Combined x-ray crystallography and computational modeling approach to investigate the Hsp90 C-terminal peptide binding to FKBP51

Rajnish Kumar,Pavel F. Pavlov,Bengt Winblad,Martin Moche

doi:10.1038/s41598-017-14731-z

Rajnish Kumar, Pavel F. Pavlov + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-14731-z

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Abstract

FK506 binding protein of 51 kDa (FKBP51) is a heat shock protein 90 (Hsp90) co-chaperone involved in the regulation of steroid hormone receptors activity. It is known for its role in various regulatory pathways implicated in mood and stress-related disorders, cancer, obesity, Alzheimer’s disease and corticosteroid resistant asthma. It consists of two FKBP12 like active peptidyl prolyl isomerase (PPIase) domains (an active FK1 and inactive FK2 domain) and one tetratricopeptide repeat (TPR) domain that mediates interaction with Hsp90 via its C-terminal MEEVD peptide. Here, we report a combined x-ray crystallography and molecular dynamics study to reveal the binding mechanism of Hsp90 MEEVD peptide to the TPR domain of FKBP51. The results demonstrated that the Hsp90 C-terminal peptide binds to the TPR domain of FKBP51 with the help of di-carboxylate clamp involving Lys272, Glu273, Lys352, Asn322, and Lys329 which are conserved throughout several di-carboxylate clamp TPR proteins. Interestingly, the results from molecular dynamics study are also in agreement to the complex structure where all the contacts between these two partners were consistent throughout the simulation period. In a nutshell, our findings provide new opportunity to engage this important protein-protein interaction target by small molecules designed by structure based drug design strategy.

Highlights

Molecular chaperones are primarily responsible for the maintenance of intracellular protein homeostasis including protein folding, transport and degradation and are involved in variety of specific functions including stress response, intracellular signaling, and transcription[1]
We have used control peptide NH2-DDDDDDDDDD-COOH to ensure that the binding to the tetratricopeptide repeat (TPR) domain of FK506 binding protein of 51 kDa (FKBP51) is sequence-specific and not a simple electrostatic attraction between peptide and its target
We observed that the incubation of FKBP51 with 200 μM control peptide did not lead to any change in the melting point of FKBP51 (Fig. 1B)

Summary

Introduction

Molecular chaperones are primarily responsible for the maintenance of intracellular protein homeostasis including protein folding, transport and degradation and are involved in variety of specific functions including stress response, intracellular signaling, and transcription[1]. Structure based drug design (SBDD) can be employed as a tool to identify small molecule inhibitors of this interaction taking the advantage of the availability of the 3D crystal structures of FKBP5229, FKBP3830, FKBP37/AIP31 and Cyp4032 in complex with the EEVD peptides. These crystal structures reveal that the TPR domain binds to the Hsp70/Hsp[90] C-terminal peptide in more or less similar fashion which makes the task of identifying selective inhibitors of a specific co-chaperone very challenging. We believe that the FKBP51-Hsp[90] C-terminal peptide complex structure reported in this study can be instrumental in design and development of novel specific and potent small molecule inhibitors of this important drug target. It worth to mention that some of the functions of FKBP51 might not be dependent on its interaction with Hsp[90] and will not be affected by such inhibitors

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