FIGURE 6.

Neither GAr₁₀ substrate nor its intermediate degradation product is trapped by ClpX. Shown is competition between I27-GAr₁₀-GFP-ssrA and GFP-ssrA for degradation by ClpXP. Each substrate was added at ∼13-fold molar excess to ClpXP complex. After a 5- or 60-min preincubation of ClpXP (0.3 μm ClpX hexamer and 0.7 μm ClpP tetradecamer) with Cy3-labeled I27-GAr₁₀-GFP-ssrA substrate (2 μm), Cy5-labeled GFP-ssrA (2 μm) was added. The time course of degradation of GFP-ssrA was monitored (left). Time-dependent GFP-ssrA degradation was quantified and plotted (right). ClpXP degradation of labeled GFP-ssrA was determined after early (5 min) or late (60 min) addition or (as control) with no addition of GAr₁₀ substrate. Error bars, S.D.