Poster Presentation BACPATH 2022

Neisseria meningitidis macrophage infectivity potentiator proteins are essential for aggregation, biofilm formation and virulence (#172)

Emily A Kibble 1 2 3 , Nicole M Bzdyl 1 3 , Jua Iwasaki 1 4 , Nichollas E Scott 5 , Charlie Bond 6 , Geoffrey Coombs 2 , Charlene Kahler 1 , Mitali Sarkar-Tyson 1 3
  1. Marshall Centre of Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA, Australia
  2. School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
  3. DMTC Limited, 620 High St Kew, Victoria, Australia
  4. Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, Crawley, WA, Australia
  5. Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
  6. School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia

Macrophage infectivity potentiators are FK506 binding proteins that are naturally inhibited by the immunosuppressant macrolides FK506 and rapamycin. They are enzymes exhibiting peptidyl-prolyl cis-trans isomerase (PPIase) activity and are known to be essential for protein folding. Deletion of PPIases results in pleiotropic effects and loss of virulence in a range of bacterial pathogens. Unlike most bacteria, Neisseria meningitidis has two macrophage infectivity potentiator (MIP) proteins, encoded by the genes NEIS1487 (mip) and NEIS0004 (mip2), this study demonstrates that both Nm-MIP and Nm-MIP2 are enzymatically active proteins which play significant roles in the virulence of N. meningitidis. Recombinant Nm-MIP and Nm-MIP2 are shown to both have peptidyl-prolyl isomerase enzyme activity which is inhibited by rapamycin, demonstrating that they are macrophage infectivity potentiator proteins. Deletion of either or both genes results in N. meningitidis strains which show reduced virulence in macrophage cells and increased sensitivity to human serum, indicating that both mip and mip2 are essential for virulence and pathogenesis. Interestingly, there were differences between the deletion strains, especially during growth at higher temperatures and formation of biofilms indicating distinct functions of mip and mip2 in N. meningitidis. Proteomic analysis of NmΔmip and NmΔmip2 identified 61 and 161 proteins, respectively, that were significantly changed. Proteins associated with outer membrane assembly and stability (BamA, BamE and Lot), stress response (DsbA-3 and MrsAB) and regulation (Hfq) have been identified as differentially present. These proteomic changes point to a novel role of the Nm-Mip2 in triggering the outer membrane stress response in N. meningitidis.