FIG. 1.

Structures of the macro domains from the alphaviruses CHIKV and VEEV. (A) Representation of CHIKV and VEEV macro domains in a purple-to-red gradient (from N terminus to C terminus). Secondary structure elements are labeled on the CHIKV macro domain. (B) Superposition of representations of the CHIKV, VEEV, SARS-CoV, and E. coli macro domains, colored, respectively, in dark blue, cyan, purple, and white. (C) Electrostatic surface potential presented between −4 and 4 kT/e for the CHIKV and VEEV macro domains. The potential was generated using the PDB2PQR server (8) and Adaptative Poisson-Boltzmann Solver (APBS) plug-in in Pymol (http://www.pymol.org). (D) Representation of the superposition between the macro domains from CHIKV (apo form in dark blue), VEEV (apo form in cyan and complexed with ADP-ribose in light orange). The two main divergences between the three structures are indicated and circled. (E) Sequence alignment of the macro domains studied. They belong to the genus Alphavirus, except for SARS-CoV. Residues in red boxes are strictly conserved, while those in yellow boxes are conserved by at least four out of seven viruses aligned. Secondary structure elements from the viral macro domain crystal structures obtained are represented above the alignment.