Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Scientists Decipher Structure of Nature’s ‘Light Switch’

Left: The newly derived 3D map of a bacterial phytochrome dimer, produced using cryo electron microscopy. Right: By fitting x-ray crystal structures of several homologous fragments into this map, scientists have created an atomic model of the whole structure. The two monomers making up the complete structure — one shown as a “ribbon” diagram, the other using a space-filling display — dimerize in parallel with the two polypeptides intimately twisting around each other.
Left: The newly derived 3D map of a bacterial phytochrome dimer, produced using cryo electron microscopy. Right: By fitting x-ray crystal structures of several homologous fragments into this map, scientists have created an atomic model of the whole structure. The two monomers making up the complete structure — one shown as a “ribbon” diagram, the other using a space-filling display — dimerize in parallel with the two polypeptides intimately twisting around each other.

Abstract:
New findings will help scientists understand how plants respond to light

Scientists Decipher Structure of Nature’s ‘Light Switch’

Upton, NY | Posted on June 2nd, 2010

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.

####

About Brookhaven National Laboratory
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 Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

For more information, please click here

Contacts:
Karen McNulty Walsh
(631) 344-8350

Peter Genzer
(631) 344-3174

Copyright © Brookhaven National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Quantum model reveals surface structure of water: National Physical Laboratory, IBM and Edinburgh University have used a new quantum model to reveal the molecular structure of water's liquid surface April 20th, 2015

Happily ever after: Scientists arrange protein-nanoparticle marriage: New biotech method could lead to development of HIV vaccine, targeted cancer treatment April 20th, 2015

Nondestructive 3-D Imaging of Biological Cells with Sound April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Quantum model reveals surface structure of water: National Physical Laboratory, IBM and Edinburgh University have used a new quantum model to reveal the molecular structure of water's liquid surface April 20th, 2015

Happily ever after: Scientists arrange protein-nanoparticle marriage: New biotech method could lead to development of HIV vaccine, targeted cancer treatment April 20th, 2015

Engineer improves rechargeable batteries with MoS2 nano 'sandwich' April 18th, 2015

New Biological Nano-Fertilizers Presented in Iran as Appropriate Replacements for Chemical Fertilizers April 18th, 2015

Possible Futures

A glass fiber that brings light to a standstill: By coupling photons to atoms, light in a glass fiber can be slowed down to the speed of an express train; for a short while it can even be brought to a complete stop April 9th, 2015

Nanotechnology in Medical Devices Market is expected to reach $8.5 Billion by 2019 March 25th, 2015

Nanotechnology Enabled Drug Delivery to Influence Future Diagnosis and Treatments of Diseases March 21st, 2015

Nanocomposites Market Growth, Industry Outlook To 2020 by Grand View Research, Inc. March 21st, 2015

Announcements

Happily ever after: Scientists arrange protein-nanoparticle marriage: New biotech method could lead to development of HIV vaccine, targeted cancer treatment April 20th, 2015

Nondestructive 3-D Imaging of Biological Cells with Sound April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Yale-NUS, NUS and UT Austin researchers establish theoretical framework for graphene physics: Making strides towards using graphene to create new electronic devices April 20th, 2015

Research partnerships

Nondestructive 3-D Imaging of Biological Cells with Sound April 20th, 2015

Yale-NUS, NUS and UT Austin researchers establish theoretical framework for graphene physics: Making strides towards using graphene to create new electronic devices April 20th, 2015

Beyond the lithium ion -- a significant step toward a better performing battery April 18th, 2015

Light in a spin: Researchers demonstrate angular accelerating light April 15th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project