Neisseria gonorrhoeae porin modulates phagosome maturation

The porin (PorB) of Neisseria gonorrhoeae has been implicated in the pathog enesis of this species. Porin is believed to translocate from the bacterial outer membrane into target cell membranes affecting various cell functions . Here we investigated the effect of porin on phagosome maturation. Phagocy tosis of latex beads by human macrophages was allowed in the presence or ab sence of purified porin. Isolation of latex bead-containing phagosomes and subsequent two-dimensional gel electrophoresis revealed substantial differe nces in the phagosomal protein composition. Immunoblotting detected higher amounts of annexin II and the early endocytic markers Rab5 and transferrin receptor and decreased levels of the late endocytic markers Rab7 and cathep sin D in phagosomes obtained in the presence of porin compared with those o btained in its absence. Furthermore, association of Rab4 with the latex bea d-containing phagosomes was revealed by flow cytometry. The amount of this small GTPase was markedly higher in the phagosomes isolated in the presence of porin. The data thus indicate that neisserial porin is itself able to a rrest phagosome maturation within macrophages.