May 08, 2015 |
Altering genes with the aid of light
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(Nanowerk News) Scientists have been manipulating genes for a while. The University of Pittsburgh's Alexander Deiters just found a way to control the process with higher precision.
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By using light.
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Deiters and his group are the first to achieve this. The resulting paper was recently published in the Journal of the American Chemical Society ("Optical Control of CRISPR/Cas9 Gene Editing").
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Since 2013, scientists have used a gene-editing tool called CRISPR/Cas9. The method employs a bacterially derived protein (Cas9) and a synthetic guide RNA to induce a double-strand break at a specific location in the genome. This enables excision of a gene, alteration of its function, or introduction of desired mutations.
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In practice, the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats of DNA base sequences) method has shown tremendous promise to enable researchers to treat cystic fibrosis and sickle-cell anemia, create laboratory animals that mimic human disease, and create a strain of wheat resistant to powdery mildew.
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Deiters, professor of chemistry in Pitt's Kenneth P. Dietrich School of Arts and Sciences, along with colleagues at the University of North Carolina at Chapel Hill, have, through a series of experiments, found a lysine residue (lysine is an amino acid) in Cas9 that can be replaced with a light-activated analog.
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The approach developed by Deiters generates a Cas9 protein that is functionally inactive, so called "caged," until the cage is removed through light exposure, activating the enzyme and thereby activating gene editing.
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"This method may allow people to engineer genes in cells or animals with better spatial and temporal control than ever before," Deiters says. "Previously, if you wanted to knock out a gene, you had limited control over where and when it would happen. Engineering a light switch into Cas9 provides a more precise editing tool. You can say, 'In this cell, at this time point, is where I want to modify the genome.'"
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The improved control over the time and location at which a gene will be manipulated, Deiters says, may help eliminate "off-target effects" and could potentially enable genetic studies with unprecedented resolution.
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