Difference between revisions of "Part:BBa K238013"

Revision as of 14:50, 19 October 2009

Exact promoter of the blue light receptor

This is a promoter which normally lies before the ycgZ gene, a part of an operon consisting of several genes used by E.coli for regulating e.g. biofilm production. It is regulated by the ycgF/E system. This system consists of a receptor, ycgF, which is responsive to blue light. When blue light strikes, the receptor changes conformation and dimerizes. This allows it to bind to the ycgE repressor through its EAL-domain, releasing the repressor from the promoter region. The inverted repeats shown here are expected to represent the binding site for ycgE. YcgE binding results in transcription repression.

after some experimental set ups following considerations need to be made:

• The promoter is weak (compared to standard I20260)
• aside from light, temperature is a very important influence (if not a bigger one). for instance when working in low copy plasmids temperature will influence the promoter/repressor ratio. Cells are grown at 37°C will have too much promoter resulting in constitutive activity. When grown at 25°C the ratio is beter leading to a good repression of the promoter.

Comparison of the blue light promotor (blue) to a standard promotor strength Template:Kulpart (orange). The blue light promotor shows at least half the strenght of the standard promotor in RPU, meaning it can be classified as a weak promotor

Effect of blue light irradiance on promotor strenght. Cells grown in blue light irradiance (blue) show a stronger expression compared to cells grown in the dark (grey)

For more info: Natalia Tschowri, Susan Busse and Regine Hengge, The BLUF-EAL protein YcgF acts as a direct anti-repressor in a blue-light response of Escherichia coli. Genes and development23: 522-534 (2009)

Sequence and Features