FIGURE 1.

AtYoeB is similar to EcYoeB both in structure and in sequence. (A) An AtYoeB dimer (blue and gray ribbons) is found in the asymmetric unit of the crystal, with important crystal packing contacts mediated by a tungstate-terillium compound (TEW). The catalytic residues Glu46, Arg65, and a C-terminal His are conserved (shown in stick form, EcYoeB, (PDB ID 2A6Q) (Kamada and Hanaoka, 2005), shown as green ribbon). (B) The sequence of AtYoeB and EcYoeB are 76% similar, depicted with conserved residues in red boxes and similar in yellow boxes. Secondary structure is depicted above the sequence (including 3₁₀ helices, indicated as “η”). Blue boxes indicate the catalytic residues, which are conserved, while the green box indicates the specificity-determining helix (determined in the current work). Asterisks denote amino acids contacting the YefM antitoxin; triangles denote contacts with the ribosome (deduced from PDB ID 6OXA) (Pavelich et al., 2019). Antitoxin contacts deduced from superposition of the AtYoeB structure (PDB ID 6N90) onto the E. coli YoeB-YefM complex (PDB ID 2A6Q) (Kamada and Hanaoka, 2005).