Mol. Cell

We show that the secreted antigen, IbpA, of the respiratory pathogen Histophilus somni induces cytotoxicity in mammalian cells via its Fic domains. Fic domains are defined by a core HPFxxGNGR motif and are conserved from bacteria to humans. We demonstrate that the Fic domains of IbpA catalyze a unique reversible adenylylation event that uses ATP to add an adenosine monophosphate (AMP) moiety to a conserved tyrosine residue in the switch I region of Rho GTPases. This modification requires the conserved histidine of the Fic core motif and renders Rho GTPases inactive. We further demonstrate that the only human protein containing a Fic domain, huntingtin yeast-interacting protein E (HYPE), also adenylylates Rho GTPases in vitro. Thus, we classify Fic domain-containing proteins as a class of enzymes that mediate bacterial pathogenesis as well as a previously unrecognized eukaryotic posttranslational modification that may regulate key signaling events.

Source:http://purl.uniprot.org/citations/19362538