Alternative interactions define Gyrase specificity in the CcdB family

Natalie De Jonge, Mario Simic, Lieven Buts, Sarah Haesaerts, Kim Roelants, Abel Garcia Pino, Yann Sterckx, Henri De Greve, Jurij Lah, Remy Loris

Research output: Contribution to journalArticle

11 Citations (Scopus)


Toxin-antitoxin (TA) modules are small operons associated with stress response of bacteria. F-plasmid CcdBF was the first TA toxin for which its target, gyrase, was identified. Plasmidic and chromosomal CcdB's form distinct families. Conserved residues crucial for gyrase poisoning activity of plasmidic CcdB's are not conserved among these families. Here we show that the chromosomal CcdBVfi from Vibrio fischeri is an active gyrase poison that interacts with its target via an alternative energetic mechanism. Changes in the GyrA14 binding surface of the Vibrio and F-plasmid CcdB family members illustrate neutral drift where alternative interactions can be used to achieve the same functionality. Differences in affinity between V. fischeri and F-plasmid CcdB for gyrase and their corresponding CcdA antitoxin possibly reflect distinct roles for TA modules located on plasmids and chromosomes.
Original languageEnglish
Pages (from-to)965-978
Number of pages14
JournalMol. Microbiol.
Issue number5
Publication statusPublished - 2012


  • structural biology
  • complementary methods in structural biology
  • biophysics
  • toxin-antitoxin module
  • gyrase poison
  • plasmid addiction
  • protein-protein interaction
  • bacterial stress response
  • bacterial toxin


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