Cohesion in E. coli chromosome structure mutants.

(A) Cohesion assay. Cohesion values (gln copies per focus) are determined by independently measuring gln copy number and resolvable gln foci per cell in asynchronous exponential cells bearing a tetO array at gln and expressing fluorescent TetR-YFP. See text for details. (B) gln copy number and TetR-YFP foci per cell in wild-type and mutant cells bearing a tetO array at the gln locus. Cells were grown exponentially in minimal alanine media, and gln copy number and foci per cell were determined (Materials and Methods). Cells were grown continually at 30°C or shifted to the indicated temperature 4 hours prior to analysis. Values are means of three independent experiments ±1 standard deviation (SD). (C) Cohesion values (average number of gln copies per gln focus) for candidate mutant strains. Focus values were adjusted for small inefficiencies of fluorescent detection (Materials and Methods).