Difference between revisions of "Part:BBa K346001:Design"

Revision as of 07:10, 24 October 2010

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

Design Notes

The native RBS of MerR is not strong enough and its intensity can not be predicted as there is no such a corresponding RBS part in Registry. In order to facilitate the use and further characterization of MerR for future team, we prefixed an RBS part BBa_B0034 from Partsregistry.

MerR, as a regulatory protein, always binds to merOP as a homodimer and enhances the occupancy of Ptpad by RNA polymerase regardless of the presence of Hg(II), although only after Hg(II)’s binding can the dimer stop preventing the formation of the open complex by RNA polymerase. Also, MerR repress its own expression independently of Hg(II)(Fig.3).

Fig.3. The model for the interaction of MerR and Hg(II) and its role in controlling PmerT transcription. Adapted from Jon L. Hobman, John Wilkie & Nigel L. Brown,2005. A: RNA polymerase (RNAP) transcribes merR from PmerR. MerR binds to the mer promoter/operator region (merOP) as a homodimer, recruits RNA polymerase, and represses transcription of merTPAD from PmerT. B: Hg(II) enters the bacterial cell by diffusion through the outer membrane, cytoplasm and inner membrane, and binds to three cysteine residues in the apo-MerR homodimer. The Hg-bound MerR homodimer causes an underwinding of merOP DNA, allowing RNAP to proceed with transcription of the resistance genes.

Source

The coding sequence of MerR comes from Tn, prefixed by an RBS part BBa_B0034 from Partsregistry

References