Unknown,Transcriptomics,Genomics,Proteomics

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Identification of a Novel Bacteriocin Regulatory System in Streptococcus mutans

ABSTRACT: Recently, we described the function of a novel two-gene regulatory system consisting of a LytTR family transcription regulator and a membrane protein, which we referred to as the hdrRM operon. We determined that the HdrRM system controls the expression of another similar regulatory system annotated as SMU.2080 and SMU.2081. Like hdrRM, the SMU.2080 – 2081 operon encodes a LytTR family transcription regulator and membrane protein, which we now refer to as BrsR and BrsM, respectively. In this study, we used microarray to examine the regulatory role of BrsR and found that it functions as a transcription activator for a variety of bacteriocins and bacteriocin-related genes. Streptococcus mutans UA140 derivatives, lacA ( genotype: ΔbrsRM /pFW5::PlacA ) and lacA2080 (genotype:ΔbrsRM /pFW5::PlacA-brsR), were cultivated overnight at 37°C in a chemically-defined medium containing 0.5% (wt/vol) glucose as carbon source . The overnight cultures were diluted 1:30 in CDM with 1% (wt/vol) lactose in a total volume of 30 ml. The cells were allowed to grow to an optical density at 600 nm of 0.3 and RNA was extracted. The transcriptional profile of the whole genome was examined with microarray.

ORGANISM(S): Streptococcus mutans

SUBMITTER: Justin Merritt

PROVIDER: E-GEOD-22902 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Subclass IIa bacteriocins have strong antilisterial activity and can control the growth of Listeria monocytogenes in food. However, L. monocytogenes may develop resistance towards such bacteriocins. In this follow-up study, the transcriptomes of a high level (L502-1) and a low level (L502-6) spontaneous sakacin P-resistant mutant strain of L. monocytogenes were compared to the wild-type (L502). The growth of the resistant strains was reduced on mannose but not affected on cellobiose and the transcriptomics was performed during growth on these sugars. The mannose phosphotransferase system (PTS) encoded by the mptACD operon (mpt) is known for transporting mannose and also act as a receptor to class IIa bacteriocins. The mpt was repressed in L502-1 and this is in accordance with abolition of the bacteriocin receptor with resistance to class IIa bacteriocins. In contrast, the mpt was induced in L502-6. Despite the induction of the mpt, L502-6 showed 1,000 times more resistance phenotype and reduced growth on mannose suggesting the mannose-PTS may not be functional in L502-6. The microarray data suggests the presence of other transcriptional responses that may be linked to the sakacin P resistance phenotype particularly in L502-6. Most of commonly regulated genes encode proteins involved in transport and energy metabolism. The resistant strains displayed shift in general carbon catabolite control possibly mediated by the mpt. Our data suggest that the resistant strains may have a reduced virulence potential. Growth sugar- and mutant-specific responses were also revealed. The two resistant strains also displayed difference in stability of the sakacin P resistance phenotype, growth in the presence of both the lytic bacteriophage P100 and activated charcoal. Taken together, the present study showed that a single time exposure to the class IIa bacteriocin sakacin P may elicit contrasting phenotypic and transcriptome responses in L. monocytogenes possibly through regulation of the mpt. Data is also available from <ahref=http://bugs.sgul.ac.uk/E-BUGS-110 target=_blank>BuG@Sbase</a>

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Identification of a Novel Bacteriocin Regulatory System in Streptococcus mutans

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