1. Modulation of p53 binding to MDM2: computational studies reveal important roles of Tyr100 Shubhra G Dastidar, David P Lane, Chandra S Verma

2. p53 network Vogelstein, B., Lane, D. P., and Levine, A. J. (2000). Surfing the p53 network. Nature 408: 307-310.

3. Transactivation domain of p53: 17-29 MDM2: 25-109 Kussie et al., Science 1996 Vassilev et al., Science 2004

4. P27S mutation Δ ΔG = -2.3kcal/mol W23 L26 F19 P27 E 17 TFSD LWKLL P EN 29 Zondlo et al. Biochemistry 2006

5. S27 Δ ΔG = -4.2 kcal/mol Δ Δ G = -4.7 kcal/mol Crystallographically observed binding mode of WT is retained Dastidar, S.G., Lane D.P., Verma C.S., J. Am. Chem. Soc. 2008 α-helix is propagated by another turn Δ ΔH = -0.8 -T Δ ΔS = -3.4 Δ ΔG = -4.2 Δ Δ H = -3.6 -T Δ ΔS = -1.1 Δ Δ G = -4.7

7. Y100 orients as in wild type Y100 flips in Ligand with extended C-terminusLigand with helical conformation Dastidar, S.G., Lane D.P., Verma C.S., J. Am. Chem. Soc. 2008

8. Modulation of binding site of MDM2 while binding to a variety of ligands in PDB p53 12/1 peptideOptimized peptide β-hairpin Nutlin Optimized peptide IC50 ~ 10-2000nM

11. L26 Y100

13. E28 K70 E17 K51 R65

14. K70 K51 R97 K94 Y100

15. K94 R97 K51

16. Apo After MD in presence of p53 p53 binding pocket

17. N-terminal lid p53 binding pocket C-terminal end, connects other domains of MDM2 Y100

20. Conclusions Plasticity of the binding pocket of MDM2 allows the binding of ligands of widely varying shapes and sizes Modulation of binding pocket leads to varying thermodynamics origin of the stability Y100 acts as a gatekeeper Lid-dynamics is correlated with Y100 orientation K51, K70, K94, R97 have role to steer the ligand towards binding pocket

21. Acknowledgement Chandra S. Verma David P. Lane Sebastian Maurer-Stroh BMAD Group BII, A*STAR INCOB organizers

22. K70 K51 R97 K94 Y100

24. H-bond !!

25. p53 binding pocket *Uhrinova et al., JMB 2005