Multiscale structuring of the E. Coli chromosome by nucleoid-associated and condensin proteins

• Autores: Virginia S. Lioy, Axel Cournac, Martial Marbouty
• Localización: Cell, ISSN 0092-8674, Vol. 172, Nº. 4, 2018, págs. 771-783
• Idioma: inglés
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• Resumen

  • As in eukaryotes, bacterial genomes are not randomly folded. Bacterial genetic information is generally carried on a circular chromosome with a single origin of replication from which two replication forks proceed bidirectionally toward the opposite terminus region. Here, we investigate the higher-order architecture of the Escherichia coli genome, showing its partition into two structurally distinct entities by a complex and intertwined network of contacts: the replication terminus ( ter) region and the rest of the chromosome. Outside of ter, the condensin MukBEF and the ubiquitous nucleoid-associated protein (NAP) HU promote DNA contacts in the megabase range. Within ter, the MatP protein prevents MukBEF activity, and contacts are restricted to ∼280 kb, creating a domain with distinct structural properties. We also show how other NAPs contribute to nucleoid organization, such as H-NS, which restricts short-range interactions. Combined, these results reveal the contributions of major evolutionarily conserved proteins in a bacterial chromosome organization.