Characterization of mleR, a positive regulator of malolactic fermentation and part of the acid tolerance response in Streptococcus mutans.

2.50
Hdl Handle:
http://hdl.handle.net/10033/97479
Title:
Characterization of mleR, a positive regulator of malolactic fermentation and part of the acid tolerance response in Streptococcus mutans.
Authors:
Lemme, André; Sztajer, Helena; Wagner-Döbler, Irene
Abstract:
BACKGROUND: One of the key virulence determinants of Streptococcus mutans, the primary etiological agent of human dental caries, is its strong acid tolerance. The acid tolerance response (ATR) of S. mutans comprises several mechanisms that are induced at low pH and allow the cells to quickly adapt to a lethal pH environment. Malolactic fermentation (MLF) converts L-malate to L-lactate and carbon dioxide and furthermore regenerates ATP, which is used to translocate protons across the membrane. Thus, MLF may contribute to the aciduricity of S. mutans but has not been associated with the ATR so far. RESULTS: Here we show that the malolactic fermentation (mle) genes are under the control of acid inducible promoters which are induced within the first 30 minutes upon acid shock in the absence of malate. Thus, MLF is part of the early acid tolerance response of S. mutans. However, acidic conditions, the presence of the regulator MleR and L-malate were required to achieve maximal expression of all genes, including mleR itself. Deletion of mleR resulted in a decreased capacity to carry out MLF and impaired survival at lethal pH in the presence of L-malate. Gel retardation assays indicated the presence of multiple binding sites for MleR. Differences in the retardation patterns occurred in the presence of L-malate, thus demonstrating its role as co-inducer for transcriptional regulation. CONCLUSION: This study shows that the MLF gene cluster is part of the early acid tolerance response in S. mutans and is induced by both low pH and L-malate.
Affiliation:
Helmholtz-Centre for Infection Research, Division of Cell Biology, Braunschweig, Germany. ale05@helmholtz-hzi.de
Citation:
Characterization of mleR, a positive regulator of malolactic fermentation and part of the acid tolerance response in Streptococcus mutans. 2010, 10:58 BMC Microbiol.
Journal:
BMC microbiology
Issue Date:
2010
URI:
http://hdl.handle.net/10033/97479
DOI:
10.1186/1471-2180-10-58
PubMed ID:
20178568
Type:
Article
Language:
en
ISSN:
1471-2180
Appears in Collections:
collections of the research group microbial communication (KOM)

Full metadata record

DC FieldValue Language
dc.contributor.authorLemme, Andréen
dc.contributor.authorSztajer, Helenaen
dc.contributor.authorWagner-Döbler, Ireneen
dc.date.accessioned2010-04-27T13:06:17Z-
dc.date.available2010-04-27T13:06:17Z-
dc.date.issued2010-
dc.identifier.citationCharacterization of mleR, a positive regulator of malolactic fermentation and part of the acid tolerance response in Streptococcus mutans. 2010, 10:58 BMC Microbiol.en
dc.identifier.issn1471-2180-
dc.identifier.pmid20178568-
dc.identifier.doi10.1186/1471-2180-10-58-
dc.identifier.urihttp://hdl.handle.net/10033/97479-
dc.description.abstractBACKGROUND: One of the key virulence determinants of Streptococcus mutans, the primary etiological agent of human dental caries, is its strong acid tolerance. The acid tolerance response (ATR) of S. mutans comprises several mechanisms that are induced at low pH and allow the cells to quickly adapt to a lethal pH environment. Malolactic fermentation (MLF) converts L-malate to L-lactate and carbon dioxide and furthermore regenerates ATP, which is used to translocate protons across the membrane. Thus, MLF may contribute to the aciduricity of S. mutans but has not been associated with the ATR so far. RESULTS: Here we show that the malolactic fermentation (mle) genes are under the control of acid inducible promoters which are induced within the first 30 minutes upon acid shock in the absence of malate. Thus, MLF is part of the early acid tolerance response of S. mutans. However, acidic conditions, the presence of the regulator MleR and L-malate were required to achieve maximal expression of all genes, including mleR itself. Deletion of mleR resulted in a decreased capacity to carry out MLF and impaired survival at lethal pH in the presence of L-malate. Gel retardation assays indicated the presence of multiple binding sites for MleR. Differences in the retardation patterns occurred in the presence of L-malate, thus demonstrating its role as co-inducer for transcriptional regulation. CONCLUSION: This study shows that the MLF gene cluster is part of the early acid tolerance response in S. mutans and is induced by both low pH and L-malate.en
dc.language.isoenen
dc.titleCharacterization of mleR, a positive regulator of malolactic fermentation and part of the acid tolerance response in Streptococcus mutans.en
dc.typeArticleen
dc.contributor.departmentHelmholtz-Centre for Infection Research, Division of Cell Biology, Braunschweig, Germany. ale05@helmholtz-hzi.deen
dc.identifier.journalBMC microbiologyen

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