Figure 1.

TSEN15 protein structure. A, Crystal structure of the TSEN15 (green)–TSEN34 (yellow and orange) heterodimer (Protein Data Bank, identification no. 6Z9U). The position of the Gln⁵⁹ residue is highlighted, and the amino acid side chain is displayed. B, Monomeric crystal structure of TSEN15 (Protein Data Bank, identification no. 2GW6), showing numbering of the α‐α‐β‐β‐β‐β‐α‐β‐β fold (α_1–3 and β_1–6). Gln⁵⁹ is labeled, and the side chain is displayed. C, TSEN15 structure, shown as in B, following in silico mutagenesis to predict the conformation of Gln⁵⁹‐His (labeled). In B and C, red shows oxygen atoms and blue shows nitrogen atoms. The PyMOL Molecular Graphics System was used to view structures and to perform mutagenesis.