@article{mbs:/content/journal/micro/10.1099/mic.0.000227, author = "Maharjan, Sunil and Saleem, Muhammad and Feavers, Ian M. and Wheeler, Jun X. and Care, Rory and Derrick, Jeremy P.", title = "Dissection of the function of the RmpM periplasmic protein from Neisseria meningitidis", journal= "Microbiology", year = "2016", volume = "162", number = "2", pages = "364-375", doi = "https://doi.org/10.1099/mic.0.000227", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000227", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", 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.", }