VKM B-3261Т) as its type strain.


Assuntos
Bactérias Anaeróbias/classificação , Compostos Férricos/metabolismo , Lagos/microbiologia , Filogenia , Bactérias Redutoras de Enxofre/classificação , Álcalis , Bactérias Anaeróbias/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Bacilos Gram-Positivos/classificação , Bacilos Gram-Positivos/isolamento & purificação , Concentração de Íons de Hidrogênio , RNA Ribossômico 16S/genética , Federação Russa , Análise de Sequência de DNA , Enxofre/metabolismo , Bactérias Redutoras de Enxofre/isolamento & purificação
15.
Proc Natl Acad Sci U S A ; 117(30): 17599-17606, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32647063

RESUMO

Fossilized carotenoid hydrocarbons provide a window into the physiology and biochemistry of ancient microbial phototrophic communities for which only a sparse and incomplete fossil record exists. However, accurate interpretation of carotenoid-derived biomarkers requires detailed knowledge of the carotenoid inventories of contemporary phototrophs and their physiologies. Here we report two distinct patterns of fossilized C40 diaromatic carotenoids. Phanerozoic marine settings show distributions of diaromatic hydrocarbons dominated by isorenieratane, a biomarker derived from low-light-adapted phototrophic green sulfur bacteria. In contrast, isorenieratane is only a minor constituent within Neoproterozoic marine sediments and Phanerozoic lacustrine paleoenvironments, for which the major compounds detected are renierapurpurane and renieratane, together with some novel C39 and C38 carotenoid degradation products. This latter pattern can be traced to cyanobacteria as shown by analyses of cultured taxa and laboratory simulations of sedimentary diagenesis. The cyanobacterial carotenoid synechoxanthin, and its immediate biosynthetic precursors, contain thermally labile, aromatic carboxylic-acid functional groups, which upon hydrogenation and mild heating yield mixtures of products that closely resemble those found in the Proterozoic fossil record. The Neoproterozoic-Phanerozoic transition in fossil carotenoid patterns likely reflects a step change in the surface sulfur inventory that afforded opportunities for the expansion of phototropic sulfur bacteria in marine ecosystems. Furthermore, this expansion might have also coincided with a major change in physiology. One possibility is that the green sulfur bacteria developed the capacity to oxidize sulfide fully to sulfate, an innovation which would have significantly increased their capacity for photosynthetic carbon fixation.


Assuntos
Cianobactérias/fisiologia , Fotossíntese , Enxofre/metabolismo , Carotenoides/química , Carotenoides/metabolismo , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas , Fotossíntese/genética , Pigmentos Biológicos/química , Pigmentos Biológicos/metabolismo
16.
Sci Rep ; 10(1): 10941, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616785

RESUMO

The transition of the martian climate from the wet Noachian era to the dry Hesperian (4.1-3.0 Gya) likely resulted in saline surface waters that were rich in sulfur species. Terrestrial analogue environments that possess a similar chemistry to these proposed waters can be used to develop an understanding of the diversity of microorganisms that could have persisted on Mars under such conditions. Here, we report on the chemistry and microbial community of the highly reducing sediment of Colour Peak springs, a sulfidic and saline spring system located within the Canadian High Arctic. DNA and cDNA 16S rRNA gene profiling demonstrated that the microbial community was dominated by sulfur oxidising bacteria, suggesting that primary production in the sediment was driven by chemolithoautotrophic sulfur oxidation. It is possible that the sulfur oxidising bacteria also supported the persistence of the additional taxa. Gibbs energy values calculated for the brines, based on the chemistry of Gale crater, suggested that the oxidation of reduced sulfur species was an energetically viable metabolism for life on early Mars.


Assuntos
Bactérias/classificação , Bactérias/genética , Biodiversidade , DNA Bacteriano/genética , Sedimentos Geológicos/análise , Marte , Enxofre/química , Bactérias/metabolismo , DNA Ribossômico/genética , Meio Ambiente Extraterreno , Filogenia , RNA Ribossômico 16S , Enxofre/metabolismo
17.
Sci Rep ; 10(1): 9922, 2020 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-32555283

RESUMO

Dimethylsulfoniopropionate (DMSP) is a key compound in the marine sulfur cycle, and is produced in large quantities in coral reefs. In addition to Symbiodiniaceae, corals and associated bacteria have recently been shown to play a role in DMSP metabolism. Numerous ecological studies have focused on DMSP concentrations in corals, which led to the hypothesis that increases in DMSP levels might be a general response to stress. Here we used multiple species assemblages of three common Indo-Pacific holobionts, the scleractinian corals Pocillopora damicornis and Acropora cytherea, and the giant clam Tridacna maxima and examined the DMSP concentrations associated with each species within different assemblages and thermal conditions. Results showed that the concentration of DMSP in A. cytherea and T. maxima is modulated according to the complexity of species assemblages. To determine the potential importance of symbiotic dinoflagellates in DMSP production, we then explored the relative abundance of Symbiodiniaceae clades in relation to DMSP levels using metabarcoding, and found no significant correlation between these factors. Finally, this study also revealed the existence of homologs involved in DMSP production in giant clams, suggesting for the first time that, like corals, they may also contribute to DMSP production. Taken together, our results demonstrated that corals and giant clams play important roles in the sulfur cycle. Because DMSP production varies in response to specific species-environment interactions, this study offers new perspectives for future global sulfur cycling research.


Assuntos
Antozoários/metabolismo , Bivalves/metabolismo , Recifes de Corais , Compostos de Sulfônio/metabolismo , Enxofre/metabolismo , Simbiose , Animais
18.
J Agric Food Chem ; 68(28): 7281-7297, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32551569

RESUMO

Glucosinolates (GSLs) are plant secondary metabolites comprising sulfur and nitrogen mainly found in plants from the order of Brassicales, such as broccoli, cabbage, and Arabidopsis thaliana. The activated forms of GSL play important roles in fighting against pathogens and have health benefits to humans. The increasing amount of data on A. thaliana generated from various omics technologies can be investigated more deeply in search of new genes or compounds involved in GSL biosynthesis and metabolism. This review describes a comprehensive inventory of A. thaliana GSLs identified from published literature and databases such as KNApSAcK, KEGG, and AraCyc. A total of 113 GSL genes encoding for 23 transcription components, 85 enzymes, and five protein transporters were experimentally characterized in the past two decades. Continuous efforts are still on going to identify all molecules related to the production of GSLs. A manually curated database known as SuCCombase (http://plant-scc.org) was developed to serve as a comprehensive GSL inventory. Realizing lack of information on the regulation of GSL biosynthesis and degradation mechanisms, this review also includes relevant information and their connections with crosstalk among various factors, such as light, sulfur metabolism, and nitrogen metabolism, not only in A. thaliana but also in other crucifers.


Assuntos
Arabidopsis/metabolismo , Glucosinolatos/biossíntese , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Vias Biossintéticas , Regulação da Expressão Gênica de Plantas , Enxofre/metabolismo
19.
Proc Natl Acad Sci U S A ; 117(27): 15599-15608, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571930

RESUMO

2(S)-dihydroxypropanesulfonate (DHPS) is a microbial degradation product of 6-deoxy-6-sulfo-d-glucopyranose (sulfoquinovose), a component of plant sulfolipid with an estimated annual production of 1010 tons. DHPS is also at millimolar levels in highly abundant marine phytoplankton. Its degradation and sulfur recycling by microbes, thus, play important roles in the biogeochemical sulfur cycle. However, DHPS degradative pathways in the anaerobic biosphere are not well understood. Here, we report the discovery and characterization of two O2-sensitive glycyl radical enzymes that use distinct mechanisms for DHPS degradation. DHPS-sulfolyase (HpsG) in sulfate- and sulfite-reducing bacteria catalyzes C-S cleavage to release sulfite for use as a terminal electron acceptor in respiration, producing H2S. DHPS-dehydratase (HpfG), in fermenting bacteria, catalyzes C-O cleavage to generate 3-sulfopropionaldehyde, subsequently reduced by the NADH-dependent sulfopropionaldehyde reductase (HpfD). Both enzymes are present in bacteria from diverse environments including human gut, suggesting the contribution of enzymatic radical chemistry to sulfur flux in various anaerobic niches.


Assuntos
Alcanossulfonatos/metabolismo , Anaerobiose , Bactérias/enzimologia , Proteínas de Bactérias/metabolismo , Microbioma Gastrointestinal/fisiologia , Biologia Computacional , Ensaios Enzimáticos , Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/toxicidade , Metilglucosídeos/metabolismo , Enxofre/metabolismo
20.
Int J Syst Evol Microbiol ; 70(5): 3273-3277, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375939

RESUMO

A chemolithoautotrophic sulfur-oxidizing bacterium, strain SGTMT was isolated from snow collected in Japan. As electron donors for growth, SGTMT oxidized thiosulfate, tetrathionate and elemental sulfur. Heterotrophic growth was not observed. Growth of the novel isolate was observed at a temperature range of 5-28 °C, with optimum growth at 18 °C. SGTMT grew at a pH range of 4.3-7.4, with optimum growth at pH 6.1-7.1. Major components in the cellular fatty acid profile were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The complete genome of SGTMT consisted of a circular chromosome of approximately 3.4 Mbp and two plasmids. Phylogenetic analysis based on the 16S rRNA gene indicated that SGTMT represented a member of the genus Sulfuriferula, and its closest relative is Sulfuriferula thiophila mst6T with a sequence identity of 98 %. A comparative genome analysis showed dissimilarity between the genomes of SGTMT and S. thiophila mst6T, as low values of average nucleotide identity (74.9 %) and digital DNA-DNA hybridization (20.4%). On the basis of its genomic and phenotypic properties, SGTMT (=DSM 109609T=BCRC 81185T) is proposed as the type strain of a novel species, Sulfuriferula nivalis sp. nov. Some characteristics of another species in the same genus, Sulfuriferula plumbiphila, were also investigated to revise and supplement its description. The type strain of S. plumbiphila can grow on thiosulfate, tetrathionate and elemental sulfur. The strain showed optimum growth at pH 6.3-7.0 and shared major cellular fatty acids with the other species of the genus Sulfuriferula.


Assuntos
Gallionellaceae/classificação , Filogenia , Neve/microbiologia , Bactérias Redutoras de Enxofre/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Gallionellaceae/isolamento & purificação , Japão , Oxirredução , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Enxofre/metabolismo , Bactérias Redutoras de Enxofre/isolamento & purificação
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