Bioinformatic analysis of outer membrane proteome of Neisseria meningitidis and Neisseria lactamica

Two-dimensional electrophoresis (isoelectric focusing/SDS-PAGE) and Western-blotting techniques were used to analyze and compare common and/or specific outer-membrane proteins and antigens from Neisseria meningitidis and Neisseria lactamica. Bioinformatic image analyses of proteome and immunoproteome maps indicated the presence of numerous proteins and several antigens shared by N. meningitidis and N. lactamica, although the inter-strain variation in the maps was of similar magnitude to the inter-species variation, and digital comparison of the maps did not reveal proteins found to be identical by MALDI-TOF fingerprinting analysis. PorA and RmpM, two relevant outer-membrane antigens, manifested as various spots at several different positions. While some of these were common to all the strains analyzed, others were exclusive to N. meningitidis and their electrophoretic mobilities were different than expected. One such spot, with a molecular mass of 19 kDa, may be the C-terminal fragment of RmpM (RmpM-Cter). The results demonstrate that computer-driven analysis based exclusively on spot positions in the proteome or immunoproteome maps is not a reliable approach to predict the identity of proteins or antigens; rather, other identification techniques are necessary to obtain accurate comparisons.