Fig. 2: Time-lapsed images capture the elongation step of DNA synthesis.
From: Following replicative DNA synthesis by time-resolved X-ray crystallography
X-ray crystal structures of polymerase intermediates observed between 2–48 h (left column). Cartoon overlays and polder maps contoured at 2–4 σ (blue boxes). Red arrow indicates conformational changes between structures. The transitions are labeled: (5) opening of the O-O1 loop to form a hydrophobic pocket, (6) closing of the O-O1 loop, and (7) reopening of the O-O1 loop following chemical bond formation. Color scheme: 5’ templating base (cyan), Y714 and Y719 (purple), 3’ nucleotide of DNA primer (blue, dCTP (green),earlier reaction time (gray), and later reaction time (yellow). Abbreviations: O (O helix), O1 (O1 helix), T (template), P (primer), Y (tyrosine), D (aspartate), S (serine), I (isoleucine), and G (glycine).
