title: Opposing selective forces for expression of the gonococcal lactoferrin receptor.
abstract: All isolates of Neisseria gonorrhoeae express receptors that bind human transferrin (Tf). Although lactoferrin (Lf) is abundant on mucosa and in purulent exudates, many gonococci do not express an Lf receptor. The naturally occurring Lf receptor deletion mutant FA1090 (LbpB-LbpA-) is infectious, but a Tf receptor mutant of FA1090 is unable to infect male volunteers [Cornelissen, C.N., Kelley, M., Hobbs, M.M., Anderson, J.E., Cannon, J.G., Cohen, M.S., and Sparling, P.F. (1998) Mol Microbiol 27: 611-616]. Here, we report that expression of an Lf receptor in the absence of the Tf receptor was sufficient for infection, and that expression of both Lf and Tf receptors resulted in a competitive advantage over a strain that made only the Tf receptor in mixed infection of male volunteers. We confirmed that nearly 50% of clinical isolates do not make an Lf receptor. Surprisingly, about half of geographically diverse Lf - isolates representing many different auxotypes and porin serovars carried an identical lbpB lbpA deletion. Among Lf+ strains, all produced the integral outer membrane protein LbpA, but 70% did not express the lipoprotein LbpB. Thus, there are apparently selective pressures for expression of the Lf receptor in the male urethra that are balanced by others against expression of the Lf receptor in niches other than the male urethra.
authors.affiliation: Department of Medicine, School of Medicine, University of North Carolina, 521 Burnett Womack Building, CB 7030, Chapel Hill 27599, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Anderson
authors.forename: Marcia M
authors.initials: MM
authors.lastname: Hobbs
authors.forename: Gour D
authors.initials: GD
authors.lastname: Biswas
authors.forename: P Frederick
authors.initials: PF
authors.lastname: Sparling
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D006069:Gonorrhea / Q000382:microbiology / Q000503:physiopathology; D006801:Humans; D007781:Lactoferrin / Q000378:metabolism; D008297:Male; D009344:Neisseria gonorrhoeae / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism; D014521:Urethra / Q000382:microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D011956:Receptors, Cell Surface; D014168:Transferrin; C027768:lactoferrin binding proteins, bacterial; C038340:lactoferrin receptors; D007781:Lactoferrin