title: Influence of operator site geometry on transcriptional control by the YefM-YoeB toxin-antitoxin complex.
abstract: YefM-YoeB is among the most prevalent and well-characterized toxin-antitoxin complexes. YoeB toxin is an endoribonuclease whose activity is inhibited by YefM antitoxin. The regions 5' of yefM-yoeB in diverse bacteria possess conserved sequence motifs that mediate transcriptional autorepression. The yefM-yoeB operator site arrangement is exemplified in Escherichia coli: a pair of palindromes with core hexamer motifs and a center-to-center distance of 12 bp overlap the yefM-yoeB promoter. YefM is an autorepressor that initially recognizes a long palindrome containing the core hexamer, followed by binding to a short repeat. YoeB corepressor greatly enhances the YefM-operator interaction. Scanning mutagenesis demonstrated that the short repeat is crucial for correct interaction of YefM-YoeB with the operator site in vivo and in vitro. Moreover, altering the relative positions of the two palindromes on the DNA helix abrogated YefM-YoeB cooperative interactions with the repeats: complex binding to the long repeat was maintained but was perturbed to the short repeat. Although YefM lacks a canonical DNA binding motif, dual conserved arginine residues embedded in a basic patch of the protein are crucial for operator recognition. Deciphering the molecular basis of toxin-antitoxin transcriptional control will provide key insights into toxin-antitoxin activation and function.
authors.affiliation: Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom.
authors.forename: Simon E S
authors.initials: SE
authors.lastname: Bailey
authors.forename: Finbarr
authors.initials: F
authors.lastname: Hayes
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D020349:Surface Plasmon Resonance; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C484519:YefM protein, E coli; C504245:YoeB protein, E coli