Project description:Streptococcus pneumoniae is opportunistic bacteria cause’s acute otitis media (AOM) in children. It colonizes the nasopharynx in the form of biofilms, and these biofilms act as reservoir, and are vital for pneumococcal infections. The pneumococcal biofilms are regulated by LuxS/AI-2 media quorum sensing. In this study, we confirmed the role of LuxS/AI-2 for in vitro formation of biofilms, assessed the effects of the absence of LuxS/AI-2 signaling, for pneumococcal middle ear infection and identified global genes regulated by LuxS/AI-2 during formation of pneumococcal biofilms. In the cDNA-microarray analysis, 117 genes were differentially expressed in D39 luxS mutant when compared with D39 wild type. Among the 66 genes encoding putative proteins and previously characterized proteins, 60 were significantly down-regulated and 6 were significantly up-regulated. The functional annotation revealed that genes involve in DNA replication and repair, ATP synthesis, capsule biosynthesis, cell division and cell cycle, signal transduction, transcription regulation, competence, virulence, and carbohydrate metabolism were down-regulated in the absence of LuxS/AI-2.
Project description:In a transcriptome based trail, we figured out that the deletion of luxS has a massive influence to cell growth and metabolism of Streptococcus sanguinis SK36. The biofilm defective luxS deletion mutant was comlemented by transgenic sahH from Pseudomonas aeruginosa. Thus 209 of 216 influenced genes of the luxS mutant compared to the isogenic wildype were restored in their expression (fold change of n M-bM-^IM-% 3; p M-bM-^IM-$ 0.05), including genes involved in cell division processes, stress response and catabolite control. Phenotypically, the reduced biofilm depth of S. sanguinis SR DELTAluxS was elevated to wild type level by the complementation with sahH. Neither the addition of physiological concentrated artificial autoinducer 2 (AI-2) to the culture of S. sanguinis SR DELTAluxS nor the presence of the wild type strain in a trans-well assay had a cumulative effect on biofilm thickness of the luxS mutant. Furthermore, we identified 9 genes in the sahH complemented luxS mutant, which were regulated directly by AI-2 (fold change M-bM-^IM-% 3; p M-bM-^IM-$ 0.05), amongst them genes involved in competence development. So we concluded that AI-2 has no influence on biofilm growth, but regulative functions in competence development in S. sanguinis. Further, we figured out the suitability of transgenic sahH for the complementation of the interrupted Pfs/LuxS pathway without restoration of AI-2 release acquiring an essential tool for further investigations on AI-2. Aim: Is the presence of AI-2 necessary for the biofilm formation of S. sanguinis SK36? What is the impact of a deletion of luxS, is a disrupted activated methionine cycle the reason for the hampered biofilm depth causes by its inactivation? Materials and Methods: S. sanguinis SK36, S. sanguinis SR M-NM-^TluxS, and S. sanguinis SR M-NM-^TluxS/sahH were grown in CDM/sucrose for 24 h anaerobically; biofilm depth was measured by safranine and crystal violet stain. Biofilm morphology was investigated by scanning electron microscopy. The AI-2 release was monitored hourly to identify the time period of its release. For transcriptome analysis total RNA was isolated after 8 hours of growth and used for microarray analysis. The chip study used total RNA recovered from S. sanguinis SK36, its luxS mutant, and the sahH complementated luxS mutant. Gene expression analysis was done with three independent replicates, each. Chip content: 10186 genes (1883 genes of P. gingivalis W83, 1964 genes of F. nucleatum DSMZ 25586, 2244 genes of S. sanguinis SK36, 2168 genes of A. actinomycetemcomitans HK1651, 1927 genes of S. mutans UA159) with up to thirteen 60-mer probes per gene, with three-fold technical redundancy and additionally 3510 random sequence probe. In this study only the S. sanguinis and RANDOM probes were used for analysis.
Project description:Autoinducer-2 (AI-2)-mediated quorum sensing has been extensively studied in relation to the regulation of microbial behaviour. There are however two potential roles for the AI-2 synthase (LuxS). The first is in the production of AI-2 and the second is as an enzyme in the activated methyl cycle where it catalyses the conversion of S-ribosylhomocysteine to homocysteine. The by-product of the reaction catalysed by LuxS is (S)-4,5-dihydroxy-2,3-pentanedione (DPD), which spontaneously forms the furanones known collectively as AI-2. The mammalian gastrointestinal tract contains a complex collection of bacterial species so a method of interspecies communication might influence community structure and function. Lactobacillus reuteri 100-23 is an autochthonous inhabitant of the rodent forestomach where it adheres to the non-secretory epithelium of the forestomach forming a biofilm. Microarray comparisons of gene expression profiles of the L. reuteri 100-23 wild type and a luxS mutant under different culture conditions revealed altered transcription of genes encoding proteins involved in cysteine biosynthesis, the oxidative stress response and cell wall proteins. Metabolomic analysis revealed that the luxS mutation affected cellular levels of fermentation products, fatty acids and amino acids. Cell density-dependent changes (log phase versus stationary phase growth) in gene transcription were not detected. Overall, the results indicated that AI-2 was unlikely to be involved in gene regulation in L. reuteri 100-23 in a classical quorum-sensing type manner.
Project description:In a transcriptome based trail, we figured out that the deletion of luxS has a massive influence to cell growth and metabolism of Streptococcus sanguinis SK36. The biofilm defective luxS deletion mutant was comlemented by transgenic sahH from Pseudomonas aeruginosa. Thus 209 of 216 influenced genes of the luxS mutant compared to the isogenic wildype were restored in their expression (fold change of n ≥ 3; p ≤ 0.05), including genes involved in cell division processes, stress response and catabolite control. Phenotypically, the reduced biofilm depth of S. sanguinis SR DELTAluxS was elevated to wild type level by the complementation with sahH. Neither the addition of physiological concentrated artificial autoinducer 2 (AI-2) to the culture of S. sanguinis SR DELTAluxS nor the presence of the wild type strain in a trans-well assay had a cumulative effect on biofilm thickness of the luxS mutant. Furthermore, we identified 9 genes in the sahH complemented luxS mutant, which were regulated directly by AI-2 (fold change ≥ 3; p ≤ 0.05), amongst them genes involved in competence development. So we concluded that AI-2 has no influence on biofilm growth, but regulative functions in competence development in S. sanguinis. Further, we figured out the suitability of transgenic sahH for the complementation of the interrupted Pfs/LuxS pathway without restoration of AI-2 release acquiring an essential tool for further investigations on AI-2. Aim: Is the presence of AI-2 necessary for the biofilm formation of S. sanguinis SK36? What is the impact of a deletion of luxS, is a disrupted activated methionine cycle the reason for the hampered biofilm depth causes by its inactivation? Materials and Methods: S. sanguinis SK36, S. sanguinis SR ΔluxS, and S. sanguinis SR ΔluxS/sahH were grown in CDM/sucrose for 24 h anaerobically; biofilm depth was measured by safranine and crystal violet stain. Biofilm morphology was investigated by scanning electron microscopy. The AI-2 release was monitored hourly to identify the time period of its release. For transcriptome analysis total RNA was isolated after 8 hours of growth and used for microarray analysis.
Project description:Autoinducer-2 (AI-2)-mediated quorum sensing has been extensively studied in relation to the regulation of microbial behaviour. There are however two potential roles for the AI-2 synthase (LuxS). The first is in the production of AI-2 and the second is as an enzyme in the activated methyl cycle where it catalyses the conversion of S-ribosylhomocysteine to homocysteine. The by-product of the reaction catalysed by LuxS is (S)-4,5-dihydroxy-2,3-pentanedione (DPD), which spontaneously forms the furanones known collectively as AI-2. The mammalian gastrointestinal tract contains a complex collection of bacterial species so a method of interspecies communication might influence community structure and function. Lactobacillus reuteri 100-23 is an autochthonous inhabitant of the rodent forestomach where it adheres to the non-secretory epithelium of the forestomach forming a biofilm. Microarray comparisons of gene expression profiles of the L. reuteri 100-23 wild type and a luxS mutant under different culture conditions revealed altered transcription of genes encoding proteins involved in cysteine biosynthesis, the oxidative stress response and cell wall proteins. Metabolomic analysis revealed that the luxS mutation affected cellular levels of fermentation products, fatty acids and amino acids. Cell density-dependent changes (log phase versus stationary phase growth) in gene transcription were not detected. Overall, the results indicated that AI-2 was unlikely to be involved in gene regulation in L. reuteri 100-23 in a classical quorum-sensing type manner. Analysis of the microarray data was obtained from two or more independent biological replicates.
Project description:Using a Vibrio harveyi reporter strain, we demonstrated that Listeria monocytogenes secretes a functional autoinducer 2 (AI-2)-like signal. A luxS-deficient mutant produced a denser biofilm and attached to a glass surface 19-fold better than the parent strain. Exogenous AI-2 failed to restore the wild-type phenotype to the mutant. It seems that an intact luxS gene is associated with repression of components required for attachment and biofilm formation.
Project description:The bacterial quorum-sensing autoinducer 2 (AI-2) has received intense interest because the gene for its synthase, luxS, is common among a large number of bacterial species. We have identified luxS-controlled genes in Escherichia coli under two different growth conditions using DNA microarrays. Twenty-three genes were affected by luxS deletion in the presence of glucose, and 63 genes were influenced by luxS deletion in the absence of glucose. Minimal overlap among these gene sets suggests the role of luxS is condition dependent. Under the latter condition, the metE gene, the lsrACDBFG operon, and the flanking genes of the lsr operon (lsrR, lsrK, tam, and yneE) were among the most significantly induced genes by luxS. The E. coli lsr operon includes an additional gene, tam, encoding an S-adenosyl-l-methionine-dependent methyltransferase. Also, lsrR and lsrK belong to the same operon, lsrRK, which is positively regulated by the cyclic AMP receptor protein and negatively regulated by LsrR. lsrK is additionally transcribed by a promoter between lsrR and lsrK. Deletion of luxS was also shown to affect genes involved in methionine biosynthesis, methyl transfer reactions, iron uptake, and utilization of carbon. It was surprising, however, that so few genes were affected by luxS deletion in this E. coli K-12 strain under these conditions. Most of the highly induced genes are related to AI-2 production and transport. These data are consistent with the function of LuxS as an important metabolic enzyme but appear not to support the role of AI-2 as a true signal molecule for E. coli W3110 under the investigated conditions. Keywords: Genetic modification
Project description:The bacterial quorum-sensing autoinducer 2 (AI-2) has received intense interest because the gene for its synthase, luxS, is common among a large number of bacterial species. We have identified luxS-controlled genes in Escherichia coli under two different growth conditions using DNA microarrays. Twenty-three genes were affected by luxS deletion in the presence of glucose, and 63 genes were influenced by luxS deletion in the absence of glucose. Minimal overlap among these gene sets suggests the role of luxS is condition dependent. Under the latter condition, the metE gene, the lsrACDBFG operon, and the flanking genes of the lsr operon (lsrR, lsrK, tam, and yneE) were among the most significantly induced genes by luxS. The E. coli lsr operon includes an additional gene, tam, encoding an S-adenosyl-l-methionine-dependent methyltransferase. Also, lsrR and lsrK belong to the same operon, lsrRK, which is positively regulated by the cyclic AMP receptor protein and negatively regulated by LsrR. lsrK is additionally transcribed by a promoter between lsrR and lsrK. Deletion of luxS was also shown to affect genes involved in methionine biosynthesis, methyl transfer reactions, iron uptake, and utilization of carbon. It was surprising, however, that so few genes were affected by luxS deletion in this E. coli K-12 strain under these conditions. Most of the highly induced genes are related to AI-2 production and transport. These data are consistent with the function of LuxS as an important metabolic enzyme but appear not to support the role of AI-2 as a true signal molecule for E. coli W3110 under the investigated conditions. Keywords: Genetic modification
Project description:Transcriptional profiling of E.coli SE15 comparing wild type E.coli SE15 with Autoindecur 2 synthesis gene LuxS mutnat E.coli SE15. E.coli SE15 is isolated from indwelling catheter of urinary tract infected patient. Examine change of quorum sensing related gene by deleting autoinducer 2 synthesis gene LuxS in E.coli
Project description:To investigate the gene transcription profiles of Streptococcus suis in the planktonic state and biofilm state, we provided samples cultured for 8 h in the planktonic state and samples cultured for 24 h in vitro biofilm. We then performed gene expression profiling analysis using data obtained from RNA-seq of 2 different samples at two time points.