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De Jonge, N, Simic, M, Buts, L, Haesaerts, S, Roelants, K, Garcia-Pino, A, Sterckx, Y, De Greve, H, Lah, J and Loris, R (2012) Alternative interactions define gyrase specificity in the CcdB family. Mol. Microbiol. 84:965-78


Toxin-antitoxin (TA) modules are small operons associated with stress response of bacteria. F-plasmid CcdB(F) was the first TA toxin for which its target, gyrase, was identified. Plasmidic and chromosomal CcdBs belong to distinct families. Conserved residues crucial for gyrase poisoning activity of plasmidic CcdBs are not conserved among these families. Here we show that the chromosomal CcdB(Vfi) 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.


PubMed Online version:10.1111/j.1365-2958.2012.08069.x


Aliivibrio fischeri/enzymology; Aliivibrio fischeri/genetics; Aliivibrio fischeri/metabolism; Amino Acid Substitution; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; DNA Gyrase/antagonists & inhibitors; Models, Molecular; Mutagenesis, Site-Directed; Mutant Proteins/genetics; Mutant Proteins/metabolism; Plasmids; Protein Conformation; Protein Interaction Mapping; Substrate Specificity



Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status


GO:0008657: DNA topoisomerase (ATP-hydrolyzing) inhibitor activity



Fig 2. Shows CcdBvfi as a stabalizer of inhibitor activity. It is combined with different concentrations of CcdAvfi, and DNA gyrase to show the inhibition of DNA gyrase activity when CcdAvfi and CcdAvfi are unable to bind in a one to one ratio.

CACAO 8710

See also


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