Many small molecules, including toxins and some medicines, have flexible structures, which makes it difficult to detect and/or neutralize them. The pain medication fentanyl, for example, can rotate to adopt many shapes. In recent years, fentanyl drug abuse has become increasingly common, and the drug is often illegally produced. The number of deaths caused by fentanyl has risen greatly, which provides a strong reason to find new ways to detect this and other drugs.
Now, Baker et al. have created new sensors that are able to detect fentanyl. First, the 11 most likely shapes that fentanyl could adopt were identified based on known information about the structure of the molecule. Then, a computer program was used to design proteins that were predicted to strongly bind to these most common shapes. Next, genes that coded for these proteins were synthesized in the laboratory and introduced into bacteria, which read the genes to build the proteins.
Similar to a well-fitted lock and key, the shape of the newly designed protein had to complement a likely shape of the fentanyl molecule. Baker et al. used a technique called X-ray crystallography to visualize the proteins in atomic detail and confirm that these fentanyl-binders matched their corresponding computational models. Those proteins that bound fentanyl best were then engineered into plant cells, and later into whole plants, together with reporter systems that gave signals when the sensors detected fentanyl.
In future, these specifically synthesized proteins could be integrated into entire panels of plants or other systems to detect toxins and other harmful chemicals. Such systems would be of interest in a medical setting and for detecting environmental contamination.
This digest was originally published at eLife \cite{1} and is reproduced under a CC BY 4.0 license.