Crystallization and preliminary crystallographic characterization of the iron-regulated outer membrane lipoprotein FrpD from Neisseria meningitidis

Fe-regulated protein D (FrpD) is a Neisseria meningitidis outer membrane lipoprotein that may be involved in the anchoring of the secreted repeat in toxins (RTX) protein FrpC to the outer bacterial membrane. However, the function and biological roles of the FrpD and FrpC proteins remain unknown. Native and selenomethionine-substituted variants of recombinant FrpD(43-271) protein were crystallized using the sitting-drop vapour-diffusion method. Diffraction data were collected to a resolution of 2.25 A for native FrpD(43-271) protein and to a resolution of 2.00 A for selenomethionine-substituted FrpD(43-271) (SeMet FrpD(43-271)) protein. The crystals of native FrpD(43-271) protein belonged to the hexagonal space group P6(2) or P6(4), while the crystals of SeMet FrpD(43-271) protein belonged to the primitive orthorhombic space group P2(1)2(1)2(1).