Interlinked Sister Chromosomes Arise in the Absence of Condensin during Fast Replication in B. subtilis

Condensin—an SMC-kleisin complex—is essential for efficient segregation of sister chromatids in eukaryotes. In Escherichia coli and Bacillus subtilis, deletion of condensin subunits results in severe growth phenotypes and the accumulation of cells lacking nucleoids. In many other bacteria and under slow growth conditions, however, the reported phenotypes are much milder or virtually absent. This raises the question of what role prokaryotic condensin might play during chromosome segregation under various growth conditions. In B. subtilis and Streptococcus pneumoniae, condensin complexes are enriched on the circular chromosome near the single origin of replication by ParB proteins bound to parS sequences. Using conditional alleles of condensin in B. subtilis, we demonstrate that depletion of its activity results in an immediate and severe defect in the partitioning of replication origins. Multiple copies of the chromosome remain unsegregated at or near the origin of replication. Surprisingly, the growth and chromosome segregation defects in rich medium are suppressed by a reduction of replication fork velocity but not by partial inhibition of translation or transcription. Prokaryotic condensin likely prevents the formation of sister DNA interconnections at the replication fork or promotes their resolution behind the fork.

Additional file 1: of The complete and fully assembled genome sequence of Aeromonas salmonicida subsp. pectinolytica and its comparative analysis with other Aeromonas species: investigation of the mobilome in environmental and pathogenic strains

Figure S1. Sequencing and assembly strategy of the A. salmonicida subsp. pectinolytica strain 34mel genome. Figure S2. Gene similarity and Mummer alignments to other Aeromonas genomes. Figure S3. Transposon conglomerates from A. salmonicida subsp. pectinolytica strain 34mel. Figure S4. Transposon family content in analyzed Aeromonas strains. Figure S5. Comparison of the A. salmonicida subsp. pectinolytica strain 34mel genome, plasmid pFBAOT6 from Aeromonas caviae, and transposon Tn1721. Table S1. Pathogenic as well as temperature-dependent growth features of analyzed Aeromonas strains. Table S2. General genome features of A. salmonicida subsp. pectinolytica strain 34mel. Table S3. Polymorphic sites in rRNAs from A. salmonicida subsp. pectinolytica strain 34mel. Table S4. Genes disrupted by transposons in A. salmonicida subsp. pectinolytica strain 34mel. Table S5. Transposon details from analyzed Aeromonas strains. Table S6. Genes retained in transposon TnAs1 from the environmental IncP-9 TOL plasmid pWW0 from Pseudomonas putida. Text S1. Annotation details for RNA genes in the A. salmonicida subsp. pectinolytica strain 34mel genome. Text S2. Short unassigned contigs from the A. salmonicida subsp. pectinolytica strain 34mel draft genome. Text S3. Transposons: nomenclature and completeness. Text S4. On transposon counting and the meaning of “ISAs11”. Text S5. Insertions on pFBAOT6 in transposon Tn1721 and details of the regions shared with the A. salmonicida subsp. pectinolytica strain 34mel genome. Text S6. Details of PacBio library preparation, sequencing, and assembly of the genome from A. salmonicida subsp. pectinolytica strain 34mel. (PDF 1171 kb