Dissection of the function of the RmpM periplasmic protein from Neisseria meningitidis Maharjan, Sunil and Saleem, Muhammad and Feavers, Ian M. and Wheeler, Jun X. and Care, Rory and Derrick, Jeremy P.,, 162, 364-375 (2016), doi = https://doi.org/10.1099/mic.0.000227, publicationName = Microbiology Society, issn = 1350-0872, abstract= RmpM is a periplasmic protein from Neisseria meningitidis that comprises an N-terminal domain (residues 1–47) and a separate globular C-terminal domain (residues 65–219) responsible for binding to peptidoglycan. Here we show, through the use of size exclusion chromatography and pull-down assays, that a recombinant N-terminal fragment of RmpM binds to both the major outer membrane porins, PorA and PorB. Analysis by semi-native SDS-PAGE established that both recombinant full-length RmpM and an N-terminal fragment, but not the C-terminal peptidoglycan-binding domain, were sufficient to stabilize the PorA and PorB oligomeric complexes. Evidence from binding assays indicated that the meso-diaminopimelate moiety plays an important role in peptidoglycan recognition by RmpM. Site-directed mutagenesis showed that two highly conserved residues, Asp120 and Arg135, play an important role in peptidoglycan binding. The yield of outer membrane vesicles, which have been used extensively as a vaccine against N. meningitidis, was considerably higher in an N. meningitidis strain expressing a truncated N-terminal fragment of RmpM (ΔC-term rmpM) than in the WT strain. The native oligomeric state of the PorA/PorB complexes was maintained in this strain. We conclude that the dual functions of RmpM are independent, and that it is possible to use this knowledge to engineer a strain with higher yield of outer membrane vesicles, whilst preserving PorA and PorB, which are key protective antigens, in their native oligomeric state., language=, type=