Fig. 2.

Growth effects of mutants altered in the iron-sparing response. (A) The iron-sparing response is adaptive under severe iron limitation. Cell density after overnight growth under severe iron limitation (Chelex-treated glucose minimal medium with 1 μM EDDHA). Under these conditions, the fur mutant grows better than wild-type, but a fur mutant additionally lacking either fsrA or all three protein chaperones grew poorly. (B) Cell iron content (in micrograms of Fe per milligram of soluble protein) as determined by using spectrophotometric analysis of ferrozine-iron complexes.