6His-3C-HNS Protein

General information on H-NS Protein

H-NS protein stands for histone-like nucleoid structuring protein. The latter is a major component of the folded chromosome in Escherichia coli and related bacteria. This protein belongs to a family of bacterial proteins that involved in the formation of nucleoid structure and are linked to gene expression under certain conditions. H-NS protein has a homologue that is encoded by several conjugative plasmids. The protein more specifically has been linked to management of genome evolution, DNA condensation and transcription. H-NS protein has also been linked to possessing rudimentary determinants for self-association, hetero-oligomerization and DNA binding.
H-NS protein is responsible for bacterial chromosome compaction and organization. H-NS binds to AT-rich dsDNA which eventually leads to the inhibition of transcription process. This is essential for the regulation of gene expression. The suppression of H-NS protein activity can be achieved by the binding of another protein or by changing DNA topology. This protein is also involved in the upstream and downstream binding of this protein to the RNA polymerase which eventually prevents the transcription. Another major function of H-NS protein is its influence in DNA topology. It is believed that the protein achieves this by forming complexes with itself and binding to different DNA sections. Other functions of the protein involve its interaction with proteins and influencing their function. For instance, H-NS protein interacts with flagellar motor protein (FliG) which results in the increase of FliG activity.
The three-dimensional structure of the C-terminal domain (47 residues) of H-NS protein is composed of an antiparallel beta-sheet, an alpha-helix and a 3(10)-helix which builds a hydrophobic core that stabilizes the whole structure. This domain is responsible for DNA binding. The protein is capable of high-order self-association via interactions of its oligomerization domain. The crystallography shows a superhelical structure which establishes a mechanism for the self-association of H-NS via both an N-terminal antiparallel coiled-coil and a second, hitherto unidentified, helix-turn-helix dimerization interface at the C-terminal end of the oligomerization domain.