Ornithine decarboxylation (ODC) system of Shewanella baltica regulates putrescine production and acid resistance

2020 ◽  
Author(s):  
Xingyue Bao ◽  
Feifei Wang ◽  
Rendi Yang ◽  
Yan Zhang ◽  
Linglin Fu ◽  
...  
Keyword(s):  
Molecular Biology ◽  
Food System ◽  
Acid Resistance ◽  
Acidic Ph ◽  
Food Spoilage ◽  
Dual Roles ◽  
Neutral Ph ◽  
Acidic Environments ◽  
Novel Target ◽  
Shewanella Baltica

Shewanella baltica , as one of the dominant spoilers in seafoods where they encounter acidic environments during spoilage, can synthesize putrescine from ornithine and cause food spoilage as well as health problems. Here, the ornithine decarboxylation (ODC) pathway composed of ornithine decarboxylases SpeC and SpeF and an ornithine-putrescine transporter PotE were identified in S. baltica by database searches and further by molecular biology operations, and SpeC functioned as an auxiliary adjusting component of ODC system. Ornithine and putrescine were found to promote putrescine accumulation through up-regulating the expression of speF and potE rather than speC . In addition, increased putrescine biosynthesis and alkalization of cytoplasm was detected at acidic pH especially at pH 6.0 compared to neutral pH. Particularly, the maximum up-regulation of ODC genes and the optimum decarboxylation activity of SpeF were detected at acidic pH around 6.0. It’s concluded that the ODC pathway plays dual roles in cytoplasmic acid counteraction and putrescine production of S. baltica . This study contributes to our understanding of the spoilage mechanism of spoilers in the food system, and provides a novel target for seafoods preservation.

scholarly journals The Listeria monocytogenes hemolysin has an acidic pH optimum to compartmentalize activity and prevent damage to infected host cells

2002 ◽  
Vol 156 (6) ◽  
pp. 1029-1038 ◽  
Author(s):  
Ian J. Glomski ◽  
Margaret M. Gedde ◽  
Albert W. Tsang ◽  
Joel A. Swanson ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Bacterial Pathogen ◽  
Cytolytic Activity ◽  
Host Cells ◽  
Adaptive Mutation ◽  
Acidic Ph ◽  
Listeriolysin O ◽  
Lysosomal Hydrolases ◽  
Ph Optimum ◽  
Neutral Ph

Listeria monocytogenes is a facultative intracellular bacterial pathogen that escapes from a phagosome and grows in the host cell cytosol. The pore-forming cholesterol-dependent cytolysin, listeriolysin O (LLO), mediates bacterial escape from vesicles and is ∼10-fold more active at an acidic than neutral pH. By swapping dissimilar residues from a pH-insensitive orthologue, perfringolysin O (PFO), we identified leucine 461 as unique to pathogenic Listeria and responsible for the acidic pH optimum of LLO. Conversion of leucine 461 to the threonine present in PFO increased the hemolytic activity of LLO almost 10-fold at a neutral pH. L. monocytogenes synthesizing LLO L461T, expressed from its endogenous site on the bacterial chromosome, resulted in a 100-fold virulence defect in the mouse listeriosis model. These bacteria escaped from acidic phagosomes and initially grew normally in cells and spread cell to cell, but prematurely permeabilized the host membrane and killed the cell. These data show that the acidic pH optimum of LLO results from an adaptive mutation that acts to limit cytolytic activity to acidic vesicles and prevent damage in the host cytosol, a strategy also used by host cells to compartmentalize lysosomal hydrolases.

NMR studies of exocyclic 1,N2-propanodeoxyguanosine adducts (X) opposite purines in DNA duplexes: protonated X(syn).cntdot.A(anti) pairing (acidic pH) and X(syn).cntdot.G(anti) pairing (neutral pH) at the lesion site

Biochemistry ◽  
1989 ◽  
Vol 28 (13) ◽  
pp. 5647-5657 ◽  
Author(s):  
Michael Kouchakdjian ◽  
Edmund Marinelli ◽  
Xiaolian Gao ◽  
Francis Johnson ◽  
Arthur Grollman ◽  
...  
Keyword(s):  
Acidic Ph ◽  
Dna Duplexes ◽  
Lesion Site ◽  
Nmr Studies ◽  
Neutral Ph

scholarly journals Calcium fluxes in Hoplosternum littorale (tamoatá) exposed to different types of Amazonian waters

2009 ◽  
Vol 7 (3) ◽  
pp. 465-470 ◽  
Author(s):  
Bernardo Baldisserotto ◽  
Carlos Eduardo Copatti ◽  
Levy Carvalho Gomes ◽  
Edsandra Campos Chagas ◽  
Richard Philip Brinn ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Transfer ◽  
Well Water ◽  
Acidic Ph ◽  
Clear Water ◽  
Black Water ◽  
Neutral Ph ◽  
Different Types ◽  
White Water ◽  
Hoplosternum Littorale

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: "black waters", containing high dissolved organic carbon and acidic pH, "white waters", with ten fold higher Ca2+ concentrations than black waters and neutral pH, and "clear waters", with two fold higher Ca2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca2+ loss, while the amount of Ca2+ in the ion-rich white water seems adequate to prevent Ca2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca2+ disturbance.

scholarly journals Inactivation of tyrosine aminotransferase in neutral homogenates and rat liver slices

1972 ◽  
Vol 129 (5) ◽  
pp. 1131-1138 ◽  
Author(s):  
F. Auricchio ◽  
L. Mollica ◽  
A. Liguori
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Acid Concentration ◽  
Tyrosine Aminotransferase ◽  
Amino Acid Concentration ◽  
Acidic Ph ◽  
Ph Values ◽  
Neutral Ph ◽  
Liver Slices

Inactivation of tyrosine aminotransferase induced in vivo by triamcinolone was studied in a homogenate incubated at neutral pH values. The integrity and the presence of subcellular particles together with a compartment of acidic pH are necessary for inactivation of tyrosine aminotransferase. It is suggested that tyrosine aminotransferase is inactivated inside lysosomes. The system responsible for inactivation of tyrosine aminotransferase was partially purified and identified with lysosomal cathepsins B and B1. Inactivation of tyrosine aminotransferase in liver slices is controlled by the amino acid concentration and strongly stimulated by cysteine. 3,3′,5-Tri-iodo-l-thyronine reversibly and strongly decreases the rate of inactivation of tyrosine aminotransferase. The effect is not due to an increased rate of tyrosine aminotransferase synthesis.

scholarly journals Effective Removal of Fluoride onto Metal Ions Loaded Orange Waste

2012 ◽  
Vol 27 ◽  
pp. 61-66 ◽  
Author(s):  
Kedar Nath Ghimire
Keyword(s):  
Metal Ions ◽  
Removal Efficiency ◽  
Orange Juice ◽  
Experimental Results ◽  
Fluoride Removal ◽  
Acidic Ph ◽  
Neutral Ph ◽  
Effective Removal ◽  
Orange Waste ◽  
Ph Range

Removal of fluoride is investigated onto several metal ions loaded phosphorylated orange juice residue and commercially available alumina. The experimental results revealed that cerium (IV) loaded phosphorylated orange waste indicated excellent fluoride removal efficiency at acidic pH range and while that lanthanum loaded at neutral pH range. Both the metal loaded adsorbents are found superior to the commercially available activated alumina.DOI: http://dx.doi.org/10.3126/jncs.v27i1.6660 J. Nepal Chem. Soc., Vol. 27, 2011 61-66 

scholarly journals An Acid-activated Nucleobase Transporter from Leishmania major

2009 ◽  
Vol 284 (24) ◽  
pp. 16164-16169 ◽  
Author(s):  
Diana Ortiz ◽  
Marco A. Sanchez ◽  
Hans P. Koch ◽  
H. Peter Larsson ◽  
Scott M. Landfear
Keyword(s):  
Leishmania Major ◽  
De Novo ◽  
Low Ph ◽  
Acidic Ph ◽  
Physiological Conditions ◽  
Neutral Ph ◽  
Amastigote Stage ◽  
Electrode Voltage ◽  
Ph Conditions ◽  
Micromolar Range

Parasitic protozoa are unable to synthesize purines de novo and must import preformed purine nucleobases or nucleosides from their hosts. Leishmania major expresses two purine nucleobase transporters, LmaNT3 and LmaNT4. Previous studies revealed that at neutral pH, LmaNT3 is a broad specificity, high affinity nucleobase transporter, whereas LmaNT4 mediates the uptake of only adenine. Because LmaNT4 is required for optimal viability of the amastigote stage of the parasite that lives within acidified phagolysomal vesicles of mammalian macrophages, the function of this permease was examined under acidic pH conditions. At acidic pH, LmaNT4 acquires the ability to transport adenine, hypoxanthine, guanine, and xanthine with Km values in the micromolar range, indicating that this transporter is activated at low pH. Thus, LmaNT4 is an acid-activated purine nucleobase transporter that functions optimally under the physiological conditions the parasite is exposed to in the macrophage phagolysosome. In contrast, LmaNT3 functions optimally at neutral pH. Two-electrode voltage clamp experiments performed on LmaNT3 and LmaNT4 expressed in Xenopus oocytes revealed substrate-induced inward directed currents at acidic pH, and application of substrates induced acidification of the oocyte cytosol. These observations imply that LmaNT3 and LmaNT4 are nucleobase/proton symporters.

scholarly journals Adaptation of Escherichia coli O157:H7 to pH Alters Membrane Lipid Composition, Verotoxin Secretion, and Resistance to Simulated Gastric Fluid Acid

2004 ◽  
Vol 70 (6) ◽  
pp. 3500-3505 ◽  
Author(s):  
Hyun-Gyun Yuk ◽  
Douglas L. Marshall
Keyword(s):  
Escherichia Coli ◽  
Membrane Fluidity ◽  
Lipid Composition ◽  
Vaccenic Acid ◽  
Acid Resistance ◽  
Gastric Fluid ◽  
Membrane Lipid ◽  
Simulated Gastric Fluid ◽  
Acidic Ph ◽  
Membrane Lipid Composition

ABSTRACT The influence of adaptation to pH (from pH 5.0 to 9.0) on membrane lipid composition, verotoxin concentration, and resistance to acidic conditions in simulated gastric fluid (SGF) (pH 1.5, 37�C) was determined for Escherichia coli O157:H7 (HEC, ATCC 43895), an rpoS-deficient mutant of ATCC 43895 (HEC-RM, FRIK 816-3), and nonpathogenic E. coli (NPEC, ATCC 25922). Regardless of the strain, D values (in SGF) of acid-adapted cells were higher than those of non-acid-adapted cells, with HEC adapted at pH 5.0 having the greatest D value, i.e., 25.6 min. Acid adaptation increased the amounts of palmitic acid (C16:0) and decreased cis-vaccenic acid (C18:1ω7c) in the membrane lipids of all strains. The ratio of cis-vaccenic acid to palmitic acid increased at acidic pH, causing a decrease in membrane fluidity. HEC adapted to pH 8.3 and HEC-RM adapted to pH 7.3 exhibited the greatest verotoxin concentrations (2,470 and 1,460 ng/ml, respectively) at approximately 108 CFU/ml. In addition, the ratio of extracellular to intracellular verotoxin concentration decreased at acidic pH, possibly due to the decrease of membrane fluidity. These results suggest that while the rpoS gene does not influence acid resistance in acid-adapted cells it does confer decreased membrane fluidity, which may increase acid resistance and decrease verotoxin secretion.

scholarly journals Arginine-Dependent Acid Resistance in Salmonella enterica Serovar Typhimurium

2006 ◽  
Vol 188 (15) ◽  
pp. 5650-5653 ◽  
Author(s):  
Jasper Kieboom ◽  
Tjakko Abee
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Acid Resistance ◽  
Arginine Decarboxylase ◽  
Acidic Ph ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Microaerobic Conditions ◽  
Acid Challenge

ABSTRACT Salmonella enterica serovar Typhimurium does not survive a pH 2.5 acid challenge under conditions similar to those used for Escherichia coli (J. W. Foster, Nat. Rev. Microbiol. 2:898-907, 2004). Here, we provide evidence that S. enterica serovar Typhimurium can display arginine-dependent acid resistance (AR) provided the cells are grown under anoxic conditions and not under the microaerobic conditions used for assessment of AR in E. coli. The role of the arginine decarboxylase pathway in Salmonella AR was shown by the loss of AR in mutants lacking adiA, which encodes arginine decarboxylase; adiC, which encodes the arginine-agmatine antiporter; or adiY, which encodes an AraC-like regulator. Transcription of adiA and adiC was found to be dependent on AdiY, anaerobiosis, and acidic pH.

scholarly journals SEA Ligation Is Accelerated at Mildly Acidic pH. Application to the Formation of Difficult Peptide Junctions

2019 ◽  
Author(s):  
Marine Cargoet ◽  
Vincent Diemer ◽  
Laurent Raibaut ◽  
Elizabeth Lissy ◽  
Benoît Snella ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Peptide Bond ◽  
Native Chemical Ligation ◽  
Acidic Ph ◽  
Chemical Ligation ◽  
Bond Forming ◽  
Neutral Ph ◽  
Wide Range ◽  
Peptide Segments ◽  
Model Peptides

The bis(2-sulfanylethyl)amido (SEA)-mediated ligation has been introduced in 2010 as a novel chemoselective peptide bond forming reaction. SEA ligation is a useful reaction for protein total synthesis that is complementary to the native chemical ligation (NCL). In particular, SEA ligation proceeds efficiently in a wide range of pH, from neutral pH to pH 3-4. Thus, the pH can be chosen to optimize the solubility of the peptide segments or final product. It can be also chosen to facilitate the formation of difficult junctions, since the rate of SEA ligation increases significantly by decreasing the pH from 7.2 to 4.0. Here we describe a protocol for SEA ligation at pH 5.5 in the presence of 4-mercaptophenylacetic acid (MPAA) or at pH 4.0 in the presence of a newly developed diselenol catalyst. The protocols describe the formation of a valyl-cysteinyl peptide bond between two model peptides.<br>

Sign in / Sign up

Export Citation Format

Share Document