Pseudomonas aeruginosa exoenzyme S is a biglutamic acid ADP-ribosyltransferase

Kinetic analysis of two mutations within Pseudomonas aeruginosa exoenzyme S (ExoS) showed that a E379D mutation inhibited expression of ADP-ribosyltra nsferase activity but had little effect on the expression of NAD glycohydro lase activity while a E381D mutation inhibited expression of both activitie s. These data identify ExoS as a biglutamic acid ADP-ribosyltransferase, wh ere E381 is the catalytic residue and E379 contributes to the transfer of A DP-ribose to the target protein.