Difference between revisions of "Part:BBa K537000"

Revision as of 16:29, 15 September 2011

Atrazine Riboswitch-CheZ fusion

When no atrazine is present, the RBS within the riboswitch sequence is not exposed to translation machinery. When atrazine is present, it binds to the riboswitch and causes a conformational change which results in the RBS being exposed. This allows for the translation of the adjoining gene. In this case, the gene which will be expressed is CheZ - a fundamental protein in the signalling cascade of bacterial chemotaxis.

This riboswitch-CheZ fusion BioBrick regulates the expression of the CheZ gene in a atrazine-dependent fashion. It is composed of an atrazine-sensitive riboswitch, developed by Sinha et al (2010), which is detached from its associated translation unit (coding region) and fused to a CheZ gene which has the Freiburg N-fusion prefix and lacks a stop codon. While it is possible to fuse the riboswitch to the CheZ coding region by standard BioBrick assembly techniques, this approach was not used as it would increase the distance between the RBS and the ATG start codon will increase and potentially decrease the efficiency of the riboswitch. This was shown in the work of the Taipei 2010 team who used this approach for a theophylline riboswitch. The riboswitch and the adjacent CheZ coding region are considered together and should be cloned together. CheZ is the chief regulator of the molecular events that lead the counter clockwise rotation of the flagella motor during the Chemotaxis signal transduction pathway of E.coli. This counter clockwise flagella motor rotation results in bacterial swimming (instead of tumbling) in the presence of a chemoattractant (in this case atrazine).

Reference: Sinha J., Reyes S.J., and Gallivan J.P. Reprogramming Bacteria to Seek and Destroy a Herbicide. 2010, Nat Chem Biol. 6(6): 464–470

Sequence and Features