Crystal structure determination. MonoTcTIM was crystallized by the sitting drop method. One microliter of protein at 25 mg mL?1 was mixed with one microliter of the reservoir. Crystals were grown after one week at 9 °C and obtained with a reservoir solution of 100 mM HEPES,
PLX 4032 7.5, 10% PEG 6000, and 5% MPD. The crystals were cryoprotected by adding PEG 400 (30%) to the reservoir and frozen in liquid nitrogen. Diffraction data was collected on the SER-CAT beamline at APS, Argonne, USA. The data were processed using MOSFLM [13] and reduced using SCALA [14]. The structure was solved using the molecular replacement method using the PHASER program [15] using the coordinates of TcTIM (PDB code 1TCD) as the search model. Refinement and model building were done using the Refmac5 and COOT programs [16] and [17]. Data collection and refinement statistics are
parallel evolution found in Supplementary Table 2. Fig. 2B was generated with PyMOL (http://www.pymol.org). The structure has been deposited in the Protein Data Bank (code 2v5b).
