Identification of binding regions of bilirubin in the ligand-binding pocket of the peroxisome proliferator-activated receptor-a (Pparalpha)

Darren M. Gordon, Stephen H. Hong, Zachary A. Kipp, Terry D. Hinds

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Recent work has shown that bilirubin has a hormonal function by binding to the peroxisome proliferator-activated receptor-α (PPARα), a nuclear receptor that drives the transcription of genes to control adiposity. Our previous in silico work predicted three potential amino acids that bilirubin may interact with by hydrogen bonding in the PPARα ligand-binding domain (LBD), which could be responsible for the ligand-induced function. To further reveal the amino acids that bilirubin interacts with in the PPARα LBD, we harnessed bilirubin’s known fluorescent properties when bound to proteins such as albumin. Our work here revealed that bilirubin interacts with threonine 283 (T283) and alanine 333 (A333) for ligand binding. Mutational analysis of T283 and A333 showed significantly reduced bilirubin binding, reductions of 11.4% and 17.0%, respectively. Fenofibrate competitive binding studies for the PPARα LBD showed that bilirubin and fenofibrate possibly interact with different amino acid residues. Furthermore, bilirubin showed no interaction with PPARγ. This is the first study to reveal the amino acids responsible for bilirubin binding in the ligand-binding pocket of PPARα. Our work offers new insight into the mechanistic actions of a well-known molecule, bilirubin, and new fronts into its mechanisms.

Original languageEnglish
Article number2975
JournalMolecules
Volume26
Issue number10
DOIs
StatePublished - May 2 2021

Bibliographical note

Funding Information:
Funding: This work was supported by the National Institutes of Health 1R01DK121797 (T.D.H.J.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Albumin
  • Autofluorescence
  • BVRA
  • Bilirubin
  • Biliverdin reductase
  • HO-1
  • Heme oxygenase
  • Mutagenesis analysis
  • Nuclear receptor
  • PPAR

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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