Difference between revisions of "Part:BBa K629008"

Revision as of 05:06, 5 November 2011

recAp-cheZ

Introduction

In our project, this part consist of recAp , cheZ, when this part is under irradiation, recAp can be started to promote the expression of CheZ, which will make the direction of rotation of the flagellar motor counterclockwise and E. Coli would move forward. Without irradiation or E. Coli moves into a normal environment, the quantity of CheZ would decrease dramatically, leading the direction of rotation of the flagellar motor to be clockwise. As a result, this part will make e.coli move forward to the radiation source.

Background

Ionizing radiation activates the SOS repair system of bacteria through DNA damage. The single-strand DNA breaks leads to the activation of protein RecA, which leads to proteolysis of the repressor protein LexA, resulting in the increased transcription of about 20 genes, including recA and recN (Fig.1). Therefore, recAp and recNp are radiation-inducible and can be utilized to control gene expression induced by ionizing radiation.

The rotational direction of bacteria is controlled by the flagellar motor system, of which CheY plays a pivotal role. When CheY is phosphorylated (CheY-P), it binds to the flagellar switch protein FliM and induces the flagellum to rotate clockwise, which causes the cell to tumble. Smooth swimming is restored by the phosphatase CheZ, which dephosphorylates CheY-P and causes the flagellum to rotate counterclockwise (Fig.2). E.coli lacking the cheZ gene (∆cheZ, strain RP1616, non-motile) cannot dephosphorylate CheY-P, tumble incessantly, and are thus nonmotile. So, if we controls the expression of cheZ in strain RP1616, it's possible to control the migration of bacteria.

Accordingly, in order to construct bacteria that move directionally towards ionizing radiation, we can place gene cheZ in the downstream of recAp.

Results

The results shown below:

Sequence and Features