FIC2

FIC2 is a designation used in molecular biology to denote the second member of the Fic (filamentation induced by cAMP) domain-containing protein family in a given organism or study. It is not a single universal protein; FIC2 proteins occur as paralogs or orthologs across species, with function varying by context.

Most FIC-domain enzymes catalyze AMPylation (adenylylation) of target proteins, using ATP as a donor. The Fic domain typically provides the catalytic activity, and the overall function is often regulated by additional regions or partner proteins that control substrate access and activity.

In bacteria, Fic-domain proteins frequently act as virulence factors when delivered into host cells by secretion systems, where they modify host signaling or cytoskeletal components to influence infection outcomes. FIC2 family members may participate in virulence, stress response, or intracellular survival, depending on the organism and context.

Structural architectures usually include a C-terminal Fic domain, with N-terminal regulatory regions that tune substrate specificity and activity. Substrates reported or proposed for FIC2 proteins include host signaling proteins such as small GTPases in some pathogens, and bacterial regulatory proteins in others.

Research on FIC2 is ongoing and often species-specific. Key questions address substrate range, regulatory mechanisms, and the evolutionary diversification of Fic-domain enzymes.

See also: Fic domain-containing protein, AMPylation, HYPE/FicD.