Berkeley2006-ConjugationMain

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Conjugation
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Bacterial conjugation provides the communication system for our networks.  Based on the natural F and RP4 plasmids, DNA "messages" can be sent from a donor cell to a recipient cell based on conjugation when the two cell types are mixed in liquid media or on a surface.  Natural conjugative plasmids are large 60-100kb, circular plasmids that encode all the genes necessary for plasmid transfer including pili for bacteria-bacteria interactions, and genes that prevent superinfection of F and RP4-containing cells with secondary messages.  Although F-type cells cannot send send plasmids to one another, F plasmid cells can send plasmids to R-type cells and vice versa.  A critical component of transfer is the origin of transfer (oriT).  This sequence within the conjugative plasmid initiates rolling circle amplification and transfer of the plasmid to the recipient cell.  In our system, we have deleted the oriT region of the RP4 and F plasmid such that these plasmids can no longer be transferred. 
[[Image:Berkeley2006_Conjugation1.jpg]]
[[Image:Berkeley2006_Conjugation1.jpg]]

Revision as of 02:45, 29 October 2006

Bacterial conjugation provides the communication system for our networks. Based on the natural F and RP4 plasmids, DNA "messages" can be sent from a donor cell to a recipient cell based on conjugation when the two cell types are mixed in liquid media or on a surface. Natural conjugative plasmids are large 60-100kb, circular plasmids that encode all the genes necessary for plasmid transfer including pili for bacteria-bacteria interactions, and genes that prevent superinfection of F and RP4-containing cells with secondary messages. Although F-type cells cannot send send plasmids to one another, F plasmid cells can send plasmids to R-type cells and vice versa. A critical component of transfer is the origin of transfer (oriT). This sequence within the conjugative plasmid initiates rolling circle amplification and transfer of the plasmid to the recipient cell. In our system, we have deleted the oriT region of the RP4 and F plasmid such that these plasmids can no longer be transferred.

Berkeley2006 Conjugation1.jpg



F plasmid Conjugation Can be Controlled Via OriTf Activity Berkeley2006 Conjugation2.GIF


R plasmid Conjugation Can be Controlled Via OriTr Activity

Conjugation3.jpg


Cell Sends "Key" to Recipient Cell which Unlocks Message

Berkeley2006 Conjugation4.GIF


Riboregulator's Don't Effect Conjugation Efficiency

Berkeley2006 Conjugation5.GIF


Conjugation Does Not Impede Riboregulator Function

Berkeley2006 Conjugation6.GIF


Next Section: Tuning Expression Levels with Synthetic Promoters

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