AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
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 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 Wilkins, J. C.
Right arrow Articles by Beighton, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wilkins, J. C.
Right arrow Articles by Beighton, D.
Agricola
Right arrow Articles by Wilkins, J. C.
Right arrow Articles by Beighton, D.
Applied and Environmental Microbiology, May 2002, p. 2382-2390, Vol. 68, No. 5
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.5.2382-2390.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Analysis of Streptococcus mutans Proteins Modulated by Culture under Acidic Conditions

Joanna C. Wilkins,* Karen A. Homer, and David Beighton

Department of Oral Microbiology, Guy's, King's and St. Thomas' Dental Institute, King's College London, London, United Kingdom

Received 16 October 2001/ Accepted 19 February 2002

Streptococcus mutans, a major etiological agent of dental caries, causes demineralization of the tooth tissue due to the formation of acids from dietary carbohydrates. Dominant among the virulence determinants of this organism are aciduricity and acidogenicity, the abilities to grow at low pH and to produce acid, respectively. The mechanisms underlying the ability of S. mutans to survive and proliferate at low pH are currently under investigation. In this study we cultured S. mutans at pH 5.2 or 7.0 and extracted soluble cellular proteins. These were analyzed using high-resolution two-dimensional gel electrophoresis, and replicate maps of proteins expressed under each of the two conditions were generated. Proteins with modulated expression at low pH, as judged by a change in the relative integrated optical density, were excised and digested with trypsin by using an in-gel protocol. Tryptic digests were analyzed using matrix-assisted laser desorption ionization mass spectrometry to generate peptide mass fingerprints, and these were used to assign putative functions according to their homology with the translated sequences in the S. mutans genomic database. Thirty individual proteins exhibited altered expression as a result of culture of S. mutans at low pH. Up-regulated proteins (n = 18) included neutral endopeptidase, phosphoglucomutase, 60-kDa chaperonin, cell division proteins, enolase, lactate dehydrogenase, fructose bisphosphate aldolase, acetoin reductase, superoxide dismutase, and lactoylglutathione lyase. Proteins down-regulated at pH 5.2 (n = 12) included protein translation elongation factors G, Tu, and Ts, DnaK, small-subunit ribosomal protein S1P, large-subunit ribosomal protein L12P, and components of both phosphoenolpyruvate:protein phosphotransferase and multiple sugar binding transport systems. The identification of proteins differentially expressed following growth at low pH provides new information regarding the mechanisms of survival and has identified new target genes for mutagenesis studies to further assess their physiological significance.

* Corresponding author. Mailing address: Department of Oral Microbiology, GKT Dental Institute, King's College London, Caldecot Rd., Denmark Hill, London SE5 9RW, United Kingdom. Phone: 44 20 7346 3272. Fax: 44 020 7346 3073. E-mail: joanna.wilkins{at}kcl.ac.uk.

Applied and Environmental Microbiology, May 2002, p. 2382-2390, Vol. 68, No. 5
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.5.2382-2390.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2002 by the American Society for Microbiology. All rights reserved.