Purification, crystallization and preliminary X-ray crystallographic analysis of human ppGpp hydrolase, Mesh1

Bacterial SpoT is a Mn2+-dependent pyrophosphohydrolase to hydrolyze guanosine 3’-diphosphate-5’-diphosphate to guanosine diphosphate and pyrophosphate. In this study, SpoT ortholog from Homo sapiens (hMesh1), was over-expressed in Escherichia coli, purified and crystallized using hanging-drop vapour-diffusion method with polyethylene glycol and sodium citrate. The native crystal of hMesh1 was diffracted to 2.1 Å using a synchrotron-radiation source and belonged to the monoclinic space group P21 with cell dimensions of a = 53.27 Å, b = 62.61 Å, c = 52.45 Å and β= 94.96˚. The crystal contains two molecules in the asymmetric unit, with a solvent content of 44% and a Matthews coefficient VM value of 2.18 Å3/Da.