FIGURE 1.

Domain organization of trypanosomal TUTases. (A) Domains are diagrammed based on crystal structures of RET2 (Deng et al. 2005) and TUT4 (Stagno et al. 2007b). (B) Partial multiple sequence alignment of N-terminal (NTD) and C-terminal (CTD) domains. Middle domain boundaries within NTD are shown by dotted lines. Protein sequences used in the alignment are TbRET1 (AAK38334), TbRET2 (AAO63567), TbTUT3 (XP_822966), TbTUT4 (DQ923393), and TbMEAT1 (FJ561337). Signature motif of the Pol β nucleotidyl transferase superfamily is boxed. Identical amino acids are white on black; blocks of similar amino acids are black on a gray background. Amino acids participating in UTP binding by TUTases are indicated by asterisks. Metal-coordinating catalytic carboxylate residues are shown by arrows. Double-headed arrow underlines a MEAT1-specific insertion within the CTD.