Light-induced changes in photosensory proteins

December 03, 2018

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

Phytochromes are proteins, which are responsible for converting light 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, which 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 triggered in response to light result in phytochrome undergoing a complex process of structural transformation.

Researchers from Charité's Institute of Medical Physics and Biophysics were able to shed light on the structural transformations taking place. The researchers used X-ray crystallography to determine the 3D structure of a dark-adapted phytochrome photoreceptor 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. By protein structural analysis 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 how 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 particular application 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 in a non-invasive and side effect-free manner. Photoreceptors could also prove suitable as light-controlled tools, which could be used to treat genetic diseases at the molecular level. 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.
* Schmidt et al. Structural snapshot of a bacterial phytochrome in its functional intermediate state. Nature Communications. 2018 Nov 21. doi: 10.1038/s41467-018-07392-7

Charité - Universitätsmedizin Berlin

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to