title: The Escherichia coli extracellular death factor EDF induces the endoribonucleolytic activities of the toxins MazF and ChpBK.
abstract: Escherichia coli (E. coli) mazEF is a toxin-antitoxin (TA) stress-induced module that mediates cell death requiring the quorum-sensing pentapeptide NNWNN designated EDF (extracellular death factor). E. coli toxin MazF is a sequence-specific endoribonuclease cleaving single-stranded mRNAs at ACA sequences. E. coli ChpBK, a toxin homologous to MazF, is a sequence-specific endoribonuclease cleaving single-stranded mRNAs at ACA, ACG, and ACU sequences. Here we report that, in vitro, the signaling molecule EDF significantly amplifies the endoribonucleolytic activities of both MazF and ChpBK. EDF also overcomes the inhibitory activity of the antitoxins MazE over the toxin MazF and ChpBI over ChpBK. EDF sequence is important for both functions. Moreover, direct sequence-specific binding of EDF to MazF has been confirmed. Peptide-protein modeling revealed parallel contacts between EDF-MazF and MazE-MazF. These findings are intriguing, since most known quorum-sensing molecules monitor gene expression on the transcriptional level, while EDF monitors posttranscriptionally.
authors.affiliation: Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: Maria
authors.initials: M
authors.lastname: Belitsky
authors.forename: Haim
authors.initials: H
authors.lastname: Avshalom
authors.forename: Ariel
authors.initials: A
authors.lastname: Erental
authors.forename: Idan
authors.initials: I
authors.lastname: Yelin
authors.forename: Sathish
authors.initials: S
authors.lastname: Kumar
authors.forename: Nir
authors.initials: N
authors.lastname: London
authors.forename: Michal
authors.initials: M
authors.lastname: Sperber
authors.forename: Ora
authors.initials: O
authors.lastname: Schueler-Furman
authors.forename: Hanna
authors.initials: H
authors.lastname: Engelberg-Kulka
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C422954:MazE protein, E coli; C422955:MazF protein, E coli; D009842:Oligopeptides; C528802:asparagyl-aspargyl-tryptophyl-asparagyl-asparagine; D004722:Endoribonucleases; C503487:ChpBK protein, E coli