Extracellular Death Factor is a symmetrical linear five-peptide, its amino acid sequence is H-Asn-Asn-Trp-Asn-Asn-OH (NNWNN). The 5 amino acids of each EDF are symmetrically distributed, and the asparagine at the end of the peptide chain is very important for mazEF (a kind of bacterial chromosome)-mediated killing activity. EDF is the only individual that can initiate mazEF-mediated cell death signal molecule. EDF is currently the only single signal molecule involved in E. coli quorum sensing, and EDF is also a special type of molecule related to gram-positive bacteria quorum sensing peptide.