Journal article
Role of the Streptococcus mutans irvA Gene in GbpC-Independent, Dextran-Dependent Aggregation and Biofilm Formation
Applied and environmental microbiology, Vol.75(22), pp.7037-7043
11/2009
DOI: 10.1128/AEM.01015-09
PMCID: PMC2786544
PMID: 19783751
Abstract
Dextran-dependent aggregation (DDAG) of
Streptococcus mutans
is an in vitro phenomenon that is believed to represent a property of the organism that is beneficial for sucrose-dependent biofilm development. GbpC, a cell surface glucan-binding protein, is responsible for DDAG in
S. mutans
when cultured under defined stressful conditions. Recent reports have described a putative transcriptional regulator gene,
irvA
, located just upstream of
gbpC
, that is normally repressed by the product of an adjacent gene,
irvR
. When repression of
irvA
is relieved, there is a resulting increase in the expression of GbpC and decreases in competence and synthesis of the antibiotic mutacin I. This study examined the role of
irvA
in DDAG and biofilm formation by engineering strains that overexpressed
irvA
(IrvA+) on an extrachromosomal plasmid. The IrvA+ strain displayed large aggregation particles that did not require stressful growth conditions. A novel finding was that overexpression of
irvA
in a
gbpC
mutant background retained a measure of DDAG, albeit very small aggregation particles. Biofilms formed by the IrvA+ strain in the parental background possessed larger-than-normal microcolonies. In a
gbpC
mutant background, the overexpression of
irvA
reversed the fragile biofilm phenotype normally associated with loss of GbpC. Real-time PCR and Northern blot analyses found that expression of
gbpC
did not change significantly in the IrvA+ strain but expression of
spaP
, encoding the major surface adhesin P1, increased significantly. Inactivation of
spaP
eliminated the small-particle DDAG. The results suggest that IrvA promotes DDAG not only by GbpC, but also via an increase in P1.
Details
- Title: Subtitle
- Role of the Streptococcus mutans irvA Gene in GbpC-Independent, Dextran-Dependent Aggregation and Biofilm Formation
- Creators
- Min Zhu - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242Dragana Ajdić - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242Yuan Liu - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242David Lynch - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242Justin Merritt - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242Jeffrey A Banas - Dows Institute for Dental Research, Department of Pediatric Dentistry, College of Dentistry, University of Iowa, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Applied and environmental microbiology, Vol.75(22), pp.7037-7043
- DOI
- 10.1128/AEM.01015-09
- PMID
- 19783751
- PMCID
- PMC2786544
- NLM abbreviation
- Appl Environ Microbiol
- ISSN
- 0099-2240
- eISSN
- 1098-5336
- Publisher
- American Society for Microbiology (ASM)
- Language
- English
- Date published
- 11/2009
- Academic Unit
- Pediatric Dentistry; Dental Research
- Record Identifier
- 9984065809102771
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