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 P3(1)21 or its enantiomorph P3(2)21, with unit-cell parameters a = b = 53.74, c = 67.45 A, alpha = beta = 90, gamma = 120 degrees. They diffract to at least 1.75 A. A selenomethionine derivative of the protein was prepared and crystallized for multiwavelength anomalous diffraction (MAD) phasing.