Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Structural basis for photoswitching in fluorescent proteins brought into focus

12.04.2007
UO discovery likely to advance uses of these already revolutionary molecules

University of Oregon scientists have identified molecular features that determine the light-emitting ability green fluorescent proteins, and by strategically inserting a single oxygen atom they were able to keep the lights turned off for up to 65 hours.

The findings, published online this week by the Proceedings of the National Academy of Sciences, likely are applicable to most photoswitchable fluorescent proteins, said S. James Remington, professor of physics and member of the UO Institute of Molecular Biology.

"This new model makes specific predictions and improves the qualities of the protein as a photo-switchable label," Remington said. "It gives us the first picture of how these molecules can be switched on and off. That allows us to design new variants to make the proteins more useful."

... more about:
»fluorescent »oxygen atom »structure

For more than a decade, fluorescent proteins – first isolated in jellyfish and since found in a variety of colors from coral reef organisms – revolutionized molecular biology, allowing scientists to use them as markers for genetic expression, to locate molecules and observe activity within cells.

The recent discovery of photoswitchable fluorescent proteins – which can be manipulated with a laser – has been a significant development for cellular research.

"Photoswitchable fluorescent proteins have tremendous advantages over passive proteins," Remington said. "You can label all molecules but using a laser under a microscope, you can activate only a small group of them. That lets you follow the motion of subsets of molecules. We wanted to understand the process, so that we can permanently switch them off and on or vary the time delay."

However, he said, the mechanism of photoswitching was unknown, and in many cases the proteins returned to their stable state randomly and spontaneously.

Using a combination of rational mutagenesis and directed evolution, UO doctoral student J. Nathan Henderson determined high-resolution crystal structures of both the on and off states of a fluorescent protein isolated from a sea anemone.

In the stable or fluorescent state of the molecule, two side chains of atoms align in a coplanar fashion, flat and in orderly fashion. When hit with bright laser light, the researchers observed that the protein rapidly went dark as the rings rotated about 180 degrees and flip by some 45 degrees, coming to rest in a non-coplanar and unstable alignment. The two structures gave the researchers a chance to observe changes in the interactions between neighboring groups.

Remington said that in the dark state, the molecule absorbs ultraviolet light and doesn't emit any light at all. However, when the chromophore (a group of atoms and electrons forming part of an molecule) absorbs ultraviolet light, it occasionally ionizes and become negatively charged. This causes the rings to flip back into the fluorescent state.

Having control of light emission would allow for more precise studies within cells, he said.

Henderson studied the structures, noticing that in the dark state there was an unfavorable interaction where carbon and oxygen atoms were adjacent to each other. "Nathan looked at this and wondered what would happen if an oxygen atom was inserted at a precise place," Remington said. "That would make for a favorable interaction that stabilized the dark state. Based on the structure, Henderson made a single mutation that delays the switch-on time from five minutes to 65 hours.

Eventually, he added, the ability to control the on-off states could lead to improvements in optical memory, such as single molecule information storage, in addition to enhancing microscopic work and molecular labeling.

Jim Barlow | EurekAlert!
Further information:
http://www.uoregon.edu
http://morel.uoregon.edu/facres/remington.html

Further reports about: fluorescent oxygen atom structure

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>