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Frustrational Analysis of Na+/H+ Exchanger 1 (NHE1) and Calcineurin B Homologous Protein 1 & 2
Author(s) -
Silva Daniela,
Latzer Joachim,
Wallert Mark,
Provost Joseph John
Publication year - 2016
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.30.1_supplement.600.12
Subject(s) - gene isoform , chemistry , biochemistry , docking (animal) , kinase , microbiology and biotechnology , biophysics , biology , medicine , nursing , gene
The sodium hydrogen exchanger isoform 1 (NHE1) is involved in tumor cell proliferation, metastasis, invasion and morbidity in several cancers including non‐small cell lung cancer. While several proteins, lipids and kinases are responsible for regulating NHE, two proteins, calcineurin homologous protein isoform 1 (CHP1) and 2 (CHP2) are of particular interest in lung cancer cells. While CHP1 binds NHE1 and is responsible for basal activation of NHE1, CHP2 expression is nearly limited to cancer cells and has been reported to replace CHP1‐NHE1 interactions with unknown consequences. Thus an important target for anti‐lung cancer drug design is the binding of a drug which would block CHP2 but not CHP1 from NHE1 activation. To determine unique and common binding sites for CHP isoforms with NHE, we performed molecular dynamics simulations with a coarse‐grained funneled energy function that provided an atomic level picture of the association (and hence activation) of NHE1 with CHP1 and CHP2. In these simulations NHE1 collaboratively folds and binds correctly to both CHP proteins lowering the overall binding free energy. The molecular detail of the simulations helped identify “hot‐spot” residues involved in the encounter complex and in the binding interface that can guide the design of non‐binding mutants. To understand the association of NHE1 on a residue level, frustrated (residues unlikely to bind) and minimally frustrated (residues that bind strongly) contacts of NHE1 residues were computed for bound structures and also the encounter complexes. Based on circular dichroism studies and computational analysis the binding energies were determined for the bound complexes of NHE1 and CHP1/CHP2. In order to assess the optimal storage conditions and establish a time frame for CHP1 and CHP2 structural stability a validation assay was conducted. The nature of the interactions probed served to understand, in molecular detail, the activation of NHE1 and could serve as input for pharmacomodeling to design a therapeutic drugs that fights lung cancer growth.