PDBsum entry 3d08

Transcription

PDB id: 3d08

Contents

Protein chain

182 a.a.

Metals

_ZN

Waters ×231

References listed in PDB file

Key reference

Title

Structural basis of restoring sequence-Specific DNA binding and transactivation to mutant p53 by suppressor mutations.

Authors

O.Suad, H.Rozenberg, R.Brosh, Y.Diskin-Posner, N.Kessler, L.J.Shimon, F.Frolow, A.Liran, V.Rotter, Z.Shakked.

Ref.

J Mol Biol, 2009, 385, 249-265. [DOI no: 10.1016/j.jmb.2008.10.063]

PubMed id

18996393

Abstract

The tumor suppressor protein p53 is mutated in more than 50% of invasive cancers. About 30% of the mutations are found in six major "hot spot" codons located in its DNA binding core domain. To gain structural insight into the deleterious effects of such mutations and their rescue by suppressor mutations, we determined the crystal structures of the p53 core domain incorporating the hot spot mutation R249S, the core domain incorporating R249S and a second-site suppressor mutation H168R (referred to as the double mutant R249S/H168R) and its sequence-specific complex with DNA and of the triple mutant R249S/H168R/T123A. The structural studies were accompanied by transactivation and apoptosis experiments. The crystal structures show that the region at the vicinity of the mutation site in the R249S mutant displays a range of conformations [wild-type (wt) and several mutant-type conformations] due to the loss of stabilizing interactions mediated by R249 in the wt protein. As a consequence, the protein surface that is critical to the formation of functional p53-DNA complexes, through protein-protein and protein-DNA interactions, is largely distorted in the mutant conformations, thus explaining the protein's "loss of function" as a transcription factor. The structure of this region is restored in both R249S/H168R and R249S/H168R/T123A and is further stabilized in the complex of R249S/H168R with DNA. Our functional data show that the introduction of H168R as a second-site suppressor mutation partially restores the transactivation capacity of the protein and that this effect is further amplified by the addition of a third-site mutation T123A. These findings together with previously reported data on wt and mutant p53 provide a structural framework for understanding p53 dysfunction as a result of oncogenic mutations and its rescue by suppressor mutations and for a potential drug design aimed at restoring wt activity to aberrant p53 proteins.

Figure 5.
Fig. 5. Dimerization surfaces. Stereo view of the superposition of core domain regions that form the symmetrical dimer interface upon DNA binding (one-half of the symmetrical dimer), including the nine structures of Fig. 1 (with the same color code) and the thermostable mutant T-p53C-R249S (PDB code 2BIO)^38 shown in light blue. The various structural elements (L2, L3, H1, H1″) and the boundaries of the corresponding regions (residues 168–195 and 236–250) are indicated. Zinc atoms are shown by the corresponding colored spheres.

Figure 8.
Fig. 8. Different views of the R249S/H168R tetramer bound to DNA. Four core domains (designated A–D) shown in ribbon representation interact with two double-stranded DNA half-sites (shown in grey). The core tetramer is a dimer of dimers: A, B (cyan and red) and C, D (green and magenta). (a) View down the central dyad of the core tetramer. (b) View perpendicular to the central dyad and the DNA helix axis. (c) View down the DNA helix axis.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2009, 385, 249-265) copyright 2009.