A regulatory role for Staphylococcus aureustoxin–antitoxin system PemIKSa

摘要

Toxin–antitoxin systems were shown to be involved in plasmid maintenance when they wereinitially discovered, but other roles have been demonstrated since. Here we identify andcharacterize a novel toxin–antitoxin system (pemIKSa) located on Staphylococcus aureusplasmid pCH91. The toxin (PemKSa) is a sequence-specific endoribonuclease recognizing thetetrad sequence UkAUU, and the antitoxin (PemISa) inhibits toxin activity by physicalinteraction. Although the toxin–antitoxin system is responsible for stable plasmidmaintenance our data suggest the participation of pemIKSa in global regulation of staphylococcalvirulence by alteration of the translation of large pools of genes. We propose acommon mechanism of reversible activation of toxin–antitoxin systems based on antitoxintranscript resistance to toxin cleavage. Elucidation of this mechanism is particularlyinteresting because reversible activation is a prerequisite for the proposed general regulatoryrole of toxin–antitoxin systems.