<center><b>Figure 6: </b>Proposed model for calprotectin-dependent quorum sensing and lysis</center>
<center><b>Figure 6: </b>Proposed model for calprotectin-dependent quorum sensing and lysis</center>
Figure 6 illustrates the quorum-sensing circuit regulated by a calprotectin-dependent promoter. Zinc deficiency leads to elevated calprotectin levels, which activate the ykgMO promoter to express LuxR. LuxI produces the autoinducer AHL, creating a positive feedback loop where increasing amounts of LuxR-AHL complexes are formed. These complexes ultimately trigger lysis, resulting in the release of IL-10.
Figure 6 illustrates the quorum-sensing circuit regulated by a calprotectin-dependent promoter. Zinc deficiency leads to elevated calprotectin levels, which activate the ykgMO promoter to express LuxR. LuxI produces the autoinducer AHL, creating a positive feedback loop where increasing amounts of LuxR-AHL complexes are formed. These complexes ultimately trigger lysis, resulting in the release of IL-10.
<center><b>Figure 7: </b>Model for bacteria sensing different concentrations of calprotectin</center>
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The figure illustrates an AND gate, where lysis proteins are produced only in the presence of calprotectin. In the absence of calprotectin, no lysis protein is expressed. The plot demonstrates a switch-like behavior, allowing bacteria to respond synchronously to varying concentrations of calprotectin across different locations. In theory, lysis is triggered in the presence of calprotectin, leading to the coordinated release of IL-10 at the site of inflammation. This AND gate mechanism ensures that lysis occurs only when calprotectin is present, preventing unnecessary release of IL-10.
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Latest revision as of 05:00, 2 October 2024
LuxI_LuxR_Plux_rzrz1
This construct integrates the luxI/luxR quorum sensing system to drive the inducible production of the rzrz01 lysis gene in Escherichia coli. Modeled after the quorum sensing system of Vibrio fischeri, this design enables cell-to-cell communication, ultimately triggering cell lysis. When the luxI gene synthesizes the signaling molecule acyl homoserine lactone (AHL), it binds to the LuxR regulator. The LuxR-AHL complex then interacts with the Plux promoter, activating the transcription of the rzrz01 lysis gene. This results in controlled self-lysis of the bacterial cells in response to AHL accumulation.
Images and Figures
Figure 1: Calprotectin-Dependent System
Figure 1 demonstrates the impact of calprotectin-dependent lysis. Increases in calprotectin concentration result in zinc deficiency, which can then be detected by the ykgMO promoter. When there is a high concentration of zinc, this pathway is suppressed, showing the feedback mechanism of calprotectin in controlling the lysis mechanism.
Figure 2: Quorum Sensing Dependent Lysis
Figure 2 illustrates the positive feedback loop of the quorum-sensing-dependent lysis plasmid. At a critical cell density, LuxR is activated and binds to acyl homoserine lactone (AHL), forming LuxR-AHL complexes. These complexes both activate the expression of LuxI, which synthesizes more AHL, and induce the expression of the lysis genes. This feedback amplifies the production of AHL and triggers the lysis mechanism, ensuring coordinated cell lysis once quorum sensing thresholds are reached.
Figure 3: Optical density of quorum sensing induced lysis
Figure 3 shows the optical density changes associated with quorum-sensing-induced lysis. Successful lysis is indicated by the plateau in optical density after lysis protein expression, in contrast to the continuous increase observed in the GFP control. This plateau reflects the reduction in cell growth due to lysis, while the control demonstrates ongoing cell proliferation without lysis activation.
Figure 4: Modeling results for quorum sensing lysis regardless of calprotectin concentration
The figure illustrates the modeling results of a simulation involving 100 cells within a quorum-sensing system independent of calprotectin. The simulation reveals a direct proportional relationship between the concentrations of AHL, LuxI, the LuxR-AHL complex, and the lysis proteins. This indicates that the production of lysis proteins is driven by the presence of the autoinducer (AHL), the LuxR-AHL complex, and LuxI, emphasizing the dependency of lysis protein expression on the quorum-sensing components.
Figure 5: Mathematical Model of Low and High Calprotectin Concentrations
This figure presents a mathematical model showing the relationship between calprotectin concentration and the expression of the lysis gene. At low calprotectin levels, the model predicts minimal lysis gene expression, leading to cell survival. However, as calprotectin concentration increases, the model demonstrates a sharp rise in lysis gene expression, resulting in cell lysis. The model helps illustrate the calprotectin-dependent nature of the proposed lysing mechanism, which is important for dynamic interaction in an intestinal environment.
Figure 6: Proposed model for calprotectin-dependent quorum sensing and lysis
Figure 6 illustrates the quorum-sensing circuit regulated by a calprotectin-dependent promoter. Zinc deficiency leads to elevated calprotectin levels, which activate the ykgMO promoter to express LuxR. LuxI produces the autoinducer AHL, creating a positive feedback loop where increasing amounts of LuxR-AHL complexes are formed. These complexes ultimately trigger lysis, resulting in the release of IL-10.
Figure 7: Model for bacteria sensing different concentrations of calprotectin
The figure illustrates an AND gate, where lysis proteins are produced only in the presence of calprotectin. In the absence of calprotectin, no lysis protein is expressed. The plot demonstrates a switch-like behavior, allowing bacteria to respond synchronously to varying concentrations of calprotectin across different locations. In theory, lysis is triggered in the presence of calprotectin, leading to the coordinated release of IL-10 at the site of inflammation. This AND gate mechanism ensures that lysis occurs only when calprotectin is present, preventing unnecessary release of IL-10.
