Crystallization and initial X-ray diffraction study of the three PASTA domains of the Ser/Thr kinase Stk1 from the human pathogen Staphylococcus aureus.

PASTA subunits (approximately 70 amino acids) are specific to bacterial serine/threonine kinases and to penicillin-binding proteins (PBPs) and are involved in the synthesis of peptidoglycan. The human pathogen Staphylococcus aureus contains a serine/threonine kinase, Stk1, which plays a major role in virulence. A recombinant His-tagged portion of the extracellular domain of Stk1 containing three PASTA subunits has been crystallized using zinc sulfate as a crystallizing agent. The crystals belonged to the tetragonal space group P4(1)22, with unit-cell parameters a = 68.0, b = 68.0, c = 158.1 angstrom. Structure determination by the MAD method is now in progress.