THE FAMILY OF BACTERIAL ADP-RIBOSYLATING EXOTOXINS

Pathogenic bacteria utilize a variety of virulence factors that contri bute to the clinical manifestation of their pathogenesis. Bacterial AD P-ribosylating exotoxins (bAREs) represent one family of virulence fac tors that evert their toxic effects by transferring the ADP-ribose moi ety of NAD onto specific eucaryotic target proteins. The observations that some bAREs ADP-ribosylate eucaryotic proteins that regulate signa l transduction, like the heterotrimeric GTP-binding proteins and the l ow-molecular-weight GTP-binding proteins, has extended interest in bAR Es beyond the bacteriology laboratory. Molecular studies have shown th at bAREs possess little primary amino acid homology and have diverse q uaternary structure-function organization. Underlying this apparent di versity, biochemical and crystallographic studies have shown that seve ral bAREs have conserved active-site structures and possess a conserve d glutamic acid within their active sites.