Difference between revisions of "Part:BBa K117002"

Revision as of 22:05, 26 October 2008

LsrA promoter (indirectly activated by AI-2)

AI-2 quorum sensing system

The integral part of the AI-2 quorum-sensing (QS) system consists of a transporter complex, LsrABCD; its repressor, LsrR; and a cognate signal kinase, LsrK. Once uptaken into the cell, AI-2 will be phosphorylated under the effect of LsrK. Without the presence of AI-2, LsrA promoter is inhibited by the repressor, LsrR. Phosphorylated AI-2 will prevent LsrR from inhibiting this promoter, hence activating it so that the downstream sequence can be expressed. To prevent the cell from self-inducing this promoter, we must suppress its AI-2 producing capability. It can be done by knocking out LuxS, one of the vital gene required for producing AI-2. By doing that, LsrA promoter can only be activated under the presence of AI-2 from other sources than the host cell which is LuxS mutant (say, by contact with normal cells).

‎Effects of AI-2 on LsrA promoter

More information on AI-2 quorum-sensing (QS) system please refer to: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1952038

Important notice:

• This part is only the promoter region of LsrA gene which is normally inhibited by LsrR. It is NOT the entire LsrA gene.
• It is INDIRECTLY induced by AI-2, through a complex network involving LsrK,LsrR.

How this promoter works:

By ligating LsrA promoter with a protein coding sequence downstream, we can regulate the expression of that protein by AI-2 as the inducer. To prevent self-inducing by the host cell, the plasmid must be transformed into cell with LuxS gene knocked out.

Sequence and Features