Histone modification cross talk between a host and pathogen

Abstract

Significance Bacterial pathogens reprogram host gene expression by delivering effector proteins that modify chromatin, but it is not known how the host epigenetic environment impacts effector function. Here, we show that the Legionella effector RomA senses and responds to the host’s existing epigenetic landscape and is selectively active only in specific chromatin contexts through mechanisms resembling those used by eukaryotic chromatin regulators. Notably, we uncover that RomA utilizes cis-histone and trans-histone cross talk mechanisms previously observed only in eukaryotic systems. These reveal an unexpected form of host–pathogen cross talk in which bacterial effector activity can be constrained by host epigenetic modifications.