Member of the two-component regulatory system RssA/RssB involved in regulation of swarming motility which has been shown to be inhibited by saturated fatty acids. RssA/RssB regulates cellular fatty acid composition, hemolysin production and cell surface topography. RssA/RssB negatively regulates the activity of SlhBA. It can also act as a negative regulator for the control of the swarming initiation. RssB binds its own promoter. Mutation in either rssA or rssB confers a precocious-swarming phenotype on LB agar: swarming occurs at 37 degrees Celsius and is initiated at a lower cell density and more rapidly than the swarming of the parent strain at 30 degrees Celsius. Both mutants also exhibit increased hemolysin activity and altered cell surface topology.