Cloning, expression, purification, crystallization and initial crystallographic analysis of the preprotein translocation ATPase SecA from Thermus thermophilus.

The Thermus thermophilus gene encoding the preprotein translocation ATPase SecA was cloned and expressed and the purified protein was crystallized by the hanging-drop vapour-diffusion technique in two different space groups P3(1(2))21 (a = b = 168.6, c = 149.8 A) and P6(1(5))22 (a = b = 130.9, c = 564.6 A). The crystals, improved by macroseeding, diffracted to beyond 2.8 and 3.5 A resolution for the trigonal and hexagonal crystal forms, respectively. Structure determination using the multiple isomorphous replacement method is in progress.