Segmental isotope labelling and solid-state NMR of a 12 × 59 kDa motor protein: identification of structural variability

J Biomol NMR. 2018 Aug;71(4):237-245. doi: 10.1007/s10858-018-0196-z. Epub 2018 Jun 12.


Segmental isotope labelling enables the NMR study of an individual domain within a multidomain protein, but still in the context of the entire full-length protein. Compared to the fully labelled protein, spectral overlap can be greatly reduced. We here describe segmental labelling of the (double-) hexameric DnaB helicase from Helicobacter pylori using a ligation approach. Solid-state spectra demonstrate that the ligated protein has the same structure and structural order as the directly expressed full-length protein. We uniformly 13C/15N labeled the N-terminal domain (147 residues) of the protein, while the C-terminal domain (311 residues) remained in natural abundance. The reduced signal overlap in solid-state NMR spectra allowed to identify structural "hotspots" for which the structure of the N-terminal domain in the context of the oligomeric full-length protein differs from the one in the isolated form. They are located near the linker between the two domains, in an α-helical hairpin.

Keywords: DnaB; Helicase; Magic-angle spinning; Segmental labelling; Solid-state NMR.

MeSH terms

  • Bacterial Proteins / chemistry
  • Carbon-13 Magnetic Resonance Spectroscopy
  • DnaB Helicases / chemistry
  • Helicobacter pylori / chemistry
  • Isotope Labeling / methods*
  • Molecular Motor Proteins / chemistry*
  • Nitrogen Isotopes
  • Nuclear Magnetic Resonance, Biomolecular / methods*
  • Protein Conformation
  • Protein Conformation, alpha-Helical
  • Protein Domains


  • Bacterial Proteins
  • Molecular Motor Proteins
  • Nitrogen Isotopes
  • Nitrogen-15
  • DnaB Helicases