Crystallization of AcpA, a respiratory burst-inhibiting acid phosphatase from Francisella tularensis.

Francisella tularensis is a highly infectious bacterial pathogen that is classified as a Category A Pathogen by the Centers for Disease Control and Prevention. Here, we report crystallization of a recombinant form of F. tularensis AcpA, a unique and highly expressed acid phosphatase that is thought to play a role in intracellular survival by inhibiting the host respiratory burst. Three crystal forms have been obtained, with form III being the most suitable for high-resolution structure determination. Form III crystals were grown in the presence of PEG 1500 and the competitive inhibitor sodium orthovanadate (5 mM). The space group is C222(1) with unit cell parameters a=112.1 A, b=144.4 A, c=123.9 A. The asymmetric unit is predicted to contain two protein molecules and 43% solvent. A 1.75-A native data set was recorded at beamline 8.3.1 of the Advanced Light Source. To our knowledge, this is the first report of high-resolution crystals of any F. tularensis protein.