Evidence for symmetric chromosomal inversions around the replication origin in bacteria
Evidence for symmetric chromosomal inversions around the replication origin in bacteria
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Date
2000-12-04
Authors
Eisen, Jonathan A.
Heidelberg, John F.
White, Owen
Salzberg, Steven L.
Advisor
Citation
Evidence for symmetric chromosomal inversions around the replication origin in bacteria. Jonathan A. Eisen, John F. Heidelberg, Owen White, and Steven L. Salzberg. Genome Biology 1:6 (2000), 1-9.
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Abstract
Background: Whole-genome comparisons can provide great insight into many aspects of biology.
Until recently, however, comparisons were mainly possible only between distantly related species.
Complete genome sequences are now becoming available from multiple sets of closely related
strains or species.
Results: By comparing the recently completed genome sequences of Vibrio cholerae, Streptococcus
pneumoniae and Mycobacterium tuberculosis to those of closely related species - Escherichia coli,
Streptococcus pyogenes and Mycobacterium leprae, respectively - we have identified an unusual and
previously unobserved feature of bacterial genome structure. Scatterplots of the conserved
sequences (both DNA and protein) between each pair of species produce a distinct X-shaped
pattern, which we call an X-alignment. The key feature of these alignments is that they have
symmetry around the replication origin and terminus; that is, the distance of a particular conserved
feature (DNA or protein) from the replication origin (or terminus) is conserved between closely
related pairs of species. Statistically significant X-alignments are also found within some genomes,
indicating that there is symmetry about the replication origin for paralogous features as well.
Conclusions: The most likely mechanism of generation of X-alignments involves large chromosomal
inversions that reverse the genomic sequence symmetrically around the origin of replication. The
finding of these X-alignments between many pairs of species suggests that chromosomal inversions
around the origin are a common feature of bacterial genome evolution.