Rhodopsin Mimic Advances Light-Sensitive Artificial Cell Design

An artificial mimic of a key light-sensitive molecule could enable techniques for building light-sensitive artificial cells.

Professor Jonathan Clayden and colleagues in the University of Bristol's School of Chemistry, along with collaborators at the universities of Manchester and Hull, created an artificial mimic of rhodopsin, a protein that resides in cell membranes in the retina. The absorption of light by rhodopsin is the first step in the biochemistry of vision.

Scientists mimic the way the eye perceives light using a synthetic molecule. Courtesy of the School of Chemistry, University of Bristol.

Using molecular design features taken from some antibiotic molecules that also bind to membranes, the researchers were able to design and build a molecule that finds its way into a membrane and switches between different shapes in response to light of specific wavelengths.

Working with the dynamic properties of foldamers — synthetic molecules that mimic folded biomolecules — has mainly been done in free solution, but here the team reported on the design, synthesis, and conformational behavior of photoresponsive foldamers bound in a phospholipid bilayer akin to a biological membrane phase.

The foldamers contained a chromophore, which could be switched between two configurations by different wavelengths of light, attached to a helical oligoamide that both promoted membrane insertion and communicates conformational change along its length.

Light-induced structural changes in the chromophore were translated into global conformational changes, detected by monitoring the solid state 19F nuclear magnetic resonance signals of a remote fluorine-containing residue located 1 to 2 nm away. The behavior of the foldamers in the membrane phase was similar to that of analogous compounds in organic solvents, the researchers said.

The work revealed that unlike many natural molecules, these artificial structures have similar properties in solution and in membranes, making the prediction of their behavior more reliable.

Clayden said this is the first time an artificial mimic of rhodopsin has been created, and that the discovery could enable light-sensitive artificial cells and allow scientists to bypass the usual communication mechanisms used by cells.

The research was published in Science (doi: 10.1126/science.aad8352).