NEWS OF THE WEEK
COPPER CAPTURE METAL SENSING: A copper-sensitive
protein controls gene transcription in a who's who of pathogens
Giedroc
This protein helps bacteria respond to copper.
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HE NEED FOR COPPER is an Achilles'heel of pathogenic bugs, and researchers have just dis covered the mechanism by which bacteria may control this vulnerability. Bacteria require both Cu(I) and Cu(II) to survive, but too much copper.creates harmful reactive oxygen species. The human immune system capitalizes on this distinction by sequestering bacterial invaders in macrophages, which have been reported to have large quantities of copper. Biochemists at Texas A&M University and their colleagues now have identified and characterized a protein called GsoR that allows the causative agent of tuberculo sis—and likely close to 200 other bacterial species, includ ing Staphylococcus aureus, the culprit in many antibiotic-resistant hospital infections—to respond to copper (Nat. Chem. Bio., DOI: io.i038/nchembio844). They find that CsoR normally sits on bacterial DNA
DOE PROMOTES NUCLEAR ENERGY REPROCESSING PROPOSED: Spent
fuel would be 'recycled' until delayed repository opens Sell
EGINNING CONSTRUCTION of the first U.S. > nuclear power plant in more than 30 years and 1 convincing the public that the government can handle!nuclear waste are key Bush Administration en ergy policy goals for its last 800 days in office, accord ing to Clay Sell, deputy secretary of the Department of Energy. Sell spoke on Dec. 5 to a conference of several hun dred nuclear advocates, drawn together by the promise of the Administration's proposed Global Nuclear Energy Partnership. GNEP would have the U.S. lead an international partnership to expand use of nuclear energy and to reprocess spent nuclear fuel for reuse throughout the world. Currently, however, the U.S. by law may not reprocess spent fuel and must place it in an underground repository. But Sell laid out a new U.S. nuclear waste program
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in a dimer formation until reduced copper binds the protein. The bound Cu(I) forms a trigonally coordi nated complex that in turn triggers a conformational change, releasing the protein from the DNA. CsoR's departure allows the bacterial transcription machinery to turn on a selection of genes, one of which appears to encode a protein pump that kicks out copper, says David P. Giedroc, one of the researchers. When copper levels are low again, CsoR settles back on its DNA spot and blocks gene transcription again. "This stellar work may have uncovered what amounts to the primary copper-sensing proteins in the vast majority of bacteria," comments P. John Hart, a biochemist at the University of Texas, San Antonio. "Research about copper homeostasis and its role in biofilm formation, virulence, and infection is still in its infancy," adds Marc Solioz, from the University of Berne, in Switzerland. "CsoR provides us with a new, potentially interesting lead." To boot, when the researchers solved the X-ray crystal structure of CsoR, they found that it has an "all a-helical structure that has not been seen for any pro tein before," Solioz says. "CsoR possesses a novel DNA binding fold. This may lead us to novel copper homeostatic genes and copper-regulated genes. The descrip tion of CsoR has clearly opened a new door." Next up, Giedroc's group is trying to character ize the function of CsoR in other pathogenic bacteria and identify other genes turned on by copper-bound CsoR.—SARAH EVERTS
that will undertake reprocessing and reuse of spent fuel while work goes forward on the long-stalled Yucca Mountain repository in Nevada. Under the most opti mistic scenarios, the repository will not open until 2017 to 2020, Sell said. Meanwhile, the Bush Administration wants nuclear power to advance. "We think we can develop—on a temporary basis— the consolidation of spent nuclear fuel at several U.S. recycling locations where it can be dealt with and where we can extract great energy value while we are working on the long-term goal of licensing and building a perma nent geological repository," Sell said. "Let's be real about 'temporary/ " he added, "we are talking about decades." Some 11 U.S. communities have expressed an inter est in housing a GNEP reprocessing facility, DOE says. Recent changes in congressional leadership will present a stumbling block, particularly in the Senate, where Harry Reid (D-Nev.) will become majority lead er. Reid, although a nuclear power supporter, opposes the waste repository's location in Nevada. The Administration's and nuclear industry's chal lenge, Sell said, is to show Nevada residents that nuclear reprocessing and the repository will be a "tremendously positive thing," with new jobs and a new state industry. "I see a future in Nevada where facilities out there become centers of excellence for some of the most im portant materials in the world."—JEFF JOHNSON
DECEMBER 11, 2006
