FIGURE 8.

Distribution of the non-canonical Cys-His-Glu catalytic triad throughout species. NAT homologue sequences from Bacillus species cluster differently from canonical bacterial NATs and are closely related to lower eukaryotes as reported previously (5). The Bacillus sequences cluster in three main clades corresponding to (BACCR)NAT1, (BACCR)NAT2, and (BACCR)NAT3 orthologous sequences. All NAT homologues present in the (BACCR)NAT3-containing clade have a Glu residue instead of the Asp at catalytic position 123 (in green). Three sequences from lower eukaryotes and four bacterial sequences also possess a putative Glu as the third catalytic residue (in red). Characterized NAT sequences are indicated according to the NAT nomenclature; other sequences are indicated as genus species strain followed by the UniProt identifier in brackets.