An Alternative DNA Structure Is Necessary for Pilin Antigenic Variation in Neisseria gonorrhoeae

Abstract

Taking Shape DNA recombination mechanisms enable certain pathogens to modify the proteins on their outer surfaces by rearranging their genes and so avoid repeated detection by the immune system. Cahoon and Seifert (p. 764 ) have found that antigenic variation of a single genetic locus in the human pathogen Neisseria gonorrhoeae is triggered by a specific cis-acting DNA element. This 16–base pair DNA sequence formed an unusual DNA structure in vitro; a guanine quartet (G4), which has been implicated in only a few other biological processes. The G4 forming sequence is required for processing the gene conversion reaction leading to antigenic variation. These findings have implications both for understanding mechanisms of DNA recombination and its role in microbial pathogenesis.