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. We have demonstrated that the crystals, in all forms observed, contain an intact complex. Diffraction data to 2.0Å resolution have been measured.
PDB id: 1OKK
Comment:
This paper reports the conditions for crystallization of the SRP GTPase complex, and presents the X-ray crystallographic data collection statistics. Important details of the structure determination discussed in the Science paper are also presented here. This project was a real pain in the ass - we obtained a lot of poor crystals, but happily, found one 'lucky' crystal that had good morphology and diffracted to 2.0 Å resolution (it's in the picture).