Format

Send to

Choose Destination
PLoS Pathog. 2013 Jan;9(1):e1003074. doi: 10.1371/journal.ppat.1003074. Epub 2013 Jan 17.

Transcription of a cis-acting, noncoding, small RNA is required for pilin antigenic variation in Neisseria gonorrhoeae.

Author information

1
Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.

Abstract

The strict human pathogen Neisseria gonorrhoeae can utilize homologous recombination to generate antigenic variability in targets of immune surveillance. To evade the host immune response, N. gonorrhoeae promotes high frequency gene conversion events between many silent pilin copies and the expressed pilin locus (pilE), resulting in the production of variant pilin proteins. Previously, we identified a guanine quartet (G4) structure localized near pilE that is required for the homologous recombination reactions leading to pilin antigenic variation (Av). In this work, we demonstrate that inactivating the promoter of a small non-coding RNA (sRNA) that initiates within the G4 forming sequence blocks pilin Av. The sRNA promoter is conserved in all sequenced gonococcal strains, and mutations in the predicted transcript downstream of the G4 forming sequence do not alter pilin Av. A mutation that produces a stronger promoter or substitution of the pilE G4-associated sRNA promoter with a phage promoter (when the phage polymerase was expressed) produced wild-type levels of pilin Av. Altering the direction and orientation of the pilE G4-associated sRNA disrupted pilin Av. In addition, expression of the sRNA at a distal site on the gonococcal chromosome in the context of a promoter mutant did not support pilin Av. We conclude that the DNA containing the G-rich sequence can only form the G4 structure during transcription of this sRNA, thus providing a unique molecular step for the initiation of programmed recombination events.

Comment in

PMID:
23349628
PMCID:
PMC3547852
DOI:
10.1371/journal.ppat.1003074
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center