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

2020; Nature Portfolio; Volume: 11; Issue: 1 Linguagem: Inglês

10.1038/s41467-020-15238-4

2041-1723

Kati Böhm, Giacomo Giacomelli, Andreas Schmidt, Axel Imhof, Romain Koszul, Martial Marbouty, Marc Bramkamp,

RNA and protein synthesis mechanisms

Abstract 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.