Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists decipher structure of nature's 'light switch'

01.06.2010
New findings will help scientists understand how plants respond to light

When the first warm rays of springtime sunshine trigger a burst of new plant growth, it's almost as if someone flicked a switch to turn on the greenery and unleash a floral profusion of color.

Opening a window into this process, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and collaborators at the University of Wisconsin, Madison, have deciphered the structure of a molecular "switch" much like the one plants use to sense light. Their findings, described online in the Proceedings of the National Academy of Sciences the week of May 31, 2010, help explain how the switch works and could be used to design new ways to modify plant growth.

Previous studies showed that the light-sensing structure, called a phytochrome, exists in two stable states. Each state is sensitive to a slightly different wavelength, or color, of light — from red to "far red," which is close to the invisible infrared end of the light spectrum. As the phytochrome absorbs photons of one wavelength or the other, it changes shape and sends signals that help plants know when to flower, produce chlorophyll, and grow.

"The phytochrome is almost like nature's light switch," said Brookhaven biophysicist Huilin Li, who is also an associate professor at Stony Brook University and a lead author on the study. "Finding out how this switch is flipped on or off by a signal as subtle as a single photon of light is fascinating."

As with all biological molecules, one key to the phytochrome's function is its structure. But scientists trying to get a molecular-level picture of a phytochrome have a formidable challenge: The phytochrome molecule is too dynamic to capture in a single image using techniques like x-ray crystallography. So, scientists have studied only the rigid and smaller pieces of the molecule, yielding detailed, but fragmented, information.

Now using additional imaging and computational techniques, the Brookhaven researchers and their collaborators have pieced together for the first time a detailed structure of a whole phytochrome.

Li and his collaborators studied a phytochrome from a common bacterium that is quite similar in biochemistry and function to those found in plants, but easier to isolate. Plant biologist Richard Vierstra of the University of Wisconsin provided the purified samples.

At Brookhaven, Li's group used two imaging techniques. First, they applied a layer of heavy metal dye to the purified phytochrome molecules to make them more visible, and viewed them using an electron microscope. This produced many two-dimensional images from a variety of angles to give the researchers a rough outline of the phytochrome map.

The scientists also froze the molecules in solution to produce another set of images that would be free of artifacts from the staining technique. For this set of images, the scientists used a cryo-electron microscope.

Using computers to average the data from each technique and then combine the information, the scientists were able to construct a three-dimensional map of the full phytochrome structure. The scientists then fitted the previously determined detailed structures of phytochrome fragments into their newly derived 3-D map to build an atomic model for the whole phytochrome.

Though the scientists knew the phytochrome was composed of two "sister" units, forming a dimer, the new structure revealed a surprisingly long twisted area of contact between the two individual units, with a good deal of flexibility at the untwisted ends. The structure supports the idea that the absorption of light somehow adjusts the strength or orientation of the contact, and through a series of conformation changes, transmits a signal down the length of the molecular interface. The scientists confirmed the proposed structural changes during photo-conversion by mutagenesis and biochemical assay.

The scientists studied only the form of the phytochrome that is sensitive to red light. Next they plan to see how the structure changes after it absorbs red light to become sensitive to "far red" light. Comparing the two structures will help the scientists test their model of how the molecule changes shape to send signals in response to light.

This research was supported by Brookhaven's Laboratory Directed Research and Development program, the National Institutes of Health, the National Science Foundation, and a grant from the University of Wisconsin College of Agricultural and Life Science.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation of State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more: http://www.bnl.gov/newsroom

Karen McNulty Walsh | EurekAlert!
Further information:
http://www.bnl.gov

More articles from Life Sciences:

nachricht Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>