The structure of the JCV OBD. A

<p>. The amino acid sequence of the JCV T-ag origin binding domain (OBD). The associated secondary structures are presented above the primary sequence. The positions of the A1, B2 and B3 motifs are indicated. <b>B</b>. A ribbon diagram of the JCV OBD crystal structure. The individual beta strands and alpha helices are indicated, as are the N and C termini. The individual secondary elements were named as previously described for the SV40 OBD <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003966#ppat.1003966-Luo1" target="_blank">[48]</a>. <b>C</b>. Superposition of all four structures of the JCV OBD (forms 1, 2 and 3), indicating where the DNA binding A1 and B2 loops are located along with the B3 motifs (in brown, blue and orange, respectively). Structurally, the most variable region in the OBD is the B3 motif.