Structure of the catalytic domain of the Salmonella virulence factor SseI.
SseI is secreted into host cells by Salmonella and contributes to the
establishment of systemic infections. The crystal structure of the C-terminal
domain of SseI has been solved to 1.70 Å resolution, revealing it to be a
member of the cysteine protease superfamily with a catalytic triad consisting of
Cys178, His216 and Asp231 that is critical to its virulence activities.
Structure-based analysis revealed that SseI is likely to possess either acyl
hydrolase or acyltransferase activity, placing this virulence factor in the
rapidly growing class of enzymes of this family utilized by bacterial pathogens
inside eukaryotic cells.