1 / 16

Lecture 8

Lecture 8. 8.8 Attenuation 8.9 Other Global Control Networks 8.10 Signal Transduction and Two-Component Regulatory Systems 8.11 Regulation of Chemotaxis. RNA and termination. RNA: single stranded nucleic acid can form secondary structures Rho-dependent termination: protein signal

otylia
Download Presentation

Lecture 8

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 8 • 8.8 Attenuation • 8.9 Other Global Control Networks • 8.10 Signal Transduction and Two-Component Regulatory Systems • 8.11 Regulation of Chemotaxis

  2. RNA and termination • RNA: single stranded nucleic acid • can form secondary structures • Rho-dependent termination: protein signal • Rho-independent signal: hairpin or stem-loop RNA structure, followed by several uracils

  3. Tryptophan Operon Figure 8.20

  4. Tryptophan Operon: mRNA 1 2 3 4 trpE  • regions 1, 2: synthesis of leader peptide • regions 2, 3: form stem-loop structure • regions 3, 4: form stem-loop structure

  5. Attenuation Figure 8.21

  6. Figure 8.22 Bioluminescent Vibrio fischeri

  7. Vibrio bioluminescence • Vibrio fischeri inhabits the open sea (in small densities), as well as in squid light organs (in high densities) • Luminescence occurs only at high cell concentrations

  8. Quorum Sensing • Regulation of genes expression in response to population density • Acylated homoserine lactone (AHL) molecules might be produced and excreted by all cells in a given population • Higher population density results in greater concentration of AHL • AHL molecules activate a specific transcriptional activator protein, resulting in specific transcription induction

  9. Quorum-sensing model from University of Nottingham Quorum Sensing Research Group (Paul Williams)

  10. Two-component regulatory system Figure 8.23

  11. Chemotaxis Figure 8.24

  12. Chemotaxis in Review • no attractant: CheACheA-P, CheY-P • tumble • attractant: MCP blocks CheA-P • CheZ: CheY-PCheY • run • over time: CheR methylates, desensitizes MCP • new baseline: as if no attractant present • CheACheA-P, CheY • tumble • CheB-P demethylates, re-sensitizes MCP

  13. Taxis Receptors • multiple MCPs sense different substrates • other, similar systems respond to different conditions (light, oxygen, etc.) • taxic responses studied by mutational analyses

More Related