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Proton transport

Jorge Antunes, Sandra Pereira, Tiago Ribeiro, Jeffrey E Plowman, Ancy Thomas, Stefan Clerens, Alexandre Campos, Vitor Vasconcelos, Joana R Almeida
The cyclic peptides portoamides produced by the cyanobacterium Phormidium sp. LEGE 05292 were previously isolated and their ability to condition microcommunities by allelopathic effect was described. These interesting bioactive properties are, however, still underexplored as their biotechnological applications may be vast. This study aims to investigate the antifouling potential of portoamides, given that a challenge in the search for new environmentally friendly antifouling products is to find non-toxic natural alternatives with the ability to prevent colonization of different biofouling species, from bacteria to macroinvertebrates...
February 12, 2019: Marine Drugs
Chiara Pagliarani, Valentino Casolo, Maryam Ashofteh Beiragi, Silvia Cavalletto, Ilenia Siciliano, Andrea Schubert, Maria Lodovica Gullino, Maciej A Zwieniecki, Francesca Secchi
Some plant species are capable of significant reduction of xylem embolism during recovery from drought despite that stem water potential remains negative. However, the functional biology underlying this process remains elusive. We subjected poplar trees to drought stress followed by a period of recovery. Water potential, hydraulic conductivity, gas exchange, xylem sap pH and carbohydrate content in sap and woody stems were monitored in combination with an analyses of carbohydrate metabolism, enzyme activity and expression of genes involved in sugar metabolic and transport pathways...
February 12, 2019: Plant, Cell & Environment
Gang Sa, Jun Yao, Chen Deng, Jian Liu, Yinan Zhang, Zhimei Zhu, Yuhong Zhang, Xujun Ma, Rui Zhao, Shanzhi Lin, Cunfu Lu, Andrea Polle, Shaoliang Chen
Salt stress is an important environmental cue impeding poplar nitrogen nutrition. Here, we characterized the impact of salinity on proton-driven nitrate fluxes in ectomycorrhizal roots and the importance of Hartig net for nitrate uptake. We employed two Paxillus involutus strains for root colonization: MAJ, which forms typical ectomycorrhizal structures (mantle and Hartig net) and NAU, colonizing roots with a thin, loose hyphal sheath. Fungus-colonized and non-colonized Populus × canescens were exposed to NaCl and used to measure root surface pH, NO3 - flux and transcription of nitrate transporters (PcNRT1...
February 12, 2019: New Phytologist
Maria A Battistone, Maria Merkulova, Yoo-Jin Park, Maria A Peralta, Flavia Gombar, Dennis Brown, Sylvie Breton
KEY POINTS: In the epididymis, elaborate communication networks between epithelial cells are important to establish an optimal acidic luminal environment for the maturation and storage of spermatozoa, which is essential for male fertility. Proton secretion by epididymal clear cells is achieved via the proton pumping V-ATPase located in their apical membrane. Here, we dissect the molecular mechanisms by which clear cells respond to luminal ATP and adenosine to modulate their acidifying activity via the adenosine receptor ADORA2B and the pH-sensitive ATP receptor P2 × 4...
February 12, 2019: Journal of Physiology
Ryan Hawtof, Souvik Ghosh, Evan Guarr, Cheyan Xu, R Mohan Sankaran, Julie Nicole Renner
There is a growing need for scalable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks to replace the Haber-Bosch process. Electrically driven approaches are an ideal strategy for the reduction of nitrogen to ammonia but, to date, have suffered from low selectivity associated with the catalyst. Here, we present a hybrid electrolytic system characterized by a gaseous plasma electrode that facilitates the study of ammonia formation in the absence of any material surface...
January 2019: Science Advances
Sang-Hyun Park, Ji Young Hyun, Injae Shin
Lysosomal pHs are maintained at low values by the cooperative action of a proton pump and a chloride channel to maintain electroneutrality. Owing to the biological significance of lysosomal chloride ions, measurements of their levels are of great importance to understand lysosome-associated biological events. However, appropriate probes to selectively detect Cl- ions within acidic lysosomes have not been developed to date. In this study, we prepared MQAE-MP, a lysosomal Cl- -selective fluorescent probe, and applied it to gain information about biological processes associated with lysosomes...
January 7, 2019: Chemical Science
Marvin Asido, Peter Eberhardt, Clara Nassrin Kriebel, Markus Braun, Clemens Glaubitz, Josef Wachtveitl
We report a comparative study on the structural dynamics of the light-driven sodium pump Krokinobacter eikastus rhodopsin 2 wild type under sodium and proton pumping conditions by means of time-resolved IR spectroscopy. The kinetics of KR2 under sodium pumping conditions exhibits a sequential character, whereas the kinetics of KR2 under proton pumping conditions involves several equilibrium states. The sodium translocation itself is characterized by major conformational changes of the protein backbone, such as distortions of the α-helices and probably of the ECL1 domain, indicated by distinct marker bands in the amide I region...
February 8, 2019: Physical Chemistry Chemical Physics: PCCP
Guendalina Olivero, Matteo Vergassola, Francesca Cisani, Cesare Usai, Anna Pittaluga
Mouse hippocampal glutamatergic nerve endings express presynaptic release-regulating NMDA autoreceptors (NMDARs). The presence of GluN1, GluN2A, GluN2B, and GluN3A subunits in hippocampal vesicular glutamate transporter type 1-positive synaptosomes was confirmed with confocal microscopy. GluN2C, GluN2D, and GluN3B immunopositivity was scarcely present. Incubation of synaptosomes with the anti-GluN1, the anti-GluN2A, the anti-GluN2B, or the anti-GluN3A antibody prevented the 30 μM NMDA/1 μM glycine-evoked [3 H]D-aspartate ([3 H]D-ASP) release...
February 7, 2019: Molecular Neurobiology
Aaron T Bozzi, Christina M Zimanyi, John M Nicoludis, Brandon K Lee, Casey H Zhang, Rachelle Gaudet
Nramp family transporters-expressed in organisms from bacteria to humans-enable uptake of essential divalent transition metals via an alternating-access mechanism that also involves proton transport. We present high-resolution structures of Deinococcus radiodurans (Dra)Nramp in multiple conformations to provide a thorough description of the Nramp transport cycle by identifying the key intramolecular rearrangements and changes to the metal coordination sphere. Strikingly, while metal transport requires cycling from outward- to inward-open states, efficient proton transport still occurs in outward-locked (but not inward-locked) DraNramp...
February 4, 2019: ELife
Georgios Katsoukis, Heinz Frei
Artificial photosynthesis is an attractive approach for the generation of renewable fuels because such systems will be suitable for deployment on highly abundant, non-arable land. Recently emerged methods of nanoscience to create conformal, ultrathin oxide layers enable the hierarchical integration of light absorbers, catalysts, and membranes into systems with far simpler synthetic approaches than available till now. This holds in particular for the coupling of molecular light absorbers and catalysts for sunlight to fuel conversion, providing photoelectrodes with greatly improved stability...
January 28, 2019: Journal of Chemical Physics
Y Lei, Q Z Xing, B C Wang, S X Zheng, R Tang, P F Ma, H Y Zhang, X L Guan, X W Wang, C T Du, Q K Guo, J Li, W Q Guan
This paper describes the radio frequency (RF) measurement and tuning result of a 13 MeV Alvarez-type drift tube linac (DTL) for a compact pulsed hadron source (CPHS) at Tsinghua University. The design, machining, assembly, and alignment of the DTL are presented for integrity. The CPHS project consists of a high-current proton linac (13 MeV, 16 kW, peak current of 50 mA, 0.5 ms pulse width at 50 Hz), a neutron target station, a small-angle neutron scattering instrument, and a neutron imaging/radiology station...
January 2019: Review of Scientific Instruments
Paola Bartoccioni, Joana Fort, Antonio Zorzano, Ekaitz Errasti-Murugarren, Manuel Palacín
Many key cell processes require prior cell uptake of amino acids from the environment, which is facilitated by cell membrane amino acid transporters such as those of the L-type amino acid transporter (LAT) subfamily. Alterations in LAT subfamily amino acid transport are associated with several human diseases, including cancer, aminoacidurias, and neurodegenerative conditions. Therefore, from the perspective of human health, there is considerable interest in obtaining structural information about these transporter proteins...
January 29, 2019: Journal of General Physiology
Shuning Cai, Wenting Deng, Feifei Huang, Lijue Chen, Chun Tang, Wenxiang He, Shichuan Long, Ruihao Li, Zhibing Tan, Junyang Liu, Jia Shi, Zitong Liu, Zongyuan Xiao, Deqing Zhang, Wenjing Hong
Photoresponsive molecular systems are essential for the molecular optoelectronic devices, but most molecular building blocks are non-photoresponsive. Herein, we employ the photoinduced proton transfer (PIPT) strategy to control the charge transport through single-molecule azulene junctions with visible light under ambient conditions, which leads to a reversible and controllable photoresponsive molecular device based on non-photoresponsive molecules and a photoacid. We further demonstrate the application of PIPT in two single-molecule AND gate and OR gate devices with electrical signal as outputs...
January 28, 2019: Angewandte Chemie
Bing Zhang, Jun Li, Xiaolin Yang, Lijie Wu, Jia Zhang, Yang Yang, Yao Zhao, Lu Zhang, Xiuna Yang, Xiaobao Yang, Xi Cheng, Zhijie Liu, Biao Jiang, Hualiang Jiang, Luke W Guddat, Haitao Yang, Zihe Rao
Despite intensive efforts to discover highly effective treatments to eradicate tuberculosis (TB), it remains as a major threat to global human health. For this reason, new TB drugs directed toward new targets are highly coveted. MmpLs (Mycobacterial membrane proteins Large), which play crucial roles in transporting lipids, polymers and immunomodulators and which also extrude therapeutic drugs, are among the most important therapeutic drug targets to emerge in recent times. Here, crystal structures of mycobacterial MmpL3 alone and in complex with four TB drug candidates, including SQ109 (in Phase 2b-3 clinical trials), are reported...
January 24, 2019: Cell
Damien Johann Bolinius, Matthew MacLeod, Francesco Iadaresta, Jan Holmbäck, Annika Jahnke
Vegetation plays an important role in the partitioning, transport, and fate of semivolatile hydrophobic organic chemicals (HOCs) in the environment. Leaf/air partition ratios ( Kleaf/air ) of HOCs are highly variable for different plant species. The differences cannot be fully explained by the fraction of lipids in the leaves or the thickness of the cuticle. Our goal was to elucidate the importance of nonpolymeric lipids in determining Kleaf/air . To do this, we extracted organic matter from 7 plant species using solvents that do not extract the polymeric lipids cutin and cutan, to yield extractable organic matter (EOM)...
January 25, 2019: Environmental Science & Technology
Emanuela Berrino, Claudiu T Supuran
In all living species, pH regulation is a tightly controlled process, with a plethora of proteins involved in its regulation. These include sodium-proton exchangers, carbonic anhydrases, anion exchangers, bicarbonate transporters/cotransporters, H+ -ATPases, and monocarboxylate transporters. All of them play crucial roles in acid-base balancing, both in eukaryotic as well as in prokaryotic organisms, making them interesting drug targets for the management of pathological events (in)directly involved in pH regulation...
January 25, 2019: Expert Opinion on Drug Discovery
Alice E Webb, Shirley A Pomponi, Fleur C van Duyl, Gert-Jan Reichart, Lennart J de Nooijer
Coral reefs are threatened by a multitude of environmental and biotic influences. Among these, excavating sponges raise particular concern since they bore into coral skeleton forming extensive cavities which lead to weakening and loss of reef structures. Sponge bioerosion is achieved by a combination of chemical dissolution and mechanical chip removal and ocean acidification has been shown to accelerate bioerosion rates. However, despite the ecological relevance of sponge bioerosion, the exact chemical conditions in which dissolution takes place and how chips are removed remain elusive...
January 24, 2019: Scientific Reports
Peter Aasted Paulsen, Tânia F Custódio, Bjørn Panyella Pedersen
Plants are dependent on controlled sugar uptake for correct organ development and sugar storage, and apoplastic sugar depletion is a defense strategy against microbial infections like rust and mildew. Uptake of glucose and other monosaccharides is mediated by Sugar Transport Proteins, proton-coupled symporters from the Monosaccharide Transporter (MST) superfamily. We present the 2.4 Å structure of Arabidopsis thaliana high affinity sugar transport protein, STP10, with glucose bound. The structure explains high affinity sugar recognition and suggests a proton donor/acceptor pair that links sugar transport to proton translocation...
January 24, 2019: Nature Communications
Santanu Chand, Syed Meheboob Elahi, Arun Pal, Madhab C Das
Proton conducting materials in solid state have received immense attention for their role as electrolytes for proton exchange membrane fuel cells. Recently, crystalline materials (metal organic frameworks-MOFs, hydrogen-bonded organic frameworks-HOFs, covalent organic framework-COFs, polyoxometalates-POMs, and porous organic solids) are a hot research topic in the field of proton-conducting materials. For a better electrolyte, a high proton conductivity in the order of 10-2 S cm-1 or higher is preferred as efficient proton transport between the electrodes is ultimately necessary...
January 24, 2019: Chemistry: a European Journal
Jing Wen, Qishan Fu, Wanying Wu, Hong Gao, Xitian Zhang, Bin Wang
The high intercalation capacitance of MXenes is attractive, but their performance as electrodes in supercapacitors is limited by mass transport when increasing the thickness and mass loading of the electrodes. Here, we report a combined experimental and computational study, through which we reveal the diffusion of hydrated ionic species at the interlayer spaces. We find that the cyclic voltammetry curves for the delaminated Ti3 C2 T x exhibit distinct features in acid (H2 SO4 ) and alkaline (KOH) electrolytes...
January 24, 2019: ACS Applied Materials & Interfaces
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