|Title||A unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Sterckx, Y. G. - J., T. Jové, A. V. Shkumatov, A. Garcia-Pino, L. Geerts, M. De Kerpel, J. Lah, H. De Greve, L. Van Melderen, and R. Loris|
|Journal||J Mol Biol|
|Date Published||2016 Apr 24|
|Keywords||Amino Acid Sequence, Antitoxins, Bacterial Toxins, Calorimetry, Chromatography, Gel, Crystallography, X-Ray, DNA Gyrase, Enterotoxins, Escherichia coli O157, Escherichia coli Proteins, Molecular Conformation, Molecular Sequence Data, Phylogeny, Protein Multimerization, Surface Plasmon Resonance|
Many bacterial pathogens modulate their metabolic activity, virulence and pathogenicity through so-called "toxin-antitoxin" (TA) modules. The genome of the human pathogen Escherichia coli O157 contains two three-component TA modules related to the known parDE module. Here, we show that the toxin EcParE2 maps in a branch of the RelE/ParE toxin superfamily that is distinct from the branches that contain verified gyrase and ribosome inhibitors. The structure of EcParE2 closely resembles that of Caulobacter crescentus ParE but shows a distinct pattern of conserved surface residues, in agreement with its apparent inability to interact with GyrA. The antitoxin EcPaaA2 is characterized by two α-helices (H1 and H2) that serve as molecular recognition elements to wrap itself around EcParE2. Both EcPaaA2 H1 and H2 are required to sustain a high-affinity interaction with EcParE2 and for the inhibition of EcParE2-mediated killing in vivo. Furthermore, evidence demonstrates that EcPaaA2 H2, but not H1, determines specificity for EcParE2. The initially formed EcPaaA2-EcParE2 heterodimer then assembles into a hetero-hexadecamer, which is stable in solution and is formed in a highly cooperative manner. Together these findings provide novel data on quaternary structure, TA interactions and activity of a hitherto poorly characterized family of TA modules.
|Alternate Journal||J. Mol. Biol.|
A unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex.