A Eukaryotic-like Serine/Threonine Kinase Protects Staphylococci against Phages

International audienceOrganisms from all domains of life are infected by viruses, the most abundant biological entities on earth. In eukaryotes, Serine/Threonine kinases play a central role in antiviral response. Bacteria, however, are not commonly known to use protein phosphorylation as part of their defense against phages. Here we identify Stk2, a Serine/Threonine kinase that provides efficient immunity against bacteriophages in staphylococci through abortive infection. A phage protein of unknown function activates the kinase activity of Stk2 when expressed in the cell. This leads to the phosphorylation of several proteins involved in translation, global transcription control, cell cycle control, stress response, DNA topology, DNA repair and central metabolism. Cells die as a consequence of Stk2 activation, thereby preventing phage propagation to the rest of the bacterial population. Our work shows that mechanisms of viral defense that rely on protein phosphorylation constitute an antiviral strategy conserved across domains of life.