RT Journal Article SR Electronic T1 “mazEF mediated programmed cell death in Escherichia coli”: is it? JF bioRxiv FD Cold Spring Harbor Laboratory SP 048728 DO 10.1101/048728 A1 Bhaskar Chandra Mohan Ramisetty A1 Swati Raj A1 Dimpy Ghosh YR 2016 UL http://biorxiv.org/content/early/2016/04/14/048728.abstract AB Toxin-antitoxins systems (TAS) are prokaryotic operons containing two small overlapping genes which encode two components referred to as Toxin and Antitoxin. Involvement of TAS in bacterial programmed cell death (PCD) is highly controversial. MazEF, a typical type II TAS, is particularly implicated in mediating PCD in Escherichia coli. Hence, we compared the metabolic fitness and stress tolerance of E. coli strains (MC4100 and its mazEF- derivative) which were extensively used by proponents of mazEF- mediated PCD. We found that both the strains are deficient in relA gene and that the ΔmazEF strain has lower fitness and stress tolerance compared to wild type MC4100. Furthermore, these strains are likely not isogenic. We could not reproduce mazEF mediated PCD which emphasizes the need for skeptic approach to the PCD hypothesis.