This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Liu, Y.
Right arrow Articles by Burne, R. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Liu, Y.
Right arrow Articles by Burne, R. A.
Agricola
Right arrow Articles by Liu, Y.
Right arrow Articles by Burne, R. A.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, May 2009, p. 2629-2637, Vol. 75, No. 9
0099-2240/09/$08.00+0     doi:10.1128/AEM.02145-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

AguR Is Required for Induction of the Streptococcus mutans Agmatine Deiminase System by Low pH and Agmatine{triangledown}

Yaling Liu, Lin Zeng, and Robert A. Burne*

Department of Oral Biology, University of Florida, Gainesville, Florida

Received 16 September 2008/ Accepted 22 February 2009

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.

* Corresponding author. Mailing address: Department of Oral Biology, University of Florida, P.O. Box 100424, Gainesville, FL 32610-0424. Phone: (352) 392-4370. Fax: (352) 392-7357. E-mail: rburne{at}dental.ufl.edu

{triangledown} Published ahead of print on 6 March 2009.

Applied and Environmental Microbiology, May 2009, p. 2629-2637, Vol. 75, No. 9
0099-2240/09/$08.00+0     doi:10.1128/AEM.02145-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Liu, Y., Burne, R. A. (2009). Multiple Two-Component Systems of Streptococcus mutans Regulate Agmatine Deiminase Gene Expression and Stress Tolerance. J. Bacteriol. 191: 7363-7366 [Abstract] [Full Text]  
  • Liu, Y., Burne, R. A. (2009). Multiple Two-Component Systems Modulate Alkali Generation in Streptococcus gordonii in Response to Environmental Stresses. J. Bacteriol. 191: 7353-7362 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»