What is porb?
Porb is an outer membrane protein of Neisseria gonorrhoeae that has been shown to modulate the function of host innate immune cells. It is also a key factor in the bacterium’s ability to adhere to epithelial cells, as well as in its ability to escape from the vaginal mucosa into the urogenital tract. The gene encoding PorB is highly conserved in Neisseria strains and shares between 60 to 70% amino acid sequence identity with its counterpart from the closely related organism, Neisseria meningitidis. SE ghosts carrying DNA encoding gonococcal PorB have been found to induce more Salmonella-specific antibodies than PE ghosts do, suggesting that gonococcal PorB can act as a nondenatured representation of the bacterial surface and may be an attractive target for a vaccine based on outer-membrane-vesicle-based delivery.
PorB is a homotrimeric pore with 16 transmembrane-spanning segments and 8 extracellular loops. It allows ions to pass in a voltage-dependent manner and facilitates ion exchange between the gonococcus and its environment. In addition, PorB is capable of binding soluble negative regulators of classical complement and alternative complement, and it contributes to N. gonorrhoeae serum resistance by modulating the activation of these complement pathways.