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Microbial Quorum Sensing - lux S

microbe microbe interaction could be studied briefly

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Microbial Quorum Sensing - lux S

  1. 1. Presented by NISHANTH S 2016601106
  2. 2. What is Quorum sensing? Quorum sensing allows populations of bacteria to collectively control gene expression, and thus synchronize group behavior. Quorum sensing is a process of bacterial cell-to-cell communication involving the production and detection of extracellular signaling molecules called autoinducers.
  3. 3. Schematic model of QS-related interactions between plants and bacteria. AHL QS signals (triangles and circles) from bacteria (ovals) affect QS- regulated behaviors in the bacteria and also elicit a diversity of responses in the plant. The plant produces and secretes AHL mimic compounds (circle/square, triangle/square) that disrupt or manipulate QS- regulated behaviors in the bacteria. Plant responses to bacterial AHLs might affect the secretion of AHL mimic compounds. AHL mimics from the plant may also affect synthesis of AHLs in the bacteria
  4. 4. Production and release of signaling molecule (Autoinducer) Diffusion of AI molecule at low cell density leaving the QS circuit in-active Activation of QS circuit by AI at higher concentration due to higher cell density Transcriptional activation of down regulating genes by AI receptor complex or other activated signaling molecule Activation of virulence, biofilm formation, sporulation, competence and antibiotic production
  5. 5.  Gram-negative use acylated homoserine lactones (HSLs) as autoinducers  Grampositive bacteria use oligopeptides as autoinducers Bioluminescence Vibrio species Biofilm formation Pseudomonas aeruginosa Virulence Vibrio cholerae Antibiotic production Photorhabdus luminescences Competence Bacillus subtilis
  6. 6. Canonical quorum-sensing circuits Gram-negative bacteria LuxI-type enzymes catalyse the formation of species-specific HSLs (orange circles), which are detected by LuxR-type transcriptional regulators. Gram-positive bacteria Oligopeptides (green bars) mediate quorum sensing in Gram- positive bacteria, and two component phosphorylation cascades are used for signal transmission.
  7. 7. Canonical quorum-sensing circuits V. harveyi quorum-sensing circuit. LuxLM synthesizes AI-1 (blue diamonds) and LuxS is required for production of AI-2 (red triangles).
  8. 8. Model for quorum sensing in V. harveyi • a V. harveyi regulates light production using two parallel quorum-sensing circuits. A complex two-component signal transduction system is responsible for detection of the autoinducers and information relay to the luciferase structural operon (luxCDABEGH). H - histidine D - aspartate HTH - helix–turn–helix

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