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Computational Modeling Suggests a Mechanism of Inhibition of SPAK/OSR1 by a known RF x V Pocket Inhibitor
Author(s) -
Austin Thomas,
Deluca Samuel,
Meiler Jens,
Delpire Eric
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.845.20
Subject(s) - mechanism (biology) , chemistry , pharmacology , medicine , physics , quantum mechanics
The kinases SPAK and OSR1 activate Na + ‐dependent cation‐Cl ‐ cotransporters by anchoring themselves through a C‐terminal domain that binds RFxV/I peptides. Compounds that disrupt this interaction would constitute specific inhibitors. In this work, we used the ROSETTA software suite to dock a library of 14,400 fragments to the known structure of the CCT domain of OSR1. Each fragment was placed at the position that corresponded to the side chain of the Phe from the RFxV/I motif, and allowed to rotate and translate on a flexible CCT backbone. Using a supercomputer, 200 runs were performed on 5 energetically‐relaxed structures plus the native structure per fragment, representing a total of 17.3 x 10 6 simulations. We observed that the structures with the best energy values were placed into a hole behind F452. RosettaHoles confirmed the existence of a void in the crystal structure accessible by displacing the phenyl ring of the F452. Importantly, we were able to model the binding of STOCK2S‐26016, a known inhibitor of SPAK. We found that part of the molecule also reached the hydrophobic void behind F452. ROSETTA assigned a high binding energy to the inhibitor and a much lower energy to an inactive variant. In addition, the known inhibitor shares structural features with fragments from our computational screen. Interestingly, the binding energies of these fragments were better, indicating that the inhibitor may likely be improved upon. In conclusion, we were able to model the binding of chemical structures to the CCT domain of OSR1. The models gave us information regarding the binding location of a known inhibitor. Chemical synthesis and functional studies are underway to assess the binding and inhibitory properties of improved molecules.