Team:Michigan/Project
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== Hy-Bi: Pili Hyperexpression == | == Hy-Bi: Pili Hyperexpression == | ||
- | [[Image:Michigan-Pili2.png|350px|thumb|left|Fig. 1 An electron micrograph view of E. coli, with a close-up of the pili in the inset [ | + | [[Image:Michigan-Pili2.png|350px|thumb|left|Fig. 1 An electron micrograph view of E. coli, with a close-up of the pili in the inset [5].]] |
- | Type 1 pili (also known as fimbriae) are proteinaceous adhesins that are found on the surface of E. coli. One cell can contain up to 100 pili, which can form up to 2 um long (Fig. 1)[ | + | Type 1 pili (also known as fimbriae) are proteinaceous adhesins that are found on the surface of E. coli. One cell can contain up to 100 pili, which can form up to 2 um long (Fig. 1)[5]. The pili help E. coli form biofilms, and can also be involved in urinary tract infections. However, the strains of E. coli that our team worked with were strictly nonpathogenic. |
- | The pili are controlled by the ''fim'' operon. This operon consists of several genes, FimA-H. The pili themselves are composed of several thousand subunits of FimA. The tip of each pili consists of the genes FimF, FimG, and FimH. FimH is an adhesin and is linked to FimA through FimF and FimG. Inside the cell, FimC carries proteins to the structural platform, FimD, which then assembles the pilus rod (Fig. 2)[ | + | The pili are controlled by the ''fim'' operon. This operon consists of several genes, FimA-H. The pili themselves are composed of several thousand subunits of FimA. The tip of each pili consists of the genes FimF, FimG, and FimH. FimH is an adhesin and is linked to FimA through FimF and FimG. Inside the cell, FimC carries proteins to the structural platform, FimD, which then assembles the pilus rod (Fig. 2)[6]. This whole process is regulated by the recombinases FimB and FimE. These genes control an invertible DNA sequence, which, when in the "on" position, promotes the production of pili (Fig 3). |
- | The pili neural network has been characterized in several papers [ | + | The pili neural network has been characterized in several papers [7,8,9]. Essentially, the two recombinases FimB and FimE control an invertible DNA element that acts as a switch, known as FimS. When FimS is in the "on" position, the cell becomes fimbriated. It has been previously determined that the level of piliation depends on the ratio [FimE]/[FimB]. Fig 4 describes the pili regulatory system as a stochastic model. There is only one stable state, when FimB and FimE are both off. After FimB turns on, the cell starts to grow pili and accumulate FimE. When the cell reaches a critical amount of FimE, the cell stops producing pili and the system returns to the stable state. It has been shown that removing the FimE gene will cause the cell to constantly flocculate. |
The reason we are so interested in the pili is their capability to flocculate. Several papers have shown that the pili bind to mannose through FimH. By overproducing the pili, we hope to increase flocculation. We plan to accomplish this goal by putting the FimB gene on a plasmid. You can find the pili team's lab notebook [[Team:Michigan/Pili Expression|here]]. | The reason we are so interested in the pili is their capability to flocculate. Several papers have shown that the pili bind to mannose through FimH. By overproducing the pili, we hope to increase flocculation. We plan to accomplish this goal by putting the FimB gene on a plasmid. You can find the pili team's lab notebook [[Team:Michigan/Pili Expression|here]]. | ||
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- | [[Image:Michigan-Pili.png|300px|thumb|left|Fig. 2 A representation of a single pilus and how the different genes in the fim operon function [ | + | [[Image:Michigan-Pili.png|300px|thumb|left|Fig. 2 A representation of a single pilus and how the different genes in the fim operon function [6].]] |
- | [[Image:Michigan-PiliReg.png|300px|thumb|left|Fig. 3 The recombinases FimB and FimE regulate the fim operon via an invertible segment of DNA [ | + | [[Image:Michigan-PiliReg.png|300px|thumb|left|Fig. 3 The recombinases FimB and FimE regulate the fim operon via an invertible segment of DNA [7].]] |
- | [[Image:Michigan-PiliReg2.png|200px|thumb|left|Fig. 4 A model that illustrates the different states of the regulatory system [ | + | [[Image:Michigan-PiliReg2.png|200px|thumb|left|Fig. 4 A model that illustrates the different states of the regulatory system [7].]] |
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Revision as of 03:41, 27 October 2010