Gene expressions with nisin A or nukacin ISK-1 treatment of nsrRS deletion mutant or lcrRS deletion mutant in Streptococcus mutans UA159
ABSTRACT: The two-component system (TCS) is a specific regulatory system in bacteria and plays an important role in sensing and adapting to the environment. In this study, we evaluated the roles of TCSs in the major cariogenic pathogen Streptococcus mutans in resistance to several types of bacteriocin. In a comprehensive analysis using individual TCS mutants, we found that two novel TCSs were associated with resistance against distinct lantibiotics nisin A (class I type A[I]) and nukacin ISK-1(class I type A[II]). One TCS, SMU.659-660 (designated as NsrRS), was related to resistance against nisin A produced by Lactococcus lactis ATCC 11454. The other TCS, SMU.1146-1145 (designated as LcrRS), was related to resistance against nukacin ISK-1 produced by Staphylococcus warneri ISK-1. NsrRS induced the expression of SMU.658 (designated as NsrX), which constitutes an operon with nsrRS, in response to nisin A. Inactivation of nsrX increased susceptibility to nisin A. Additionally, NsrX expression in S. mutans increased the binding affinity to nisin A compared to a no-expression strain. LcrRS induced the expression of SMU.1148-50 (lctFEG), which encodes an ABC transporter and is located upstream of lcrRS, in response to nukacin ISK-1. Inactivation of lctFEG significantly increased susceptibility to nukacin ISK-1. Electrophoretic mobility shift assay analysis revealed that NsrR and LcrR bound directly to regions upstream of nsrX and lctFEG, respectively. This is the first report that two distinct TCSs, NsrRS and LcrRS, are independently involved in resistance to nisin A and nukacin ISK-1 in S. mutans. Total of 14 samples were analyzed. Total RNA from each test strain and control described below were labeled with Alexa Fluor® 555 and Alexa Fluor® 647, respectively, and were cohybridized on a single array. Labeling and hybridization were performed once or twice independently. UA159 wild type as control vs. UA159 with nisinA or nukacin ISK-1, UA159 wild type with nisinA or nukacin ISK-1 vs. nsrRS or lcrRS deletion mutant in UA159 with nisinA or nukacin ISK-1.
Project description:Streptococcus mutans is a bacterial cause of dental caries that is resistant to bacitracin. This study aimed to elucidate the mbrABCD-related bacitracin resistance mechanism of S. mutans. Transcriptome data demonstrated that 33 genes were induced more than 2 times in expression by bacitracin. Fourteen genes were selected from the upregulated genes and each defective mutants were constructed for measurement of their sensitivity to bacitracin. Among the mutants, only the mbrA- or mbrB-deficient mutants exhibited 100 to 121-fold greater sensitivity to bacitracin when compared with the wild-type strain. Moreover, knockout of the mbrC and mbrD genes abolished the bacitracin-induced mbrAB upregulation. These results suggest that bacitracin upregulates mbrAB transcription via mbrCD, which confers the bacitracin resistant phenotype on S. mutans. Single experiment data using Streptcoccus mutans wild-type strain UA159, a comparison of transcriptome between control sample and experimental (bacitracin-treated) one.
Project description:Nucleotide signaling pathways are found in all kingdoms of life and are utilized to coordinate a rapid response to changes in the environment. One more recently discovered signaling nucleotide is the secondary messenger cyclic diadenosine monophosphate (c-di-AMP), which is widely distributed among bacteria and is also found in several archaea. This cyclic nucleotide has been shown to involve in several important cellular processes, including maintenance of DNA integrity, cell wall metabolism, stress tolerance, transcription regulation and virulence. However, the mechanisms by which c-di-AMP modulates these physiological changes have remained largely unknown.In the present study, we identified and characterized a c-di-AMP synthase (CdaA) in S. mutans UA159. Furthermore, we investigated the role of CdaA in S. mutans cell physiology and global gene expression by utilizing cdaA gene in-frame deletion mutant. Our findings suggest that CdaA is an important global modulator of optimal growth and environmental adaption in this pathogen. Streptococcus mutans UA159 whole-genome arrays (8 x 15 K) were obtained from Agilent and included 1998 probes for S. mutans transcripts. For microarray analysis, S. mutans UA159 and S. mutans ΔcdaA cells were routinely grown at 37°C anaerobically (90% N2, 5% CO2, 5% H2) in brain heart infusion broth (BHI; Difco, Sparks, MD, USA) to an optical density at 600 nm (OD600) of 0.5. Four RNA samples isolated from four independent cultures of UA159 and cdaA mutant strains were hybridized to the arrays and analyzed.
Project description:Transcriptional analysis of glucose shock vs. steady-state growth in the parent strain and an acid sensitive mutant strain of S. mutans RNA was extracted from 4 replicate samples of S. mutans UA159 and UR117 (fabM mutant strain) grown in continuous culture to a steady-state pH value of 7. The cultures were exposed to a glucose shock (200mM) and samples were collected upon achieving culture pH value of 5.5. pH control was re-established and cultures were allowed to grow to a steady-state pH value of 5 (for UA159) and 5.5 (for fabM mutant). RNA was labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from S. mutans UA159 cultures grown to mid-log.
Project description:Transcriptional analysis of the effects of oxygen concentraion in S. mutans RNA was extracted from 3 or 4 replicate samples of S. mutans UA159, UA159 grown in 8.4 % oxygen concentration and MU1020 (∆nox) grown in continuous culture to steady-state pH values of 7. RNA was labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from S. mutans UA159 cultures grown to mid-log.
Project description:Transcriptional analysis of the effects of sugar source in S. mutans RNA was extracted from 4 replicate samples of S. mutans UA159, UA159 grown in glucose or maltose in continuous culture to steady-state pH values of 7 or 5. RNA was labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from S. mutans UA159 cultures grown to mid-log.
Project description:Transcriptional analysis of the effects of oxygen concentraion in S. mutans RNA was extracted from 3 or 4 replicate samples of S. mutans UA159, UA159 grown in 8.4 % oxygen concentration and MU1020 (∆nox) grown in continuous culture to steady-state pH values of 5. RNA was labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from S. mutans UA159 cultures grown to mid-log.
Project description: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
Project description:Transcriptional analysis of the regulator FabT in S. mutans RNA was extracted from 4 replicate samples of S. mutans UA159 and MU1591 (∆fabT) grown in continuous culture to steady-state pH values of 7 and 5. RNA was labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from S. mutans UA159 cultures grown to mid-log.
Project description:Global transcriptional analysis of acid-inducible genes in Streptococcus mutans: multiple two-component systems involved in acid adaptation pH is a major environmental factor that regulates gene expression in many bacteria. Streptococcus mutans in dental biofilms is regularly exposed to cycles of acidic pH during the ingestion of fermentable dietary carbohydrates. The ability of S. mutans to tolerate low pH is crucial for its virulence and the pathogenesis in dental caries. To better understand its acid tolerance mechanisms, we used DNA microarray to perform genome-wide transcriptional analysis of S. mutans in response to acidic pH. The results showed that adaptation of S. mutans to pH 5.5 for 2 hrs induced differential expression of nearly 14% of genes in the genome, including 169 up-regulated genes and 108 down-regulated genes, largely categorized into six groups. Especially, we found that the genes encoding multiple two-component systems, including CiaHR, LevSR, LiaSR, ScnKR, HK/RR07 and ComDE, were up-regulated during acid adaptation. These findings were further confirmed by real time qRT-PCR and phenotypic assays of the gene deletion mutants. The results support that the multiple two-component systems are required for S. mutans to orchestrate its signal transduction networks for optimal adaptation to acidic pH. Total RNAs were isolated from S. mutans UA159 cells (0.6 at OD600) grown in a TYG broth (3% tryptone, 0.3% yeast extract and 20 mM glucose) at either pH 5.5 or pH 7.5. The RNAs were treated with RNase-free DNase 1 and purified by Qiagen RNeasy mini columns. The purified RNAs were used to generate cDNA probes by an indirect labeling method based on the protocol from TIGR. The cDNAs were coupled with AlexaFluor 555 or AlexaFluor 647 (Invitrogen). The labeled cDNA probes from three different cultures of UA159 were hybridized to the S. mutans microarray slides obtained from PFGRC (http://pfgrc.tigr.org). Array hybridization was conducted using a protocol from the PFGRC with minor modification. After hybridization, washes and dried, the array slides were scanned by ScanArray 5000XL Reader (Perkin Elmer, Boston, MA). After the array slides were scanned, the resulting images were loaded into TIGR Spotfinder software (http://www.tigr.org/software/) and overlaid. A spot grid was created according to TIGR specifications and manually adjusted to fit all spots within the grid, and the intensity values of each spot were determined. Signal intensities of individual channels from an array slide were averaged and normalized using an array data analysis software (MIDAS) by using LOWESS and iterative log mean centering with default settings, followed by in-slide replicate analysis. A t-test was used to determine the consistency of ratios across replicate hybridizations. Only genes whose ratios were ≥ 2-fold changes (either increase or decrease) with 99% confidence interval (P ≤ 0.01) were considered statistically significant.
Project description:Oral streptococci metabolize carbohydrate to produce organic acids, not only decrease the environmental pH, but also increase osmolality of dental plaque fluid due to tooth demineralization and consequent calcium and phosphate accumulation. Thus, to persevere in the dental plaque, acidogenic bacteria should evolve sophisticated molecular machineries to counter the detrimental effect of elevated osmolality. This study was aimed to obtain a global view on strategies taken by streptococcus mutans to deal with physiologically relevant elevated osmolality, and preserves within a cariogenic dental plaque. We investigated phenotypic change of S. mutans biofilm upon sub-lethal level of hyperosmotic challenge. We found that hyperosmotic condition was able to initiate S. mutans biofilm dispersal by reducing both microbial content and extracellular polysaccharides matrix. We then used DNA microarray with qPCR validation to systemically investigate the underlying molecular machinery of this bacteria in response to hyperosmotic stimuli. Among those identified 50 differentially regulated genes, down-regulation of gtfB and comC were believed to be responsible for the observed biofilm dispersal. Further analysis of microarray data showed significant up-regulation of genes and pathways involved in carbohydrates metabolism. Specific genes involved in heat shock response and acid tolerance were also upregulated, indicating potential cross-talk between hyperosmotic and other environmental stress. Based on the data obtained in this study, we believe that although hyperosmotic condition may induce significant stress response on S. mutans, this cariogenic bacterium has evolved sophisticated molecular machineries to counter those elicited detrimental effects. In the meantime, it will take full advantage of these environmental stimuli to better fit the fluctuating environments within oral cavity, and thus emerge as numeric-predominant bacteria under cariogenic conditions. A six-chip study using total RNA recovered from mid-logarithmic phase of S. mutans UA159 from three separate cultures of strains submitted for 15 minutes to hyperosmotic stimuli (0.4M NaCl) and three separate cultures of strains kept under no stress condition.