Turned off ABC transporter keeps toxins from forming in mice, claims PLoS Pathogens article.

Scientists from the Scripps Research Institute have discovered a key chemical that signals Bacillus anthracis to become lethal. Without the presence of the bicarbonate transporter in the bloodstream, the bacteria do not become virulent.

An ATP-binding cassette transporter (ABC-transporter), identified by the gene number BAS2714-12, was shown to be essential to transporting bicarbonate. When the genes that code for the BAS2714-12 ABC transporter were deleted, the rate of bicarbonate uptake inside the cell greatly decreased, induction of toxin gene expression did not occur, and virulence in a mouse model of infection was abolished.

Scientists have known for some time that bicarbonate is implicated in many diseases, but were not certain whether bicarbonate, carbon dioxide, or some combination of these two molecules are responsible for triggering bacterial pathogenesis. Because in this study the elimination of carbon dioxide production within the bacterial cell had no effect on toxin production, it seems carbon dioxide activity is not essential to virulence factor induction.

That is significant because other pathogenic bacteria such as Streptococcus pyogenes, Escherichia coli, Borrelia burgdorferi, and Vibrio cholera have bicarbonate transport pathways similar to Bacillus anthracis and thus are likely to have similar virulence triggering mechanisms.

The study was published in the November 21 edition of PLoS Pathogens.

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