Now you can “turn down the brightness” of a fluorescent protein remotely using magnets. Magnetic sensitivity in these engineered proteins can be exploited to remotely control biosensors and develop therapies that can be turned on and off as needed.
“We want to make a toolbox of magnetically remote-controlled protein functions,” says Andrew York, a physicist at the Chan Zuckerberg Biohub in San Francisco, California. York is a co-author of a study published in Nature that demonstrated the activity of magnet-responsive proteins in bacteria, as well as a co-author of a separate preprint study that showcased the use of similar proteins in nematode worms.
York and his former colleague, biochemist Maria Ingaramo, discovered that green fluorescent protein (GFP), a common biomolecule used to label other molecules, dims when exposed to a weak magnetic field. The effect wasn’t noticeable, with just about a percent of dimming achieved. This is when the researchers ventured out to develop a more responsive protein, resulting in MagLOV, which dims by half or more in the presence of a magnet.
A team led by biophysicist Gabriel Abrahams and bioengineer Harrison Steel, both at the University of Oxford, UK, ran tests to explore the optimal use of the MagLOV. They were also interested in identifying the mechanism that conferred magnetic sensitivity to the protein. In experiments reported in the Nature paper, the team points to changes in the quantum properties of the electron pair in the protein induced by a magnetic field, resulting in the drop in brightness.
In Escherichia coli cells expressing MagLOV, this ‘magnetic resonance effect’ enabled the researchers to control fluorescence brightness by combining magnetic fields and radio waves. Next, the scientists used these data to locate the MagLOV-expressing bacterial cells entrapped inside a silicon block by applying a magnetic field of varying strengths. Whether the process is suitable for mapping MagLOV-expressing cells has not yet been determined.
MagLOV can be used to monitor many molecular processes using magnets, as a gene encodes it. Polishing the protein to produce different versions using a method called directed evolution, such as one that responds faster to magnetic fields, is underway. Karen Sarkisyan, a synthetic biologist at the MRC Laboratory of Medical Sciences in London, envisions that proteins such as MagLOV could trigger additional responses beyond fluorescence, revealing a whole new dimension of magnetic sensors and actuators.
Ingaramo, co-founder of Nonfiction Laboratories, a company based in San Francisco, has York as an adviser. Last week, the company reported developing a remote-controlled antibody called MagBodies, whose binding strength can be controlled by a magnet. The aim is to take cues from this research and bring an arsenal of therapies that can be controlled externally.
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