Histone-like nucleoid-structuring protein

In molecular biology, the histone-like nucleoid-structuring (H-NS) protein belongs to a family of bacterial proteins that play a role in the formation of nucleoid structure and affect gene expression under certain conditions. The protein has a homologue that is encoded by many large, conjugative plasmids.
Mechanism.
A major function of H-NS is to influence DNA topology. It is believed that H-NS achieves this by forming complexes with itself and binding to different sections of DNA, bringing them together. Another major role of H-NS is to turn off the expression of genes. H-NS regulates gene expression by binding to AT rich DNA, which is a common feature of promoters, and of horizontally acquired genes. Relief of suppression by H-NS can be achieved by the binding of another protein, or by changes in DNA topology which can occur due to changes in temperature and osmolarity, for example.
H-NS can also interact with other proteins and influence their function, for example it can interact with the flagellar motor protein FliG to increase its activity.