MecA-(121–218) stimulates the ATPase activity of ClpC. A, MecA-(121–218) stimulated the ATPase activity of ClpC in a concentration-dependent manner. At 0.3 μm ClpC, the ATPase activity reached a maximum of 0.34 μm/s with a saturating amount of MecA-(121–218). B, the full-length MecA protein stimulated the ATPase activity of ClpC in a concentration-dependent manner. At 0.3 μm ClpC, the maximal ATPase activity was 0.3 μm/s. C, MecA-(121–218) stimulated the ATPase activity of ClpC to a similar extent as the full-length MecA protein.