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Pneumonia-causing pathogen from copper.

Bacterial pathogens like Streptococcus pneumoniae--responsible for infections that include pneumonia, meningitis, and sepsis--have evolved various strategies to limit copper levels in their cells to prevent toxicity.

"Copper is highly reactive metal and is carefully handled by all cells that require it," points out David Giedroc, professor of chemistry at Indiana University, Bloomington. "There is emerging evidence to suggest that human cells use copper toxicity as a weapon to kill microbial pathogens. The novel copper trafficking system that we describe in our study represents a new functional twist on an evolutionary ancient family of proteins that opens up a potential new antibacterial strategy."

Giedroc and his coworkers describe the structure and function of the protein Cup A as a chaperone that buffers copper to very low concentration--in turn protecting S. pneumoniae from damage.

"We're proposing that the primary role of CupA in S. pneumoniae is to bind copper ions near the plasma membrane as soon as they enter the cell and, after diffusion of copper-bound CupA in the membrane, to deliver copper directly to the exporter CopA, which extrudes copper out of the cell."

Copper chaperones are known to exist in all cells, from bacteria to humans. In this report, the authors describe a completely novel way in which a copper chaperone and a domain of a copper recipient target protein, CopA, bind copper. Using nuclear magnetic resonance spectroscopy--a technique to obtain mechanistic and structural information about molecules --they are able to determine the pathway by which copper is transferred from CupA to CopA.

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Title Annotation:Pathogens
Publication:USA Today (Magazine)
Article Type:Brief article
Geographic Code:1USA
Date:Jun 1, 2013
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