Crystallization of TRI_05.

TRI_05 was dialyzed against 25 mM Tris buffer (pH 8.0) containing 150 mM NaCl and concentrated via centrifugal ultrafiltration to a final concentration of 12 mg/mL. Concentrated TRI_05 was screened by using the sparse matrix method (28), with a Phoenix Robot and the following crystallization screens: Crystal Screen, SaltRx, PEG/Ion, Index, and PEGRx (Hampton Research) and Berkeley Screen (Lawrence Berkeley National Laboratory). Crystals of TRI_05 were found in the Berkeley Screen condition consisting of 0.1 M magnesium chloride, 0.1 M sodium acetate trihydrate (pH 4.5), and 30% (vol/vol) pentaerythritol propoxylate. TRI_05 crystals were obtained after 5 d by the sitting-drop vapor-diffusion method with the drops consisting of a mixture of 0.2 μL of protein solution and 0.2 μL of reservoir solution.