GORASP1 and legionellosis: Legionella infection-induced GRASP55 and GRASP65 PR-ubiquitination was lost when cells were infected with Legionella ∆sidEs, and was increased in cells infected with the Legionella ΔdupA/B (Fig. 4C, D), thus, confirming that SidE family effectors are essential for PR-ubiquitination of host substrate proteins.