Researchers Find Color Sensitive Atomic Switch in Bacteria
Researchers using extremely high resolution imaging have found an atomic switch capable of discriminating color in a bacterial membrane protein.
In a paper posted today on Science Express, the rapid advance publication page of Science, scientists from The University of Texas Medical School at Houston and the University of California , Irvine , describe the versatile light-sensing protein at levels of resolution smaller than a nanometer – one billionth of a meter.
“High-resolution X-ray crystallography revealed the light-absorbing part of the protein was present in two alternative positions, suggesting to us that light of different colors drives this protein back and forth between two differently colored states of the protein,” said corresponding author John L. Spudich, Ph.D., director of the Center for Membrane Biology in the UT Medical School Department of Biochemistry and Molecular Biology. “Chemical analysis and spectroscopic methods then proved that the switch, buried in the middle of this membrane-embedded protein, similar in structure to our visual pigments, is controlled by blue versus orange photon absorption.” Spudich said.
That function makes the protein novel among its family of light-sensing proteins known as rhodopsins, which are present in microbes and higher animals. In human eyes, rhodopsin is the light-absorbing pigment of the rods, located in the retina. The team studied a new-found rhodopsin on the surface membrane of the bacterium Anabaena, classified as “blue-green algae” or cyanobacteria, which rely on photosynthesis to generate energy.
Having a single sensory protein capable of distinguishing color would provide Anabaena with information about the color of light available in its environment, enabling more efficient harvesting of light for photosynthesis, Spudich said. “Understanding rhodopsins helps us understand the large number of related membrane receptors involved in cell signaling that govern biological functions,” Spudich said. In the longer term, the novel protein found in Anabaena has the potential to be used in nano-machinery as a color-sensor; however the authors point out that this practical application is years in the future.
First author of the paper is Lutz Vogeley, a graduate student in the UC Irvine Department of Molecular Biology and Biochemistry. Senior authors are Dr. Spudich and Dr. Hartmut Luecke, Ph.D., professor of molecular biology and biochemistry and of physiology and biophysics at UC-Irvine. Co-authors include Oleg Sineshchekov, Ph.D., of Moscow State University in Russia, and visiting professor in the UT Center for Biology, and research fellow Vishwa Trivedi, Ph.D., and Jun Sasaki, Ph.D., assistant professor, both of the UT Center for Membrane Biology. “One of the key frontiers of biomedical science in the genomic era is the crucial role of cell membranes in normal cell function and disease states,” said Spudich, who holds the Robert A. Welch Distinguished Chair in Chemistry and is a professor in the UT Graduate School of Biomedical Sciences. “Ask virtually any investigator and youll find his or her research program bumps up against a membrane.”
Cell membrane surfaces and their exposed proteins are the most accessible targets to treat human tissue or destroy infectious microbes, he said. More than 60 percent of medications target membrane proteins on human cells and many antibiotics target membranes on pathogens.
Scott Merville | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
Larsen C Ice Shelf rift finally breaks through
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...