Atomic structure and handedness of the building block of a biological assembly

J Am Chem Soc. 2013 Dec 26;135(51):19135-8. doi: 10.1021/ja411362q. Epub 2013 Dec 17.


Noncovalent supramolecular assemblies possess in general several unique subunit-subunit interfaces.The basic building block of such an assembly consists of several subunits and contains all unique interfaces. Atomic-resolution structures of monomeric subunits are typically accessed by crystallography or solution NMR and fitted into electron microscopy density maps. However, the structure of the intact building block in the assembled state remains unknown with this hybrid approach. Here, we present the solid-state NMR atomic structure of the building block of the type III secretion system needle. The building block structure consists of a homotetrameric subunit complex with three unique supramolecular interfaces. Side-chain positions at the interfaces were solved at atomic detail. The high-resolution structure reveals unambiguously the helical handedness of the assembly, determined to be right-handed for the type III secretion system needle.Additionally, the axial rise per subunit could be extracted from the tetramer structure and independently validated by mass-per-length measurements.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Magnetic Resonance Spectroscopy
  • Models, Molecular*
  • Proteasome Endopeptidase Complex / chemistry
  • Protein Structure, Secondary
  • Saccharomyces cerevisiae Proteins / chemistry


  • Saccharomyces cerevisiae Proteins
  • PRE2 protein, S cerevisiae
  • Proteasome Endopeptidase Complex