Biomedical Beat - A monthly digest of research news from NIGMS

IN THIS ISSUE . . .
July 16, 2008

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The National Institute of General Medical Sciences (NIGMS), one of the National Institutes of Health, supports all research featured in this digest. Although only the lead scientists are named, coworkers and other collaborators also contributed to the findings. To read additional news items, visit NIGMS News. To check out free NIGMS publications, go to the order form.

Cool Image: Engineered Ecosystem

Courtesy of Hao Song, Duke University.
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“Predator” bacteria (green) surround “prey” bacteria (red) in this petri dish version of the Serengeti. Rather than eating their prey, however, predator cells release a chemical that activates a suicide gene in the prey. Prey cells also release a chemical, but one that promotes survival of the predators. Researchers genetically programmed the cells to “communicate” with each other in this way and function as a synthetic ecosystem. The artificial system acts as an experimental model and can help us understand behaviors in more complex, natural ecosystems. Courtesy of Hao Song, Duke University.

Full story
Arnold lab home page
Article abstract (from the April 15 online issue of Molecular Systems Biology)

Lean, Green Amine Machine

A gold catalyst promotes the addition of ammonia to organic compounds. Courtesy of Guy Bertrand.
A gold catalyst promotes the addition of ammonia to organic compounds. Courtesy of Guy Bertrand.
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University of California, Riverside chemists have developed an economical and environmentally-friendly method for making amines, organic compounds found in many drugs and vitamins and used to make plastics, cosmetics, solvents, and detergents. Until now, the commercial production of amines, which are derived from ammonia, has led to large amounts of waste byproducts. Guy Bertrand and his team made the process greener and cheaper by using a tiny, reusable amount of gold to catalyze the addition of ammonia to certain organic compounds, leading to amine formation. The work could guide the discovery of similar catalytic processes that use even cheaper, more plentiful organic compounds for making amines.

Full story
Bertrand lab home page
Article abstract (from the June 4 online issue of Angewandte Chemie)

Viral DNA Gets “Knotty” to Infect

A donut-shaped twist of DNA (red) wedges the viral genome tightly within the protein tail structure of a bacteriophage. Courtesy of Jinghua Tang.
A donut-shaped twist of DNA (red) wedges the viral genome tightly within the protein tail structure of a bacteriophage. Courtesy of Jinghua Tang.
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Viruses are highly efficient infection machines, and now a collaborative team led by structural biologist Timothy Baker of University of California, San Diego has gained insight into how a virus infects its host. After recording thousands of microscopic images of frozen particles from a bacteriophage, the team found an unlikely twist of DNA sitting in the neck of the virus. This knot, or toroid, remains poised under a pressure about 20 times greater than an uncorked champagne bottle. Researchers suspect the toroid remains wedged in until the virus docks onto a host and injects its DNA through the cell wall. This distorted DNA structure has never been seen or previously predicted in a virus.

This work also was supported by NIH’s National Institute of Dental and Craniofacial Research.

Full story
Baker lab home page
Article abstract (from the June 2008 issue of Structure)

Protein Enables DDT Resistance

Models of CYP6Z1 (green) and another protein (brown) with the predicted binding of DDT shown in ball-and-stick format. Courtesy of Sanjeewa G. Rupasinghe and Michael Hallock.
Models of CYP6Z1 (green) and another protein (brown) with the predicted binding of DDT shown in ball-and-stick format. Courtesy of Sanjeewa G. Rupasinghe and Michael Hallock.
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The insecticide DDT has been used to control the mosquitoes that spread malaria since World War II. But some mosquito strains have developed resistance to DDT and, as a result, survive to spread the disease. Now, molecular biologist and biochemist Mary Schuler and her colleagues at the University of Illinois at Urbana-Champaign have identified a protein in mosquitoes that metabolizes and inactivates DDT. Schuler and her team used molecular modeling to predict the configuration and action of the protein, CYP6Z1. Results suggest that inhibiting this DDT-metabolizing protein could prevent mosquitoes from developing resistance and thus improve pest control efforts and help prevent the transmission of malaria.

Full story
Schuler lab home page
Article abstract (from the July 1 issue of PNAS)

Finding the Middle Ground

This movie shows that some proteins (darker colors) are more likely to be modified by Aurora B. Courtesy of Rockefeller University. This movie shows that some proteins (darker colors) are more likely to be modified by Aurora B. Courtesy of Rockefeller University.
Full movie
This movie shows that some proteins (darker colors) are more likely to be modified by Aurora B. Courtesy of Rockefeller University.

Note: You may need to download the free Quicktime player to view the movie.

During a final stage of cell division, the cell membrane pinches inward in the middle. To do this, the cell’s proteins must find the center. According to new work by Rockefeller University chemist Tarun Kapoor, the activity of the enzyme Aurora B charts the path. A key regulator of mitosis, Aurora chemically modifies proteins by attaching phosphate groups to them during the process of phosphorylation. By engineering biosensors that could track the enzyme’s activity, Kapoor and his colleagues found that proteins in the middle of the cell were more likely to be phosphorylated, suggesting that Aurora provides a map to the center of the cell.

Full story
Kapoor lab home page
Article abstract (from the June 19 issue of Nature)