title: Pore formation and mitogenicity in blood cells by the class 2 protein of Neisseria meningitidis.
abstract: The class 2 outer membrane protein (MIEP) of Neisseria meningitidis has recently been shown to be mitogenic for lymphocytes (Liu, M.A., Friedman, A., Tai, J., Martinez, D., Deck, R. R., Hawe, L. A., Shieh, J. T.-C., Jenkins, T. D., Donnelly, J. J., and Oliff, A. I. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 4633-4637. In this study, a possible connection between MIEP's mitogenicity and its possible action as a porin was investigated. MIEP, purified from the bacterial outer membrane protein complex under denaturing conditions, caused a modest but specific release of ions (86Rb) from both erythrocytes and lymphocytes, ultimately resulting in cell lysis. The dose-response of MIEP on erythrocyte lysis was qualitatively similar to a known porin (protein I from Neisseria gonorrhoeae) but was much less efficient. Induction or preservation of native structure in MIEP increased pore formation, resulting in levels comparable to that of the protein I porin. These observations suggest that native MIEP, free of the other outer membrane proteins of Neisseria meningitidis, can efficiently form pores in cells, but that denatured MIEP is variably and marginally effective. However, pore formation by MIEP was not related to its mitogenicity in lymphocytes, based on: (i) native MIEP was not mitogenic; (ii) denatured MIEP was highly mitogenic; and (iii) denatured MIEP was mitogenic at concentrations below the threshold level for pore formation. Therefore, mitogenicity is dependent upon MIEP being in a denatured, monomeric state and is masked by native conformation.
authors.affiliation: Department of Cancer Research, Merck Research Laboratories, West Point, Pennsylvania 19486.
authors.forename: J B
authors.initials: JB
authors.lastname: Ulmer
authors.forename: C J
authors.initials: CJ
authors.lastname: Burke
authors.forename: C
authors.initials: C
authors.lastname: Shi
authors.forename: A
authors.initials: A
authors.lastname: Friedman
authors.forename: J J
authors.initials: JJ
authors.lastname: Donnelly
authors.forename: M A
authors.initials: MA
authors.lastname: Liu
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D002463:Cell Membrane Permeability; D003902:Detergents; D004910:Erythrocyte Membrane / Q000737:chemistry; D006454:Hemoglobins; D006801:Humans; D008214:Lymphocytes / Q000737:chemistry; D008934:Mitogens / Q000737:chemistry*; D009345:Neisseria meningitidis / Q000737:chemistry; D018272:Porins; D011487:Protein Conformation; D011489:Protein Denaturation; D013329:Structure-Activity Relationship
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003902:Detergents; D006454:Hemoglobins; D008934:Mitogens; D018272:Porins; C057699:porin protein, Neisseria