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Understanding Signal Transduction in Regulatory Systems

Explore the intricate processes of signal transduction in regulatory systems, including chemotaxis, genetic exchange, and conjugation. Learn about sensor proteins, kinase activity, genetic engineering basics, and more.

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Understanding Signal Transduction in Regulatory Systems

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  1. 2 component regulatory systems • Maltose=effector, BUT if signal not DIRECTLY involved, but needs to be transmitted and changed = signal transduction • Sensor protein= • kinase, phosphorylates compounds, • membrane associated • Phosphoryl group transmitted to another regulator IN the cell • Often a DNA binding protein involved in transcription • Many examples, N-fixation, sporulation,chemotaxis

  2. Chemotaxis • Attractants decrease rate of autophosphorylation • Repellant increased autophosphorylation • CheA-CheW=transducer • CheY controls switch • cheY-P tumbles, CCW-CW • CheB phosporylated by CheA-P, but slower response than CheY-P • CheB involved methylation • Fully methylated = best for repellants • cheB-P demethylates, occurs when attractants High • Degree of methylation regulates attraction/repulsion

  3. Chemotaxis

  4. Genetic exchange: transformation

  5. Genetic exchange: plasmid transfer • Small, usually circular, independently replicating DNA molecules • Generally, G- plasmids replicate as does chromosomal DNA, G+ plasmids by “rolling circle” replication • Genes of replication control, timing initiation on plasmid (ori) • Some plasmids integrate (F+, Hfr) • Most are double-stranded • About 1- 100kb • Code for: • R-factors (R-plasmids) : antibiotic resistance, heavy metal resistance • Virulence plasmids : adhesins, hemolytic factors, toxin, Ti, bacteriocins • Degradation, tol, nah, • Plasmid copy # • Compatibility (inc)

  6. Genetic exchange: plasmid transfer • Small, usually circular, independently replicating DNA molecules • Generally, G- plasmids replicate as does chromosomal DNA, G+ plasmids by “rolling circle” replication • Genes of replication control, timing initiation on plasmid (ori) • Some plasmids integrate (F+, Hfr) • Most are double-stranded • About 1- 100kb • Code for: • R-factors (R-plasmids) : antibiotic resistance, heavy metal resistance • Virulence plasmids : adhesins, hemolytic factors, toxin, Ti, bacteriocins • Degradation, tol, nah, • Plasmid copy # • Compatibility (inc)

  7. Avery Experiment

  8. Transformation • Competence: ability to be transformed • Steps in transformation • DNA binding and uptake (SS or DS, depending on species) • Integration (recA) • Competence may be induced by electroporation, Ca

  9. Mechanism of transformation

  10. Transduction • Generalized—can be carried out by either lytic or temperate phage • Specialized—requires specific integration

  11. Generalized transduction

  12. Specialized transduction

  13. Specialized transduction

  14. Genetic exchange: conjugation

  15. Conjugation: early Cell-surface structure

  16. Conjugation: middle

  17. Conjugation: late

  18. Genetic Engineering-basics • Basic steps in cloning • Restriction-modification enzymes • “shot gun” or PCR • Ligase • Recombination Plasmids (or phage)= vectors • Expression vectors • Selection of clones • Looking for a clone with a specific gene • Probes (DNA, RNA or antibody) • Wave of the future: DNA chips or “microarrays”, BAC libraries, automated sequencing etc

  19. Genomics • Bioinformatics • Harvesting genes for biotech (Diversa) • Recent Science article • Comparing gene families

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