Structure of the uncomplexed Neisseria meningitidis factor H-binding protein fHbp (rLP2086)

fHbp, a highly immunogenic outer membrane protein of Neisseria meningitidis, is responsible for binding to human factor H, a multi-domain protein which is the central regulator of the alternative complement pathway. Here, the crystal structure of mature fHbp determined at 2 A resolution is presented and is compared with the structure of the same protein in complex with factor H domains 6 and 7 recently solved using X-ray techniques. While the overall protein fold is well conserved, modifications are observed mainly in the loop regions involved in the interaction, reflecting a specific adaptation of fHbp in complexing factor H with high affinity. Such a comparison has to date been impaired by the fact that fHbp models determined by NMR show remarkable differences over the entire structure.