Regulatory
Exponentia

Part:BBa_J45994:Experience

Designed by: Reshma Shetty   Group: iGEM06_MIT   (2008-01-29)

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Applications of BBa_J45994

Intended to be a exponential phase-dependent PoPS source.

User Reviews

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Reshma Shetty

BBa_J45994, when used to regulate transcription of GFP in BBa_J45996, demonstrated the expected behavior. BBa_J45994 produced a high transcriptional signal in exponential phase and a low transcriptional signal in stationary phase. However, when we used BBa_J45994 to regulated transcription of the wintergreen odor enzyme generator in the exponential phase dependent wintergreen odor generator (BBa_J45181), methyl salicylate production was indistinguishable from the constitutive wintergreen odor generator (BBa_J45120).

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Characterization

Transcriptional control of GFP generator

Growth phase dependent transcriptional control devices
We successfully designed, constructed and tested transcriptional control devices for constitutive, stationary phase dependent and exponential phase dependent protein production (A-C). To test and verify function of our three transcriptional control devices, we assembled each control device with the GFP protein generator BBa_E0840 and monitored the fluorescence of E. coli cultures with each device over time. For each device, we plot the change in fluorescence per unit time (normalized GFP synthesis rate) versus the cell density (OD600nm) (D). The constitutive transcriptional control device produced a high GFP synthesis rate irrespective of cell density. The stationary phase transcriptional control device produced a low initial GFP synthesis rate which increased with culture cell density. The exponential phase transcriptional control device produced an initially high GFP synthesis rate which dropped off as cell density increased. Data shown are averages of triplicate measurements of cultures grown from three individual colonies of each device. Error bars are the standard deviation of the three individual cultures.


Transcriptional control of wintergreen odor generator

Growth phase dependent wintergreen odor production
To demonstrate growth phase dependent wintergreen odor production, we compared the behavior of constitutive and exponential phase dependent wintergreen odor generators (A and B, respectively). We measured methyl salicylate concentration (relative to the pentachloronitrobenzene internal standard) of cultures of the constitutive and exponential phase wintergreen odor generators at different culture cell densities (OD600nm) (C). The constitutive and exponential phase wintergreen odor generators produced similar levels of methyl salicylate at all cell densities examined. Thus, the exponential phase wintergreen odor generator does not work as intended.