Team:MIT phage

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Revision as of 23:48, 27 October 2010

Bacteria

Phage

Mammalian

hairy cells and polymerizing phage - introduction

Living Material--Bacteriophage Polymer
M13 bacteriophage, a filamentous virus of E. coli, has been used as the starting component for polymers and other materials. To make these phage materials, one must purify large amounts of the virus, and then cross-link them with chemicals such as glutaraldehyde. Although once part of a living system, these materials are static--once made, they cannot be changed.

Figure 1: M13 polymer This polymer was created using external cross-linking, and is an example of a "static" material. In contrast, we want our material to be "dynamic" and biologically encoded--no external linkers required.

Willis, et al. 2007

We set out with the goal of constructing a system in which living cells would be programmed with a set of instructions, and given a stimulus, would be able to form material in a pattern. Because it is truly living, this system would have the potential to change and adapt, given more sophisticated programming.

For the bacterial path of our "living materials" project, we had to find a way of forming material without destroying the cells that created it. Luckily, M13 bacteriophage is non-lytic, which means that cells infected with M13 secrete phage continuously, without lysing.

The phage material that we set out to create is composed of polyphage strands, produced by cells that carry an M13 plasmid that lacks the gene necessary for termination of the phage particle. These strands cross-link with one another via the coiled-coil interactions of proteins displayed on the phage coat.

Figure 2: Electron micrograph of E. coli with polyphage hairs
Our goal is to get these hairs to cross-link via coiled coil interactions. (Despite what it may look like, these are not cross-linking.)
Image from: Rakonjac and Model, Roles of pIII in Filamentous Phage Assembly, 1998

Image from: Rakonjac and Model, Roles of pIII in Filamentous Phage Assembly, 1998

Rakonjac and Model, 1998

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 <tr><td>
 <br>
-<b>INTRODUCTION</b>
+<b>Living Material--Bacteriophage Polymer</b>
 <br>
-Integrating the BioBrick assembly standard, synthetic biology, and phage display, a system has been developed to translate UV light input into M13 bacteriophage polymerization and biomaterial formation using <i>E. coli</i> as a chassis.  Utilizing a previously characterized toggle-switch (Kobayashi, et al. 2004), the system created is set to a stable “on” state with the introduction of UV light.  The “on” state turns on transcription of the genes necessary for phage polymerization.  The phage polymerization can occur due to engineered coiled coal interactions of proteins being displayed on the phage coat.  Cells infected with phage that lack a certain gene (gIII) produce long fibril-like polyphage that stick out of the cell; it is these polyphage that are designed to cross-link.  In the future, these technologies could lead to advances in nanoscale fabrication, biomaterial production, and new applications for phage display technology.
+M13 bacteriophage, a filamentous virus of E. coli, has been used as the starting component for polymers and other materials. To make these phage materials, one must purify large amounts of the virus, and then cross-link them with chemicals such as glutaraldehyde. Although once part of a living system, these materials are static--once made, they cannot be changed.
 <br><br>
 <img src="https://static.igem.org/mediawiki/2010/f/f9/Polymer_block.jpg" style="float: left; height: 200px; padding-right:10px">
-Our goal is to obtain something like that pictured to the left: a solid polymer.  But this polymer was obtained through means of external cross-linking of M13 bacteriophage; we would like ours to be patterned by UV and controlled completely by genetic programming--no external linkers required.
+<u>Figure 1: M13 polymer </u> This polymer was created using external cross-linking, and is an example of a "static" material. In contrast, we want our material to be "dynamic" and biologically encoded--no external linkers required.
 <br><br><br><br><br><br>
-<div style="font-size:8px"><i>Willis, et al. 2007 </i></div>
+<div style="font-size:10px"><i>Willis, et al. 2007 </i></div>
-<br>
-Below is an EM of <i>E. coli</i> with polyphage hairs.  Our goal is to get these hairs to cross-link via coiled coil interactions.  (Despite what it may look like, these are not cross-linking.)
 <br><br>
+We set out with the goal of constructing a system in which living cells would be programmed with a set of instructions, and given a stimulus, would be able to form material in a pattern. Because it is truly living, this system would have the potential to change and adapt, given more sophisticated programming.
+<br><br>
+For the bacterial path of our "living materials" project, we had to find a way of forming material without destroying the cells that created it. Luckily, M13 bacteriophage is non-lytic, which means that cells infected with M13 secrete phage continuously, without lysing.
+<br><br>
+The phage material that we set out to create is composed of polyphage strands, produced by cells that carry an M13 plasmid that lacks the gene necessary for termination of the phage particle. These strands cross-link with one another via the coiled-coil interactions of proteins displayed on the phage coat.
+<br><br>
+<u>Figure 2: Electron micrograph of <i>E. coli</i> with polyphage hairs </u> <br> Our goal is to get these hairs to cross-link via coiled coil interactions.  (Despite what it may look like, these are not cross-linking.)
+<br>
 <img style="float: left;" src="https://static.igem.org/mediawiki/2010/b/b1/Hairy_cells.jpg" title="Image from: Rakonjac and Model, Roles of pIII in Filamentous Phage Assembly, 1998"><div style="font-size:8pt"><i>Rakonjac and Model, 1998</i></div>