Crystallization and preliminary X-ray analysis of the inducible lysine decarboxylase from Escherichia coli

The decameric inducible lysine decarboxylase (LdcI) from Escherichia coli has been crystallized in space groups C2 and C222₁; the Ta ₆Br₁₂²⁺ cluster was used to derivatize the C2 crystals. The method of single isomorphous replacement with anomalous scattering (SIRAS) as implemented in SHELXD was used to solve the Ta₆Br ₁₂²⁺-derivatized structure to 5 Å resolution. Many of the Ta₆Br₁₂²⁺-binding sites had twofold and fivefold noncrystallographic symmetry. Taking advantage of this feature, phase modification was performed in DM. The electron-density map of LdcI displays many features in agreement with the low-resolution negative-stain electron-density map [Snider et al. (2006), J. Biol. Chem. 281, 1532-1546].