Genomic organization of the <i>Nwd2/het-S</i> locus and homology between the HET-S PFD region and the N-terminal region of NWD2.

<p>A. Gene structure at the <i>het-s/Nwd2</i> locus in wild-type <i>het-S</i> and <i>het-s</i> strains. NWD2 is encoded by the gene immediately adjacent to <i>het-S</i> in the genome. The two genes are divergently transcribed. Open reading frames are separated by 0.6 kb. In <i>het-s</i> wild-type strains, <i>nwd2</i> contains a <i>repa</i> transposon scar corresponding to an approximately 0.5 kb insertion, leading to premature stop codons; <i>nwd2</i> is thus in an inactive pseudogene form in all wild-type <i>het-s</i> strains (after [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002059#pbio.1002059.ref014" target="_blank">14</a>,<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002059#pbio.1002059.ref024" target="_blank">24</a>]). B. Sequence alignment of the NWD2 N-terminal region (3–23) and the first (226–246) and second 21 amino acid repeat (262–282) of the prion-forming region of HET-S.