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Auto‐ADP‐ribosylation inhibits the catalytic activity of ExoS, a type‐III effector of Pseudomonas aeruginosa
Author(s) -
Stevens Linda Ann,
Park Sunhee,
Barbieri Joseph,
Bortell Rita,
Moss Joel
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a45-b
Subject(s) - pseudomonas aeruginosa , effector , adp ribosylation , chemistry , microbiology and biotechnology , pseudomonas , bacteria , biology , biochemistry , enzyme , genetics , nad+ kinase
Pseudomonas aeruginosa, an opportunistic organism responsible for infections in immunocompromised hosts, produces a number of virulence factors, e.g., Exoenzyme S (ExoS), which are delivered into host cells through a type III secretion system. ExoS is a bifunctional type III effector which has ADP‐ribosyltranferase (ART) activity localized in the carboxyl‐terminal domain and GTPase‐Activating Protein (GAP) activity for Rho GTPases in an amino‐terminal domain. The ART domain is dependent on Factor‐Activating ExoS (FAS), a 14‐3‐3 protein, for expression of ART activity. ExoS was previously shown to auto‐ADP‐ribosylate arginine 146 in the GAP domain, inhibiting GAP activity. We report here that the 49‐kDa full length ExoS and the ART domain of ExoS auto‐ADP‐ribosylate both GAP‐ and ART‐ domains in a FAS‐dependent manner. Increasing [NAD] and the time of incubation increased the amount of ADP‐ribose bound to ExoS and the ART domain. ART activity of ExoS (ADP‐ribosyl‐agmatine formation) was reduced dramatically by auto‐ADP‐ribosylation. The ADP‐ribose amino acid linkage was hydroxylamine sensitive, consistent with modification of arginine. FAS, ADP‐ribosylated by ExoS, still stimulated ExoS activity. Auto‐ADP‐ribosylation thus down regulates the activities of both the GAP‐ and ART‐ domains and thereby, may limit the intracellular activity and toxicity of ExoS. Intramural Research Program, NIH/NHLBI