Nucleoidets

Nucleoidets is a term used in speculative models of prokaryotic chromosome organization to describe small, discrete DNA-protein assemblies within the bacterial nucleoid. The word combines nucleoid with the diminutive suffix -et, implying a small subunit of the larger nucleoid structure.

In these models, nucleoidets would arise from interactions among the DNA double helix, DNA supercoiling, and nucleoid-associated proteins such as HU, IHF, and FIS in bacteria, and possibly SMC-like complexes. They are envisioned as dynamic, reversible domains that can form and dissolve as cells grow, replicate, or respond to environmental cues.

The existence of nucleoidets is not established as a widely accepted concept. Evidence is indirect, drawing on high-resolution imaging and chromosome conformation capture studies that reveal organizing principles within the nucleoid, such as domains or loops. The term is not routinely used in the mainstream literature, with researchers typically describing chromosomal domains, macrodomains, or DNA-protein complexes.

If real, nucleoidets could influence gene expression by sequestering or exposing loci, coordinate replication with transcription by organizing nearby regions, and facilitate recombination through localized DNA topology. Their properties would be expected to reflect the balance between DNA supercoiling, transcriptional activity, and the availability of architectural proteins.

Nucleoidets remain a hypothetical concept awaiting experimental validation and consensus on definition, measurement, and nomenclature.