Cloning, purification, crystallization and preliminary X-ray studies of flagellar hook scaffolding protein FlgD from Pseudomonas aeruginosa PAO1.

FlgD regulates the assembly of the hook cap structure to prevent leakage of hook monomers into the medium and hook monomer polymerization and also plays a role in determination of the correct hook length, with the help of the FliK protein. In order to better elucidate the functions of FlgD in flagellar hook biosynthesis, the three-dimensional structure of FlgD is being determined by X-ray crystallography. Here, the expression, purification, crystallization and preliminary crystallographic analysis of FlgD from P. aeruginosa are reported. The crystal belonged to space group I222 and diffracted to a resolution of 2.5 A, with unit-cell parameters a = 116.47, b = 118.71, c = 118.85 A. The crystals are most likely to contain three molecules in the asymmetric unit, with a V(M) value of 2.73 A(3) Da(-1).