is a toxin-antitoxin module located on chromosomes of most bacteria. MazF toxins are endoribonucleases antagonized by MazE antitoxins. Previously， we characterized several quorum sensing peptides called "xtracellular eath actors" (EDFs). When secreted from bacterial cultures， EDFs induce interspecies cell death. EDFs also enhance the endoribonucleolytic activity of MazF. carries several modules. Among them， the endoribonucleolytic activities of MazF proteins mt-1， mt-3， and mt-6 were identified. MazF-mt6 and MazF-mt-3 cleave rRNAs. Here we report the effects of EDFs on the endoribonucleolytic activities of MazFs. EDF (EDF) and the three EDFs (EDFs) individually enhance the endoribonucleolytic activities of MazF-mt6 and MazF-mt3 and overcome the inhibitory effect of MazE-mt3 or MazE-mt6 on the endoribonucleolytic activities of the respective toxins. We propose that these EDFs can serve as a basis for a novel class of antibiotics against is one of the leading causes of death from infectious disease. is highly drug resistant， and drug delivery to the infected site is very difficult. In previous studies， we showed that xtracellular eath actors (EDFs) can work as quorum sensing molecules which participate in interspecies bacterial cell death. In this study， we demonstrated the role of different EDFs in the endoribonucleolytic activities of MazFs. EDF (EDF) and the three EDFs (EDFs) individually enhance the endoribonucleolytic activities of MazF-mt6 and MazF-mt3. The current report provides a basis for the use of the EDF peptides EDF and EDF as novel antibiotics against .