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 n umber of metabolic genes. The crystals of pot1216151 diffracted to 2.3 Angs trom using a conventional X-ray source and to 1.8 Angstrom using a synchrot ron-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 Angstrom. In combinati on with diffraction data obtained from K-2[Pt(CN)(6)] and K(AuCl4) derivati ves, an electron-density map was calculated at a resolution of 3.0 Angstrom . Four monomers were identified in the asymmetric unit, with four beta -str ands and two alpha -helices in each monomer.