Overexpression, crystallization and preliminary X-­ray crystallographic analysis of Nudix hydrolase Orf141 from Escherichia coli K-1

Nudix hydrolases are a family of proteins that contain the characteristic amino-acid sequence GX₅EX₇REUXEEXGU (where U is usually I, L or V), the Nudix signature sequence. They catalyze the hydrolysis of a variety of nucleoside diphosphate derivatives such as nucleoside triphosphates, nucleotide sugars, ADP-ribose, dinucleotide coenzymes, diadenosine oligophosphates and capped RNAs. Recently, three new Nudix hydrolases have been found from Escherichia coli; one of them is Orf141, which cleaves pyrimidine deoxynucleoside triphosphates. Orf141 was cloned directly from E. coli K1 strain and was overexpressed in E. coli without any extra residues. Orf141 crystals were successfully obtained using polyethylene glycol 1500 as a precipitant at 285 K. X-ray diffraction data were collected to 3.1 Å resolution using synchrotron radiation. The crystal is a member of the rhombohedral space group H32, with unit-cell parameters a = b = 182.2, c = 62.3 Å, α = 90, β = 90, γ = 120° (hexagonal setting). Two or three monomers are likely to be present in the asymmetric unit, with corresponding V_M values of 2.92 and 1.95 ų Da⁻¹ and solvent contents of 57.9 and 36.9%, respectively.