Assignment-free solution NMR method reveals CesT as an unswapped homodimer.
The X-ray structure of the homodimeric chaperone CesT is the only structure among the type three secretion system (TTSS) chaperones that shows a domain swap. This swap has potential importance for the mechanism of effector translocation through a TTSS. Here we present two nuclear magnetic resonance strategies exploiting pre-existing structural models and residual dipolar couplings (RDCs), which reveal the unswapped 35.4-kDa dimer to be present in solution. Particularly efficient is the discrimination of a swapped and unswapped structural state performed simultaneously to automatic backbone assignment using only HN-RDCs and carbonyl backbone chemical shifts. This direct approach may prove to be generally useful to rapidly differentiate two structural models.
Rumpel
Sigrun
S
Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Lakshmi
Raghavendran
R
Becker
Stefan
S
Zweckstetter
Markus
M
D029968:Escherichia coli Proteins / Q000737:chemistry*; D018832:Molecular Chaperones / Q000737:chemistry*; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary
C122044:CesT protein, E coli; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones