Pathways & interactions
Fido domain (IPR003812)
Short name: Fido
This globular domain is named fido after the Fic and Doc proteins where is found. It is approximately 125 to 150 residues long, and is present in proteins from all kingdoms of life [PMID: 14659018, PMID: 18757857, PMID: 19127588, PMID: 19503829], including:
- Fic (filamentation induced by cAMP) from diverse bacteria. It contains a longer insert in the fido domain.
- Doc (death on curing) proteins from phage P1 and several bacteria. All these proteins contain a minimal stand-alone version of the fido domain.
- HypE (Huntingtin associated protein E) from animal. In humans, HypE is thought to interact with Huntingtin, one of the major proteins in the Huntington's disease protein interaction network. Proteins related to HypE are also found in several bacteria and some archaea. HypE proteins contain a longer insert in their fido domain and are typically multidomain proteins.
- Type IV secretion system effector AnkX from Legionella.
- VopS, a type III secretion system effector from Vibrio that causes eukaryotic cell cytotoxicity.
- IbpA (virulence factor p76) from Haemophilus somnus. It includes an N- terminal haemagglutination activity domain, two fido domains and a peptidase C58 domain.
- BepA, an anti-apoptotic bacterial effector protein, which is a type IV secretion system substrate.
The fido domain of Vibrio VopS covalently modifies Rho GTPase threonine with AMP to inhibit downstream signaling events in host cells. The AMPylation activity extends to a eukaryotic fido domain in Drosophila fic homologue CG9523. AMPylation represents a newly discovered posttranslational modification used to stably modify proteins with AMP. This signaling mechanism is predicted to be functionally similar to other posttranslation modifications such as phosphorylation, SUMOylation or acetylation, because the added moiety changes the activity of the modified protein. The covalent attachment of AMP by a phosphodiester bond is predicted to be reversible and is bulky enough to provide a docking site for a putative AMP binding domain [PMID: 19503829].
The fido domain contains a central motif conserved in most sequences (H-x-F-x-[DE]-[AG]-N-[GK]-R), with the motif His contributing to fic AMPylation. The fido domain adopts an alpha-helical fold, arranged as a six-helix up and down bundle [PMID: 18757857, PMID: 19127588, PMID: 19503829].