Quantification of intracellular ATP and ADP levels.

<p>Intracellular ATP (A, C) and ADP (B, D) levels were quantified in the WT (grey histograms) and the <i>phoP</i> mutant (white histograms) grown on a Pi proficient (A, B) or Pi limited (C, D) medium. The error bars the represent the standard deviation of at least three independent experiments.