Comparison of the genome organization of pathogenic Neisseriae

Current efforts to completely sequence the meningococcal and gonocococcal genomes raise the question whether the lessons learned from the sequenced strains may be safely extrapolated to other members of these species, or whether, in view of the fact that Neisseriae are highly recombinogenic and exhibit a high degree of horizontal intra-and interspecies genetic transfer, only clone-specific conclusions are valid. From the known physical and genetic maps of each of two gonococcal and meningococcal strains, it would appear that both species exhibit a species-specific conservation in their genetic organization while the interspecies comparison revealed several rearrangements, although still with a high overall similarity. However, these data contrast with other evidence suggesting intra-species rearrangements, such as the nonconserved I-CeuI macrorestriction patterns of different meningococcal and other neisserial strains. Since I-CeuI cuts within the 23S-rRNA sequence, the restriction pattern should give reliable information on the distribution of rrn loci in the neisserial genomes. Further studies are warranted to answer these questions.