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January 16, 2008
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After 9 years of intense effort, a collaborative research team has succeeded in dissecting the structure of the nuclear pore complex (NPC), an assembly of 456 proteins that controls the flow of molecules between the DNA-storing nucleus and the rest of the cell. This video highlights 30 different types of proteins found in the donut-shaped complex from yeast. The work—led by Andrej Sali of the University of California, San Francisco, and Michael P. Rout and Brian Chait of Rockefeller University—may shed light on the function and evolution of the NPC and other large protein assemblies. Video featured by permission from Macmillan Publishers Ltd: Nature 450:695-701, 2007.
Researchers have determined that cancer cells are "softer" than healthy cells. Nanotechnologist James Gimzewski of the University of California, Los Angeles, collected fluid from the chest cavities of people with lung, breast, and pancreatic cancers. Using a powerful microscope with a thin, sharp tip on a spring to gently poke individual cells and measure their stiffness, he found that cancer cells are more pliable than healthy ones. This discovery may offer a more precise way to detect cancer cells, since current methods rely mostly on appearance, which does not differ much between healthy and cancerous cells.
This work also was supported by NIH's National Cancer Institute.
A new computer program can predict likely drug side effects before clinical studies begin. Developed by pharmacologist Philip Bourne and computational biologist Lei Xie at the University of California, San Diego, the technique uses three-dimensional molecular structures to predict interactions between drug molecules and thousands of human proteins. With the program, Bourne's team learned that the anticancer drug tamoxifen binds to both its intended target and another protein, possibly explaining why the drug can cause cardiac abnormalities, blood clots, and eye problems. In the future, scientists could use the computer program to help them develop drugs with fewer side effects.
The H5N1 strain of avian flu virus has infected several hundred people, but person-to-person transmission has been limited. Work led by biological engineer Ram Sasisekharan of the Massachusetts Institute of Technology suggests that to infect and sustain its spread in people, the virus must adapt so that it can latch onto a certain set of sugars, or glycans, coating human upper respiratory tract cells. The researchers found that human-adapted flu viruses bind mainly to long and umbrella-shaped glycans, while avian flu viruses bind to short and cone-shaped ones. This knowledge could help track key mutations in the H5N1 virus and point to new therapeutic targets for both seasonal and pandemic flu.
When bacterial cells divide, small DNA molecules called plasmids that encode antibiotic resistance genes are distributed into the two resulting daughter cells. Biochemist Maria Schumacher of the University of Texas M.D. Anderson Cancer Center has now determined the looplike structure of a molecular complex that is key to the distribution process. The finding may lead to new strategies for defeating antibiotic resistance and offer insights on how other types of cells distribute their genetic material.