 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 2]](hm5049fig2mag.jpg)
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Figure 2
Ball-and-stick and electron-density maps of the engineered U·U mismatch at the top of helix 2 (H2). (a) The U−5·A14 base pair as observed in one of two molecules in the asymmetric unit of the 4WJ structure (PDB code 1m5k ). O atoms are colored red and N atoms are blue. Dashed gray lines indicate putative hydrogen bonds with corresponding distances. (b) The minimal junctionless ribozyme 64-mer structure (PDB code 1x9k ) with an orientation equivalent to that in (a). Two symmetry-related U−5 residues are separated by a 3 Å translation and are not base-paired. (c) The original syn–anti base-pairing conformation of U−5 modeled for the 2.05 Å resolution junctionless ribozyme (PDB code 1zfr ). Alternate conformations were modeled with equal occupancy and are colored green or cyan. A single set of hydrogen bonds is indicated; the symmetry-related hydrogen bonds and labels were omitted for clarity. A σA-weighted simulated-annealing omit electron-density map calculated for the U−5 residue and nearby solvent molecules is shown contoured at 3.5σ with coefficients mFo − DFc. (d) The revised 2.05 Å resolution minimal hairpin-ribozyme structure of this study depicting the new anti–anti or `Calcutta' model for U−5 fitted into an omit map as described in (c). |
![[Figure 2]](hm5049fig2.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
