Crystallization of Saccharomyces cerevisiae aminopeptidase 1, the major cargo protein of the Cvt pathway.

The vacuole hydrolase aminopeptidase 1 (Ape1) is a cargo protein transported to the vacuole by the cytosol-to-vacuole targeting (Cvt) pathway during conditions of growth and by autophagy during conditions of starvation. After transport to the vacuole, Ape1 is processed into mature Ape1 (mApe1). mApe1 has been expressed, purified and crystallized in two crystal forms. Form I belongs to space group P2(1), with unit-cell parameters a = 120.6, b = 219.5, c = 133.1 A, beta = 116.5 degrees. Form II belongs to space group R3, with unit-cell parameters a = 141.2, c = 349.4 A. Diffraction data were collected from these crystals to a resolution of 2.5 A for form I and 1.83 A for form II. Self-rotation functions and the volume-to-weight ratio values suggest that forms I and II contain 12 and four mApe1 molecules per asymmetric unit, respectively, and that mApe1 exists as a tetrahedral dodecamer in both crystal forms.