Toxin PAU_02230

UniProtKB accession:  C7BKP9

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UniProtKB description:  Toxin that acts on host cells by modifying Rho proteins by tyrosine GlcNAcylation and heterotrimeric G alpha proteins by deamidation. Catalyzes the mono-O-GlcNAcylation of small GTPases of the Rho family (RhoA, RhoB, RhoC, Rac1, Rac2, Rac3, Cdc42) in eukaryotic host cells at the conserved tyrosine residue located in the switch I region (Tyr-32/34), using UDP-N-acetylglucosamine (UDP-GlcNAc) as the sugar donor; other GTPases of the Rho, Ras or Rab families are not substrates. Tyrosine glycosylation inhibits Rho activation and prevents interaction with downstream effectors, resulting in actin disassembly, inhibition of phagocytosis, cell rounding, and toxicity toward insects and mammalian cells. Also catalyzes the deamidation of the catalytic glutamine in heterotrimeric G alpha proteins (Gi, Gq/11), which blocks GTP hydrolysis and arrests the G proteins in a permanent active state leading to activation of Rho GTPases. Thus, PaTox hijacks host GTPase signaling in a bidirectional manner by deamidation-induced activation and glycosylation-induced inactivation of GTPases.