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. 2021 Jun 24;297(2):100909. doi: 10.1016/j.jbc.2021.100909

Figure 1.

Figure 1

Structure and active site loops of A3s.A, crystal structure of ssDNA-bound A3A where the active site loops 1, 3, 5, and 7 are highlighted (PDB ID: 5KEG). ssDNA (orange) and the residues coordinating the zinc (H70, E72A, C101, and C106) are shown as sticks. The catalytic zinc is shown as gray sphere. Amino acid sequence alignments of active site loops in A3A, A3B-CTD, and A3G-CTD are given on the right. B, crystal structure of chimeric A3B-CTD (PDB ID: 5TD5) and A3G-CTD (PDB ID: 6BUX) in cartoon representation. C, schematic representation of the ssDNA binding conformations: U-shape as seen in A3A or chimeric A3B-CTD, or a more extended linear (L) shape as seen in A3G-CTD. The target C is in the zero (0) position with the active site zinc indicated by the dark orange circle, and the other nucleotide positions are represented by orange diamonds along the ssDNA from 5′ to 3′ direction (blue arrow).