FIGURE 1.
Cytoplasmic CueO does not contain detectable copper. A, affinity purification of Strep-tagged CueO from the cytoplasm of strain MC4100/pBW-matCueO-strep. Coomassie-stained SDS-PAGE of purification fractions are shown. C, cytoplasm; W, last wash fraction. The CueO band and the positions of marker proteins are indicated. B, UV-visible absorption spectrum of CueO as purified from the cytoplasm, showing the absence of copper cofactor absorption. C, titration of CuSO4 to apo-CueO (as shown in B) and gradual increase of the type 3 and type 1 copper absorption signals.