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Microbial Genetics (Micr340)

Microbial Genetics (Micr340) . Lecture 8 Conjugation and Transformation. Conjugation. Definitions. Conjugation - a process in which a plasmid transfer itself and other DNA elements from one cell to another Donor bacterium - a bacterium originally contains the plasmid

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Microbial Genetics (Micr340)

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  1. Microbial Genetics (Micr340) Lecture 8 Conjugation and Transformation

  2. Conjugation

  3. Definitions • Conjugation - a process in which a plasmid transfer itself and other DNA elements from one cell to another • Donor bacterium - a bacterium originally contains the plasmid • Recipient bacterium - a bacterium that receives the transferred plasmid • Transconjugant - a recipient cell that has received DNA as a result of conjugation

  4. Conjugation • Most naturally occurring plasmids are either: • self-transmissible • mobilizable • In Gram- bacteria, sex pili facilitate conjugation • “Promiscuous plasmids” possess transfer systems that enable them to transfer DNA between unrelated species

  5. pKM101

  6. Conjugation in Gram- • Transfer (tra) genes • Dtr component • Mpf component • The oriT sequence and function

  7. Mpf function

  8. Mpf function

  9. Mpf function

  10. Pilus formation

  11. Regulation of tra genes

  12. oriT identification

  13. oriT identification

  14. Plasmidmobilization

  15. Plasmidmobilization(continued)

  16. Conjugation in Gram- • Triparental mating

  17. Triparental mating

  18. Chromosome transfer by plasmids • Formation of Hfr strains • Transfer of chromosomal DNA by integrated plasmids • Genetic mapping with Hfr crosses

  19. Transformation

  20. DNA exchange in bacteria • Three ways • Conjugation • Transformation • Transduciton

  21. Natural transformation • Natural competence • Discovery - the Griffith experiment

  22. Gram+ DNA uptake system

  23. Gram- DNA uptake system

  24. Transformation in Streptococcus pneumoniae

  25. Transformation in Streptococcus pneumoniae

  26. Transformation in Haemophilusinfluenzae

  27. Artificially induced competence • Calcium Ion Induction • transformation by plasmids • transfection - use of viral DNAs or genomic RNA in transformation • Electroporation

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