Cahoon LA and Seifert HS. (2013) Transcription of a Cis-Acting, Noncoding, Small RNA is Required for Pilin Antigenic Variation in Neisseria gonorrhoeae. PLoS Pathog, 9(1):e1003074.
Guanine quartets (G4) are important regulatory structures for a variety of biological processes. In this paper the authors identify a small RNA (sRNA) that facilitates the formation of a G4 structure, in the pilE gene of N. gonorrhoeae, which is critical for the cells to avoid the host immune response. The authors used IDT gBlocks™ Gene Fragments (www.idtdna.com/gblocks) to create 3 mutated sRNA sequences: inverted (bases on the wrong strand), reverse, and combination inverted-reverse sequences. Only the wild type direction and orientation was able to produce the characteristic antigenic variation. These results led the authors to the conclusion that the sRNA acts in cis on the G4 region, with sRNA strand orientation and direction being critical for formation of the G4 structure.