Difference between revisions of "Part:BBa K346001"

Revision as of 03:01, 24 October 2010

RBS (B0034) + MerR (mercury-responsive transcription factor)

This part was designed as a translational unit for MerR expression.

The mercury resistance operon, mer, can enable bacteria to avoid and remove toxic metal Hg under the regulation of the MerR family transcriptional factor MerR. MerR acts as an activator of mer genes in response to the presence of Hg (II), while it will be reversed into a weak repressor in the absence of Hg (II), to maintain its own expression at certain level.

The MerR protein, in the form of homodimer, binds to the mer operon between the RNA polymerase binding sites of the promoter region. The attachment is independent on the presence of Hg(II). When the apo-MerR dimer bind to the dyad symmetrical operator DNA between the -35 and – 10 elements of mercury inducible promoter, PmerT, which has a unusually long spacer of 19 bp for MerR to bind on, the binding of RNA polymerase is inhibited. When Hg(II) is available in the environment, the ion binds to merR between the two subunits. The Hg-bound MerR can result in an a structural distortion of PmerT, allowing the RNA polymerase contacts to be made, leading to the expression of down-stream genes(Fig.1).

Sequence and Features