Crystallization and secondary-structure determination of a protein of the Lrp/AsnC family from a hyperthermophilic archaeon.

A protein belonging to the Lrp/AsnC transcription-factor family, pot1216151, from the hyperthermophilic archaeon Pyrococcus sp. OT3 was crystallized. In Escherichia coli, leucine-responsive protein (Lrp) and AsnC regulate a number of metabolic genes. The crystals of pot1216151 diffracted to 2.3 A using a conventional X-ray source and to 1.8 A using a synchrotron-radiation source. The space group was identified to be P3(1)21 or P3(2)21, with unit-cell parameters a = b = 96.9, c = 98.5 A. In combination with diffraction data obtained from K(2)[Pt(CN)(6)] and K(AuCl(4)) derivatives, an electron-density map was calculated at a resolution of 3.0 A. Four monomers were identified in the asymmetric unit, with four beta-strands and two alpha-helices in each monomer.