Crystallization and preliminary X-ray data of the FadA adhesin from Fusobacterium nucleatum.

Fusobacterium nucleatum is a gram-negative anaerobe prevalent in the oral cavity that is associated with periodontal disease, preterm birth and infections in other parts of the human body. The bacteria attach to and invade epithelial and endothelial cells in the gum tissue and elsewhere via a 13.7 kDa adhesin protein FadA (Fusobacterium adhesin A). FadA exists in two forms: the intact form (pre-FadA), consisting of 129 amino acids, and the mature form (mFadA), which lacks an 18-residue signal sequence. Both forms have been expressed in Escherichia coli and purified. mFadA has been crystallized. The crystals belong to the hexagonal space group P6(1) or P6(5), with unit-cell parameters a = b = 59.3, c = 125.7 A and one molecule per asymmetric unit. The crystals exhibit an unusually high solvent content of 74%. Synchrotron X-ray data have been collected to 1.9 A. The crystals are suitable for X-ray structure determination. The crystal structure of FadA may provide a basis for the development of therapeutic agents to combat periodontal disease and other infections associated with F. nucleatum.