Figure 3.

Loop1 conformation in TdT WT, TdT-μ chimera, and Pol μ without or with dNTP. The new structures described in this paper are framed in red. No structure of the binary complex with an incoming nucleotide is available for Pol μ. Residues in Loop1 depicted in pink belong to TdT, whereas residues colored in blue belong to Pol μ. In addition, a more detailed picture of the interaction of the incoming base ddCTP with the ion pair Arg⁴⁰³-Asp³⁹⁹ (Lys⁴⁰³-Asp³⁹⁹ in TdT) of Loop1 is shown at the bottom; close distances are shown with dotted lines.