Purification, crystallization and preliminary X-ray crystallographic analysis of the C-terminal cytoplasmic domain of FlhB from Aquifex aeolicus.

FlhB is a key protein in the regulation of protein export by the bacterial flagellar secretion system. It is composed of two domains: an N-terminal transmembrane domain and a C-terminal cytoplasmic domain (FlhBc). Here, the crystallization and preliminary crystallographic analysis of FlhBc from Aquifex aeolicus are reported. Purified protein was crystallized using the vapour-diffusion technique. The crystals diffracted to 2.3 Å resolution and belonged to space group C2, with unit-cell parameters a = 114.49, b = 33.89, c = 122.13 Å, β = 107.53°.