Characterization of a silent pilin gene locus from Neisseria meningitidis strain FAM18

We cloned and characterized a silent pilin locus (pilS) in the chromosome of Neisseria meningitidis strain FAM18. This locus represents the sole region of the FAM18 chromosome with strong homology to a gonococcal pilin gene. The FAM18 pilS locus encodes two tandem, in-frame, truncated pilin genes and shares many features with the previously described pilS locus of N. meningitidis strain C114. However, DNA sequence comparison shows that different information resides in the hypervariable region of one of the gene copies between the two strains. The conservation of reading frames within silent copies and the sequence diversity in hypervariable regions are reminiscent of gonococcal pilS loci and suggest that pilS loci may be of functional importance in the meningococcus.