Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Fluorescence or flexibility

Figure 1: Comparison of the bright (DronpaB) and dark (DronpaD) states of the Dronpa protein. In the bright state, the chromophore (green) is tethered to the molecule by a hydrogen bond (dotted blue line), while in the dark state the hydrogen bond is gone and the chromophore can vibrate. 

Copyright © 2008 Atsushi Miyawaki
Figure 1: Comparison of the bright (DronpaB) and dark (DronpaD) states of the Dronpa protein. In the bright state, the chromophore (green) is tethered to the molecule by a hydrogen bond (dotted blue line), while in the dark state the hydrogen bond is gone and the chromophore can vibrate.
Copyright © 2008 Atsushi Miyawaki

Abstract:
Researchers shed light on the molecular mechanism responsible for fluorescent and dark states of a genetically engineered protein

Fluorescence or flexibility

Japan | Posted on October 25th, 2008

Some organic substances have a property called photochromism, meaning that their absorption spectrum, or color, changes when they are exposed to certain types of light. In particular, a new artificial protein called Dronpa shows great promise for applications because it can be switched back and forth between a ‘bright' state and a ‘dark' state. Now Atsushi Miyawaki, Hideaki Mizuno at the RIKEN Brain Science Institute in Wako and co-workers1 have explained for the first time exactly what causes Dronpa to move between these two states.

Dronpa was developed by Miyawaki and colleagues by genetic engineering on a wild coral protein. Usually Dronpa absorbs light of around 503 nanometers wavelength and emits green fluorescence—the so-called bright state. However if it is exposed to strong radiation at 488 nanometers it converts into the dark state, which emits no fluorescence. The protein will switch back to the bright state if it is re-irradiated at an even shorter wavelength.

"Such reliable photochromism for Dronpa prompted us to develop it for information storage with the ability to record, erase, or read information," says Miyawaki. However to date no-one has proven exactly what causes the photochromism.

To unlock this mystery the researchers used nuclear magnetic resonance (NMR) spectroscopy to study the Dronpa molecule, which takes a cylindrical shape called a β-barrel, like other fluorescent proteins. They discovered that the bright and dark states arise from interactions between the β-barrel and the chromophore—the part of the molecule responsible for light absorption.

In the bright state, the chromophore is tightly tethered to the β-barrel by a hydrogen bond (Fig. 1). This holds the chromophore in a rigid, flat configuration, so that when it is excited by light it releases its excess energy by fluorescing.

When the dark state is induced, the hydrogen bond is lost and the chromophore becomes much more flexible. Therefore it releases the excess energy by vibrating instead of fluorescing.

In other compounds that have been studied, photochromism results from physical rearrangements of atoms in the molecules. This is the first time that photochromism has been linked to structural flexibility.

"We present a new molecular mechanism for photochromism of a fluorescent protein," says Miyawaki. "The mechanism requires a special microenvironment involving a β-barrel, a structure not present in organic photochromic compounds."

Miyawaki hopes that Dronpa could eventually be used in very high-resolution optical microscopy. "The next stage will be to develop many mutants of Dronpa with different photochromic properties," he says.
Reference

1. Mizuno, H., Mal, K.T., Wälchli, M., Kikuchi, A., Fukano, T., Ando, R., Jeyakanthan, J., Taka, J., Shiro, Y., Ikura, M. & Miyawaki, A. Light-dependent regulation of structural flexibility in a photochromic fluorescent protein. Proceedings of the National Academy of Sciences USA 105, 9927-9932 (2008).
The corresponding author for this highlight is based at the RIKEN Laboratory for Cell Function Dynamics

####

For more information, please click here

Copyright © Riken

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 Links

article

Related News Press

News and information

CubeSat Structures Competition Opens Space Design to Students of the World December 16th, 2017

Record high photoconductivity for new metal-organic framework material December 15th, 2017

Error-free into the quantum computer age December 15th, 2017

Leti Will Demonstrate First 3D Anti-Crash Solution for Embedding in Drones: Fitted on a Mass-Market Microcontroller, 360Fusion Software Technology Detects any Dynamic Obstacle and Helps Guide Drones Away from Collisions December 15th, 2017

Imaging

Perking up and crimping the 'bristles' of polyelectrolyte brushes December 13th, 2017

JPK Instruments announce partnership with Swiss company, Cytosurge AG. The partnership makes Cytosurge’s FluidFM® technology available on the JPK NanoWizard® AFM platform December 8th, 2017

Researchers advance technique to detect ovarian cancer: Rice, MD Anderson use fluorescent carbon nanotube probes to achieve first in vivo success November 30th, 2017

Deben reports on a new publication from scientists at La Trobe University in Australia where their CT500 stage is used in micro scanning tomography experiments to better understand ceramic matrix composites under load November 29th, 2017

Discoveries

Quantum memory with record-breaking capacity based on laser-cooled atoms December 15th, 2017

Record high photoconductivity for new metal-organic framework material December 15th, 2017

Error-free into the quantum computer age December 15th, 2017

Synthetic protein packages its own genetic material and evolves computationally designed protein assemblies are advancing research in synthetic life and in targeted drug delivery December 15th, 2017

Announcements

CubeSat Structures Competition Opens Space Design to Students of the World December 16th, 2017

Record high photoconductivity for new metal-organic framework material December 15th, 2017

Error-free into the quantum computer age December 15th, 2017

Leti Will Demonstrate First 3D Anti-Crash Solution for Embedding in Drones: Fitted on a Mass-Market Microcontroller, 360Fusion Software Technology Detects any Dynamic Obstacle and Helps Guide Drones Away from Collisions December 15th, 2017

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