Cleavage of the protein III and major iron-regulated protein of Neisseria gonorrhoeae by lysosomal cathepsin G.
Incubation of either 125I-labelled or unlabelled Neisseria gonorrhoeae with enzymically active preparations of human polymorphonuclear leucocyte lysosomal cathepsin G revealed that surface-exposed outer-membrane proteins were susceptible to proteolytic modification. Electroimmunoblotting experiments confirmed that outer-membrane protein III (PIII) and the major iron-regulated protein (MIRP), two conserved gonococcal proteins, were cleaved by cathepsin G. A direct relationship was observed between susceptibility to the antibacterial properties of cathepsin G and cleavage of PIII among isogenic strains differing in their level of resistance to the bactericidal activity of cathepsin G. Although the antibacterial property of cathepsin G is known to be independent of serine-esterase activity, the data suggest that gonococcal outer-membrane proteins are involved in the binding of cathepsin G, and that variation in the level of resistance reflects the degree to which target outer-membrane proteins such as PIII are exposed.
D001345:Autoradiography; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D056649:Cathepsin G; D002403:Cathepsins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007158:Immunologic Techniques; D009344:Neisseria gonorrhoeae / Q000378:metabolism*; D012697:Serine Endopeptidases
D001425:Bacterial Outer Membrane Proteins; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G