Table 1.
Simple K-turns classified by the A2b receptor for the hydrogen bond donated by − 1n O2′; this can be N3 or N1. Inter-atomic distances (Å) for this cross-strand interaction and for the 2b·2n basepairing. Abbreviations: rsw = riboswitch, 50S = large ribosomal subunit, strain names H. m. = H. marismortui, E. c. = E. coli, T. t. = T. thermophilus and T. s. = T. solenopsae.
| K-turn | PDB | − 1n: 2b/Å |
2b·2n pair/Å |
|||
|---|---|---|---|---|---|---|
| O–N3 | O–N1 | N2–N7 | N3–N6 | 2b·2n | ||
| N3 class | ||||||
| Kt-7 H. m. (free RNA) | 4C4O | 2.5 | 2.7 | 3.0 | A·G | |
| Box C/D | 1RLG | 2.8 | 2.9 | 3.1 | A·G | |
| U4 snRNA | 1E7K | 3.2 | 2.7 | 3.1 | A·G | |
| Cyclic-diGMP rsw | 3Q3Z | 2.8 | 2.7 | 3.0 | A·G | |
| SAM rsw | 3GX5 | 2.6 | 2.5 | 3.4 | A·G | |
| SAM + YbxF | 3V7E | 3.1 | 3.0 | 3.3 | A·G | |
| T-box | 4LCK | 2.7 | 2.9 | 3.2 | A·G | |
| SAM rsw G2nA | 2YGH | 2.8 | 3.3 | A·A | ||
| N1 class | ||||||
| Kt-38 H. m. | 1FFK | 2.8 | 2.9 | 4.7 | A·G | |
| Kt-7 H. m. (50S) | 1FFK | 2.7 | 3.0 | 4.3 | A·G | |
| L30e | 1T0K | 2.7 | 2.7 | 4.6 | A·G | |
| Cobalamine rsw | 4GXY | 2.5 | 3.1 | 5.3 | A·G | |
| Kt-7 E. c. | 2AWB | 2.8 | 3.8 | A·G | ||
| Kt-23 T. t. | 2WH1 | 2.6 | A·U | |||
| Kt-23 T. s. | 4AEB | 2.5 | 5.0 | A·A | ||