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1.
Opt Lett ; 49(11): 2982-2985, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38824308

RESUMO

We demonstrate a compact ultrafast fiber laser system that can deliver 1.87 GHz pulse train at 1550 nm with a pulse energy of 52 pJ and an ultrashort pulse duration of 57 fs. While an acousto-optic mode-locking fiber laser was used as the seed light source at GHz rate, a stage of Er-doped fiber amplifier boosted the laser power to ∼320 mW, giving a pulse energy of ∼170 pJ. Then, a pulse compression setup was constructed, providing a high compression ratio of ∼10 with a total efficiency of ∼32%. In the cascaded compression configuration, multiple fiber samples with alternately normal and anomalous dispersion were fused together, providing efficient nonlinear spectral broadening while suppressing excessive pulse broadening over propagation. This GHz-rate ultrafast fiber laser, with compact configuration, broad optical spectrum, and high time-resolving ability could be used as the seed light source for constructing high-rate, high-power ultrafast laser systems and may find a few applications in optical measurements and microwave photonics.

2.
Endocrine ; 2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38851643

RESUMO

PURPOSE: Variants in the Aryl hydrocarbon receptor-interacting protein (AIP) gene have been identified in sporadic acromegaly and pituitary gigantism, especially in young patients, with a predisposition to aggressive clinical phenotype and poor treatment efficacy. The clinical characteristics of patients with sporadic acromegaly and pituitary gigantism as well as AIP variants in Han Chinese have been rarely reported. We aimed to identify AIP gene variants and analyze the clinical characteristics of patients with sporadic acromegaly and pituitary gigantism in Han Chinese. METHODS: The study included 181 sporadic acromegaly (N = 163) and pituitary gigantism (N = 18) patients with an onset age of no more than 45 years old, who were diagnosed, treated, and followed up in Huashan Hospital. All 6 exons and their flanking regions of the AIP gene were analyzed with Sanger sequencing or NGS. The clinical characteristics were compared between groups with and without AIP variants. RESULTS: Germline AIP variants were found in 15/181 (8.29%) cases. In patients with an onset age ≤30 years old, AIP variants were identified in 12/133 (9.02%). Overall, 13 variants were detected. The pathogenic (P) variants p.R304X and p.R81X were identified in four cases, with two instances of each variant. Six exon variants (p.C254R, p.K103fs, p.Q228fs, p.Y38X, p.Q213*, and p.1115 fs) have not been reported before, which were likely pathogenic (LP). Patients with P/LP variants had younger onset ages, a higher prevalence of pituitary gigantism, larger tumor volumes, and a higher percentage of Ki-67-positive cells in tumors. In addition, the group with P/LP variants showed a less significant reduction of GH levels in an acute octreotide suppression test (OST) [17.7% (0, 65.0%) vs. 80.5% (63.9%, 90.2%), P = 0.001], and a trend of less GH decrease after the 3-month treatment with long-acting somatostatin analogs (SSAs). CONCLUSION: Germline AIP variants existed in sporadic Chinese Han acromegaly and pituitary gigantism patients and were more likely to be detected in young patients. AIP variants were associated with more aggressive tumor phenotypes and less response to SSA treatment.

3.
Chem Commun (Camb) ; 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38874564

RESUMO

Solution plasma-Co(OH)2 interaction significantly boosts nitrogen fixation and achieves a high concentration of NOx- at 9.42 mmol L-1. This surpasses the nitrogen content requirement of 7.67 mmol L-1 for commercial nutrient solutions, offering a sustainable approach for nitrogen fixation from nitrogen, water and electricity.

4.
J Adv Res ; 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38879122

RESUMO

INTRODUCTION: Metabolic inflammation (metaflammation) in obesity is primarily initiated by proinflammatory macrophage infiltration into adipose tissue. SelenoM contributes to the modulation of antioxidative stress and inflammation in multiple pathological processes; however, its roles in metaflammation and the proinflammatory macrophage (M1)-like state in adipose tissue have not been determined. OBJECTIVES: We hypothesize that SelenoM could effectively regulate metaflammation via the Hippo-YAP/TAZ-ROS signaling axis in obesity derived from a high-fat diet. METHODS: Morphological changes in adipose tissue were examined by hematoxylin-eosin (H&E) staining and fluorescence microscopy. The glucose tolerance test (GTT) and insulin tolerance test (ITT) were used to evaluate the impact of SelenoM deficiency on blood glucose levels. RNA-Seq analysis, LC-MS analysis, Mass spectrometry analysis and western blotting were performed to detect the levels of genes and proteins related to glycolipid metabolism in adipose tissue. RESULTS: Herein, we evaluated the inflammatory features and metabolic microenvironment of mice with SelenoM-deficient adipose tissues by multi-omics analyses. The deletion of SelenoM resulted in glycolipid metabolic disturbances and insulin resistance, thereby accelerating weight gain, adiposity, and hyperglycemia. Mice lacking SelenoM in white adipocytes developed severe adipocyte hypertrophy via impaired lipolysis. SelenoM deficiency aggravated the generation of ROS by reducing equivalents (NADPH and glutathione) in adipocytes, thereby promoting inflammatory cytokine production and the M1-proinflammatory reaction, which was related to a change in nuclear factor kappa-B (NF-κB) levels in macrophages. Mechanistically, SelenoM deficiency promoted metaflammation via Hippo-YAP/TAZ-ROS-mediated transcriptional regulation by targeting large tumor suppressor 2 (LATS2). Moreover, supplementation with N-acetyl cysteine (NAC) to reduce excessive oxidative stress partially rescued adipocyte inflammatory responses and macrophage M1 activation. CONCLUSION: Our data indicate that SelenoM ameliorates metaflammation mainly via the Hippo-YAP/TAZ-ROS signaling axis in obesity. The identification of SelenoM as a key regulator of metaflammation presents opportunities for the development of novel therapeutic interventions targeting adipose tissue dysfunction in obesity.

5.
Phys Rev E ; 109(4): L042902, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38755816

RESUMO

Heat transfer across a granular flow is comprised of two resistances in series : near the wall and within the bulk particle bed, neither of which is well understood due to the lack of experimental probes to separate their respective contribution. Here, we use a frequency modulated photothermal technique to separately quantify the thermal resistances in the near-wall and the bulk bed regions of particles in flowing states. Compared to the stationary state, the flowing leads to a higher near-wall resistance and a lower thermal conductivity of bulk beds. Coupled with discrete element method simulation, we show that the near-wall resistance can be explained by particle diffusion in granular flows.

6.
Spectrochim Acta A Mol Biomol Spectrosc ; 319: 124536, 2024 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-38815312

RESUMO

Antibiotic mycelia residues (AMRs) contain antibiotic residues. If AMRs are ingested in excess by livestock, it may cause health problems. To address the current problem of unknown pixel-scale adulteration concentration in NIR-HSI, this paper innovatively proposes a new spectral simulation method for the evaluation of AMRs in protein feeds. Four common protein feeds (soybean meal (SM), distillers dried grains with solubles (DDGS), cottonseed meal (CM), and nucleotide residue (NR)) and oxytetracycline residue (OR) were selected as study materials. The first step of the method is to simulate the spectra of pixels with different adulteration concentrations using a linear mixing model (LMM). Then, a pixel-scale OR quantitative model was developed based on the simulated pixel spectra combined with local PLS based on global PLS scores (LPLS-S) (which solves the problem of nonlinear distribution of the prediction results due to the 0%-100% content of the correction set). Finally, the model was used to quantitatively predict the OR content of each pixel in hyperspectral image. The average value of each pixel was calculated as the OR content of that sample. The implementation of this method can effectively overcome the inability of PLS-DA to achieve qualitative identification of OR in 2%-20% adulterated samples. In compared to the PLS model built by averaging the spectra over the region of interest, this method utilizes the precise information of each pixel, thereby enhancing the accuracy of the detection of adulterated samples. The results demonstrate that the combination of the method of simulated spectroscopy and LPLS-S provides a novel method for the detection and analysis of illegal feed additives by NIR-HSI.


Assuntos
Ração Animal , Antibacterianos , Micélio , Espectroscopia de Luz Próxima ao Infravermelho , Antibacterianos/análise , Ração Animal/análise , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Micélio/química , Imageamento Hiperespectral/métodos , Resíduos de Drogas/análise , Análise dos Mínimos Quadrados
7.
Int J Mol Sci ; 25(7)2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38612840

RESUMO

The monoamine transporters, including the serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET), are the therapeutic targets for the treatment of many neuropsychiatric disorders. Despite significant progress in characterizing the structures and transport mechanisms of these transporters, the regulation of their transport functions through dimerization or oligomerization remains to be understood. In the present study, we identified a conserved intramolecular ion-pair at the third extracellular loop (EL3) connecting TM5 and TM6 that plays a critical but divergent role in the modulation of dimerization and transport functions among the monoamine transporters. The disruption of the ion-pair interactions by mutations induced a significant spontaneous cross-linking of a cysteine mutant of SERT and an increase in cell surface expression but with an impaired specific transport activity. On the other hand, similar mutations of the corresponding ion-pair residues in both DAT and NET resulted in an opposite effect on their oxidation-induced dimerization, cell surface expression, and transport function. Reversible biotinylation experiments indicated that the ion-pair mutations slowed down the internalization of SERT but stimulated the internalization of DAT. In addition, cysteine accessibility measurements for monitoring SERT conformational changes indicated that substitution of the ion-pair residues resulted in profound effects on the rate constants for cysteine modification in both the extracellular and cytoplasmatic substrate permeation pathways. Furthermore, molecular dynamics simulations showed that the ion-pair mutations increased the interfacial interactions in a SERT dimer but decreased it in a DAT dimer. Taken together, we propose that the transport function is modulated by the equilibrium between monomers and dimers on the cell surface, which is regulated by a potential compensatory mechanism but with different molecular solutions among the monoamine transporters. The present study provided new insights into the structural elements regulating the transport function of the monoamine transporters through their dimerization.


Assuntos
Cisteína , Proteínas da Membrana Plasmática de Transporte de Serotonina , Dimerização , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Biotinilação , Membrana Celular , Proteínas da Membrana Plasmática de Transporte de Norepinefrina , Polímeros
8.
J Hazard Mater ; 470: 134204, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38579586

RESUMO

Selenium (Se) plays a critical role in diverse biological processes and is widely used across manufacturing industries. However, the contamination of Se oxyanions also poses a major public health concern. Microbial transformation is a promising approach to detoxify Se oxyanions and produce elemental selenium nanoparticles (SeNPs) with versatile industrial potential. Yeast-like fungi are an important group of environmental microorganisms, but their mechanisms for Se oxyanions reduction remain unknown. In this study, we found that Aureobasidium melanogenum I15 can reduce 1.0 mM selenite by over 90% within 48 h and efficiently form intracellular or extracellular spherical SeNPs. Metabolomic and proteomic analyses disclosed that A. melanogenum I15 evolves a complicated selenite reduction mechanism involving multiple metabolic pathways, including the glutathione/glutathione reductase pathway, the thioredoxin/thioredoxin reductase pathway, the siderophore-mediated pathway, and multiple oxidoreductase-mediated pathways. This study provides the first report on the mechanism of selenite reduction and SeNPs biogenesis in yeast-like fungi and paves an alternative avenue for the bioremediation of selenite contamination and the production of functional organic selenium compounds.


Assuntos
Ascomicetos , Ácido Selenioso , Selênio , Ácido Selenioso/metabolismo , Selênio/metabolismo , Ascomicetos/metabolismo , Oxirredução , Nanopartículas/química , Nanopartículas/metabolismo , Nanopartículas Metálicas/química , Biodegradação Ambiental , Proteínas Fúngicas/metabolismo , Proteômica
9.
Opt Express ; 32(6): 9384-9396, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38571174

RESUMO

Colored information is crucial for humans to perceive the world. Plasmonic spectra modulation can serve as an effective means to create different colors. Although several solutions for plasmonic color-printing have been proposed, further information encryption has not received any attention. Herein, we exhibit a fine color modulation strategy to construct noble-metal-based micro-nano hybrid structures in the bi-path of photo-thermal deformation and liquid-phase-chemical reaction. Ag/Ta2O5 bi-layer films are ablated at the center of the machined lines of nanosecond pulsed laser, while silver nanoparticles are formed in other regions by thermal radiation of the infrared laser, which can be further dissolved and shape-modulated in KCl solution under different periods. The variation of size and spacing of nano-Ag particles results in a precise shift of plasmonic spectra in visible region. Colored information can be hidden by adjusting the scan number and the energy density during laser processing, and will emerge after the subsequent chemical dissolution reactions. The bi-path color adjustment strategy is easy to operate and can play a role in key information protection and color image switching.

10.
Bioorg Chem ; 147: 107317, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38583252

RESUMO

By inducing steric activation of the 10CH bond with a 12-acyl group to form a key imine oxime intermediate, 20 novel (10S)-10,12-disubstituted aloperine derivatives were successfully synthesized and assessed for their antiviral efficacy against HCoV-OC43. Of them, compound 3i exhibited the moderate activities against HCoV-OC43, as well as against the SARS-CoV-2 variant EG.5.1 with the comparable EC50 values of 4.7 and 4.1 µM. A mechanism study revealed that it inhibited the protease activity of host TMPRSS2 by binding to an allosteric site, rather than the known catalytic center, different from that of camostat. Also, the combination of compound 3i and molnupiravir, as an RdRp inhibitor, showed an additive antiviral effect against HCoV-OC43. The results provide a new binding mode and lead compound for targeting TMPRSS2, with an advantage in combating broad-spectrum coronavirus.


Assuntos
Sítio Alostérico , Antivirais , Coronavirus Humano OC43 , Quinolizidinas , Serina Endopeptidases , Antivirais/farmacologia , Antivirais/química , Antivirais/síntese química , Serina Endopeptidases/metabolismo , Humanos , Coronavirus Humano OC43/efeitos dos fármacos , Coronavirus Humano OC43/química , Quinolizidinas/química , Quinolizidinas/farmacologia , Quinolizidinas/síntese química , Sítio Alostérico/efeitos dos fármacos , Relação Estrutura-Atividade , Descoberta de Drogas , SARS-CoV-2/efeitos dos fármacos , Estrutura Molecular , Testes de Sensibilidade Microbiana , Relação Dose-Resposta a Droga
11.
Opt Lett ; 49(6): 1611, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38489463

RESUMO

This publisher's note contains a correction to Opt. Lett.49, 674 (2024)10.1364/OL.509981.

14.
Int J Cardiol ; 403: 131886, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38382850

RESUMO

BACKGROUND: A novel automated method for measuring left ventricular (LV) global longitudinal strain (GLS) along the endocardium has advantages in terms of its rapid application and excellent reproducibility. However, it remains unclear whether the available normal range for conventional GLS using the manual method is applicable to the automated GLS method. This study aimed to compare automated GLS head-to-head with manual layer-specific GLS, and to identify whether a specialized normal reference range for automated GLS is needed and explore the main determinants. METHODS: In total, 1683 healthy volunteers (men, 43%; age, 18-80 years) were prospectively enrolled from 55 collaborating laboratories. LV GLS was measured using both manual layer-specific and automated methods. RESULTS: Automated GLS was higher than endocardial, mid-myocardial, and epicardial GLS. Women had a higher automated GLS than men. GLS had no significant age dependency in men, but first increased and then decreased with age in women. Accordingly, sex- and age-specific normal ranges for automated GLS were proposed. Moreover, GLS appeared to have different burdens in relation to dominant determinants between the sexes. GLS in men showed no dominant determinants; however, GLS in women correlated with age, body mass index, and heart rate. CONCLUSIONS: Using the novel automated method, was LV GLS higher than when using the manual GLS method. The normal ranges of automated GLS stratified according to sex and age were provided, with dominant determinants showing sex disparities that require full consideration in clinical practice.


Assuntos
Ecocardiografia , Deformação Longitudinal Global , Masculino , Humanos , Feminino , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Valores de Referência , Ecocardiografia/métodos , Função Ventricular Esquerda/fisiologia , Reprodutibilidade dos Testes
15.
Int Rev Cell Mol Biol ; 383: 41-66, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38359970

RESUMO

Prostate cancer is the second most prevalent cancer in men globally. De novo neuroendocrine prostate cancer (NEPC) is uncommon at initial diagnosis, however, (treatment-induced) t-NEPC emerges in up to 25% of prostate adenocarcinoma (PRAD) cases treated with androgen deprivation, carrying a drastically poor prognosis. The transition from PRAD to t-NEPC is underpinned by several key genetic mutations; TP53, RB1, and MYCN are the main genes implicated, bearing similarities to other neuroendocrine tumours. A broad range of epigenetic alterations, such as aberrations in DNA methylation, histone post-translational modifications, and non-coding RNAs, may drive lineage plasticity from PRAD to t-NEPC. The clinical diagnosis of NEPC is hampered by a lack of accessible biomarkers; recent advances in liquid biopsy techniques assessing circulating tumour cells and ctDNA in NEPC suggest that the advent of non-invasive means of monitoring progression to NEPC is on the horizon. Such techniques are vital for NEPC management; diagnosis of t-NEPC is crucial for implementing effective treatment, and precision medicine will be integral to providing the best outcomes for patients.


Assuntos
Tumores Neuroendócrinos , Neoplasias da Próstata , Masculino , Humanos , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Neoplasias da Próstata/terapia , Antagonistas de Androgênios , Tumores Neuroendócrinos/genética , Tumores Neuroendócrinos/patologia , Epigênese Genética
16.
Opt Lett ; 49(3): 674-677, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38300087

RESUMO

We demonstrate that through inserting a short length of highly birefringent small-core photonic crystal fiber (Hi-Bi SC-PCF) into a soliton fiber laser, the nonlinear polarization rotation effect in this laser can be manipulated, leading to continuous tuning of the output pulse parameters. In experiments, we observed that by adjusting the polarization state of light launched into the Hi-Bi SC-PCF and varying the cavity attenuation, the laser spectral width can be continuously tuned from ∼7.1 to ∼1.7 nm, corresponding to a pulse-width-tuning range from ∼350 fs to ∼1.56 ps. During the parameter tuning, the output pulses strictly follow the soliton area theory, giving an almost constant time-bandwidth-product of ∼0.31. This soliton fiber laser, being capable of continuous parameter tuning, could be applied as the seed source in ultrafast laser systems and may find some applications in nonlinear-optics and soliton-dynamics experiments.

17.
J Invertebr Pathol ; 203: 108066, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38246321

RESUMO

Ameson portunus, the recently discovered causative agent of "toothpaste disease" of pond-cultured swimming crabs in China has caused enormous economic losses in aquaculture. Understanding the process of spore germination is helpful to elucidate the molecular mechanism of its invasion of host cells. Here, we obtained mature and germinating spores by isolation and purification and in vitro stimulation, respectively. Then, non-germinated and germinated spores were subjected to the comparative transcriptomic analysis to disclose differential molecular responses of these two stages. The highest germination rate, i.e., 71.45 %, was achieved in 0.01 mol/L KOH germination solution. There were 9,609 significantly differentially expressed genes (DEGs), with 685 up-regulated and 8,924 down-regulated DEGs. The up-regulated genes were significantly enriched in ribosome pathway, and the down-regulated genes were significantly enriched in various metabolic pathways, including carbohydrate metabolism, amino acid metabolism and other metabolism. The results suggested that spores require various carbohydrates and amino acids as energy to support their life activities during germination and synthesize large amounts of ribosomal proteins to provide sites for DNA replication, transcription, translation and protein synthesis of the spores of A. portunus within the host cells. Functional genes related to spore germination, such as protein phosphatase CheZ and aquaporin, were also analyzed. The analysis of transcriptome data and identification of functional genes will help to understand the process of spore germination and invasion.


Assuntos
Microsporídios , Transcriptoma , Animais , Esporos , Microsporídios/genética , Perfilação da Expressão Gênica , Esporos Bacterianos/genética
18.
Fish Shellfish Immunol ; 145: 109324, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38134977

RESUMO

Ameson portunus (Microsporidia) has caused serious economic losses to the aquaculture industry of swimming crab, Portunus trituberculatus. The hemolymph and hepatopancreas are the main immune organs of P. trituberculatus, and the main sites of A. portunus infection. Elucidating the response characteristics of hemolymph and hepatopancreas to microsporidian infection facilitates the development of microsporidiosis prevention and control strategy. This study performed comparative transcriptomic analysis of hemolymph (PTX/PTXA) and hepatopancreas (PTG/PTGA) of P. trituberculatus uninfected and infected with A. portunus. The results showed that there were 223 and 1309 differentially expressed genes (DEGs) in PTX/PTXA and PTG/PTGA, respectively. The lysosome pathway was significantly enriched after the invasion of the hemolymph by A. portunus. Also, immune-related genes were all significantly up-regulated in the hemolymph and hepatopancreas, suggesting that the invasion by A. portunus may activate host immune responses. Unlike hemolymph, antioxidant and detoxification-related genes were also significantly up-regulated in the hepatopancreas. Moreover, metabolism-related genes were significantly down-regulated in the hepatopancreas, suggesting that energy synthesis, resistance to pathogens, and regulation of oxidative stress were suppressed in the hepatopancreas. Hemolymph and hepatopancreas have similarity and tissue specificity to microsporidian infection. The differential genes and pathways identified in this study can provide references for the prevention and control of microsporidiosis.


Assuntos
Braquiúros , Microsporídios , Microsporidiose , Animais , Braquiúros/genética , Hemolinfa , Hepatopâncreas/metabolismo , Microsporídios/genética , Microsporidiose/metabolismo , Transcriptoma
19.
Heliyon ; 9(11): e21855, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38045155

RESUMO

In this paper, the collapse behavior of a single cavitation bubble at different distances near a solid particle of typical scales is numerically simulated and researched with the volume of fluid (VOF) method. Based on the key parameters analysis of the pressure field, velocity vector, collapse time the tendency of cavitation bubble collapse characteristics at different distances during the change of particle size is studied with the variable of the distance and relative size between the particle and the cavitation bubble. The dimensionless distance parameter 'γ' is specifically presented in the simulation process, the cavitation bubble collapse impact is largely directed to the particle when 3>γ > 2, while the wall hardly affects the interaction between the cavitation bubble and the solid particle as γ > 3. The results illustrate that as the solid particle and wall exist, the distance and particle size affect both the peak collapse pressure and the collapse jet velocity of the cavitation bubble, and the influence of solid wall on the cavitation bubble at the same distance is much greater than that of solid particles. When the particle size increases, the particle gradually affects the cavitation bubble in a way similar to the wall. While as the distance decreases or the particle size increases, the influence of particle and wall on the evolution process of the cavitation bubble expands, meanwhile, the collapse pressure and collapse jet velocity of the cavitation bubble are promoted with the optimized distance and particle size, which brings marvelous cavitation effect. The numerical methods and conclusions of this paper provide a valuable reference for cavitation applications of sand-containing fluids.

20.
Int J Mol Sci ; 24(23)2023 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-38069433

RESUMO

All resolved high-resolution structures of the transporters in the neurotransmitter sodium symporter (NSS) family revealed that the NSS members share common structural and mechanistic features for substrate and ion binding and transport. However, a recently reported bacterial orthologue of the human serotonin transporter (hSERT), TuriSERT, possesses a structural characteristic specific for amino acid substrate binding but does transport a biogenic amine. The unique structural feature of TuriSERT requires a novel configuration for coordinating its substrate and ions. In the present study, we characterized TuriSERT expressed in Escherichia coli cells with a fluorescent substrate by biochemical, structural, and pharmacological approaches. Substrate transport by TuriSERT requires Na+ but not Cl-. Replacement of Asp262 by asparagine renders TuriSERT Cl--dependent. Substitutions of the corresponding Na1 residues did not alter Na+ dependence on substrate transport, whereas the mutation of a Na2 site residue led to a loss of transport activity, suggesting that Na+ binds only to the Na2 site in TuriSERT. In addition, substitutions of several residues essential for recognizing 5-hydroxytryptamine (5-HT) in hSERT had little effect on 5-HT displacement potency in transport assay for TuriSERT. In contrast, mutations of the residues that are proposed to coordinate with 5-HT in our docking model dramatically reduced 5-HT displacement. Furthermore, our results indicated that all tested antidepressants showed a weak inhibitory effect on TuriSERT. The present study demonstrated the existence of a unique substrate binding site and 1:1 stoichiometry of sodium-substrate binding in TuriSERT, a novel structural finding for the NSS transporters.


Assuntos
Proteínas da Membrana Plasmática de Transporte de Serotonina , Simportadores , Humanos , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Serotonina/metabolismo , Sódio/metabolismo , Sítios de Ligação , Antidepressivos , Simportadores/genética , Simportadores/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo
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