Modification of plant immune complexes by pathogen effectors can trigger strong immune responses mediated by the action of nucleotide binding-leucine rich repeat immune receptors. Although some strains of the pathogen Pseudomonas syringae harbor effectors that individually can trigger immunity, the plant’s response may be suppressed by other virulence factors. This work shows a new strategy for immune suppression. After injection into host cells, the suppressing effector binds to and acetylates multiple members of an immune complex, including another effector that on its own can trigger immunity. Acetylations modify serine, threonine, lysine and/or histidine residues in the targets resulting in the inactivation of the whole immune complex and increased growth of the pathogen.