NMR dynamics and antibody recognition of the meningococcal lipidated outer membrane protein LP2086 in micellar solution.
Neisseria meningitidis is a major cause of meningitis. Although protective vaccination is available against some pathogenic serogroups, serogroup B meningococci have been a challenge for vaccinologists. A family of outer membrane lipoproteins, LP2086 (or factor H binding proteins, fHbp), has been shown to elicit bactericidal antibodies and is currently part of a cocktail vaccine candidate. The NMR structure of the variant LP2086-B01 in micellar solution provided insights on the topology of this family of proteins on the biological membrane. Based on flow cytometry experiments on whole meningococcal cells, binding experiments with monoclonal antibodies, and the NMR structure in micellar solution, we previously proposed that LP2086-B01 anchors the outer bacterial membrane through its lipidated N-terminal cysteine, while a flexible 20 residue linker positions the protein above the layer of lipo-oligosaccharides that surrounds the bacteria. This topology was suggested to increase the antigen exposure to the immune system. In the present work, using micellar solution as a membrane mimicking system, we characterized the backbone dynamics of the variant LP2086-B01 in both its lipidated and unlipidated forms. In addition, binding experiments with a Fab fragment derived from the monoclonal MN86-1042-2 were also performed. Our data suggests that due to the length and flexibility of the N-terminal linker, the antigen is not in contact with the micelle, thus making both N- and C-domains highly available to the host immune system. This dynamic model, combined with the binding data obtained with MN86-1042-2, supports our previously proposed arrangement that LP2086-B01 exposes one face to the extracellular space. Binding of MN86-1042-2 antibody shows that the N-domain is the primary target of this monoclonal, providing further indication that this domain is immunologically important for this family of proteins.
Mascioni
Alessandro
A
Wyeth Research, Structural Biology and Computational Chemistry, 200 Cambridge Park Drive, Cambridge, MA 02140, USA.
Moy
Franklin J
FJ
McNeil
Lisa K
LK
Murphy
Ellen
E
Bentley
Breagh E
BE
Camarda
Rosaria
R
Dilts
Deborah A
DA
Fink
Pamela S
PS
Gusarova
Viktoria
V
Hoiseth
Susan K
SK
Malakian
Karl
K
Mininni
Terri
T
Novikova
Elena
E
Lin
Shuo
S
Sigethy
Scott
S
Zlotnick
Gary W
GW
Tsao
Désirée H H
DH
D000818:Animals; D000907:Antibodies, Bacterial / Q000737:chemistry* / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology; D051379:Mice; D008823:Micelles; D008958:Models, Molecular; D009345:Neisseria meningitidis / Q000737:chemistry* / Q000276:immunology; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary / Q000502:physiology
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D008823:Micelles; C484699:factor H-binding protein, Neisseria meningitidis; C023023:lipid-linked oligosaccharides