Small-Angle X-Ray Scattering- and Nuclear Magnetic Resonance-Derived Conformational Ensemble of the Highly Flexible Antitoxin PaaA2.

Yann Sterckx, Oleksandr Volkov, Wim Vranken, Jaka Kragelj, Malene Ringkjøbing Jensen, Lieven Buts, Abel Garcia Pino, Thomas Jove, Laurence Van Melderen, Martin Blackledge, Nico Van Nuland, Remy Loris

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Antitoxins from prokaryotic type II toxin-antitoxin modules are characterized by a high degree of intrinsic disorder. The description of such highly flexible proteins is challenging because they cannot be represented by a single structure. Here, we present a combination of SAXS and NMR data to describe the conformational ensemble of the PaaA2 antitoxin from the human pathogen E. coli O157. The method encompasses the use of SAXS data to filter ensembles out of a pool of conformers generated by a custom NMR structure calculation protocol and the subsequent refinement by a block jackknife procedure. The final ensemble obtained through the method is validated by an established residual dipolar coupling analysis. We show that the conformational ensemble of PaaA2 is highly compact and that the protein exists in solution as two preformed helices, connected by a flexible linker, that probably act as molecular recognition elements for toxin inhibition.
Original languageEnglish
Pages (from-to)854–865
Number of pages12
JournalStructure
Volume22
Issue number6
Publication statusPublished - 2014

Keywords

  • structural biology
  • bacterial stress response
  • biochemistry
  • molecular biophysics
  • bio-SAXS
  • bio-NMR
  • intrinsically disordered proteins
  • NMR spectroscopy
  • small angle X-ray scatter

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