Nucleoid Structure and Gene Regulation in Bacteria

The bacterial nucleoid is a dynamic, membrane-less compartment in which chromosomal DNA associates with various proteins and RNA molecules to achieve a compact yet accessible organisation. A combination of supercoiling, macromolecular crowding and binding by nucleoid-associated proteins creates hierarchical domains that balance genome stability with the need for rapid environmental responses. Gene regulation arises from the interplay between DNA topology, transcription factors and global silencers, which can act combinatorially to repress or activate gene clusters. Mechanisms such as transcription-coupled structural rearrangements, local supercoil diffusion and long-range bridging interactions enable coordinated regulation of replication, repair and expression. This structural framework underpins bacterial adaptation, virulence regulation and antibiotic tolerance, and informs strategies to target nucleoid architecture for novel therapeutics.

Research from Nature Portfolio

Recent studies have uncovered an environment-sensing mechanism in which cyclic di-GMP binds to a global silencer protein to modulate its DNA-binding activity and relieve transcriptional repression in response to external cues. This reveals a direct link between second-messenger signalling and nucleoid structure. Foundational work on the Structural Maintenance of Chromosomes complex has delineated how its interaction with the terminus-binding protein directs the localisation of decatenase activity, coordinating origin and terminus dynamics to ensure faithful segregation of replicated chromosomes. These insights clarify the molecular choreography by which bacteria spatially organise their genome during the cell cycle.

Nucleoid Structure and Gene Regulation in Bacteria publication trend

The graph below shows the total number of articles in nucleoid structure and gene regulation in bacteria across all publications each year (not limited to Nature Index journals).

Technical terms

Nucleoid: The organised, protein-bound bacterial chromosome without a surrounding membrane.

Nucleoid-associated proteins (NAPs): Small, abundant DNA-binding proteins that shape nucleoid architecture and regulate transcription.

Supercoiling: The torsional strain of DNA induced by under- or overwinding of the double helix influencing gene accessibility.

H-NS: A histone-like nucleoid structuring protein that silences AT-rich or foreign gene regions by DNA bridging.

c-di-GMP: A cyclic dinucleotide second messenger that modulates bacterial physiology and interacts with nucleoid proteins.

Structural Maintenance of Chromosomes (SMC): A protein complex that organises, condenses and segregates chromosomes through ATP-dependent interactions.

Topoisomerase IV: An enzyme that resolves DNA catenanes by cutting and rejoining duplexes during replication and segregation.

References

1. c-di-GMP inhibits the DNA binding activity of H-NS in Salmonella. Nature Communications (2023).
2. Insights in bacterial genome folding. Current Opinion in Structural Biology (2023).
3. H-NS Mediates the Silencing of Laterally Acquired Genes in Bacteria. PLOS Pathogens (2006).
4. Bridged filaments of histone-like nucleoid structuring protein pause RNA polymerase and aid termination in bacteria. eLife (2015).
5. MatP regulates the coordinated action of topoisomerase IV and MukBEF in chromosome segregation. Nature Communications (2016).