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Team:Tokyo Tech/cph
From 2009.igem.org
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Contents |
Introduction
Mars also has day and night like Earth. The strength of the sunlight reaching Mars varies from day to night. During the day, the Mars’ surface temperature is about at most -20 degrees Celsius and in the night it drops to -100 degrees Celsius, so it natural that E. coli should behave differently in the day and night. Photo-sensor can be one powerful tool to control or regulate gene expression that is suitable for the temperature. For example, we introduced anti-freeze protein into E. coli, and it should express an appropriate amount of the protein based on the surface temperature, which is in proportion to the strength of light. We believe that this sensor can also be applied and utilized for terra-forming in some other way.
The mechanism of photo-sensor
Figure 1 shows the mechanism of photo-sensor. Cph8 consists of cph1 and envZ. Cph1 is an extracellular sensor and cph1 bound to PCB (converted from heam by ho1 and pcyA) responds to the light. EnvZ is an intracellular response regulator and has a histidine kinase domain that phosphorylates ompR protein so that it can regulate gene expression. When cph8 is not exposed to the light, the histidine kinase domain phosphorylates ompR, and then ompR-phosphate activates the PompC by binding to it. When cph8 is exposed to the light, the histidine kinase can’t phosphorylate ompR so PompC is inactive.
