Secreted exoenzyme S

UniProtKB accession:  G3XDA1

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UniProtKB description:  Bifunctional effector protein that is secreted and delivered by the type III secretion system into eukaryotic target cells (PubMed:15252013). The N-terminus encodes a GTPase-activating protein activity, whereas the C-terminus encodes an ADP-ribosyltransferase activity. ADP-ribosylates several eukaryotic proteins including ezrin/radixin/moesin (ERM), cyclophilin A and several members of the Ras superfamily (PubMed:15252013, PubMed:9516428). Host Ras ADP-ribosylation blocks its activation by its guanine nucleotide exchange factor, thereby interfering with Ras-mediated signal transduction (PubMed:10419499). For instance, prevents Ras from interacting with and activating phosphoinositol-3-kinase (PI3K), which is required to stimulate the phagocytic NADPH-oxidase that generates reactive oxygen species (PubMed:28494242). The ADPRT domain contributes also to bacterial dissemination to the blood during pneumonia (PubMed:26090668). In addition to this activity, acts via its N-terminal region as a GTPase-activating protein (GAP) for host Rho GTPases including RhoA, Rac1, Cdc42 and Ras (PubMed:10593930). The GAP domain activity induces mitochondrial disruption in the target host cell by activating host caspases 3 and 9 that execute cellular death (PubMed:30232373).