Involvement of Neisseria meningitidis Lipoprotein GNA2091 in the Assembly of a Subset of Outer Membrane Proteins [Membrane Biology]

April 22nd, 2014 by Bos, M. P., Grijpstra, J., Tommassen-van Boxtel, R., Tommassen, J.

GNA2091 of Neisseria meningitidis is a lipoprotein of unknown function that is included in the novel 4CMenB vaccine. Here, we investigated the biological function and the subcellular localization of the protein. We demonstrate that GNA2091 functions in the assembly of outer membrane proteins (OMPs) since its absence resulted in the accumulation of misassembled OMPs. Cell-fractionation and protease-accessibility experiments showed that the protein is localized at the periplasmic side of the outer membrane. Pull-down experiments revealed that it is not stably associated with the BAM complex, the previously identified machinery for OMP assembly. Thus, GNA2091 constitutes a novel outer membrane-based lipoprotein required for OMP assembly. Furthermore, its location at the inner side of the outer membrane indicates that protective immunity elicited by this antigen cannot be due to bactericidal or opsonic activity of antibodies.