Figure 2.

Temporal regulation of effector activity by effectors. (A) Regulation of SidH by LubX. The expression of lubX does not become apparent until after several hours postinfection. This ubiquitin E3 ligase functions with the host machinery to ubiquitinate SidH, resulting its degradation by the proteasome. (B) Regulation of SidEs by SidJ. SidEs catalyze the ubiquitination of RTN4 or ER-associated Rab small GTPases such as Rab33b whereas SidJ reverses such modification by its phosphodiesterase activity. In the early phase of infection, the ratio between translocated SidEs and SidJ favors ubiquitination of relevant substrates, which is beneficial for the biogenesis of the LCV. Several hours after bacterial uptake, the activity of SidJ becomes dominant due to higher amount of translocated protein, which reverses the ubiquitination imposed by the SidEs.