Crystallization of the coiled-coil domain of Atg16 essential for autophagy.

Atg16 is a scaffold protein that interacts with Atg12-Atg5 protein conjugates via its N-terminal domain and self-assembles via its coiled-coil domain, thus forming a multimeric Atg12-Atg5-Atg16 complex that is essential for autophagy. The coiled-coil domain of Atg16 was expressed, purified and crystallized. The crystal belonged to space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = 127.7, c = 77.8 A. Self-rotation functions and volume-to-weight ratio values suggested that the crystal may contain six molecules per asymmetric unit. Since the domain does not contain a methionine residue, selenomethionine-labelled crystals were prepared with a leucine-to-methionine substitution in the coiled-coil domain and these crystals were used for the collection of single-wavelength anomalous dispersion data to 2.5 A resolution.