Purification, crystallization and preliminary X-ray analysis of isocitrate dehydrogenase kinase/phosphatase from Escherichia coli

The Escherichia coli aceK gene encodes isocitrate dehydrogenase kinase/phosphatase (EC 2.7.11.5), a bifunctional protein that phosphorylates and dephosphorylates isocitrate dehydrogenase (IDH), resulting in its inactivation and activation, respectively. This reversible (de)phosphorylation directs iso­citrate, an intermediate of the citric acid cycle, to either go through the full cycle or to enter the glyoxylate bypass. In the present study, the AceK protein from E. coli has been purified and crystallized. Three crystal forms were obtained from very similar crystallization conditions. The crystals belong to space groups P4₁2₁2, P3₂21 and P2₁2₁2₁ and diffracted X-rays to resolutions of 2.9, 3.0 and 2.7 Å, respectively.