Identification of an iron-regulated 37,000-dalton protein in the cell envelope of Neisseria gonorrhoeae

Abstract

We examined the outer membrane proteins which appear during the growth of Neisseria gonorrhoeae F62 in complex medium supplemented with 25 microM Desferal mesylate, a potent iron chelator. Outer membranes were prepared by Sarkosyl extraction and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Several higher-molecular-weight (74,000 to greater than 94,000) proteins increased under iron-limiting conditions. In addition we observed the appearance of an iron-regulated protein with an apparent molecular weight of 37,000. This protein comigrated with the gonococcal protein I under normal Laemmli gel conditions. By increasing the ionic strength of the lower gel buffer, separation of protein I and the 37,000-dalton iron-regulated protein occurred. The 37,000-dalton protein stained poorly with Coomassie blue. However, when a silver stain was used, the protein appeared as a major component of the gonococcal outer membrane. Production of this 37,000-dalton protein was suppressed by the addition of iron to the medium. An iron-regulated protein with a similar molecular weight was observed in four clinical isolates and in an additional laboratory strain. Peptide mapping indicated that the 37,000-dalton protein was distinct from protein I and was identical between strains of the WI and WII serogroups.

Serum antibodies to cross‐reactive Neisseria outer membrane antigens in healthy persons and patients with meningococcal disease

“…Neisseria gonorrhoeue (Ng) and N. meningitidis (Nm) strains harbour several cross-reacting antigens or epitopes, including the lipopolysaccharide (LPS; 3,21), pili (23), the H.8 antigen (8), iron-regulated proteins ( 19,20,28), and a 70,000-molecular-weight protein (2). The commensal Neisseriu species N .…”

Effect of iron limitation on protein composition and ultrastructure of Haemophilus ducreyi

“…2). The results presented [1], N. gonorrhoeae [7], and Bacteroides ureolyticus [8]. At present, the function of the novel proteins seen in H. ducreyi is unknown, although it is reasonable to speculate that they may be involved in iron acquisition, uptake or metabolism under conditions where supplies of these nutrient are limited.…”

The effect of iron on the metabolism and pathogenicity of Neisseria gonorrhoeae

“…OM proteins of 76 and 86 kDa were also detected, but the expression of these proteins varied between strains. In a subsequent study by Mietzner and co-workers [15], each of 6 strains grown under conditions of iron limitation produced OM proteins of 103 and 37 kDa. 5 Other iron-repressible OM proteins were also detected, but there was considerable inter-strain variation in their expression.…”

“…These workers also observed other proteins of 70-100 kDa, but the expression of these proteins was strain-dependent. The expression of the various iron-repressible proteins was found to vary depending on the iron source, although the 36 kDa protein (which may be the same as the 37 kDa protein described by Mietzner and colleagues [15]) was produced with each of 4 iron sources tested.…”