A unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex.

TitleA unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex.
Publication TypeJournal Article
Year of Publication2016
AuthorsSterckx, 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
JournalJ Mol Biol
Volume428
Issue8
Pagination1589-603
Date Published2016 Apr 24
ISSN1089-8638
KeywordsAmino 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
Abstract

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.

DOI10.1016/j.jmb.2016.03.007
Alternate JournalJ. Mol. Biol.
PubMed ID26996937
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