Na+ Efflux from Apple Dwarfing Rootstocks is Associated with High-Salt Resistance of Their Scions

The role of betaine as a factor influencing the salt resistance of the respiratory system in resting cells of the moderately halophilic halotolerant bacterium Ba1 was studied. Betaine accelerated succinate oxidation in cells obtained from low-salt medium, and stimulation of the respiratory rate was stronger the higher the sodium chloride concentration in the assay medium. The stimulatory effect also depended on the ratio of betaine concentration to the amount of bacteria present. Accumulation of labelled betaine by the bacterial cells was demonstrated; like the respiratory stimulation, it was favourably influenced by an increase in the sodium chloride concentration of the medium. In cells harvested from a high-salt medium and washed with 2·0m-sodium chloride, betaine caused no increase in the respiratory rate, nor was the already high salt resistance of the respiratory system further improved by the addition of betaine. When, however, these cells lost their salt resistance as a result of washing in the absence of sodium chloride, betaine was able to restore it to its original level. In contrast with respiration in low-salt-grown bacteria, that in high-salt-grown cells was not affected by betaine, even after they were washed in the absence of sodium chloride, when the sodium chloride concentration was optimum.

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Easy Strategy To Increase Salt Resistance of Antimicrobial Peptides

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00202-11 ◽

2011 ◽

Vol 55 (10) ◽

pp. 4918-4921 ◽

Cited By ~ 54

Author(s):

Hui-Yuan Yu ◽

Chih-Hsiung Tu ◽

Bak-Sau Yip ◽

Heng-Li Chen ◽

Hsi-Tsung Cheng ◽

...

Keyword(s):

Amino Acids ◽

Antimicrobial Peptides ◽

Pharmaceutical Compounds ◽

Salt Resistance ◽

High Salt ◽

Histidine Residues

ABSTRACTThe efficacies of many antimicrobial peptides are greatly reduced under high salt concentrations, limiting their development as pharmaceutical compounds. Here, we describe an easy strategy to increase salt resistance of antimicrobial peptides by replacing tryptophan or histidine residues with the bulky amino acids β-naphthylalanine and β-(4,4′-biphenyl)alanine. The activities of the salt-sensitive peptide P-113 were diminished at high salt concentrations, whereas the activities of its β-naphthylalanine and β-(4,4′-biphenyl)alanine-substituted variant were less affected.

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Effect of Solvent Quality on the Phase Behavior of Polyelectrolyte Complexes

10.26434/chemrxiv.12248786 ◽

2020 ◽

Author(s):

Lu Li ◽

Artem M. Rumyantsev ◽

Samanvaya Srivastava ◽

Siqi Meng ◽

Juan de Pablo ◽

...

Keyword(s):

Phase Behavior ◽

Phase Diagrams ◽

Random Phase ◽

Salt Resistance ◽

High Salt ◽

Phase Boundaries ◽

Two Phase ◽

Polyelectrolyte Complexes ◽

Solvent Interactions ◽

Very High

<div> <div> <div> <p>The role of polyelectrolyte-solvent interactions, among other non-Coulomb interactions, in dictating the thermodynamics and kinetics of polyelectrolyte complexation is prominent, yet sparingly studied. In this article, we present systematic comparisons of the binodal phase behavior of polyelectrolyte complexes (PECs) comprising polyelectrolytes with varying quality of backbone-solvent interactions. Experimental phase diagrams of polyelectrolyte complexes with either a peptide or an aliphatic backbone highlight the influence of backbone chemistry on the composition of complexes and their salt resistance. Corresponding theoretical phase diagrams, obtained from a framework combining the random phase approximation and Flory- Huggins approach, reveal a transition from closed phase boundaries with confined two-phase regions for PECs in good solvents to open phase boundaries, wherein two-phase systems are predicted to exist even at very high salt concentrations, for PECs in poor solvents. These predictions compare fittingly with experimental observations of low salt resistance (~1 M NaCl) of PECs comprising hydrophilic polyelectrolytes and persistence of complexes, stabilized by short-range hydrophobic interactions, even at very high salt concentrations (~6 M NaCl) for PECs comprising hydrophobic polyelectrolytes. </p> </div> </div> </div>

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A Chimeric Cationic Peptide Composed of Human β-Defensin 3 and Human β-Defensin 4 Exhibits Improved Antibacterial Activity and Salt Resistance

Frontiers in Microbiology ◽

10.3389/fmicb.2021.663151 ◽

2021 ◽

Vol 12 ◽

Author(s):

Wenjing Yu ◽

Nianzhi Ning ◽

Ying Xue ◽

Yanyu Huang ◽

Feng Guo ◽

...

Keyword(s):

Antibacterial Activity ◽

Antimicrobial Agents ◽

A549 Cells ◽

Multidrug Resistant ◽

Salt Resistance ◽

High Salt ◽

Resistant Isolate ◽

Klebsiella Pneumonia ◽

Staphyloccocus Aureus

Human beta-defensins (hBDs) play an important role in the host defense against various microbes, showing different levels of antibacterial activity and salt resistance in vitro. It is of interest to investigate whether can chimeric hBD analogs enhanced antibacterial activity and salt resistance. In this study, we designed a chimeric human defensin, named H4, by combining sequences of human beta-defensin-3 (hBD-3) and human beta-defensin-4 (hBD-4), then evaluated its antibacterial activity, salt resistance, and cytotoxic effects. The result showed that the antibacterial activity of H4 against most tested strains, including Klebsiella pneumonia, Enterococcus faecalis, Staphyloccocus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Acinetobacter baumannii was significantly improved compared to that of hBD-3 and hBD-4. Notably, H4 exhibited significantly better antibacterial activity against multidrug resistant isolate A. baumannii MDR-ZJ06 than commonly used antibiotics. Chimeric H4 still showed more than 80% antibacterial activity at high salt concentration (150 μM), which proves its good salt tolerance. The cytotoxic effect assay showed that the toxicity of H4 to Hela, Vero, A549 cells and erythrocytes at a low dose (<10 μg/ml) was similar to that of hBD-3 and hBD-4. In conclusion, given its broad spectrum of antibacterial activity and high salt resistance, chimeric H4 could serve as a promising template for new therapeutic antimicrobial agents.

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Studies on halotolerance in a moderately halophilic bacterium. Effect of growth conditions on salt resistance of the respiratory system

Biochemical Journal ◽

10.1042/bj1090679 ◽

1968 ◽

Vol 109 (4) ◽

pp. 679-685 ◽

Cited By ~ 28

Author(s):

Dvora Rafaeli-Eshkol

Keyword(s):

Sodium Chloride ◽

Respiratory System ◽

Chloride Concentration ◽

Growth Conditions ◽

Salt Resistance ◽

High Salt ◽

Resting Cells ◽

Moderately Halophilic ◽

Moderately Halophilic Bacterium ◽

Low Salt

The effect of sodium chloride on the respiratory activity of a moderately halophilic halotolerant bacterium was studied. Irrespective of growth conditions, resting cells oxidized succinate at a low rate unless sodium chloride was included in the assay mixture, maximum respiratory rates being obtained for sodium chloride concentrations between 0·2m and 0·8m. Neither potassium chloride nor sucrose could replace the sodium salt. The response of the respiratory system to sodium chloride concentration above the optimum depended on growth conditions. Respiration of cells harvested from a low-salt medium was almost inhibited completely by 2·0m-sodium chloride, and that of cells grown and washed in the presence of 2·0m-sodium chloride by 30%. After preincubation with a growth medium containing 2·0m-sodium chloride, even with all multiplication suppressed by chloramphenicol, the resistance of the respiratory system of low-salt-grown organisms to high salt concentrations increased considerably and resembled that of their high-salt-grown counterparts. A similar increase in resistance occurred after preincubation with yeast extract or with choline. With labelled choline, energy-dependent accumulation of labelled material occurred, the conditions required for maximum accumulation and retention being the same as those that increased the salt resistance of the respiratory system. The chromatographic behaviour of the labelled material indicated that the substance was not choline but a derivative, possibly betaine.

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Abstract 11: Role Of Pro-saas Peptides In Salt Resistance

Hypertension ◽

10.1161/hyp.76.suppl_1.11 ◽

2020 ◽

Vol 76 (Suppl_1) ◽

Author(s):

Megha Kumar ◽

Gina Capece ◽

Prasad R Konkalmatt ◽

Xiaoxu Zheng ◽

Laureano Asico ◽

...

Keyword(s):

Blood Pressure ◽

Glutamic Acid ◽

Gene Interaction ◽

Salt Resistance ◽

High Salt ◽

High Salt Diet ◽

Salt Diet ◽

Akt Phosphorylation ◽

Renal Proximal Tubule Cells ◽

20 Nm

The recently deorphanized G protein couple receptor 83 (GPR83) is expressed in proximal and distal convoluted tubules of the mouse kidney and in human renal proximal tubule cells (hRPTCs). Peptides derived from the cleavage of the precursor neuroendocrine hormone pro-SAAS (pro serine, alanine, alanine, serine), in particular PEN (proline, glutamic acid, and asparagine), have been proposed as the endogenous ligands of GPR83 but their function in the kidney is unknown. GPR83 is constitutively active; silencing (siRNA, 20 nM, 72h) its expression in hRPTCs decreases the phosphorylation of ERK1/2, p38, p90RSK and AKT (43%, 52%, 65%, and 25% respectively, n=4/group, P<0.05 vs non-silencing siRNA). Conversely, PEN (proline, glutamic acid, and asparagine) treatment of hRPTCs (1 μM, 1h) increases ERK1/2, p38, p90RSK, and AKT phosphorylation (15-fold, 1.7-fold, 2-fold, 18-fold respectively, n=4/group, P<0.05 vs vehicle). We hypothesized that GPR83 and its ligands PEN and pro-SAAS are involved in the regulation of blood pressure. Global deletion or renal-specific silencing of the Gpr83 gene in mice increased systolic blood pressure (SBP). High salt diet increased Gpr83 transcription 2-fold (P<0.05; n=4/group) in SJL/J and BALB/c salt-resistant mice, relative to C57Bl/6J salt-sensitive mice. Renal-restricted infusion of PEN (1 μg/day; 7 days) did not affect SBP, slightly decreased Na + excretion and renal NHE3 expression (P<0.05 all) and did not affect renal Na + /K + -ATPase expression, suggesting that PEN is only a partial ligand of GPR83. By contrast, the renal specific siRNA-mediated silencing of pro-SAAS in mice increased SBP (130±4 vs control wild-type 100±1 mmHg, n=3/group; P<0.05) that was associated with decreased urinary Na + excretion (P<0.05) and increased renal expressions of NHE3, SGLT2, NaPi2, NKCC2, NCC, and Na + /K + -ATPase (P<0.05 all). Renal expression of GRK4, another regulator of BP was also increased. Renal pro-SAAS expression was increased by a high salt diet (4%NaCl) in non-transgenic mice but was decreased in the salt-sensitive GRK4 486V mice on the same diet. Our results suggest that pro-SAAS peptides may be involved in the development of salt sensitivity through gene-gene interaction between GPR83 and GRK4 486.

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