Streptococcus pneumoniae infection promotes histone H3 dephosphorylation by modulating host PP1 phosphatase

Pathogenic bacteria can alter host gene expression through post-translational modifications of histones. We show for the first time that a natural colonizer, Streptococcus pneumoniae, also induces specific histone modifications, including robust dephosphorylation of histone H3 on serine 10, during infection of respiratory epithelial cells. Two bacterial factors are important for the induction of this modification: the bacterial toxin PLY, a pore-forming toxin, and the pyruvate oxidase SpxB, an enzyme responsible for H2O2 production. The combined effects of PLY and H2O2 lead to host signaling which culminates in H3S10 dephosphorylation, mediated by the host cell phosphatase PP1. Strikingly, S. pneumoniae infection induces dephosphorylation and associated activation of PP1 catalytic activity. Colonization of cells, which lacked active PP1, resulted in the impairment of intracellular S. pneumoniae survival. Interestingly, PP1 activation mediating H3S10 dephosphorylation is not restricted to S. pneumoniae and appears to be a general epigenomic mechanism favoring intracellular survival.