Light-induced changes in photosensory proteins

December 4, 2018, Charité - Universitätsmedizin Berlin
When light hits a phytochrome, a complex process of transformation is triggered which changes the 3D structure of the protein. Credit: Scheerer/Charité

Researchers from Charité - Universitätsmedizin Berlin have demonstrated on a molecular level how a specific protein allows light signals to be converted into cellular information. Their findings have broadened the understanding of how plants and bacteria adapt to changes in light conditions that regulate essential processes such as photosynthesis. Their research has been published in Nature Communications.

Phytochromes are proteins that are responsible for converting into cellular information. Found in plants, fungi and bacteria, these photoreceptors use light to regulate fundamental physiological processes. Phytochromes contain a light-sensitive tetrapyrrole molecule known as chromophore that changes its form when exposed to light of a very specific wavelength. The protein detects these changes and implements further structural rearrangements. Activation and deactivation pathways are triggered in response to light, resulting in a complex process of structural transformation.

The researchers used X-ray crystallography to determine the 3-D structure of a dark-adapted phytochrome and went on to compare this structure with its light-adapted state. To do this, the researchers started by creating a crystalline form of the protein, which they then irradiated with X-rays. Via , the researchers were able to calculate the position of atoms inside the molecule. Results of their work show the contribution of individual amino acids in the light-induced activation and deactivation of these proteins. "Our research has delivered fundamental structural data, which will enhance our understanding of the way environmental signals are transmitted into an organism. These are important insights, particularly if we hope to be in a position to use photoreceptors for future clinical applications," explains the study's lead researcher, Dr. Patrick Scheerer.

One potential application would be in the field of oncology, where photoreceptors might be used to visualize cancerous tissues. This would be based on their ability to absorb and emit light in the red and near-infrared regions of the visible spectrum. Given that near-infrared light has a greater depth of penetration in human tissues, phytochromes could be used to visualize deeper-lying tissue cells non-invasively and without side effects. Photoreceptors could also prove suitable as light-controlled tools to treat genetic diseases at the . In order to explore these potential applications further, Dr. Scheerer and his team hope to use future research studies to gain a better understanding of phytochrome fluorescence (another property of these photoreceptors), as well as exploring other aspects of their structural transformation.

Explore further: The many structures of the light-active biomolecules

More information: Andrea Schmidt et al, Structural snapshot of a bacterial phytochrome in its functional intermediate state, Nature Communications (2018). DOI: 10.1038/s41467-018-07392-7

Related Stories

The many structures of the light-active biomolecules

October 9, 2018

How the light-sensitive part of the biomolecule phytochrome changes from a light-adapted state to a dark-adapted state has been investigated by researchers at Ruhr-Universität Bochum and Philipps-Universität Marburg. So ...

Light-sensitive 'eyes' in plants

May 5, 2014

Most plants try to turn towards the sun. Scientists from the University of Gothenburg have worked with Finnish colleagues to understand how light-sensitive proteins in plant cells change when they discover light. The results ...

How plants see light

January 19, 2018

Plants react sensitively to changes in their surroundings and possess the ability to adapt to them. They use the photoreceptor protein phytochrome B to see light and then regulate processes such as seed germination, seedling ...

Recommended for you

Researchers engineer a tougher fiber

February 22, 2019

North Carolina State University researchers have developed a fiber that combines the elasticity of rubber with the strength of a metal, resulting in a tougher material that could be incorporated into soft robotics, packaging ...

A quantum magnet with a topological twist

February 22, 2019

Taking their name from an intricate Japanese basket pattern, kagome magnets are thought to have electronic properties that could be valuable for future quantum devices and applications. Theories predict that some electrons ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.