Unknown,Transcriptomics,Genomics,Proteomics

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Streptococcus mutans UA159; 10 mM Glucose Versus 100 mM Glucose

ABSTRACT: Transcriptional Profiling of Streptococcus mutans UA159 Grown in Continuous Culture using TV Media Supplemented With 10 mM vs 100 mM Glucose. The genetic and phenotypic responses of Streptococcus mutans, an organism known to be strongly associated with the development of dental caries, to changes in carbohydrate availability were investigated. S. mutans UA159 or a derivative of UA159 lacking ManL, which is the EIIAB component (EIIABMan) of a mannose/glucose permease of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) and a dominant effector of catabolite repression, were grown in continuous culture to steady-state in conditions of excess (100 mM) or limiting (10 mM) glucose. Microarrays using RNA from S. mutans UA159 revealed that 174 genes were differentially expressed in response to changes in carbohydrate availability (P < 0.001). Glucose-limited cells possessed higher PTS activity, could acidify the environment more rapidly and to a greater extent, and produced more ManL protein than cultures grown with excess glucose. Loss of ManL adversely affected carbohydrate transport and acid tolerance. Comp arison of the HPr protein in S. mutans UA159 and the manL deletion strain indicated that the differences in behaviors of the strains were not due to major differences in HPr pools or HPr phosphorylation status. Therefore, carbohydrate availability alone can dramatically influence the expression of physiologic and biochemical pathways that contribute directly to the virulence of S. mutans, and ManL has a profound influence on this behavior. Two-condition experiment, growth in 10 mM vs 100 mM glucose. Biological replicates: 3 per condition, independently grown and harvested. One replicate per array

ORGANISM(S): Streptococcus mutans UA159

SUBMITTER: Zachary Moye

PROVIDER: E-GEOD-51362 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:CcpA is a global regulator of transcription in Gram-positive bacteria that controls gene expression in response to carbohydrate availability. Using the fructan hydrolase (fruA) gene of S. mutans as a model, we demonstrate that CcpA does indeed play a major role in carbohydrate catabolite repression. Using DNA microarrays, the expression of at least 170 genes differed in CcpA-deficient cells compared to the parental strains when cells are grown in the presence of glucose, but only 90 genes showed altered expression when cells were cultivated in the poorly-repressing substrate galactose. Interestingly, 90 genes were differently expressed in wild-type S. mutans in response to cultivation in glucose versus galactose, but the expression of over 500 genes was altered when growth in glucose and galactose were compared in the CcpA-deficient strain. The results support a major role for CcpA in regulation of gene expression, but reveal that a substantial CcpA-independent network exists in S. mutans to regulate gene expression in response to carbohydrate source. A reference RNA that had been isolated from 2 liters of UA159 cells grown in BHI broth to OD600 = 0.5 was used in every experiment. Our experimental conditions consisted of S. mutans UA159 and TW1 grown in TV supplemented with 0.5% glucose or 0.5% galactose and collected at the mid-exponential phase of growth (OD600 = 0.5). All RNAs were purified as described above and used to generate cDNA according to the protocol provided by TIGR with the following minor modifications. The amount of RNA in each reaction was increased to 10 ug and the molar ratio of dTTP:aa-dUTP was increased to 1:2. SuperscriptIII Reverse transcriptase (Invitrogen, Gaithersburg, MD) was used to increase cDNA yields. Purified cDNAs were coupled with indocarbocyanine (Cy3)-dUTP, while reference cDNA was coupled with indodicarbocyanine (Cy5)-dUTP (Amersham Biosciences, Piscataway, NJ). Four individual Cy3-labeled cDNA samples originating from four different cultures of UA159 or TW1, grown in each experimental condition, were hybridized to the arrays along with Cy5-labeled reference cDNA, generating a total of 16 slides. Hybridizations were carried out in a Maui 4-chamber hybridization system (BioMicro Systems, Salt Lake City, Utah) for 17 h at 42ºC. The slides were then washed according to TIGR protocols and scanned using a GenePix Scanner (Axon Instruments Inc., Union City, CA). After the slides were scanned, single-channel images were loaded into TIGR Spotfinder software and overlayed. A spot grid was created according to TIGR specifications and manually adjusted to fit all spots within the grid, then the intensity values of each spot were measured. Data was normalized using TIGR Microarray data analysis software (MIDAS), by using LOWESS and Iterative Log Mean Centering with default settings, followed by In-Slide Replicate Analysis. Statistical analysis was carried out using BRB Array Tools with a cutoff P value of 0.001 for class prediction and class comparison.

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Streptococcus mutans UA159; 10 mM Glucose Versus 100 mM Glucose

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