Separation of Chromosome Termini during Sporulation of Bacillus subtilis Depends on SpoIIIE

Abstract

Bacillus subtilis undergoes a highly distinctive division during spore formation. It yields two unequal cells, the mother cell and the prespore, and septum formation is completed before the origin-distal 70% of the chromosome has entered the smaller prespore. The mother cell subsequently engulfs the prespore. Two different probes were used to study the behavior of the terminus (ter) region of the chromosome during spore formation. Only one ter region was observed at the time of sporulation division. A second ter region, indicative of chromosome separation, was not distinguishable until engulfment was nearing completion, when one was in the mother cell and the other in the prespore. Separation of the two ter regions depended on the DNA translocase SpoIIIE. It is concluded that SpoIIIE is required during spore formation for chromosome separation as well as for translocation; SpoIIIE is not required for separation during vegetative growth.

Bacillus subtilischromosome organization oscillates between two distinct patterns

“…The ±87°a nd ±120°loci localized linearly between them. These results confirm and extend previous observations (24,25,28) that the sporulating chromosomes are organized linearly along their length from the poles to midcell in a C. crescentus-like ori-ter ter-ori organization (Fig. 1B).…”

“…At early stages in this developmental process, the replicated chromosomes adopt a structure called the axial filament, in which the origins are anchored at the cell poles and the termini are present near midcell (16,(24)(25)(26). We visualized six chromosomal loci [−7°(ori) and ±87°, ±120°, and +174°(ter)] during sporulation and determined their population-average, normalized position relative to cell length using automated image analysis software (27) (Fig.…”

SpoIIIE strips proteins off the DNA during chromosome translocation

“…Similar results were obtained when tetO arrays were placed at 100°or near the terminus at 162°(data not shown). As reported previously, arrays close to the terminus are not easily resolved prior to translocation (Bogush et al 2007). However, moments before translocation of the 162°re-gion, we could detect two foci in the mother cell compartment of some cells (Supplemental Fig.…”

Coupling of σ G Activation to Completion of Engulfment during Sporulation of Bacillus subtilis Survives Large Perturbations to DNA Translocation and Replication

“…The conditions used for the growth and imaging of samples were similar to those described previously (2,10). Samples (300 l) were taken from cultures grown at 37°C in MSSM and mixed with FM4-64 to a final concentration of 1 ng/l.…”

“…The time from septation to completion of engulfment is not known precisely; the best estimate is about 70 min at 37°C (12,32). Different studies indicate that chromosome replication is completed by stage IIi (2,18,21). However, in striking contrast to vegetative division, chromosome partitioning is not complete at the time of the sporulation division; approximately 70% of the chromosome destined for the prespore is still in the mother cell (47,48).…”