Expression, purification, crystallization and preliminary X-ray diffraction studies of triosephosphate isomerase from methicillin-resistant Staphylococcus aureus (MRSA252)

Abstract

Triosephosphate isomerase from methicillin-resistant Staphylococcus aureus (MRSA252) was cloned in pQE30 vector, overexpressed in Escherichia coli M15 (pREP4) cells and purified to homogeneity. The protein was crystallized from 1.6 M trisodium citrate dihydrate pH 6.5 using the hanging-drop vapour-diffusion method. The crystals belonged to space group P4(3)2(1)2, with unit-cell parameters a = b = 79.15, c = 174.27 A. X-ray diffraction data were collected and processed to a maximum resolution of 1.9 A. The presence of two molecules in the asymmetric unit gave a Matthews coefficient (V(M)) of 2.64 A(3) Da(-1), with a solvent content of 53.63%.

Figure 1

Mechanistic outline of the interconversion between DHAP and GAP by TIM.

Figure 2

15% SDS–PAGE analysis. Lane 1, molecular-weight markers (kDa); lane 2, uninduced M15 cells; lane 3, induced M15 cells; lane 4, supernatant; lane 5, SaTIM after Ni–NTA chromatography; lane 6, purified SaTIM after size-exclusion chromatography.

Figure 3

Crystals of SaTIM: a typical crystal of SaTIM grown from 1.6 M trisodium citrate dihydrate pH 6.5 at 298 K measured 1.5 × 1.3 × 0.9 mm.