Cloning, expression, purification, crystallization and initial crystallographic analysis of transcription factor DksA from Escherichia coli

The Escherichia coli gene encoding a regulator of stringent response and virulence, DksA, which contains a canonical Zn finger motif, was cloned and expressed, and the purified protein was crystallized by the hanging-drop vapox-diffusion technique in two different space groups, P2₁2 ₁2₁ (a = 91.32, b = 96.59, c = 117.48 Å) and C222 (a = 80.6, b = 115.1, c = 149.57 Å). The crystals belonging to space group P2₁2₁2₁, improved by macroseeding, diffract beyond 2.0 Å at a synchrotron. Three complete atomic resolution multiple anomalous dispersion diffraction data sets were collected from the same crystal of the P2₁2₁2₁ crystal form at the absorption edge for Zn atoms.