Characterization of AIM2 DNA-Binding Properties and Filament Formation

Abstract

AIM2-Like Receptors (ALRs) are a class of innate immune receptors for foreign DNA, members of which exist in both the cytosol and nucleus. The eponymous member of this family, AIM2, is a cytosolic DNA sensor composed of an N-terminal pyrin domain (PYD) and a C-terminal HIN-200 domain (HIN). Previous studies of this protein has been limited to an N-terminal tag-protected version of the full-length or a truncated version of the protein. From these studies it has been concluded that AIM2 exists in a resting, autoinhibited form in which the PYD is bound to the HIN. Upon DNA binding, the PYD is released and forms a larger complex with its downstream partners to initiate the inflammation process. Recently, we have been successful in purifying the native (tag-less) full length protein. Using a combination of fluorescence, electron microscopy, and gel-shift assays, coupled with mutagenesis studies, we have characterized the DNA-binding properties of AIM2 and its ability to form filaments in solution.