Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Discover DNA Knot Keeps Viral Genes Tightly Corked Inside Shell

19.06.2008
A novel twist of DNA may keep viral genes tightly wound within a capsule, waiting for ejection into a host, a high-resolution analysis of its structure has revealed.

Using electron microscopy and three-dimensional computer reconstruction, UC San Diego biologists and chemists have produced the most detailed image yet of the protein envelope of an asymmetrical virus and the viral DNA packed within, they report this week in the journal Structure. The image, with a resolution of less than a nanometer, or a millionth of a millimeter, will help to unravel how the virus locks onto its host and infects the cells by injecting its DNA.

By assembling more than 12,000 microscopic views of frozen viral particles from different angles, UCSD chemists Jinghua Tang, Norman Olson and Timothy Baker, a professor of chemistry and biological sciences, have determined the structure of a bacteriophage called phi29 with a resolution finer than 8 Angstroms (one Angstrom equals a tenth of a nanometer). Their project was part of a long-term collaboration with molecular virologist Dwight Anderson and his colleagues at the University of Minnesota.

Although the structures of spherical viruses with a high degree of symmetry have been resolved using similar methods, many more images were required to accomplish the same task for the head-and-tail shape of phi29. The UCSD scientists said their images of phi29 are twice as fine as those created in previous efforts to visualize viruses with a similar shape.

... more about:
»DNA »structure

A comparison between images of the virus with and without its DNA cargo revealed that the DNA twists tightly into a donut shape, or toroid, in the neck of the virus between its head and tail. “This highly distorted DNA structure is unlike anything previously seen or even predicted in a virus,” said Timothy Baker who headed the research team. “It’s an improbably tight turn for DNA, which is generally considered inflexible over very small distances.”

During assembly of the virus, a molecular motor in the neck winds the DNA strand into a tight coil within the head. “It’s under tremendous pressure -- about 20 times that of champagne in a bottle,” said Tang, the lead author of the paper.

The knot-like shape of the toroid, along with interlocking bumps in the protein envelope, may keep the DNA wedged into the capsid until the virus docks onto the host cell.

"It's poised in this tube waiting to go through the bacterial wall," Baker said. "All of the components work together to create an infection machine."

Susan Brown | EurekAlert!
Further information:
http://www.ucsd.edu

Further reports about: DNA structure

More articles from Life Sciences:

nachricht Water world
20.11.2017 | Washington University in St. Louis

nachricht Carefully crafted light pulses control neuron activity
20.11.2017 | University of Illinois at Urbana-Champaign

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>