Chromosome organization by a conserved condensin-ParB system in the actinobacterium Corynebacterium glutamicum

Kati Böhm (1) , Giacomo Giacomelli (1, 2) , Andreas U. Schmidt (1) , Axel Imhof (1) , Romain Koszul (3, 4) , Martial Marbouty (3) , Marc Bramkamp (1, 2)

1 LMU - Ludwig Maximilian University [Munich] = Ludwig Maximilians Universität München
2 Institut für Allgemeine Mikrobiologie
3 Régulation spatiale des Génomes - Spatial Regulation of Genomes
4 C3BI - Centre de Bioinformatique, Biostatistique et Biologie Intégrative

Higher-order chromosome folding and segregation are tightly regulated in all domains of life. In bacteria, details on nucleoid organization regulatory mechanisms and function remain poorly characterized, especially in non-model species. Here, we investigate the role of DNA-partitioning protein ParB and SMC condensin complexes in the actinobacterium Corynebacterium glutamicum. Chromosome conformation capture reveals SMC-mediated long-range interactions around ten centromere-like parS sites clustered at the replication origin (oriC). At least one oriC-proximal parS site is necessary for reliable chromosome segregation. We use chromatin immunoprecipitation and photoactivated single-molecule localization microscopy to show the formation of distinct, parS-dependent ParB-nucleoprotein subclusters. We further show that SMC/ScpAB complexes, loaded via ParB at parS sites, mediate chromosomal inter-arm contacts (as previously shown in Bacillus subtilis). However, the MukBEF-like SMC complex MksBEFG does not contribute to chromosomal DNA-folding; instead, this complex is involved in plasmid maintenance and interacts with the polar oriC-tethering factor DivIVA. Our results complement current models of ParB-SMC/ScpAB crosstalk and show that some condensin complexes evolved functions that are apparently uncoupled from chromosome folding.

Domaines: Sciences du Vivant [q-bio]; Microbiologie et Parasitologie

Kati Böhm, Giacomo Giacomelli, Andreas U. Schmidt, Axel Imhof, Romain Koszul, et al.. Chromosome organization by a conserved condensin-ParB system in the actinobacterium Corynebacterium glutamicum. Nature Communications, 2020, 11 (1), pp.1485. ⟨10.1038/s41467-020-15238-4⟩. ⟨pasteur-02612484⟩