Overproduction, purification, crystallization and preliminary X-ray diffraction studies of the human transcription repressor ERH

The human gene coding for the enhancer of rudimentary homologue (ERH) protein was overexpressed in Escherichia coli. The ERH protein was purified by anion-exchange, hydrophobic interaction and gel-filtration chromatography. Well diffracting single crystals were obtained by the vapour-diffusion method in hanging drops. The crystals belong to the trigonal space group P3₁21 or its enantiomorph P3₂21, with unit-cell parameters a = b = 53.74, c = 67.45 Å, α = β = 90, γ = 120°. They diffract to at least 1.75 Å. A selenomethionine derivative of the protein was prepared and crystallized for multiwavelength anomalous diffraction (MAD) phasing.