Cloning, expression, purification, crystallization and preliminary X-ray analysis of the pilus-associated sortase C from Streptococcus pneumoniae.

The pilus-associated sortase C from Streptococcus pneumoniae (SrtC or Srt-2) acts as a polymerase for the pilus subunit proteins RrgA and RrgB. Here, the crystallization and preliminary X-ray diffraction analysis of three crystal forms of SrtC are reported. One crystal form belongs to space group P2(1)2(1)2(1), with unit-cell parameters a = 48.9, b = 96.9, c = 98.9 A, alpha = beta = gamma = 90 degrees . The other two crystal forms belong to space group P222, with unit-cell parameters a = 48.8, b = 97.2, c = 99.2 A, alpha = beta = gamma = 90 degrees and a = 48.6, b = 96.5, c = 98.8 A, alpha = beta = gamma = 90 degrees , respectively. Preliminary analysis indicates the presence of two molecules in the asymmetric unit of the crystal for all three forms.