scholarly journals Characterization of a Glutamate Transporter Operon, glnQHMP, in Streptococcus mutans and Its Role in Acid Tolerance

2009 ◽  
Vol 192 (4) ◽  
pp. 984-993 ◽  
Author(s):  
Kirsten Krastel ◽  
Dilani B. Senadheera ◽  
Richard Mair ◽  
Jennifer S. Downey ◽  
Steven D. Goodman ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Glutamate Transporter ◽  
Acid Tolerance ◽  
Wild Type ◽  
Acid Tolerance Response ◽  
Gram Positive Bacteria ◽  
Oral Bacterium ◽  
Tolerance Response ◽  
Kinetics Of

ABSTRACT Glutamate contributes to the acid tolerance response (ATR) of many Gram-negative and Gram-positive bacteria, but its role in the ATR of the oral bacterium Streptococcus mutans is unknown. This study describes the discovery and characterization of a glutamate transporter operon designated glnQHMP (Smu.1519 to Smu.1522) and investigates its potential role in acid tolerance. Deletion of glnQHMP resulted in a 95% reduction in transport of radiolabeled glutamate compared to the wild-type UA159 strain. The addition of glutamate to metabolizing UA159 cells resulted in an increased production of acidic end products, whereas the glnQHMP mutant produced less lactic acid than UA159, suggesting a link between glutamate metabolism and acid production and possible acid tolerance. To investigate this possibility, we conducted a microarray analysis with glutamate and under pH 5.5 and pH 7.5 conditions which showed that expression of the glnQHMP operon was downregulated by both glutamate and mild acid. We also measured the growth kinetics of UA159 and its glnQHMP-negative derivative at pH 5.5 and found that the mutant doubled at a much slower rate than the parent strain but survived at pH 3.5 significantly better than the wild type. Taken together, these findings support the involvement of the glutamate transporter operon glnQHMP in the acid tolerance response in S. mutans.

scholarly journals Defects in d-Alanyl-Lipoteichoic Acid Synthesis in Streptococcus mutans Results in Acid Sensitivity

2000 ◽  
Vol 182 (21) ◽  
pp. 6055-6065 ◽  
Author(s):  
David A. Boyd ◽  
Dennis G. Cvitkovitch ◽  
Arnold S. Bleiweis ◽  
Michael Y. Kiriukhin ◽  
Dmitri V. Debabov ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Growth Yield ◽  
Acid Tolerance ◽  
Lipoteichoic Acid ◽  
Wild Type ◽  
Lower Growth ◽  
Acid Tolerance Response ◽  
Acid Sensitivity ◽  
Permeabilized Cells ◽  
Tolerance Response

ABSTRACT In the cariogenic organism, Streptococcus mutans, low pH induces an acid tolerance response (ATR). To identify acid-regulated proteins comprising the ATR, transposon mutagenesis with the thermosensitive plasmid pGh9:ISS1 was used to produce clones that were able to grow at neutral pH, but not in medium at pH 5.0. Sequence analysis of one mutant (IS1A) indicated that transposition had created a 6.3-kb deletion, one end of which was indltB of the dlt operon encoding four proteins (DltA-DltD) involved in the synthesis ofd-alanyl-lipoteichoic acid. Inactivation of thedltC gene, encoding the d-alanyl carrier protein (Dcp), resulted in the generation of the acid-sensitive mutant, BH97LC. Compared to the wild-type strain, LT11, the mutant exhibited a threefold-longer doubling time and a 33% lower growth yield. In addition, it was unable to initiate growth below pH 6.5 and unadapted cells were unable to survive a 3-h exposure in medium buffered at pH 3.5, while a pH of 3.0 was required to kill the wild type in the same time period. Also, induction of the ATR in BH97LC, as measured by the number of survivors at a pH killing unadapted cells, was 3 to 4 orders of magnitude lower than that exhibited by the wild type. While the LTA of both strains contained a similar average number of glycerolphosphate residues, permeabilized cells of BH97LC did not incorporated-[14C]alanine into this amphiphile. This defect was correlated with the deficiency of Dcp. Chemical analysis of the LTA purified from the mutant confirmed the absence ofd-alanine-esters. Electron micrographs showed that BH97LC is characterized by unequal polar caps and is devoid of a fibrous extracellular matrix present on the surface of the wild-type cells. Proton permeability assays revealed that the mutant was more permeable to protons than the wild type. This observation suggests a mechanism for the loss of the characteristic acid tolerance response in S. mutans.

Effect offurmutation on acid-tolerance response and in vivo virulence of avian septicemicEscherichia coli

2002 ◽  
Vol 48 (5) ◽  
pp. 458-462 ◽  
Author(s):  
Chengru Zhu ◽  
Musangu Ngeleka ◽  
Andrew A Potter ◽  
Brenda J Allan
Keyword(s):  
Parent Strain ◽  
Acid Tolerance ◽  
Wild Type ◽  
Acid Tolerance Response ◽  
E Coli ◽  
Regulator Protein ◽  
In The Wild ◽  
Tolerance Response ◽  
Wild Type Parent

The Fur (ferric uptake regulator) protein is a master regulator of iron metabolism in gram-negative bacteria. In the present study, the effect of a partial deletion of the fur gene on the acid-tolerance response and in vivo virulence of avian Escherichia coli was examined. The fur mutant was unable to trigger the acid-tolerance response as observed in the wild-type parent strain. However, the mutant was as virulent as the wild-type parent strain when tested in 1-day-old chickens by subcutaneous inoculation. These data indicate that the fur gene is involved in the acid-tolerance response but not involved in the virulence of E. coli, as detected by the ability to cause septicemia in our experimental infection.Key words: E. coli, fur, acid-tolerance response.

High-Salt Preadaptation of Vibrio parahaemolyticus Enhances Survival in Response to Lethal Environmental Stresses

2014 ◽  
Vol 77 (2) ◽  
pp. 246-253 ◽  
Author(s):  
SAI SIDDARTH KALBURGE ◽  
W. BRIAN WHITAKER ◽  
E. FIDELMA BOYD
Keyword(s):  
Stress Response ◽  
Marine Environment ◽  
Vibrio Parahaemolyticus ◽  
High Salinity ◽  
Acid Stress ◽  
Acid Tolerance ◽  
High Salt ◽  
Wild Type ◽  
Acid Tolerance Response ◽  
Tolerance Response

Adaptation to changing environmental conditions is an important strategy for survival of foodborne bacterial pathogens. Vibrio parahaemolyticus is a gram-negative seafoodborne enteric pathogen found in the marine environment both free living and associated with oysters. This pathogen is a moderate halophile, with optimal growth at 3% NaCl. Among the several stresses imposed upon enteric bacteria, acid stress is perhaps one of the most important. V. parahaemolyticus has a lysine decarboxylase system responsible for decarboxylation of lysine to the basic product cadaverine, an important acid stress response system in bacteria. Preadaptation to mild acid conditions, i.e., the acid tolerance response, enhances survival under lethal acid conditions. Because of the variety of conditions encountered by V. parahaemolyticus in the marine environment and in oyster postharvest facilities, we examined the nature of the V. parahaemolyticus acid tolerance response under high-salinity conditions. Short preadaptation to a 6% salt concentration increased survival of the wild-type strain but not that of a cadA mutant under lethal acid conditions. However, prolonged exposure to high salinity (16 h) increased survival of both the wild-type and the cadA mutant strains. This phenotype was not dependent on the stress response sigma factor RpoS. Although this preadaptation response is much more pronounced in V. parahaemolyticus, this characteristic is not limited to this species. Both Vibrio cholerae and Vibrio vulnificus also survive better under lethal acid stress conditions when preadapted to high-salinity conditions. High salt both protected the organism against acid stress and increased survival under −20°C cold stress conditions. High-salt adaptation of V. parahaemolyticus strains significantly increases survival under environmental stresses that would otherwise be lethal to these bacteria.

Proteomic characterization of the acid tolerance response inLactococcus lactis MG1363

PROTEOMICS ◽  
2005 ◽  
Vol 5 (18) ◽  
pp. 4794-4807 ◽  
Author(s):  
Aurélie Budin-Verneuil ◽  
Vianney Pichereau ◽  
Yanick Auffray ◽  
Dusko S. Ehrlich ◽  
Emmanuelle Maguin
Keyword(s):  
Acid Tolerance ◽  
Acid Tolerance Response ◽  
Tolerance Response

scholarly journals Characterization of the Shewanella oneidensis Fur gene: roles in iron and acid tolerance response

BMC Genomics ◽  
2008 ◽  
Vol 9 (Suppl 1) ◽  
pp. S11 ◽  
Author(s):  
Yunfeng Yang ◽  
Daniel P Harris ◽  
Feng Luo ◽  
Liyou Wu ◽  
Andrea B Parsons ◽  
...  
Keyword(s):  
Shewanella Oneidensis ◽  
Acid Tolerance ◽  
Acid Tolerance Response ◽  
Tolerance Response

scholarly journals HtrA Is Essential for Efficient Secretion of Recombinant Proteins by Lactococcus lactis

2008 ◽  
Vol 74 (23) ◽  
pp. 7442-7446 ◽  
Author(s):  
Kalpana Sriraman ◽  
Guhan Jayaraman
Keyword(s):  
Recombinant Protein ◽  
Lactococcus Lactis ◽  
Protein Secretion ◽  
Recombinant Proteins ◽  
Acid Tolerance ◽  
Wild Type ◽  
Acid Tolerance Response ◽  
Recombinant Protein Secretion ◽  
Tolerance Response ◽  
Secretion Of Recombinant Proteins

ABSTRACT HtrA is a unique protease on the extracellular surface of Lactococcus lactis. It is known to take part in the proteolysis of many secreted recombinant proteins, and the mutation of htrA can lead to the complete stabilization of recombinant proteins. In this work, we have shown that htrA mutation also leads to significant reduction of the efficiency of recombinant-protein secretion. We also show that the level of HtrA can be lowered by the suppression of the acid tolerance response (ATR) in L. lactis. Instead of using an L. lactis htrA mutant, the reduction of the HtrA level in wild-type recombinant cultures of L. lactis by ATR suppression may serve as a better strategy for the production of secreted recombinant proteins.

scholarly journals SloR modulation of the Streptococcus mutans acid tolerance response involves the GcrR response regulator as an essential intermediary

Microbiology ◽  
2008 ◽  
Vol 154 (4) ◽  
pp. 1132-1143 ◽  
Author(s):  
Daniel W. Dunning ◽  
Lathan W. McCall ◽  
William F. Powell ◽  
W. Tristram Arscott ◽  
Erin M. McConocha ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Response Regulator ◽  
Acid Tolerance ◽  
Acid Tolerance Response ◽  
Tolerance Response
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