negatively charged NTD and positively charged CTD. Magnesium concentrations below 2 mM, allows for the formation of rigid nucleoprotein filaments and high concentrations promote the formation of H-NS DNA bridges. The charges seen in the NTD and CTD may explain how H-NS remains sensitive to changes in temperature and osmolarity (pH below 7.4). 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. Clinical Significance H-NS has a conserved role in the pathogenicity of gram-negative bacteria including Shigella spp., Escherichia coli, Salmonella spp., and many others. It is implicated in the transcription of the virF gene causing what is known as the virF leading to bacillary dysentery, a disease affecting children mainly seen in developing countries. These two bacterial species contain a virulence plasmid that is responsible for invasion of host cells and is regulated by H-NS. Interestingly, almost 70% of the open reading frames (ORF) of the specialized virulence plasmid in Shigella spp. is AT-rich, allowing for long term regulation of this plasmid by H-NS. Aforementioned, studies show that temperature sensitive H-NS will dissociate from bacterial DNA at 37°C, triggering RNA polymerase to transcribe virF, the gene responsible for the expression of VirF. VirF is the main regulator of the virulence cascade and is expressed due to the temperature sensitive "hinge" region of the virF promoter changing conformation so that is no longer favorable for DNA-bridging by H-NS (Figure 3). Once VirF is expressed, it up regulates the production of icsA, functions to promote motility, and virB, encodes the next regulation protein in the Shigella cascade. As soon as VirB is expressed, it will disrupt H-NS for the rest of the virulence plasmid. Shigella spp. contain "molecular backups", or paralogues, to H-NS that have been studied in detail due to their apparent assistance in organization of the virulence plasmid. StpA is a paralogue of H-NS that is conserved across the species but the other, Sfh is expressed solely in the S. flexneri mutant strain 2457T. This mutant strain is of much interest to researchers because it acts as a replacement for H-NS since 2457T does not contain the hns gene. The correlation between H-NS and its paralogues is poorly understood at this time. Due to importance of these paralogues in the absence of H-NS in the mutant, further research and focus on these