Discovery of armored viruses may inspire new designs for nanotechnology

September 21, 2000

Anyone suffering from a cold knows how tough and persistent viruses can be.

Now scientists have discovered that one type of virus actually comes equipped with an armored coat made of interlocking rings of protein.

The structure of this virus - remarkably similar to chain mail suits worn by medieval knights - had been predicted but never directly observed in a protein until now. Researchers say the discovery could have applications for the booming field of nanotechnology.

The armored virus was detected by an international team of scientists from Stanford, the Scripps Research Institute, the University of Pittsburgh and the University of Uppsala in Sweden. Their findings are published in the Sept. 22 issue of the journal Science.

A typical virus consists of little more than a chromosome of DNA or RNA wrapped in a protein coat.

Although viruses are among the simplest microbes, determining their molecular structure requires very sophisticated instrumentation.

The authors of the Science study used special micro-imaging techniques to analyze the outer coating of a virus called bacteriophage HK97.

Bacteriophages are viruses that only infect bacteria. They come in very bizarre shapes, some of which resemble NASA-designed satellites or Martian landers.

HK97 is no exception. It has an odd, balloon-shaped head attached to a short tail. Analyzing this strange protein exterior required both electron microscopy and X-ray crystallography, says Hiro Tsuruta, a senior research associate with the Stanford Synchrotron Radiation Laboratory (SSRL) and the Department of Chemistry.

"The head of the virus is thousands of times narrower than a human hair," adds Tsuruta, a co-author of the Science study.

With the help of a small angle X-ray diffraction instrument at SSRL, Tsuruta and his colleagues were able to determine that HK97's head is made of 72 protein rings - 12 pentagons and 60 hexagons - locked together to form a protective coating that surrounds the virus's DNA.

"Its protein rings are cross-linked in a manner similar to the five-ring Olympic symbol," observes Tsuruta. "Together, the rings form a rigid, spherical cage shaped like a 20-sided soccer ball."

This unique chain-link structure makes the HK97 virus extraordinarily stable, adds Scripps biologist John E. Johnson, a co-author of the Science study.

"The head is organized exactly like medieval armor," says Johnson, referring to the chain mail suits worn by knights in the Middle Ages. These protective outfits - made of interwoven rings of iron - were designed to deflect arrows while allowing maximum freedom of movement during battle.

The protein armor discovered in HK97 may have a similar function, allowing the virus mobility while protecting its precious cargo of DNA.

"The virus has developed a very clever way of keeping its DNA intact," notes Tsuruta.

Interlocking molecular rings, called catenanes, are an important focus of biochemical research. Johnson points out that HK97's catenane structure should be of particular interest for nanotechnology, where engineers and scientists are designing new devices that will operate at the atomic scale.

"People are looking at viruses as containers," notes Johnson, "and the chain mail structure could provide a novel way to create a container that's very thin yet stable.

"No one expected that proteins could do this," adds Johnson, "and now we know they can."
-end-
9/19/00

COMMENT: Hiro Tsuruta, Stanford Synchrotron Radiation Laboratory
(650) 926-3104
e-mail tsuruta@slac.stanford.edu

EDITORS: Tsuruta's study, "Bacteriophage HK97 capsid formed by topologically linked protein rings," appears in the Sept. 22 issue of Science magazine

Other contributors to the Science study are lead author William R. Wikoff of the Scripps Research Institute; Lars Liljas of the University of Uppsala; and Robert L. Duda and Roger W. Hendrix of the University of Pittsburgh.

Stanford University

Related Nanotechnology Articles from Brightsurf:

Hiring antibodies as nanotechnology builders
Researchers at the University of Rome Tor Vergata recruit antibodies as molecular builders to assemble nanoscale structures made of synthetic DNA.

Nanotechnology delivers hepatitis B vaccine
X-ray imaging shows that nanostructured silica acts as a protective vehicle to deliver intact antigen to the intestine so that it can trigger an immune response.

Want in on nanotechnology? Capitalize on collaborative environments
Patent law experts demonstrate that private-public partnerships lead to promising innovation output measured in patents.

Nanotechnology makes it possible for mice to see in infrared
Mice with vision enhanced by nanotechnology were able to see infrared light as well as visible light, reports a study published Feb.

Healing kidneys with nanotechnology
In new research appearing in the journal Nature Biomedical Engineering, Hao Yan and his colleagues at the University of Wisconsin-Madison and in China describe a new method for treating and preventing Acute Kidney Injury.

A treasure trove for nanotechnology experts
A team from EPFL and NCCR Marvel has identified more than 1,000 materials with a particularly interesting 2-D structure.

Nanotechnology could redefine oral surgery
A trip to the dentist or orthodontist usually instills a sense of dread in most patients, and that's before the exam even begins.

MEDLINE indexes Pharmaceutical Nanotechnology
Pharmaceutical Nanotechnology, an important journal published by Benthm Science, is accepted to be included in MEDLINE.

Nanotechnology and nanopore sequencing
DNA is the hereditary material in our cells and contains the instructions for them to live, behave, grow, and develop.

Nanotechnology: Lighting up ultrathin films
Based on a study of the optical properties of novel ultrathin semiconductors, researchers of Ludwig-Maximilians-Universitaet in Munich have developed a method for rapid and efficient characterization of these materials.

Read More: Nanotechnology News and Nanotechnology Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.