Difference between revisions of "Part:BBa K239001"

Revision as of 13:18, 18 October 2009

Spy promoter, activated by Phosporylated CpxR, BaeR and Sigma70

Sequence contains 2 phosphorylated BaeR (Bacterial Adaptative rEsponse) binding sites, 1 phosphorylated CpxR (Conjugative Plasmid eXpression) binding site and transcription is initiated by sigma factor 70. Experiments by Bury-Moné et al. (2009) indicates that also RcsB (Regulator of colanic acid Capsule Synthesis) induces expression of the Spy gene.

Function: Can detect various periplasmic stresses such as Copper (4mM CuCl2), Indole (4mM) and Ethanol (5%). Possibly it can also be used to detect presence of heterogeneous unfolded proteins in the periplasmic space (e.g. target pharmaceuticals) or to detect high levels of shear stress during cultivation in a bioreactor.

Note: DegP is dependent of Sigma E and can not be induced only by over expression of CpxR. In comparison, the Spy promoter, which is dependent on sigma factor 70, can be induced up to 40 fold by over expression of CpxR. (Bury-Moné et al. 2009)

Analysis of the upstream region of spy, mdtA and arcD, by Nishino et al. (2005), has led to the identification of a 18bp long binding sequence for BaeR. The sequence reads 5’-TTTTTCTCCATDATTGGC-3’, where D is any nucleotide G, A or T. Experiments, by Yamamoto et al. (2008), in which spy promoter fragments have been exposed to purified BaeR and acetyl phosphate have revealed a promoter-distal site between -162 and -137 and a promoter-proximal site between -109 and -79. The BaeR-box TCTNCANAA is present as a direct repeat in the distal promoter. The proximal promoter site includes one single copy of the BaeR-box.

Sequence and Features