SEQUENCE VARIABILITY OF FRPB, A MAJOR IRON-REGULATED OUTER-MEMBRANE PROTEIN IN THE PATHOGENIC NEISSERIAE

The FrpB protein from pathogenic neisseriae is a 77 kDa iron-regulated outer-membrane protein that belongs to the family of TonB-dependent r eceptors and may have potential as a vaccine component. Comparison bet ween the frpB gene from three different meningococcal strains and a pu blished gonococcal one revealed that the region from residues 350 to 3 90 displays pronounced sequence variability. In a model for the topolo gy of FrpB in the outer membrane, this region corresponds to loop 7, t he longest of the predicted 13 surface-exposed loops. Binding of four out of a total of eight bactericidal monoclonal antibodies to syntheti c peptides corresponding to loop 7 showed that their epitopes are loca ted here. The frpB genes from five additional meningococcal strains we re cloned and sequenced in this region. Pairwise comparisons showed di fferent degrees of similarity.