Cloning, purification and preliminary X-ray crystallographic analysis of the OmpA-like domain of peptidoglycan-associated lipoprotein from Acinetobacter baumannii

Peptidoglycan-associated lipoprotein (Pal) is one component of the Tol–Pal system that is involved in maintaining the integrity and stability of the outer membrane. The C-terminal OmpA-like domain of Pal interacts noncovalently with peptidoglycan. In this study, the OmpA-like domain of Pal from Acinetobacter baumannii was overexpressed in Escherichia coli strain BL21 (DE3), purified and crystallized using the vapour-diffusion method. A native crystal diffracted to 1.4 Å resolution and belonged to space group P6₁ or P6₅, with unit-cell parameters a = b = 72.58, c = 44.65 Å, a calculated Matthews coefficient of 2.64 ų Da⁻¹ and one molecule per asymmetric unit.