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 Å using a conventional X-ray source and to 1.8 Å using a synchrotron-radiation source. The space group was identified to be P3₁21 or P3₂21, with unit-cell parameters a = b = 96.9, c = 98.5 Å. In combination with diffraction data obtained from K₂[Pt(CN)₆] and K(AuCl₄) derivatives, an electron-density map was calculated at a resolution of 3.0 Å. Four monomers were identified in the asymmetric unit, with four β-strands and two α-­helices in each monomer.