title: 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.
mesh_terms: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000502:physiology; D008565:Membrane Proteins / Q000302:isolation & purification*; D008970:Molecular Weight; D009344:Neisseria gonorrhoeae / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D007501:Iron