SspA negatively affects H-NS levels in EHEC. The levels of H-NS were determined in wild type (lane 1) and sspA mutant (lane 2) derivatives of EHEC EDL933 grown to stationary phase cells by western blot. Equal amounts of total protein were resolved on a 10% Bis-Tris SDS-PAGE gel and transferred to a nitrocellulose membrane. Levels of H-NS and Fis were detected using polyclonal antibodies against the respective proteins. Fis served as an internal control for total protein levels. The relative amounts of H-NS normalized to that of Fis are indicated by the numbers in parenthesis.