Crystallization and preliminary X-ray analysis of the catalytic domain of the adenylate cyclase GRESAG4.1 from Trypanosoma brucei.

Adenylate cyclases (ACs) are involved in signal transduction by generating the second messenger, cAMP. In Trypanosoma brucei, 3', 5'-cyclic adenosine monophosphate (cAMP) controls the life cycle of this unicellular parasite. cAMP is generated by a class of adenylate cyclases which are either constitutively (GRESAG4.1-4.3) or transiently expressed (ESAG4) during the life cycle. Unlike mammalian ACs, the trypanosomal ACs have a simple topology comprising of a large extracellular region, a transmembrane helix and a cytosolic catalytic region. Two orthorhombic crystal forms of the catalytic AC domain of GRESAG4.1 (residues Ala884-Thr1132) were generated by the hanging-drop vapour-diffusion method. X-ray diffraction data from GRESAG4.1 crystals were collected at 1.9 A resolution using synchrotron radiation. Furthermore, two heavy-metal derivative data sets were collected from crystal form A; heavy-atom sites were subsequently located in difference Patterson maps.