Revealing binding selectivity of inhibitors toward bromodomain-containing proteins 2 and 4 using multiple short molecular dynamics simulations and free energy analyses

ABSTRACT

Emerging evidences indicate bromodomain-containing proteins 2 and 4 (BRD2 and BRD4) play critical roles in cancers, inflammations, cardiovascular diseases and other pathologies. Multiple short molecular dynamics (MSMD) simulations combined with molecular mechanics generalized Born surface area (MM-GBSA) method were applied to investigate the binding selectivity of three inhibitors 87D, 88M and 89G towards BRD2 over BRD4. The root-mean-square fluctuation (RMSF) analysis indicates that the structural flexibility of BRD4 is stronger than that of BRD2. Moreover the calculated distances between the C_α atoms in the centres of the ZA_loop and BC_loop of BRD4 are also bigger than that of BRD2. The rank of binding free energies calculated using MM-GBSA method agrees well with that determined by experimental data. The results show that 87D can bind more favourably to BRD2 than BRD4, while 88M has better selectivity on BRD4 over BRD2. Residue-based free-energy decomposition method was utilized to estimate the inhibitor-residue interaction spectrum and the results not only identify the hot interaction spots of inhibitors with BRD2 and BRD4, but also demonstrate that several common residues, including (W370, W374), (P371, P375), (V376, V380) and (L381, L385) belonging to (BRD2, BRD4), generate significant binding difference of inhibitors to BRD2 and BRD4.

KEYWORDS:

• Bromodomain-containing proteins 2 and 4
• MSMD
• MM-GBSA
• binding selectivity
• principal component analysis

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 21863003) and Science Foundation of Shandong Jiaotong University (No. Z201703, Z201206, and Z201202). The authors sincerely thank Prof. Jianzhong Chen (School of Science, Shandong Jiaotong University, Jinan 250357, China) for useful discussions and invaluable comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed at: https://doi.org/10.1080/1062936X.2020.1748107.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China (No. 21863003) and Science Foundation of Shandong Jiaotong University (No. Z201703, Z201206, and Z201202).