V. cholerae FtsK Orienting Polar Sequences.
A. Growth competition of E. coli cells encoding FtsK hybrids. N: cells carrying a complete deletion of the C-terminal domain and linker region of FtsKEc; NLCEc: cells carrying full length FtsKEc; NLCVc and NLCHi: cells in which the C-terminal domain FtsKEc was replaced by the one of FtsKVc and FtsKHi, respectively. f: frequency of cells that the parental N strain fails to produce at each generation compared to the FtsK hybrids. B. 5′-GGGCAGGG-3′ inhibits recombination activation by FtsKVc. Plasmid recombination at E. coli dif by XerCDEc was induced with 0.5% arabinose. Ec[NRE]: FtsK50CEc[NRE]; Vc[NRE]: FtsKVc[NRE]. KOPS-0: substrate without GGGCAGGG sequences; KOPS-2: substrate with triple overlapping GGGCAGGG sequences in the non-permissive orientation on both sides of the two dif sites. C. Scheme of the two V. cholerae chromosomes showing the distributions of the GGGCAGGG and GGGNAGGG motifs. Upper bars: motifs found in the leading strand; Lower bars: motifs found in the lagging strand. Number, frequency, skew and skew significance (p-skew) are indicated for each motif. Recently acquired genomic regions are indicated (superintegron, CTX and TLC prophages and the Vibrio Pathogenicity Island VPI).