Variability and conservation of structural domains in divide-and-conquer approaches.

The use of protein building blocks for the structure determination of multidomain proteins and protein-protein complexes, also known as the "divide and conquer" approach, is an important strategy for obtaining protein structures. Atomic-resolution X-ray or NMR data of the individual domains are combined with lower-resolution electron microscopy maps or X-ray data of the full-length protein or the protein complex. Doing so, it is often assumed that the individual domain structures remain invariant in the context of the superstructure. In this work, we show the potentials and limitations of NMR to validate this approach at the example of the dodecameric DnaB helicase from Helicobacter pylori. We investigate how sequentially assigned spectra, as well as unassigned spectral fingerprints can be used to indicate the conservation of individual domains, and also to highlight conformational differences.