Figure 2.
Intermolecular PRE effects between KRAS-GTPγS molecules. (A) Intensity ratios of peaks in the presence of paramagnetic versus diamagnetic (reduced) spin labels (Ipara/Idia) for ILV 13C-methyls and Lys 15N-amides of MC-KRAS-GTPγS in the presence of FP-KRAS-GTPγS (‘homo-dimerization’, black lines) and FP-KRAS-GDP (‘cross-dimerization’, green lines) bearing TEMPO labels at one of Cys118, Cys169, or Cys39. Probes are categorized according to the extent of PRE (Ipara/Idia threshold values < 0.8, moderate, yellow and < 0.6, strong, red). (B) Mapping PRE-affected probes onto the crystal structure of KRAS-GTPγS (PDB ID: 4DSO). Probes that exhibit moderate and strong PREs are colored as in panel (A), and PRE-unaffected probes are gray. Dotted lines represent PRE effects that arise from TEMPO conjugated to Sγ atoms of Cys118 (red) and Cys169 (blue) in the opposing (arbitrarily positioned) FP-KRAS-GTPγS protomer.