Fructose increases the resistance of Rhodobacter capsulatus to the toxic oxyanion tellurite through repression of acetate permease (ActP)

The highly toxic oxyanion tellurite (TeO3 (2-)) enters the cells of the facultative photosynthetic bacterium Rhodobacter capsulatus through an acetate permease. Here we show that actP gene expression is down-regulated by fructose and this in turn determines a strong decrease of tellurite uptake and a parallel increase in the cells resistance to the toxic metalloid (from a minimal inhibitory concentration of 8 mu M up to 400 mu M tellurite under aerobic growth conditions). This demonstrates that there exists a direct connection between the level of tellurite uptake and the sensitivity of the cells to the oxyanion.