View source for Part:BBa K318512

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<partinfo>BBa_K318512 short</partinfo>


===Usage and Biology===

'''gadAp: A pH Sensitive Promoter.''' One of the striking abilities of ''E. coli'' is its ability to pass through the acidic conditions of animal digestive tracts---GadA and the promoters and proteins around it may play a role in this. Results of northern blot analysis (Tucker et al., 2002; Waterman et al., 2003) indicate that a particular glutamate decarboxylase (GadA) is up-regulated, most likely as a part of a glutamate to gamma-aminobutyrate reaction which exports intercelluar protons which is required for E. coli stationary phase cell survival of highly acidic (pH 2) conditions (Castanie-Cornet et al., 1999). Based on a high ratio of low pH:neutral pH expression and a wealth of available information, we chose to use GadA's promoter, gadAp, as a native-E. coli sensor for acidic conditions. In order to maximize pH-mediated response of the gadA promoter and minimize induction caused by other known responses (such as the stationary phase), we plan to run error-prone PCR followed by screening of clones for maximal, dedicated acid response.

===Low pH/Stationary Phase Induction===

This part was tested in BBa_K318513

Download part information (.zip) [[Media:K318512.zip|here]].

Below are two figures of sample data:

[[Image:pH_7_gadAp_with_controls.jpg|center]]

'''Figure 4.''' Lines represent OD600 and are associated with the right axis. Dots indicate RFU/OD600 and associated with the left axis. In this trial, maximum induction occurred at an OD600 of approximately 6 (right axis, associated with line) and yielded about 10000 RFU/OD. Note that immediately before maximum OD600 was reached, RFU/OD increased about 5-fold. Controls included for this trial were a lacI promoter + RBS + mRFP1 + TT construct in the same plasmid (pSB1A2) and a WT control of MG1655 cells. These controls and results indicate that (1) mRFP1 expression by gadAp at high OD600 is a function of the gadA promoter, not of promoters at large (lacI promoter did not express) or of the cells themselves (MG1655 did not fluoresce).

[[Image:pH_5.5_gadAp_with_controls.jpg|center]]
'''Figure 5.'''This trial was run parallel to the pH 7 trial in Figure 4. It indicates that cells grown in LB media at pH 5.5 do not exhibit a drastically different promotion behavior from their gadA promoters than those grown in neutral media.

[[Image:Additional data points.jpg|center|550px]]
Additional data points

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<span class='h3bb'>Sequence and Features</span>
<partinfo>BBa_K318512 SequenceAndFeatures</partinfo>


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===Functional Parameters===
<partinfo>BBa_K318512 parameters</partinfo>
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