FIGURE 5.

IpaH9.8 possesses two distinct Ubc5B∼ubiquitin thioester binding sites. A, double reciprocal plots of initial rates of ¹²⁵I-ubiquitin conjugation determined as in Fig. 3 under IpaH9.8-limiting conditions in assays containing 5 nm IpaH9.8 and the indicated concentrations of Ubc5B in the absence (closed circles) or presence (open circles) of 270 nm Ubc5BC85S-¹²⁵I-ubiquitin oxyester. B, double reciprocal plot of initial rates of ¹²⁵I-ubiquitin conjugation determined as in Fig. 3 under IpaH9.8-limiting conditions in assays containing 2.5 nm IpaH9.8 and the indicated concentrations of Ubc5B in the absence (closed circles) or presence (open circles) of 3.5 μm Ubc5BC85A product analog.