The impact of the neisserial DNA uptake sequences on genome evolution and stability

@article{citeulike:2599983, abstract = {BACKGROUND:We investigated the origin and distribution of the abundant short DNA uptake sequence (DUS) in six genomes of Neisseria, a naturally transformable group of human pathogens. DUS are required for efficient transformation and their distribution may reflect their evolutionary role and that of transformation itself. RESULTS:We made a multiple alignment of 6 neisserial genomes and found that DUS arise by recombination. The spacing of DUS in the chromosomes matches the average size of conversion fragments. This is taken as evidence that transformation and recombination are tightly linked in genome evolution and also that recombination plays a key role in the establishment of DUS. DUS are overrepresented in the core genome, under-represented in regions under selective pressure driving diversification and totally absent in both recently acquired genes and recently lost core genes. This further suggests that DUS are implicated in genome stability rather than in variation. The substitution patterns in the core genome show that DUS elements are located in permissive regions but are highly conserved, suggesting that they are in mutation-selection balance and/or fuelled by molecular drive. Preliminary analyses indicate that these results also apply to the functionally analogous uptake signal sequence (USS) in Pasteurellaceae. CONCLUSION:The distribution of DUS is best explained by its recombinogenic past. As many other pathogens, Neisseria and Pasteurellaceae have hyperdynamic genomes generating deleterious mutations by intra-chromosomal recombination and by transient hypermutation. The results presented here suggest that transformation in Neisseria and Pasteurellaceae allows counteracting the deleterious effects of genome instability in the core genome. Thus, rather than promoting hypervariation, bacterial sex could be regenerative.}, author = {Treangen, Todd and Ambur, Ole H. and Tonjum, Tone and Rocha, Eduardo }, citeulike-article-id = {2599983}, doi = {http://dx.doi.org/10.1186/gb-2008-9-3-r60}, journal = {Genome Biology}, number = {3}, posted-at = {2008-04-15 14:33:07}, priority = {2}, title = {The impact of the neisserial DNA uptake sequences on genome evolution and stability}, url = {http://dx.doi.org/10.1186/gb-2008-9-3-r60}, volume = {9}, year = {2008} }

TY - JOUR ID - citeulike:2599983 L3 - citeulike-article-id:2599983 TI - The impact of the neisserial DNA uptake sequences on genome evolution and stability JF - Genome Biology VL - 9 IS - 3 N2 - BACKGROUND:We investigated the origin and distribution of the abundant short DNA uptake sequence (DUS) in six genomes of Neisseria, a naturally transformable group of human pathogens. DUS are required for efficient transformation and their distribution may reflect their evolutionary role and that of transformation itself. RESULTS:We made a multiple alignment of 6 neisserial genomes and found that DUS arise by recombination. The spacing of DUS in the chromosomes matches the average size of conversion fragments. This is taken as evidence that transformation and recombination are tightly linked in genome evolution and also that recombination plays a key role in the establishment of DUS. DUS are overrepresented in the core genome, under-represented in regions under selective pressure driving diversification and totally absent in both recently acquired genes and recently lost core genes. This further suggests that DUS are implicated in genome stability rather than in variation. The substitution patterns in the core genome show that DUS elements are located in permissive regions but are highly conserved, suggesting that they are in mutation-selection balance and/or fuelled by molecular drive. Preliminary analyses indicate that these results also apply to the functionally analogous uptake signal sequence (USS) in Pasteurellaceae. CONCLUSION:The distribution of DUS is best explained by its recombinogenic past. As many other pathogens, Neisseria and Pasteurellaceae have hyperdynamic genomes generating deleterious mutations by intra-chromosomal recombination and by transient hypermutation. The results presented here suggest that transformation in Neisseria and Pasteurellaceae allows counteracting the deleterious effects of genome instability in the core genome. Thus, rather than promoting hypervariation, bacterial sex could be regenerative. AU - Treangen, Todd AU - Ambur, Ole AU - Tonjum, Tone AU - Rocha, Eduardo PY - 2008/// UR - http://dx.doi.org/10.1186/gb-2008-9-3-r60 ER -