Figure 6

Role of the T147F and K160R co-substitution at the recognition of NNTTCA half sites. A: hTRβ on TRE (PDB 2NLL) showing double hydrogen bonding between R160 and the central basis step. B: VDR on canonical AGGTCA half site (PDB 1KB4), showing packing of R160 against the T147F substituted residue, which, in turn, move the R160 away from the central basis step and distort the above cited hydrogen bonds. C: VDR on AGTTCA half site (PDB:1KB2). R160 is over-packed between the C7 atom from the thimidine at the third basis-pair and the F147 side chain. D: model of VDR with a F147T substitution showing distorted interaction of the T147 with the backbone due to stereochemical hindrance.