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| [[File:ETH Zurich 2014 2nd order rhl.png|400px|thumb|center| '''Figure 3 Overview of possible crosstalk of the [https://parts.igem.org/Part:BBa_I14017 pRhl] promoter with both the regulator and inducer being unrelated to the promoter and each other.''' Usually, [https://parts.igem.org/Part:BBa_C0171 RhlR] together with inducer [[AHL|C4-HSL]] activate their corresponding promoter [https://parts.igem.org/Part:BBa_I14017 pRhl] (green). However, [https://parts.igem.org/Part:BBa_I14017 pRhl] may also be activated by another regulator together with an unrelated inducer. For example, the inducer [[3OC6HSL|3OC6-HSL]] (light blue) may interact with the [https://parts.igem.org/Part:BBa_C0179 LasR] regulator (red) and together activate [https://parts.igem.org/Part:BBa_I14017 pRhl] (green).]] | | [[File:ETH Zurich 2014 2nd order rhl.png|400px|thumb|center| '''Figure 3 Overview of possible crosstalk of the [https://parts.igem.org/Part:BBa_I14017 pRhl] promoter with both the regulator and inducer being unrelated to the promoter and each other.''' Usually, [https://parts.igem.org/Part:BBa_C0171 RhlR] together with inducer [[AHL|C4-HSL]] activate their corresponding promoter [https://parts.igem.org/Part:BBa_I14017 pRhl] (green). However, [https://parts.igem.org/Part:BBa_I14017 pRhl] may also be activated by another regulator together with an unrelated inducer. For example, the inducer [[3OC6HSL|3OC6-HSL]] (light blue) may interact with the [https://parts.igem.org/Part:BBa_C0179 LasR] regulator (red) and together activate [https://parts.igem.org/Part:BBa_I14017 pRhl] (green).]] |
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− | In this set of experiments the promoter [https://parts.igem.org/Part:BBa_I14017 pRhl] was tested for potential crosstalk. In the top left position we observe the induction of [https://parts.igem.org/Part:BBa_I14017 pRhl] by C4-HSL bound to the [https://parts.igem.org/Part:BBa_C0171 regulator RhlR]. The switching behaviour was observed at a C4-HSL concentration of 1 μM.
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− | In the case of 3OC12-HSL binding the [https://parts.igem.org/Part:BBa_C0171 RhlR regulator] and subsequently the [https://parts.igem.org/Part:BBa_I14017 promoter pRhl]insignificant crosstalk has been observed.
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− | Severe crosstalk was observed in the case of 3OC6-HSL binding the [https://parts.igem.org/Part:BBa_C0171 RhlR regulator] followed by induction of [https://parts.igem.org/Part:BBa_R0071 pRhl]. The transition occurred at a concentration of the inducer molecule of 1 μM but compared to the reference curve a lower value of fluorescence per OD was observed (1000 a.u.). Another case of crosstalk with the [https://parts.igem.org/Part:BBa_I14017 pRhl] was detected with 3OC12-HSL binding to the corresponding [https://parts.igem.org/Part:BBa_C0179 LasR regulator] followed by inducing the promoter [https://parts.igem.org/Part:BBa_I14017 pRhl]. Here switching occurred at a concentration 1 nM of 3OC12-HSL and reached fluorescence per OD of 750 a.u.. This is approximately 0.5 fold the value of the fluorescence per OD shown by the reference curve indicated in green.
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− | |style="width:100px"|[[File:ETH_Zurich_2014_qs-table_CornerRhl.png|100px|link=https://parts.igem.org/Part:BBa_I14017:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_C4-HSL.png|100px|link=https://parts.igem.org/Part:BBa_I14017:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_3OC6-HSL.png|100px|link=https://parts.igem.org/Part:BBa_I14017:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_3OC12-HSL.png|100px|link=https://parts.igem.org/Part:BBa_I14017:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_RhlR.png|100px|link=https://parts.igem.org/Part:BBa_C0171:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlRef.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlRhlRLuxAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlRhlRLasAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_LuxR.png|100px|link=https://parts.igem.org/Part:BBa_C0062:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLuxRRhlAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLuxRLuxAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLuxRLasAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_LasR.png|100px|link=https://parts.igem.org/Part:BBa_C0179:Experience]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLasRRhlAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLasRLuxAHL.png|200px]]
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− | |[[File:ETH_Zurich_2014_qs-table_PrhlLasRLasAHL.png|200px]]
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− | |}
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− | === Modeling crosstalk ===
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− | Each experimental data set was fitted to an Hill function using the Least Absolute Residual method.
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− | [[File:ETHZ_HillEq.png|center|200px]]
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− | <p>The fitting of the graphs was performed using the following equation :<br><br>
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− | rFluo = the relative fluorescence (absolute measured fluorescence value over OD)[a.u.]<br>
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− | a = basal expression rate [a.u.](“leakiness”)<br>
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− | b = maximum expression rate [a.u.]("full induction")<br>
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− | n = Hill coefficient (“cooperativity”)<br>
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− | K<sub>m</sub> = Half-maximal effective concentration (“sensitivity”)<br>
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− | [AHL] = AHL concentration [nM]</p>
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− | <br clear="all"/>
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− | {| border="1" class="wikitable" style="margin: 1em auto 1em auto;text-align:center;"
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− | |+ Parameters of HillFunction for crosstalk with Prhl (with 95% confidence bounds)
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− | !
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− | ! [[AHL|C4-HSL]]
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− | ! [[3OC6HSL|3OC6-HSL]]
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− | ! [[AHL|3OC12-HSL]]
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− | ! [https://parts.igem.org/Part:BBa_C0171 RhlR]
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− | | a = 178.4 (174.9, 182) [a.u.]<br> n = 1.053 (0.9489, 1.157)<br> Km = 1969 (1625, 2313) [nM]<br>b = 1736 (1629, 1842) [a.u.]<br>
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− | | a = 169.1 (155.2, 182.9) [a.u.]<br> n = 0.507 (0.2303, 0.7837) <br> Km = 1.08e8(0, 2.681e10) [nM]<br> b = 9.708e4 (0, 1.192e7) [a.u.]<br>
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− | | a = 162.8 (150.4, 175.1) [a.u.]<br> n = 0.404 (0, 0.998)<br> Km = 9.627e8 (0, 7.824e11) [nM]<br>b = 2.537e4 (0, 8.109e6) [a.u.]<br>
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− | ! [https://parts.igem.org/Part:BBa_C0062 LuxR]
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− | | No crosstalk
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− | | No crosstalk
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− | | No crosstalk
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− | ! [https://parts.igem.org/Part:BBa_C0179 LasR]
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− | | No crosstalk
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− | | No crosstalk
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− | | a = 149.3 (140.6, 158.1) [a.u.]<br>n = 1.366 (0.808, 1.923) <br> Km = 1.674 (1.259, 2.09) [nM]<br> b = 628.9 (599, 658.7) [a.u.]<br>
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− | |}
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− | |}
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