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Team:Grenoble-EMSE-LSU/Documentation/Biobricks
From 2013.igem.org
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<h3>Main Functions</h3><br> | <h3>Main Functions</h3><br> | ||
| - | <p>KillerRed is a red fluorescent protein, meaning that by illuminating it with wavelengths from a certain portion of the visible spectrum, it re-emits light in another portion with longer (less energetic) wavelengths. Below is the absorption and emission spectra for the KillerRed protein:</p><br><br> | + | <p>KillerRed is a red fluorescent protein [1], meaning that by illuminating it with wavelengths from a certain portion of the visible spectrum, it re-emits light in another portion with longer (less energetic) wavelengths. Below is the absorption and emission spectra for the KillerRed protein:</p><br><br> |
<p align="center"><img src="https://static.igem.org/mediawiki/2013/7/7f/KillerRed_spectra2.png" alt="Killer Red absorption-emission spectra" width="500px"></p><br> | <p align="center"><img src="https://static.igem.org/mediawiki/2013/7/7f/KillerRed_spectra2.png" alt="Killer Red absorption-emission spectra" width="500px"></p><br> | ||
<p id="legend"><strong><em>The KillerRed protein absorption (left peak) and emission (right peak) spectra</em></strong><br> | <p id="legend"><strong><em>The KillerRed protein absorption (left peak) and emission (right peak) spectra</em></strong><br> | ||
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<p>From the emission and absorption spectra, we can determine that the protein absorbs in the green portion of the spectrum with a peak at 585 nm and emits in the red portion of the spectrum with a peak at 610 nm, hence the name "KillerRed".<br> | <p>From the emission and absorption spectra, we can determine that the protein absorbs in the green portion of the spectrum with a peak at 585 nm and emits in the red portion of the spectrum with a peak at 610 nm, hence the name "KillerRed".<br> | ||
Emitted light from bacteria is proportional to the amount of protein in the cells. This allows for measuring protein concentration in a cell culture.<br><br> | Emitted light from bacteria is proportional to the amount of protein in the cells. This allows for measuring protein concentration in a cell culture.<br><br> | ||
| - | The | + | The most interesting function of the protein however is that it emits ROS (Reactive Oxygen Species) when fluorescing.[1]<br> |
ROS are highly unstable and react chemically with many substrates including proteins, lipids and DNA. These reactions are oxidative and damage the affected molecules, making ROS toxic to the cell. With sufficient amounts of ROS, a cell's essential components can be damaged beyond repair, and the cell killed. Thus illuminating KillerRed-expressing cells with light in the green portion of the visible spectrum kills them, a mechanism that we use to control cell density in a culture. | ROS are highly unstable and react chemically with many substrates including proteins, lipids and DNA. These reactions are oxidative and damage the affected molecules, making ROS toxic to the cell. With sufficient amounts of ROS, a cell's essential components can be damaged beyond repair, and the cell killed. Thus illuminating KillerRed-expressing cells with light in the green portion of the visible spectrum kills them, a mechanism that we use to control cell density in a culture. | ||
</p> | </p> | ||
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<h3>Structure</h3><br><br> | <h3>Structure</h3><br><br> | ||
| - | <p>In order to understand why KillerRed has its unique properties it is necessary to look at its structure. The protein is remarkably similar to other fluorescent proteins like GFP <em>(Aequorea victoria></em> and dsRed <em>(Discosoma striata)</em>, featuring a beta-barrel housing a central alpha helix with the fluorescent chromophore at its center. Normally the chromophore is protected from the outside environment by the protein shell, but this isn't the case with KillerRed. | + | <p>In order to understand why KillerRed has its unique properties it is necessary to look at its structure. The protein is remarkably similar to other fluorescent proteins like GFP <em>(Aequorea victoria></em> and dsRed <em>(Discosoma striata)</em>, featuring a beta-barrel housing a central alpha helix with the fluorescent chromophore at its center[2]. Normally the chromophore is protected from the outside environment by the protein shell, but this isn't the case with KillerRed. |
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<em><strong>Source: RCSB protein database entries <a href="http://www.rcsb.org/pdb/explore/explore.do?structureId=2WIQ">2WIQ</a> and <a href="http://www.rcsb.org/pdb/explore/explore.do?structureId=2VAD">2VAD</a>.</strong><em></p><br> | <em><strong>Source: RCSB protein database entries <a href="http://www.rcsb.org/pdb/explore/explore.do?structureId=2WIQ">2WIQ</a> and <a href="http://www.rcsb.org/pdb/explore/explore.do?structureId=2VAD">2VAD</a>.</strong><em></p><br> | ||
| - | <p>KillerRed is a 240 amino acid protein with a 3D structure similar to other fluorescent proteins, with an eleven-strand beta-barrel surrounding an alpha-helix containing the chromophore, source of the protein's | + | <p>KillerRed is a 240 amino acid protein with a 3D structure similar to other fluorescent proteins, with an eleven-strand beta-barrel surrounding an alpha-helix containing the chromophore, source of the protein's fluorescence and photoxicity.<br> |
KillerRed has a DsRed-type chromophore formed with residues 67Q (glutamine), 68Y (tyrosine), and 69G (glycine), to make QYG. The corresponding coding sequence can be found at the code segment CAGTACGGC.<br><br> | KillerRed has a DsRed-type chromophore formed with residues 67Q (glutamine), 68Y (tyrosine), and 69G (glycine), to make QYG. The corresponding coding sequence can be found at the code segment CAGTACGGC.<br><br> | ||
| - | The interesting properties of the protein are directly related to a unique structural difference among fluorescent proteins, consisting in an open channel linking the chromophore to the environment outside the protein. According to litterature, this is the reason KillerRed is able to produce 1000-fold more reactive oxygen species compared to EGFP which is another ROS-producing fluorescent protein. | + | The interesting properties of the protein are directly related to a unique structural difference among fluorescent proteins, consisting in an open channel linking the chromophore to the environment outside the protein. According to litterature, this is the reason KillerRed is able to produce 1000-fold more reactive oxygen species compared to EGFP which is another ROS-producing fluorescent protein.[2] |
</p> | </p> | ||
<h3>Origin</h3> | <h3>Origin</h3> | ||
| - | <p>KR was originally engineered from the anm2CP anthomedusa chromoprotein by individual amino acid mutations in order to obtain fluorescence and | + | <p>KR was originally engineered from the anm2CP anthomedusa chromoprotein by individual amino acid mutations in order to obtain fluorescence and phototoxicity.[1] |
</p> | </p> | ||
</li> | </li> | ||
Revision as of 16:11, 19 September 2013
