Fig. 2.

Effects on the ThrRS-dTP(2–60) ¹⁵N-HSQC spectrum upon addition of AtToc34. (A) The relative change in signal intensity of cross-peaks in ¹⁵N HSQC spectra upon titration. The bars indicate the relative change in signal intensity compared to intensities in a spectrum recorded for a 80 μM ThrRS-dTP(2–60) sample without AtToc34. Purple indicates a 1:0.1 molar ratio of ThrRS-dTP and AtToc34; Grey indicates a 1:0.2 molar ratio and black indicates a 1:0.5 molar ratio. (B) H^N and N^H chemical shift differences in the spectrum of 80 μM ThrRS-dTP(2–60) without AtToc34 and with 16 μM AtToc34 (AtToc34:ThrRS-dTP, 0.2:1). The shifts are reported as δ_with–δ_without. The cut-off limits for significant chemical shift differences, chosen as ΔδH^N > 0.01, and ΔδN^H > 0.2 are shown. Residues with shift perturbations around this cut-off are indicated. (C) Summary of the effect of adding AtToc34 to ThrRS-dTP(2–60) at a molar ratio of 0.2:1. The positions with a significant change in chemical shifts by AtToc34 addition have letters in red. The φχχφφ motif, previously reported as a Tom20 recognition element, is indicated by the red frame. The positions that show a decrease in the signal intensity ratio of more than 0.5 are highlighted yellow. Letters in grey are prolines or unassigned residues.