Scripps research scientists identify blood component that turns bacteri...(bicarbonate transporter pathway may be i...)

"How a bacterium recognizes signals in the host that trigger pathogenesis mechanisms, and the nature of the mechanisms necessary to develop pathogenesis, remain poorly understood," said Scripps Research Associate Professor Marta Perego, Ph.D., who conducted the study with Scripps Research postdoctoral fellow Adam Wilson, Ph.D., and colleagues. "We have identified an essential component for the induction of virulence gene expression in response to host bicarbonate levels and have used this finding to learn more about the extracellular and intracellular signals controlling virulence."

Theory Confirmed

Perego's latest discovery builds on her lab's expertise in the study of bacterial virulence signaling and in the regulatory networks responsible for pathogenicity in other gram-positive bacteria. Her interest in bicarbonate transport pathways as bacteria virulence signaling mechanisms grew out of an early observation that growth of B. anthracis in carbon dioxide and sodium bicarbonate strongly induced toxin production in the laboratory setting. The mechanism behind this observation, however, was never uncovered.

"It was observed that the best medium for toxin production was one that people believed mimicked conditions found in the blood of a human or animal host, where anthrax bacteria would find both carbon dioxide and bicarbonate. But we've never known which of these two molecules was the more important for bacterial pathogenesis, and whether this belief was correct," Perego said. "Now, we know that it is bicarbonate and that the growth in the presence of bicarbonate really mimics the host growth conditions."

In their current study, the Perego lab identified a previously unknown ATP-binding cassette transporter (ABC-transporter)which is identified by the gene number BAS2714-12that was shown to be essential to transpor
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