Fig. 4

Influence of BamCDE on the BamAP4P5 lateral gate and P5-barrel orientation. a Localization of the sequential ¹³C Ile, Phe (orange) and ¹⁵N Glycine (green) pairs targeted in d–f For completion, also F394 discussed in b, c is shown. b 2D ¹³C–¹³C spectra of the specifically ¹³C Ile, Phe labeled BamAP4P5 in liposomes, in the absence (blue) and presence (red) of sub-complex BamCDE. F394 at the P5-barrel interface is indicated in yellow. c Comparison of the P5-barrel orientation as described by X-ray structures (PDB 5D0O—blue and 5D0Q—red) with F394 in yellow. d, e Close-up of the Cα-Cβ region of the ¹⁵N-edited C_xC_x DNP enhanced spectra with a short (30 ms—d) or long (1 s—e) mixing time, measured on IFG-labeled BamAP4P5, in the presence and absence of unlabeled BamCDE (blue and red spectra, respectively). Crosses are the tentative assignments for the residues targeted by these experiments. f Schematic representation of the correlations observed between β-strand 1 and 16 in ¹⁵N-edited C_xC_x DNP spectra for short and long mixing times (arrows in full and dashed, respectively) for the case of a lateral gate closed (blue) and open (red). The distances between Cα residues of the closest residue in β1 to the I806 of β16 are indicated, whilst other inter-strand distant are significantly greater, as judged from PDBs 5D0O and 5D0Q, respectively