Document Detail

Role of GlnR in acid-mediated repression of genes encoding proteins involved in glutamine and glutamate metabolism in Streptococcus mutans.
MedLine Citation:
PMID:  20173059     Owner:  NLM     Status:  MEDLINE    
The acid tolerance response (ATR) is one of the major virulence traits of Streptococcus mutans. In this study, the role of GlnR in acid-mediated gene repression that affects the adaptive ATR in S. mutans was investigated. Using a whole-genome microarray and in silico analyses, we demonstrated that GlnR and the GlnR box (ATGTNAN(7)TNACAT) were involved in the transcriptional repression of clusters of genes encoding proteins involved in glutamine and glutamate metabolism under acidic challenge. Reverse transcription-PCR (RT-PCR) analysis revealed that the coordinated regulation of the GlnR regulon occurred 5 min after acid treatment and that prolonged acid exposure (30 min) resulted in further reduction in expression. A lower level but consistent reduction in response to acidic pH was also observed in chemostat-grown cells, confirming the negative regulation of GlnR. The repression by GlnR through the GlnR box in response to acidic pH was further confirmed in the citBZC operon, containing genes encoding the first three enzymes in the glutamine/glutamate biosynthesis pathway. The survival rate of the GlnR-deficient mutant at pH 2.8 was more than 10-fold lower than that in the wild-type strain 45 min after acid treatment, suggesting that the GlnR regulon participates in S. mutans ATR. It is hypothesized that downregulation of the synthesis of the amino acid precursors in response to acid challenge would promote citrate metabolism to pyruvate, with the consumption of H(+) and potential ATP synthesis. Such regulation will ensure an optimal acid adaption in S. mutans.
Pei-Min Chen; Yi-Ywan M Chen; Sung-Liang Yu; Singh Sher; Chern-Hsiung Lai; Jean-San Chia
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-02-19
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  76     ISSN:  1098-5336     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-04-05     Completed Date:  2010-06-15     Revised Date:  2013-05-30    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2478-86     Citation Subset:  IM    
Department of Microbiology and Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No. 1 Jen Ai Road Section 1, Taipei, Taiwan 10051.
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MeSH Terms
Acids / metabolism*
Adenosine Triphosphate / biosynthesis
Anti-Bacterial Agents / metabolism
Bacterial Proteins / genetics,  physiology*
Citric Acid / metabolism
Gene Deletion
Gene Expression Regulation, Bacterial*
Genes, Bacterial
Glutamic Acid / metabolism*
Glutamine / metabolism*
Hydrogen / metabolism
Metabolic Networks and Pathways / genetics
Microbial Viability / drug effects
Multigene Family
Oligonucleotide Array Sequence Analysis
Pyruvic Acid / metabolism
Repressor Proteins / genetics,  physiology*
Reverse Transcriptase Polymerase Chain Reaction
Streptococcus mutans / drug effects,  physiology*
Reg. No./Substance:
0/Acids; 0/Anti-Bacterial Agents; 0/Bacterial Proteins; 0/Repressor Proteins; 127-17-3/Pyruvic Acid; 1333-74-0/Hydrogen; 56-65-5/Adenosine Triphosphate; 56-85-9/Glutamine; 56-86-0/Glutamic Acid; 77-92-9/Citric Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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