Crystallization of the GMPPCP complex of the NG domains of Thermus aquaticus Ffh and FtsY

The GTPases Ffh and FtsY are components of the prokaryotic signal recognition particle protein-targeting pathway. The two proteins interact in a GTP-dependent manner, forming a complex that can be stabilized by use of the non-hydrolyzable GTP analog GMPPCP. Crystals of the complex of the NG GTPase domains of the two proteins have been obtained from ammonium sulfate solutions. Crystals grow with several different morphologies, predominately as poorly diffracting plates and needle clusters, but occasionally as well diffracting rods. It has been demonstrated that all forms of the crystals observed contain an intact complex. Diffraction data to 2.0 Å resolution have been measured.