How the signal from light triggers biological action in bacteria
Sunlight is the basis for all life on Earth so it should come as no surprise that many organisms have developed complex systems for detecting the quality and quantity of light in their environment. Plants, fungi, and many species of bacteria use light-sensitive proteins called phytochromes to control biological functions that respond to changes in light. In the bacterial species Deinococcus radiodurans, a red/far-red-light absorbing phytochrome controls the production of light-protective pigments. The structure of the phytochrome in the resting state has been solved, but the question of how the signal from light gets transformed into a biological action has remained elusive. Now, in work that was carried out at the BioCARS beamline 14-ID-B at the U.S. Department of Energy's Advanced Photon Source, as well as at the European Synchrotron Radiation Facility and the Swiss Light Source, researchers have collected structural data on the active state of the phytochrome sensory...