Proteomic analysis of outer membranes and vesicles from wild-type serogroup B Neisseria meningitidis and a lipopolysaccharide deficient mutant

Williams, J. N., Skipp, P. J., Humphries, H. E., Christodoulides, M., O'connor, D and Heckels, J. E. (2007) Proteomic analysis of outer membranes and vesicles from wild-type serogroup B Neisseria meningitidis and a lipopolysaccharide deficient mutant. Infection and Immunity, 75 (3), 1364-1372. (doi:10.1128/IAI.01424-06).

Abstract

Current experimental vaccines against serogroup B Neisseria meningitidis are based on meningococcal outer membrane (OM) proteins present in vesicles depleted of toxic lipopolysaccharide by detergent extraction (OMV). Knowledge of the composition of OM and OMV is essential for developing new meningococcal vaccines based on defined antigens. In the current study, SDS-PAGE and nanocapillary liquid chromatography- tandem mass spectrometry was used to investigate the proteome of OM and OMV from meningococcal strain MC58, and OM from a lipopolysaccharide-deficient mutant. Analysis of OM revealed a much more complex composition than has previously been reported, with a total of 236 proteins being identified, of which only 6.4% were predicted to be outer membrane-located. The most abundant proteins included not only the well-established major OM proteins (PorA, PorB, Opc, Rmp, Opa) but also other proteins such as pilus-associated protein Q (PilQ) and a putative macrophage infectivity protein (MIP). All of these proteins were also present in OMV obtained by extraction of the OM with deoxycholate. Some additional proteins had markedly increased abundance in OM from the lipopolysaccharide-deficient mutant, including enzymes that contribute to the TCA cycle. In all the preparations, the proteins not predicted to have an OM location were predominantly periplasmic, cytoplasmic or of unknown location with relatively few cytoplasmic membrane proteins detected. However, several proteins that have previously been identified as potential vaccine candidates were not detected in either OM preparation or in OMV. These results have important implications for the development and use of vaccines based on outer membrane proteins.

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Contributors

Author: P. J. Skipp

Author: M. Christodoulides

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