Ab initio fragment molecular orbital study of molecular interactions between liganded retinoid X Receptor and its coactivator: Roles of helix 12 in the coactivator binding mechanism

Mika Ito, Kaori Fukuzawa, Yuji Mochizuki, Tatsuya Nakano, Shigenori Tanaka

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

On the basis of the fragment molecular orbital method we addressed molecular interactions of liganded retinoid X receptor (RXR) with steroid receptor co-activating factor-1 (SRC1) coactivator to examine the contribution of helix 12 (H12), which contains the core of the transcriptional activation function 2 activating domain, to the coactivator binding of RXR. The interaction between H12 and SRC1 was proved to be the main cause for the stabilization of the coactivator binding. In particular, highly conserved charged (Glu453) and hydrophobic (Phe450) residues in H12 were found to have stronger electrostatic and dispersion interactions with SRC1 than the other charged and hydrophobic residues in H12, respectively. In addition, the charge transfer (CT) from RXR to SRC1 was found to occur mainly by the changes in charges of H12 residues. Large positive and negative charge changes were observed especially for Glu453 and for Lys631 and Ile632 in SRC1, respectively, indicating that Glu453 is an electron donor for Lys631 and Ile632 in this CT. Taken together, our findings quantitatively demonstrated that H12 and its highly conserved residues significantly contribute to the coactivator binding not only by the Coulomb and dispersion interactions but also by the CT described with the quantum-mechanical framework.

Original languageEnglish
Pages (from-to)3525-3533
Number of pages9
JournalJournal of Physical Chemistry B
Volume111
Issue number13
DOIs
Publication statusPublished - 2007 Apr 5
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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