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 Å for native FrpD_43-271 protein and to a resolution of 2.00 Å 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 P6₂ or P6₄, while the crystals of SeMet FrpD_43-271 protein belonged to the primitive orthorhombic space group P2₁2₁2₁.