Cloning, purification and preliminary X-ray crystallographic analysis of a hypothetical protein, MJ0754, from Methanococcus jannaschii DSM 2661

The protein encoded by the MJ0754 gene from the archaeon Methanococcus jannaschii DSM 2661 is an unknown hypothetical protein. Two recombinant proteins, MJ0754 (residues 1–185) and MJ0754t (a truncated form of MJ0754, residues 11–185), were cloned from MJ0754, overexpressed as His-tag fusion proteins and purified. The crystals were found to grow under two different conditions and to have two different shapes. The crystal of MJ0754 belonged to space group P6₁, with unit-cell parameters a = b = 127.015, c = 48.929 Å, a calculated Matthews coefficient of 2.85 ų Da⁻¹ and two molecules per asymmetric unit. The crystal of MJ0754t belonged to space group C222₁, with unit-cell parameters a = 51.915, b = 79.122, c = 93.869 Å, a calculated Matthews coefficient of 2.41 ų Da⁻¹ and one molecule per asymmetric unit. The SeMet-labelled P6₁ crystal diffracted to a resolution of 3.1 Å, while the native C222₁ crystal diffracted to 1.3 Å resolution.