Dominant suppressor mutation bypasses the sphingolipid requirement for growth of Saccharomyces cells at low pH: role of the CWP2 gene

2000 ◽  
Vol 38 (4) ◽  
pp. 191-201 ◽  
Author(s):  
Marek Skrzypek ◽  
Robert L. Lester ◽  
Peter Spielmann ◽  
Nathan Zingg ◽  
Judith Shelling ◽  
...  
Keyword(s):  
Low Ph ◽  
Suppressor Mutation ◽  
Dominant Suppressor

scholarly journals Role of Anions in Low pH-induced Translocation of Diphtheria Toxin

1989 ◽  
Vol 264 (19) ◽  
pp. 11367-11372 ◽  
Author(s):  
J Ø Moskaug ◽  
K Sandvig ◽  
S Olsnes
Keyword(s):  
Diphtheria Toxin ◽  
Low Ph

scholarly journals Acid tolerance in early colonizers of oral biofilms

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gabriella Boisen ◽  
Julia R. Davies ◽  
Jessica Neilands
Keyword(s):  
Acid Tolerance ◽  
Low Ph ◽  
Salivary Proteins ◽  
Confocal Scanning Laser Microscopy ◽  
Planktonic Cells ◽  
Tolerance Development ◽  
Salivary Pellicle ◽  
Oral Biofilms ◽  
Acid Tolerant

Abstract Background In caries, low pH drives selection and enrichment of acidogenic and aciduric bacteria in oral biofilms, and development of acid tolerance in early colonizers is thought to play a key role in this shift. Since previous studies have focussed on planktonic cells, the effect of biofilm growth as well as the role of a salivary pellicle on this process is largely unknown. We explored acid tolerance and acid tolerance response (ATR) induction in biofilm cells of both clinical and laboratory strains of three oral streptococcal species (Streptococcus gordonii, Streptococcus oralis and Streptococcus mutans) as well as two oral species of Actinomyces (A. naeslundii and A. odontolyticus) and examined the role of salivary proteins in acid tolerance development. Methods Biofilms were formed on surfaces in Ibidi® mini flow cells with or without a coating of salivary proteins and acid tolerance assessed by exposing them to a challenge known to kill non-acid tolerant cells (pH 3.5 for 30 min) followed by staining with LIVE/DEAD BacLight and confocal scanning laser microscopy. The ability to induce an ATR was assessed by exposing the biofilms to an adaptation pH (pH 5.5) for 2 hours prior to the low pH challenge. Results Biofilm formation significantly increased acid tolerance in all the clinical streptococcal strains (P < 0.05) whereas the laboratory strains varied in their response. In biofilms, S. oralis was much more acid tolerant than S. gordonii or S. mutans. A. naeslundii showed a significant increase in acid tolerance in biofilms compared to planktonic cells (P < 0.001) which was not seen for A. odontolyticus. All strains except S. oralis induced an ATR after pre-exposure to pH 5.5 (P < 0.05). The presence of a salivary pellicle enhanced both acid tolerance development and ATR induction in S. gordonii biofilms (P < 0.05) but did not affect the other bacteria to the same extent. Conclusions These findings suggest that factors such as surface contact, the presence of a salivary pellicle and sensing of environmental pH can contribute to the development of high levels of acid tolerance amongst early colonizers in oral biofilms which may be important in the initiation of caries.

scholarly journals The Role of Histidine Residues in Low-pH-Mediated Viral Membrane Fusion

Structure ◽  
2006 ◽  
Vol 14 (10) ◽  
pp. 1481-1487 ◽  
Author(s):  
Thorsten Kampmann ◽  
Daniela S. Mueller ◽  
Alan E. Mark ◽  
Paul R. Young ◽  
Bostjan Kobe
Keyword(s):  
Membrane Fusion ◽  
Low Ph ◽  
Viral Membrane ◽  
Histidine Residues ◽  
Viral Membrane Fusion

The stability of onoratoite, Sb8O11Cl2, in the supergene environment

2014 ◽  
Vol 78 (7) ◽  
pp. 1671-1675 ◽  
Author(s):  
Adam J. Roper ◽  
Peter Leverett ◽  
Timothy D. Murphy ◽  
Peter A. Williams
Keyword(s):  
Significant Influence ◽  
Secondary Phase ◽  
Low Ph ◽  
Stable Phase ◽  
Supergene Zone ◽  
A Value ◽  
Solubility Studies ◽  
The Stability ◽  
Very High

AbstractSynthesis and solubility studies of onoratoite have been undertaken to determine the role of this rare secondary phase in the immobilization of Sb and the conditions responsible for its formation in the supergene zone. Solubility studies were undertaken at 298.15 K. A value of ΔGfθ (Sb8O11Cl2, s, 298.15 K) = –2576 ±12 kJ mol–1 was derived. Calculations involving sénarmontite, Sb2O3, klebelsbergite, Sb4O4SO4(OH)2 and schafarzikite, FeSb2O4, show that onoratoite is a thermodynamically stable phase only at negligible activities of SO42–(aq) and low activities of Fe2+(aq), at low pH and very high activities of Cl–(aq). This explains why onoratoite is such a rare secondary phase and why it cannot exert any significant influence on the dispersion of Sb in the supergene environment.

scholarly journals Filament formation by metabolic enzymes is a specific adaptation to an advanced state of cellular starvation

2014 ◽  
Author(s):  
Ivana Petrovska ◽  
Elisabeth Nüske ◽  
Matthias C Munder ◽  
Gayathrie Kulasegaran ◽  
Liliana Malinovska ◽  
...  
Keyword(s):  
Metabolic Enzymes ◽  
Low Ph ◽  
General Mechanism ◽  
Filament Formation ◽  
Ph Change ◽  
Cooperative Process ◽  
A Cell ◽  
Enzymatic Inactivation ◽  
Physical Organization

One of the key questions in biology is how the metabolism of a cell responds to changes in the environment. In budding yeast, starvation causes a drop in intracellular pH, but the functional role of this pH change is not well understood. Here, we show that the enzyme glutamine synthetase (Gln1) forms filaments at low pH and that filament formation leads to enzymatic inactivation. Filament formation by Gln1 is a highly cooperative process, strongly dependent on macromolecular crowding, and involves back-to-back stacking of cylindrical homo-decamers into filaments that associate laterally to form higher order fibrils. Other metabolic enzymes also assemble into filaments at low pH. Hence, we propose that filament formation is a general mechanism to inactivate and store key metabolic enzymes during a state of advanced cellular starvation. These findings have broad implications for understanding the interplay between nutritional stress, the metabolism and the physical organization of a cell.

Transcriptional profiling reveals molecular basis and the role of arginine in response to low-pH stress in Pichia kudriavzevii

2019 ◽  
Author(s):  
Hao Ji ◽  
Xiameng Dong ◽  
Kailun Zhang ◽  
Libo Jin ◽  
Renyi Peng ◽  
...  
Keyword(s):  
Organic Acids ◽  
Molecular Basis ◽  
Transcriptional Profiling ◽  
Cell Aggregation ◽  
Membrane Lipid ◽  
Low Ph ◽  
Pichia Kudriavzevii ◽  
Ph Stress ◽  
Ph Conditions

Abstract BackgroundThe non-conventional yeast Pichia kudriavzevii possesses a unique ability to tolerate various environmental stresses particularly low-pH stress. Thus, it is considered to be a promising biotechnological host for the production of various organic acids under low-pH conditions. However, little is known about the low-pH stress response in P. kudriavzevii, which significantly restricts its future development. ResultsIn this study, P. kudriavzevii JLY1107 showed great tolerance to low-pH stress, but its cell aggregation upon acidic conditions is unfavorable for the development of low-pH fermentation. To explore the molecular basis, we conducted RNA-Seq to compare global gene expression in response to low-pH. Among the 429 differentially expressed genes, the genes associated with regulation of membrane lipid composition, filamentous growth and arginine metabolism were selected for in-depth discussions. The up-regulation of genes associated with arginine uptake and degradation suggests a potential role of arginine in response to low-pH strsss. We therefore present data supporting the hypothesis that P. kudriavzevii maintains intracellular homeostasis by using the ammonia produced by arginine catabolism. Furthermore, external addition of arginine significantly enhances growth and reduces cell aggregation of P. kudriavzevii under low-pH conditions.ConclusionsArginine was demonstrated to be a promising molecule for improving cell growth and preventing cell aggregation under extremely low-pH conditions. Our study is a step towards developing the non-conventional yeast P. kudriavzevii as a platform host for the production of organic acids under low-pH conditions.

scholarly journals Role of Vitamin E on Indomethacin induced low pH of Seminal Fluid in Long Evans Rats

1970 ◽  
Vol 8 (1) ◽  
pp. 13-15
Author(s):  
Md Jahangir Alam ◽  
Humaira Naushaba ◽  
Uttam Kumar Paul ◽  
Tahmina Begum ◽  
Sunjida Shahriah ◽  
...  
Keyword(s):  
Body Weight ◽  
Vitamin E ◽  
Seminal Fluid ◽  
Low Ph ◽  
The Other ◽  
Testicular Damage ◽  
Other Hand ◽  
Long Evans ◽  
Different Doses

Context: Indomethacin is the most commonly and widely used nonsteroidal antinflammatory analgesic and antipyretic drug. Though it is effective drug in various diseases, indomethacin causes inhibition of spermatogenesis by lowering the pH of seminal fluid leading to infertility. On the other hand, vitamin E enhances spermatogenesis by increasing pH of the seminal fluid. Therefore, the present study was designed to observe the protective role of vitamin E on indomethacin induced low pH of seminal fluid in testicular damage. Objective: To observe the effects of vitamin E on indomethacin induced low pH of seminal fluid in testicular damage in Long Evans rats. Study design: An experimental study. Place and period of study: The study was carried out in the Department of Anatomy, Sir Salimullah Medical College, Dhaka in the period of August, 2005 to June, 2006. Materials and methods: Eightyfour mature Long Evans male rats were divided into four groups (I, II, III and IV). The rats of group I, II and III were treated with indomethacin at different doses and duration. Group IV rats were treated with indomethacin plus vitamin E at different doses for 49 days. The pH of seminal fluid were measured biochemically. Results: There was significant reduction (P<0.001) of pH of seminal fluid when the rats were treated with indomethacin at low (2 mg/kg body weight/day) and high (10 mg/kg body weight/day) doses for 7, 14 and 42 days, respectively. On the other hand, rats treated with indomethacin plus vitamin E for 49 days showed increase in pH of seminal fluid compared to other groups (P<0.001). Conclusion: It can be concluded from the study that vitamin E has potential role in the prevention of the antispermatogenic effects of indomethacin by increasing the pH of seminal fluid. Key words: seminal fluid; indomethacin; vitamin E   DOI: 10.3329/bja.v8i1.6103 Bangladesh Journal of Anatomy January 2010, Vol. 8 No. 1 pp. 13-15

scholarly journals Dissociation of clathrin coats coupled to the hydrolysis of ATP: role of an uncoating ATPase.

1984 ◽  
Vol 99 (2) ◽  
pp. 734-741 ◽  
Author(s):  
W A Braell ◽  
D M Schlossman ◽  
S L Schmid ◽  
J E Rothman
Keyword(s):  
Atpase Activity ◽  
Atp Hydrolysis ◽  
Low Ph ◽  
Coated Vesicles ◽  
Magnesium Concentration ◽  
Cross Linking ◽  
Dependent Atpase ◽  
Event Triggering ◽  
Hydrolysis Of

ATP hydrolysis was used to power the enzymatic release of clathrin from coated vesicles. The 70,000-mol-wt protein, purified on the basis of its ATP-dependent ability to disassemble clathrin cages, was found to possess a clathrin-dependent ATPase activity. Hydrolysis was specific for ATP; neither dATP nor other ribonucleotide triphosphates would either substitute for ATP or inhibit the hydrolysis of ATP in the presence of clathrin cages. The ATPase activity is elicited by clathrin in the form of assembled cages, but not by clathrin trimers, the product of cage disassembly. The 70,000-mol-wt polypeptide, but not clathrin, was labeled by ATP in photochemical cross-linking, indicating that the hydrolytic site for ATP resides on the uncoating protein. Conditions of low pH or high magnesium concentration uncouple ATP hydrolysis from clathrin release, as ATP is hydrolyzed although essentially no clathrin is released. This suggests that the recognition event triggering clathrin-dependent ATP hydrolysis occurs in the absence of clathrin release, and presumably precedes such release.

Exposure of energy-depleted rat trabeculae to low pH improves contractile recovery: role of calcium

1995 ◽  
Vol 268 (4) ◽  
pp. H1510-H1520 ◽  
Author(s):  
C. van Hardeveld ◽  
V. J. Schouten ◽  
A. Muller ◽  
E. T. van der Meulen ◽  
G. Elzinga
Keyword(s):  
Recovery Period ◽  
Muscle Tension ◽  
Low Ph ◽  
Tyrode Solution ◽  
Normal Medium ◽  
Group Iii ◽  
Group I ◽  
Group Ii ◽  
Saving Effect

The beneficial effect of low pH during cardiac ischemia on reperfusion injury has often been attributed to its energy-saving effect due to inhibition of contraction. The role of low pH on Ca2+ accumulation and muscle tension was assessed in energy-depleted tissue by changing the pH of the medium from 7.4 to 6.2 at onset of rigor development during metabolic inhibition (MI), i.e., in the energy-depleted phase. Cytosolic free Ca2+ ([Ca2+]i) and intracellular H+ (pHi) were measured in rat trabeculae at 20 degrees C with fura 2 and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, respectively, and tension was recorded. The preparations were energy depleted by stimulation at 1 Hz in glucose-free Tyrode solution with 2 mM NaCN. Rigor developed within 20 min, indicating energy depletion. Resting [Ca2+]i was followed during 50 min (group I) or 100 min (group II) of rigor, and recovery was followed for 60 min in glucose-containing Tyrode solution at 0.2-Hz stimulation. Resting [Ca2+]i rose within 50 min (group I) but stabilized in the 50- to 100-min period (group II). All preparations from group I (n = 5) resumed contraction in the recovery period but in group II (n = 10) 70% failed to recover, and [Ca2+]i remained elevated compared with those that recovered. An extracellular pH of 6.2, resulting in similar pHi, from onset of rigor development (group III) led to only a modest rise in [Ca2+]i during the 100-min rigor period, and all preparations resumed contraction after approximately 3 min in normal medium. ATP was very low in all groups at the end of MI but was still significantly lower in group II than in groups I and III. A beneficial energy-sparing effect of low pH during the rigor phase can therefore not be excluded. We conclude that 1) the capacity of trabeculae to recover from MI depends on the time period and magnitude of the [Ca2+]i rise in the energy-depleted phase and 2) low pH in energy-depleted trabeculae protects against Ca overload, improving recovery after normalization of perfusion conditions.

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