scholarly journals The F-ATPase Operon Promoter of Streptococcus mutans Is Transcriptionally Regulated in Response to External pH

2004 ◽  
Vol 186 (24) ◽  
pp. 8524-8528 ◽  
Author(s):  
Wendi L. Kuhnert ◽  
Guolu Zheng ◽  
Roberta C. Faustoferri ◽  
Robert G. Quivey
Keyword(s):  
Streptococcus Mutans ◽  
Adaptive Response ◽  
Chloramphenicol Acetyltransferase ◽  
Low Ph ◽  
Ph Dependent ◽  
External Ph

ABSTRACT Streptococcus mutans F-ATPase, the major component of the acid-adaptive response of the organism, is transcriptionally upregulated at low pH. Fusions of the F-ATPase promoter to chloramphenicol acetyltransferase indicated that pH-dependent expression is still observed with a short promoter that contains a domain conserved between streptococcal ATPase operons.

Effects of Variations in pH and Hypothiocyanite Concentrations on S. mutans Glucose Metabolism

1987 ◽  
Vol 66 (2) ◽  
pp. 486-491 ◽  
Author(s):  
B. Mansson-Rahemtulla ◽  
D.C. Baldone ◽  
K.M. Pruitt ◽  
F. Rahemtulla
Keyword(s):  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Streptococcus Mutans ◽  
Low Ph ◽  
Oral Streptococci ◽  
Positive Correlation ◽  
Ph Changes ◽  
Glucose Incorporation ◽  
Dependent Inhibition ◽  
Ph Dependent

Hypothiocyanous acid (HOSCN) and hypothiocyanite (OSCN-) were generated by the antibody-independent salivary peroxidase (SP) system. The metabolism of Streptococcus mutans NCTC 10449 was examined by uniformly labeled glucose incorporation studies. We found that the SP-system causes a pH-dependent inhibition of 14C-labeled glucose uptake, and that the effects of HOSCN/OSCN- are bacteriostatic. The results also showed that, at low pH, bacteria required more time to recover fully from HOSCN/OSCN- inhibition. When control experiments were performed in the absence of HOSCN/OSCN-, but the pH was varied, we found a positive correlation between pH and the rate of 14C-glucose incorporation. The results also showed that pH did not affect the maximum incorporation of 14C-glucose, demonstrating that S. mutans can adapt to pH changes in the environment. Based on the data obtained, we postulate that the antibody-independent SP system plays an important role in the regulation of the metabolism of oral streptococci.

scholarly journals pH-Dependent Expression of Periplasmic Proteins and Amino Acid Catabolism in Escherichia coli

2002 ◽  
Vol 184 (15) ◽  
pp. 4246-4258 ◽  
Author(s):  
Lauren M. Stancik ◽  
Dawn M. Stancik ◽  
Brian Schmidt ◽  
D. Michael Barnhart ◽  
Yuliya N. Yoncheva ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Ph Dependence ◽  
Outer Membrane Proteins ◽  
Stress Protein ◽  
Low Ph ◽  
Wide Range ◽  
Periplasmic Proteins ◽  
Ph Dependent ◽  
External Ph

ABSTRACT Escherichia coli grows over a wide range of pHs (pH 4.4 to 9.2), and its own metabolism shifts the external pH toward either extreme, depending on available nutrients and electron acceptors. Responses to pH values across the growth range were examined through two-dimensional electrophoresis (2-D gels) of the proteome and through lac gene fusions. Strain W3110 was grown to early log phase in complex broth buffered at pH 4.9, 6.0, 8.0, or 9.1. 2-D gel analysis revealed the pH dependence of 19 proteins not previously known to be pH dependent. At low pH, several acetate-induced proteins were elevated (LuxS, Tpx, and YfiD), whereas acetate-repressed proteins were lowered (Pta, TnaA, DksA, AroK, and MalE). These responses could be mediated by the reuptake of acetate driven by changes in pH. The amplified proton gradient could also be responsible for the acid induction of the tricarboxylic acid (TCA) enzymes SucB and SucC. In addition to the autoinducer LuxS, low pH induced another potential autoinducer component, the LuxH homolog RibB. pH modulated the expression of several periplasmic and outer membrane proteins: acid induced YcdO and YdiY; base induced OmpA, MalE, and YceI; and either acid or base induced OmpX relative to pH 7. Two pH-dependent periplasmic proteins were redox modulators: Tpx (acid-induced) and DsbA (base-induced). The locus alx, induced in extreme base, was identified as ygjT, whose product is a putative membrane-bound redox modulator. The cytoplasmic superoxide stress protein SodB was induced by acid, possibly in response to increased iron solubility. High pH induced amino acid metabolic enzymes (TnaA and CysK) as well as lac fusions to the genes encoding AstD and GabT. These enzymes participate in arginine and glutamate catabolic pathways that channel carbon into acids instead of producing alkaline amines. Overall, these data are consistent with a model in which E. coli modulates multiple transporters and pathways of amino acid consumption so as to minimize the shift of its external pH toward either acidic or alkaline extreme.

scholarly journals Functional Entry of Baculovirus into Insect and Mammalian Cells Is Dependent on Clathrin-Mediated Endocytosis

2006 ◽  
Vol 80 (17) ◽  
pp. 8830-8833 ◽  
Author(s):  
Gang Long ◽  
Xiaoyu Pan ◽  
Richard Kormelink ◽  
Just M. Vlak
Keyword(s):  
Electron Microscopy ◽  
Mammalian Cells ◽  
Low Ph ◽  
Coated Pits ◽  
Immuno Electron Microscopy ◽  
Endocytosis Pathway ◽  
Ph Dependent ◽  
Budded Virus

ABSTRACT Entry of the budded virus form of baculoviruses into insect and mammalian cells is generally thought to occur through a low-pH-dependent endocytosis pathway, possibly through clathrin-coated pits. This insight is primarily based on (immuno)electron microscopy studies but requires biochemical support to exclude the use of other pathways. Here, we demonstrate using various inhibitors that functional entry of baculoviruses into insect and mammalian cells is primarily dependent on clathrin-mediated endocytosis. Our results further suggest that caveolae are somehow involved in baculovirus entry in mammalian cells. A caveolar endocytosis inhibitor, genistein, enhances baculovirus transduction in these cells considerably.

Entry of bovine viral diarrhea virus into ovine cells occurs through clathrin-dependent endocytosis and low pH-dependent fusion

2009 ◽  
Vol 46 (5) ◽  
pp. 403-407 ◽  
Author(s):  
Basavaraj Shrishail Mathapati ◽  
Niranjan Mishra ◽  
Katherukamem Rajukumar ◽  
Ram Kumar Nema ◽  
Sthita Pragnya Behera ◽  
...  
Keyword(s):  
Bovine Viral Diarrhea Virus ◽  
Low Ph ◽  
Bovine Viral Diarrhea ◽  
Diarrhea Virus ◽  
Viral Diarrhea ◽  
Ph Dependent ◽  
Viral Diarrhea Virus

pH dependence of kinetics and steady-state block of cardiac sodium channels by lidocaine

1993 ◽  
Vol 264 (5) ◽  
pp. H1588-H1598 ◽  
Author(s):  
D. J. Wendt ◽  
C. F. Starmer ◽  
A. O. Grant
Keyword(s):  
Steady State ◽  
Sodium Channel ◽  
Local Anesthetic ◽  
Ph Dependence ◽  
Membrane Depolarization ◽  
Low Ph ◽  
Proton Exchange ◽  
Phasic Block ◽  
Cardiac Sodium Channels ◽  
External Ph

The local anesthetic-class antiarrhythmic drugs produce greater depression of conduction in ischemic compared with normal myocardium. The basis for this relatively selective action is uncertain. A model of the pH-dependent interaction of tertiary amine drugs with the sodium channel suggests that the low pH occurring during ischemia slows drug dissociation from the channel by changing the drug's protonation. The importance of the proton exchange reaction and the effect of overall slowing of drug dissociation on steady-state sodium channel blockade is uncertain. We have measured whole cell sodium channel current in rabbit atrial myocytes during control and exposure to lidocaine while external pH was varied between 6.8 and 7.8 at membrane potentials of -140, -120, and -100 mV. Tonic blockade was little influenced by external pH. Decreasing the external pH from 7.8 to 6.8 slowed both the rate of development of phasic block and recovery from the block. Decreasing the membrane potential from -140 to -100 mV increased the degree of phasic block attained in the steady state. Block was further enhanced when low pH was combined with membrane depolarization. Experiments in which deuterium ions were substituted for protons suggest that the kinetics of proton exchange is not rate limiting in the dissociation of drugs from the sodium channel. We conclude that it is the combined effect of low pH and membrane depolarization that may be critical in the enhanced blocking action of local anesthetic-class drugs during ischemia.

scholarly journals Streptococcus mutans Lacking sufCDSUB Is Viable, but Displays Major Defects in Growth, Stress Tolerance Responses and Biofilm Formation

2021 ◽  
Vol 12 ◽  
Author(s):  
Kassapa Ellepola ◽  
Xiaochang Huang ◽  
Ryan P. Riley ◽  
Jacob P. Bitoun ◽  
Zezhang Tom Wen
Keyword(s):  
Stress Tolerance ◽  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Nitrosative Stress ◽  
Growth Stress ◽  
Low Ph ◽  
Luciferase Reporter ◽  
Deficient Mutant ◽  
Oxidative And Nitrosative Stress ◽  
Isoleucine Leucine

Streptococcus mutans appears to possess a sole iron-sulfur (Fe-S) cluster biosynthesis system encoded by the sufCDSUB cluster. This study was designed to examine the role of sufCDSUB in S. mutans physiology. Allelic exchange mutants deficient of the whole sufCDSUB cluster and in individual genes were constructed. Compared to the wild-type, UA159, the sufCDSUB-deficient mutant, Δsuf::kanr, had a significantly reduced growth rate, especially in medium with the absence of isoleucine, leucine or glutamate/glutamine, amino acids that require Fe-S clusters for biosynthesis and when grown with medium adjusted to pH 6.0 and under oxidative and nitrosative stress conditions. Relative to UA159, Δsuf::kanr had major defects in stress tolerance responses with reduced survival rate of > 2-logs following incubation at low pH environment or after hydrogen peroxide challenge. When compared to UA159, Δsuf::kanr tended to form aggregates in broth medium and accumulated significantly less biofilm. As shown by luciferase reporter fusion assays, the expression of sufCDSUB was elevated by > 5.4-fold when the reporter strain was transferred from iron sufficient medium to iron-limiting medium. Oxidative stress induced by methyl viologen increased sufCDSUB expression by > 2-fold, and incubation in a low pH environment led to reduction of sufCDSUB expression by > 7-fold. These results suggest that lacking of SufCDSUB in S. mutans causes major defects in various cellular processes of the deficient mutant, including growth, stress tolerance responses and biofilm formation. In addition, the viability of the deficient mutant also suggests that SUF, the sole Fe-S cluster machinery identified is non-essential in S. mutans, which is not known in any other bacterium lacking the NIF and/or ISC system. However, how the bacterium compensates the Fe-S deficiency and if any novel Fe-S assembly systems exist in this bacterium await further investigation.

scholarly journals Endocytosis of Wingless via a dynamin-independent pathway is necessary for signaling in Drosophila wing discs

2016 ◽  
Vol 113 (45) ◽  
pp. E6993-E7002 ◽  
Author(s):  
Anupama Hemalatha ◽  
Chaitra Prabhakara ◽  
Satyajit Mayor
Keyword(s):  
Signal Transduction ◽  
Wing Disc ◽  
Low Ph ◽  
Endocytic Pathway ◽  
Apical Surface ◽  
Receptor Complexes ◽  
Drosophila Wing ◽  
Wing Discs ◽  
Ph Dependent ◽  
Endocytic Pathways

Endocytosis of ligand-receptor complexes regulates signal transduction during development. In particular, clathrin and dynamin-dependent endocytosis has been well studied in the context of patterning of the Drosophila wing disc, wherein apically secreted Wingless (Wg) encounters its receptor, DFrizzled2 (DFz2), resulting in a distinctive dorso-ventral pattern of signaling outputs. Here, we directly track the endocytosis of Wg and DFz2 in the wing disc and demonstrate that Wg is endocytosed from the apical surface devoid of DFz2 via a dynamin-independent CLIC/GEEC pathway, regulated by Arf1, Garz, and class I PI3K. Subsequently, Wg containing CLIC/GEEC endosomes fuse with DFz2-containing vesicles derived from the clathrin and dynamin-dependent endocytic pathway, which results in a low pH-dependent transfer of Wg to DFz2 within the merged and acidified endosome to initiate Wg signaling. The employment of two distinct endocytic pathways exemplifies a mechanism wherein cells in tissues leverage multiple endocytic pathways to spatially regulate signaling.

scholarly journals The amino acid at position 624 in the glycoprotein of SFTSV (severe fever with thrombocytopenia virus) plays a critical role in low-pH-dependent cell fusion activity

2017 ◽  
Vol 38 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Yoshimi TSUDA ◽  
Manabu IGARASHI ◽  
Ryo ITO ◽  
Sanae NISHIO ◽  
Kenta SHIMIZU ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cell Fusion ◽  
Critical Role ◽  
Low Ph ◽  
Dependent Cell ◽  
Ph Dependent ◽  
Severe Fever

scholarly journals AguR Is Required for Induction of the Streptococcus mutans Agmatine Deiminase System by Low pH and Agmatine

2009 ◽  
Vol 75 (9) ◽  
pp. 2629-2637 ◽  
Author(s):  
Yaling Liu ◽  
Lin Zeng ◽  
Robert A. Burne
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Streptococcus Mutans ◽  
Low Ph ◽  
Binding Domain ◽  
Negative Regulator ◽  
Dna Binding Domain ◽  
Mutant Proteins ◽  
Acidic Conditions ◽  
Agmatine Deiminase

ABSTRACT Acidic conditions and the presence of exogenous agmatine are required to achieve maximal expression of the agmatine deiminase system (AgDS) of Streptococcus mutans. Here we demonstrate that the transcriptional activator of the AgDS, AguR, is required for the responses to agmatine and to low pH. Linker scanning mutagenesis was used to create a panel of mutated aguR genes that were utilized to complement an aguR deletion mutant of S. mutans. The level of production of the mutant proteins was shown to be comparable to that of the wild-type AguR protein. Mutations in the predicted DNA binding domain of AguR eliminated activation of the agu operon. Insertions into the region connecting the DNA binding domain to the predicted extracellular and transmembrane domains were well tolerated. In contrast, a variety of mutants were isolated that had a diminished capacity to respond to low pH but retained the ability to activate AgDS gene expression in response to agmatine, and vice versa. Also, a number of mutants were unable to respond to either agmatine or low pH. AguD, which is a predicted agmatine-putrescine antiporter, was found to be a negative regulator of AgDS gene expression in the absence of exogenous agmatine but was not required for low-pH induction of the AgDS genes. This study reveals that the control of AgDS gene expression by both agmatine and low pH is coordinated through the AguR protein and begins to identify domains of the protein involved in sensing and signaling.

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