Figure 4.

Genomic organization of the het-s and het-S loci. Schematic representations of the domain organization of the het-s and het-S loci are given. The gene adjacent to het-S encodes NWD2, a nucleotide-binding oligomerization domain (NOD)-like receptor with a NACHT domain and WD repeats. Upon binding of a specific ligand, NWD2 acquires β-solenoid templating activity (see text for details). HET-S activation can be achieved either by templating by the prion form of HET-s or by the activated form of NWD2. Note that Nwd2 is in an inactive pseudogene form in all het-s strains because of the insertion of a transposon.