Figure 7.
A water-mediated cross-strand ribose-base interaction stabilizes the G•U wobble pair in the minor groove. The D2O in the lower foreground links G48 and U72 by accepting and donating H-bonds to N2(D)2 and 2′-OD, respectively. The color code is identical to that in Figure 3A, H-bonds are drawn with thin solid lines and residues are labeled. Somewhat long H-bonds are indicated with dashed lines. One of them occurs between a water that sits adjacent to O4 of U72 and O6 of G48. The other occurs between a water bound to N1D and N2(D)2 of G73 and O4′ of U47.