H-NS-mediated global regulation of gene expression

In prokaryotes, the role of nucleoid-associated proteins in bacterial physiology remains largely unknown. H-NS has been initially isolated as a RNA polymerase associated factor. It is a polyanion binding protein that may have several regulatory targets

Protein profiles (Proteome analysis) and RNA expression profiles (Transcriptome analysis) of wild-type and hns strains were compared in Escherichia coli (11)

The expression of approximately 5% of the genes (Table 1) and/or the accumulation of the corresponding proteins are directly or indirectly altered in the mutant strain. About 1/5 of these genes encode proteins involved in transcription and translation, in particular many regulators. This suggests that H-NS is located at a high level in the hierarchy of regulation.(Figure 4)

One third of these genes are known or were predicted in silico to encode cell envelope components or proteins usually involved in bacterial adaptation to changes in environmental conditions, such as low pH or high osmolarity. This suggets a strong relationship between the H-NS regulon and the maintenance of intracellular homeostasis

Figure 4: Functional classification of H-NS-regulated genes. (11)