title: The frequency and rate of pilin antigenic variation in Neisseria gonorrhoeae.
abstract: The pilin antigenic variation (Av) system of Neisseria gonorrhoeae (Gc) mediates unidirectional DNA recombination from silent gene copies into the pilin expression locus. A DNA sequencing assay was developed to accurately measure pilin Av in a population of Gc strain FA1090 arising from a defined pilin progenitor under non-selective culture conditions. This assay employs a piliated parental Gc variant with a recA allele whose promoter is replaced by lac-regulatory elements, allowing for controlled induction of pilin Av. From this assay, the frequency of pilin Av was measured as 0.13 recombination events per cell, with a corresponding rate of pilin Av of 4x10(-3) events per cell per generation. Most pilin variants retained the parental piliation phenotype, providing the first comprehensive analysis of piliated variants arising from a piliated progenitor. Sequence analysis of pilin variants revealed that a subset of possible recombination events predominated, which differed between piliated and non-piliated progeny. Pilin Av exhibits the highest reported frequency of any pathogenic gene conversion system and can account for the extensive pilin variation detected during human infection.
authors.affiliation: Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
authors.forename: Alison K
authors.initials: AK
authors.lastname: Criss
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Kline
authors.forename: H Steven
authors.initials: HS
authors.lastname: Seifert
mesh_terms: D000940:Antigenic Variation; D001483:Base Sequence; D036781:Fimbriae Proteins / Q000235:genetics / Q000276:immunology*; D010861:Fimbriae, Bacterial / Q000276:immunology*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000166:cytology / Q000235:genetics / Q000276:immunology; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D036781:Fimbriae Proteins