Down-regulates hemolysin expression, in complex with H-NS, and can also stimulate transposition events in vivo. Modifies the set of genes regulated by H-NS; Hha and Cnu (YdgT) increase the number of genes DNA bound by H-NS/StpA and may also modulate the oligomerization of the H-NS/StpA-complex. Binds DNA and influences DNA topology in response to environmental stimuli. Decreases biofilm formation (By similarity). Forms a heterotrimeric complex with the H-NS dimer. Belongs to the Hha/YmoA/Cnu family.