title: H-NS suppresses pilE intragenic transcription and antigenic variation in Neisseria gonorrhoeae.
abstract: Initially, pilE transcription in Neisseria gonorrhoeae appeared to be complicated, yet it was eventually simplified into a model where integration host factor activates a single -35/ -10 promoter. However, with the advent of high-throughput RNA sequencing, numerous small pil-specific RNAs (sense as well as antisense) have been identified at the pilE locus as well as at various pilS loci. Using a combination of in vitro transcription, site-directed mutagenesis, Northern analysis and quantitative reverse transcriptase PCR (qRT-PCR) analysis, we have identified three additional non-canonical promoter elements within the pilE gene; two are located within the midgene region (one sense and one antisense), with the third, an antisense promoter, located immediately downstream of the pilE ORF. Using strand-specific qRT-PCR analysis, an inverse correlation exists between the level of antisense expression and the amount of sense message. By their nature, promoter sequences tend to be AT-rich. In Escherichia coli, the small DNA-binding protein H-NS binds to AT-rich sequences and inhibits intragenic transcription. In N. gonorrhoeae hns mutants, pilE antisense transcription was increased twofold, with a concomitant decrease in sense transcript levels. However, most noticeably in these mutants, the absence of H-NS protein caused pilE/pilS recombination to increase dramatically when compared with WT values. Consequently, H-NS protein suppresses pilE intragenic transcription as well as antigenic variation through the pilE/pilS recombination system.
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
authors.forename: Thao L
authors.initials: TL
authors.lastname: Masters
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
authors.forename: Shaun
authors.initials: S
authors.lastname: Wachter
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Wachter
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Hill
mesh_terms: D000940:Antigenic Variation; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000276:immunology; D036781:Fimbriae Proteins / Q000235:genetics* / Q000276:immunology*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D011401:Promoter Regions, Genetic; D011995:Recombination, Genetic; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; C074063:pilE protein, Neisseria gonorrhoeae; D036781:Fimbriae Proteins