PT  - JOURNAL ARTICLE
AU  - Segall, A
AU  - Mahan, MJ
AU  - Roth, JR
TI  - Rearrangement of the bacterial chromosome: forbidden inversions
AID  - 10.1126/science.3045970
DP  - 1988 Sep 09
TA  - Science
PG  - 1314--1318
VI  - 241
IP  - 4871
4099  - http://science.sciencemag.org/content/241/4871/1314.short
4100  - http://science.sciencemag.org/content/241/4871/1314.full
SO  - Science1988 Sep 09; 241
AB  - The order of genes in the chromosome of enteric bacteria has been evolutionarily conserved despite the existence of mechanisms for rearrangement. Homologous chromosomal sequences in the same orientation recombine to form deletions or duplications. When homologous sequences in inverse orientation recombine, one expects to form an inversion of the intervening chromosomal segment. This expectation was tested by placing pairs of homologous sequences in inverse order at various points in the chromosome. Sequences at many pairs of sites (permissive) do recombine to generate the expected inversion, while the same sequences placed at other pairs of sites (nonpermissive) do not form an inversion. For the one nonpermissive interval tested, the missing inversion type can be constructed by an alternative transductional method; strains with this inversion are viable. Thus mechanistic limitations must prevent sequences at particular sites from undergoing the recombination event required to form an inversion.