Integrity of the bacterial genome is essential to survival of the organism. Further, the size of the bacterial cell necessitates significant compaction of the genomic DNA, yet availability to various cellular machineries is important for cell growth. A variety of small DNA-binding proteins encompass these functions. These proteins are sometimes referred-to as histone-like, not because of sequence or structural similarity to eukaryotic histones, but because of comparable roles in nucleoid compaction. A number of such nucleoid-associated proteins have been identified in Escherichia coli, including H-NS, Fis, Dps (DNA protection during starvation), HU, and IHF (Integration Host Factor), all of which are present at concentrations up to or even exceeding 10 mM, depending on growth conditions. These proteins have different DNA-binding properties and function together (and sometimes opposing each other) to organize genomic DNA and to regulate DNA-dependent activities.

Further reading: Functional Evolution of Bacterial Histone-Like HU Proteins

Key words: HU proteins , Nucleoid structure, Histone-like HU proteins, DNA-dependent functions, Bacterial genome, DNA binding proteins, Histone-like, Replication, Repair, Recombination, DNA binding, Gene regulation, HU, HU homologs, Histone, Nucleoid-associated proteins