Inversion of Correia Repeat Enclosed Elements in Neisseria gonorrhoeae.

Neisseria gonorrhoeae is capable of causing gonorrhoea and more complex diseases in the human host. Within the gonococcal genome are over 100 copies of the IS-like Correia Repeat Enclosed Element, which has been predicted to be mobile within the neisserial genomes. Although there is evidence of ancestral movement of these elements, no previous study has provided evidence for current mobilisation. The Correia Repeat Enclosed Element has the ability to alter gene expression and regulation in many ways: by insertional mutagenesis; by introducing promoter elements; by generating mRNA processing sites, and by association with ncRNAs. Previous studies have compared the genomic locations of Correia Repeat Enclosed Elements in the Neisseria spp., demonstrating that otherwise identical regions have either the element or the target TA insertion site. In this study, we report for the first time movement of Correia Repeat Enclosed Elements, through inversion of the element at its chromosomal location. Analysis of Ion Torrent generated genome sequence data from Neisseria gonorrhoeae strain NCCP11945 passaged for 8 weeks in the laboratory under standard conditions and stress conditions revealed a total of 37 inversions: 24 were exclusively seen in the stressed sample; 7 in the control sample; and the remaining 3 were seen in both samples. These inversions have the capability to alter gene expression in N. gonorrhoeae through the previously determined activities of the sequence features of these elements, potentially resulting in reversible phase variable gene expression.