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Figure 4
Overal structure of a viral RdRP. (a) Ribbon representation of a typical RdRP (FMDV 3D, PDB entry 1u09 , Ferrer-Orta et al., 2004BB121). The seven conserved motifs are indicated in different colours: motif A, red; motif B, green; motif C, yellow; motif D, purple; motif E, cyan; motif F, blue; motif G, pink. The side chains of the catalytic Asp residues in the active site are also shown as sticks. (b) Lateral view of a surface representation of the enzyme (grey) that has been cut to expose the three channels that are the entry and exit sites of the different substrates and reaction products. The structural elements that support motifs A, B and C are also shown as ribbons. (c) Sequential structures illustrating the movement of the different residues within the palm domain from a binary RdRP-RNA open complex (left) to an RdRP-RNA-rNTP open ternary complex (middle), and a closed ternary complex (right). Image based on different poliovirus elongation complexes. The different structures correspond to the 3D-RNA (PDB entry 3ol6 , Gong & Peersen, 2010BB38), 3D-RNA-CTP open complex (PDB entry 3olb , Gong & Peersen, 2010BB38) and 3D-RNA-CTP closed complex (PDB entry 3ol7 , Gong & Peersen, 2010BB38) structures of poliovirus elongation complexes, respectively.

Volume 1| Part 6| October 2014| Pages 492-504
ISSN: 2052-2525