Difference between revisions of "Part:BBa K1104201"

Revision as of 12:28, 30 September 2013

TrxC promoter

Introduction

TrxC promoter is controlled by OxyR (transcription factor), which is activated by ROS(Reactive Oxygen Species). An intramolecular disulfide bond between Cys199 and Cys208 will form in an OxyR transcription factor, and active OxyR molecule will bind to the binding site of TrxCp, making the following circuit turned on.

In our project: Bee. coli, we use TrxCp as the sensor of Bee. coli to sense Nosema ceranae. After Nosema ceranae enter bees' midgut, the natural immune reaction will lead to ROS released by epithelia of bees' midgut. We select several promoters that can be induced by OxyR, which is activated by ROS. One of these promoters is TrxCp.

What is OxyR(activator)?

OxyR, a positive regulator of hydrogen peroxide-inducible genes in E. coli. The OxyR transcription factor regulates the H₂O₂ response of E. coli. H₂O₂ oxidizes OxyR Cys199 to an R-SOH that reacts with Cys208 in an intramolecular disulphide bond.

OxyR Activation

Structure of the OxyR Regulatory Domain
(A)Reduced Form: Inactive
(B)Oxidized Form: Activated by ROS
_{Reference: D'Autréaux, B., & Toledano, M. B. (October 01, 2007). ROS as signalling molecules: mechanisms that generate specificity in ROS homeostasis. Nature Reviews Molecular Cell Biology, 8, 10, 813-824.}

Information of TrxCp on Ecocyc

We get information of TrxCp from [http://www.ecocyc.org/ECOLI/NEW-IMAGE?type=OPERON&object=TU0-3104 Ecocyc],

Schematic drawing of the TrxC regulon in E. coli K12 (taken from [http://www.ecocyc.org/ECOLI/NEW-IMAGE?type=OPERON&object=TU0-3104 Ecocyc])

TrxCp is regulated by σ70, and there are two TFBSs upstream for OxyR. We also did some literature study, according to the citation. In E. coli genome, thioredoxin(trxC) will express in response to elevated H₂O₂ level. Expression of genes encoding thioredoxin(trxC) is regulated by OxyR. Oxidized OxyR binds directly to TrxCp and induce its expression.

_{Reference: Ritz, D. (January 28, 2000). Thioredoxin 2 Is Involved in the Oxidative Stress Response in Escherichia coli. Journal of Biological Chemistry, 275, 4, 2505-2512.}

Sequence and Features