Difference between revisions of "Part:BBa K1897018"

Latest revision as of 20:49, 15 October 2016

LuxR + LuxI + Invasin

This part consists of LuxR BBa_K1897008, LuxI BBa_K1897009 and Invasin BBa_K1897011. Both LuxR and LuxI are derived from Vibrio fischeri, while invasin is derived from Yersinia pseudotuberculosis.

Usage and Biology

This quorum sensing system was derived from Vibrio fischeri, and involves the regulatory LuxR and the autoinducer producing LuxI. Originally in Vibrio fischeri, the Lux operon can be transcribed from from the left (operonL) or right (operonR). Transcription of operonR, which consists of LuxICDABE, occurs only in the presence of N-(3-oxo-hexanoyl)-homoserine lactone (AHL), which is an autoinducer produced by LuxI (Shaldel and Baldwin, 1991). This also produces light due to the production of LuxCDABE (Shaldel and Baldwin, 1991). Transcription of operonL leads to the production of LuxR, which negatively regulates it's own transcription (Shaldel and Baldwin, 1991).

As the cell membrane is permeable to AHL, it diffuses out of the cell down a concentration gradient when there is low cell density (Fuqua et al., 1994). In high cell densities, it is able to accumulate within the cell to turn on the transcrption of genes under the control of pLuxR (see: BBa_R0062) or pLuxL (see: BBa_R0063) (Fuqua et al., 1994).This is due to rising amounts of AHL, which results in LuxR-AHL complexes begin to form, and LuxR undergoes a conformational change (likely to form a dimer) that leads to the activation of the Lux operon (Choi and Greenberg, 1992; Trott, 2000).

In this part, the activation of pLuxR by LuxR-AHL dimer complex results in the expression of both LuxI and invasin, allowing the bacteria with this part to enter mammalian cells expressing β1-integrin. This potentially allows for delivery of molecules into targeted mammalian cells since the inavsin gene is only expressed in areas of high cell density.

Sequence and Features