Ensemble averages
over TOPRNA bulge simulations reproduce experimentally
measured properties of bulge motifs. (A) |βh| averaged
over TOPRNA simulations (black) and over the ref (29) predicted allowed spaces
(gray) for different bulge motifs is plotted next to the bend angles
measured by transient electronic birefringence for polyU (red) and
polyA (blue) bulges in the absence (solid line, filled circles) and
presence (dashed line, open circles) of Mg2+.61 Error bars denote experimental error.61 “No conn.” denotes a bulge-like
junction that lacks connectivity in its bulge strand. (B) HIV-1 TAR,
HIV-1 TARGC, and HIV-2 TAR secondary structures. RDCs from
nucleotides shown in gray were excluded from the RDC analysis. (C,
D, E) HIV-1 TAR, HIV-1 TARGC, and HIV-2 TAR experimental
RDCs versus values computed from either 3-nt or 2-nt TOPRNA bulge
simulations.56,57 In part C, red and gray points
correspond to RDCs from helix I and helix II TAR elongations, respectively.56 N–H bond vectors were excluded from all
RDC analysis.