Dynamics and Mechanism of Binding of Androstenedione to Membrane-Associated Aromatase

Biochemistry. 2020 Aug 25;59(33):2999-3009. doi: 10.1021/acs.biochem.0c00460. Epub 2020 Aug 11.

Abstract

Aromatase (CYP19A1) catalyzes the synthesis of estrogens from androgens and is an invaluable target of pharmacotherapy for estrogen-dependent cancers. CYP19A1 is also one of the most primordial human CYPs and, to the extent that its fundamental dynamics are conserved, is highly relevant to understanding those of the more recently evolved and promiscuous enzymes. A complementary approach employing molecular dynamics simulations and hydrogen-deuterium exchange mass spectrometry (HDX-MS) was employed to interrogate the changes in CYP19A1 dynamics coupled to binding androstenedione (ASD). Gaussian-accelerated molecular dynamics and HDX-MS agree that ASD globally suppresses CYP19A1 dynamics. Bimodal HDX patterns of the B'-C loop potentially arising from at least two conformations are present in free 19A1 only, supporting the possibility that conformational selection is operative. Random-acceleration molecular dynamics and adaptive biasing force simulations illuminate ASD's binding pathway, predicting ASD capture in the lipid headgroups and a pathway to the active site shielded from solvent. Intriguingly, the predicted access channel in 19A1 aligns well with the steroid binding sites of other human sterol-oxidizing CYPs.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Androstenedione / metabolism
  • Androstenedione / pharmacokinetics*
  • Aromatase / chemistry*
  • Aromatase / metabolism*
  • Catalytic Domain
  • Deuterium Exchange Measurement
  • Humans
  • Hydrogen Deuterium Exchange-Mass Spectrometry
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism
  • Membranes / chemistry
  • Membranes / metabolism*
  • Models, Molecular
  • Molecular Docking Simulation
  • Molecular Dynamics Simulation
  • Protein Binding

Substances

  • Lipid Bilayers
  • Androstenedione
  • Aromatase
  • CYP19A1 protein, human