CovR-regulated genes in Streptococcus mutans strain UA159
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ABSTRACT: The goal of the study was to identify subsets of the genes, which are up-regulated and down-regulated by CovR regulator in UA159 strain. Two independently isolated RNA samples from each of the wild-type UA159 strain and its covR mutant strain grown until mid-exponential phase were analyzed. Each sample was hybridized with 5 blocks of NimbleGen arrays.
Project description:Expression of the extensive arsenal of virulence factors by Streptococcus pyogenes are controlled by many regulators, of which covR/S is one of the best characterized and can influence ~15% of the genome. Animal models have established that mutants of CovR/S arise spontaneously in vivo resulting in highly invasive organisms. We analyzed a pharyngeal and a blood isolate of S. pyogenes recovered from the same individual 13 days apart. The two isolates varied in many phenotypic properties including speB production, which were reflected in transcriptome analyses. Pulsed field gel electrophoresis, multilocus sequence typing, and partial sequencing of some key genes failed to show any differences except for an 11-base insert in the covS gene in the blood isolate. These results showing that pharyngeal and blood isolates from a single individual which differ by a simple insertion, provide evidence for the model that regulatory gene mutations allow S. pyogenes to invade different niches in the body. A chip study using total RNA recovered from two separate wild-type cultures of group A Streptococcus, Streptococcus pyogenes UH322 and UH328. Each chip measures the expression level of 1865 genes replicated twice from 7 fully sequenced strains of Streptococcus pyogenes (M1_GAS NC_002737; MGAS10394 NC_006086; MGAS315 NC_004070; MGAS5005 NC_007297; MGAS6180 NC_007296; MGAS8232 NC_003485; SSI-1 NC_004606 with fourteen 24-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.
Project description:Genome-scale models represent the link between an organism's genetic information and experimentally observable biological phenotypes. They facilitate metabolic engineering and the discovery of network properties such as the identification of novel drug targets. Most commonly, metabolite consumption data is used to limit the solution space, sometimes in combination with gene expression data. However, information about gene expression only poorly correlates with the abundance of the respective proteins within the cell. As such, we developed a method to map and integrate the whole-cell proteome into genome-scale models on the example of lactic acid bacteria (LAB). To the best of our knowledge, this work represents the first effort to integrate proteome data into genome-scale models on such a scale .
Project description:Genome-scale models represent the link between an organism's genetic information and experimentally observable biological phenotypes. They facilitate metabolic engineering and the discovery of network properties such as the identification of novel drug targets. Most commonly, metabolite consumption data is used to limit the solution space, sometimes in combination with gene expression data. However, information about gene expression only poorly correlates with the abundance of the respective proteins within the cell. As such, we developed a method to map and integrate the whole-cell proteome into genome-scale models on the example of lactic acid bacteria (LAB). To the best of our knowledge, this work represents the first effort to integrate proteome data into genome-scale models on such a scale.
Project description:The CiaRH and LiaFSR two-component regulatory systems in Streptococcus agalactiae (Group B Streptococcus, GBS) are essential mediators of the organism s response to biologically important sources of environmental stress, and positive regulators of GBS virulence. Transcriptional profiling of CiaR mutant GBS and LiaR mutant GBS reveals that LiaR is positively-regulated by CiaR, and the individual mutant transcriptomes share a number of commonly-regulated genes. To determine the GBS response to loss of both of these key regulatory systems, we constructed a GBS mutant strain with non-polar deletions in both ciaR and liaR, and performed transcriptional profiling using DNA microarray analysis, comparing wild-type GBS to CiaR/LiaR double mutant GBS under non-stressed conditions. Two separate RNA samples were extracted for each condition. One flip-dye replicate (2 hybridizations) was obtained for each pair of RNA samples for 4 hybridizations total.
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of early-onset neonatal bacterial infection. Evasion of innate immune defenses is critical to neonatal GBS disease pathogenesis. Effectors of the innate immune system such as antimicrobial peptides, as well as numerous antibiotics, target the peptidoglycan layer of the gram positive bacterial cell wall. The intramembrane-sensing histidine kinase class of two-component regulatory systems has recently been identified as important to the gram-positive response to cell wall stress. We identified and characterized the GBS homolog of LiaR, the response regulator component of the LiaFSR system and constructed site-directed, non-polar deletion mutations in the regulator gene liaR. GBS LiaR deletion mutant strains are more susceptible to cell wall active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (colistin, nisin and the human cathelicidin LL-37) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and GBS pneumonia. To determine the genes regulated by LiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to LiaR mutant GBS under non-stressed conditions. Two separate RNA samples were extracted for each condition. One flip-dye replicate (2 hybridizations) was obtained for each pair of RNA samples for 4 hybridizations total.
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: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:This transcriptional analysis is a follow up to a population genomic investigation of 3615 Streptococcus pyogenes serotype M1 strains whch are responsible for an epidemic of human invasive infections (www.pnas.org/cgi/doi/10.1073/pnas.1403138111), The goal was to assess gene expression differences between predecessor pre-epidemic M1 strains and their descendent epidemic M1 strains to gain insights into the underlying genetic basis for the shift in the frequency and severity of human infections caused by these pathogenic bacteria The transcriptomes of 7 GAS M1 strains, 4 pre-epidemic and 3 epidemic, were compared at two phases of growth, mid-exponential and early-stationary, using 3 biologial replicates, to identify genes differentially expressed between the pre-epidemic and epidemic isolates with the goal of to gaining insight into the underlying genetic basis for the evolutionary emergence, increased frequency and severity of the epidemic strains relative to the pre-epidemic strains
Project description:The proteome and phosphoproteome of Streptococcus pyogenes M49 was investigated at different growth phases of cultures grown in either rich medium (THY), chemically defined medium without carbon source, or chemically defined medium containing 1% fructose. Of the 815 phosphosites identified, 463 were included in a label-free quantitative analysis of dynamic protein phosphorylation. A small group of phosphorylation events, almost exclusively at threonine residues, was strongest during growth and decreased during stationary phase. These included phosphorylation sites of the PASTA kinase SP-STK and its putative substrates suggesting that the PASTA kinase-dependent processes regulating the cell cycle in related bacteria are also conserved in S. pyogenes. Most phosphorylation events occurred preferentially at serine residues in the stationary growth phase and under starvation conditions. The elucidation of the physiological significance and the responsible kinases of these phosphorylations require further investigations. In addition to phosphorylation events at S/T/Y residues, phosphoglycerylation of lysine (PGK) occurred frequently among the enriched phosphopeptides.
Project description:S. pyogenes strains were compared with the intact covRS form of the globally disseminated M1T1 clone to track transcriptomic changes engendered during the emergence of the M1T1 clone. The mutant covRS form of the M1T1 clone was included as a transcriptomic outlier and to provide a context for the magnitude of transcriptional shifts detected within the isolate set examined. Microarray was performed on RNA extracted from mid-logarithmic phase S. pyogenes grown in Todd-Hewitt with 1% yeast extract in vitro. Experiments were performed using a single color method. Each sample was labelled with Cy3 and hybridized to separate arrays. Each strain was analysed in 3 biological replicates. cDNA hybridized to JCVI PFGRC Streptococcus pyogenes v2 oligo arrays. Only probed representing the core M1 genome were used for analysis.