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Structural basis for PAS domain heterodimerization in the basic helix--loop--helix-PAS transcription factor
Paul J A Erbel1, Paul B Card, Ozgur Karakuzu
1Departments of Biochemistry and Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
Summary
Hypoxia-inducible factor (HIF) protein interactions are crucial for cellular oxygen adaptation. This study reveals the PAS domain
Area of Science:
- Molecular biology
- Cellular signaling
- Biochemistry
Background:
- Cellular adaptation to oxygen levels is vital for physiological homeostasis and disease.
- The hypoxia-inducible factor (HIF) pathway mediates mammalian cells' response to hypoxia.
- HIF is a heterodimeric complex involving PAS domains, whose precise roles remain unclear.
Purpose of the Study:
- To investigate the structure and interactions of the HIF-2alpha C-terminal PAS domain.
- To elucidate the role of PAS domains in HIF complex formation and function.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was employed to study the HIF-2alpha PAS-B domain.
- In vitro binding assays were performed to analyze protein-protein interactions.
- Site-directed mutagenesis was used to assess the functional impact of specific residues.
Main Results:
- The HIF-2alpha PAS-B domain directly binds the ARNT domain via residues on a solvent-exposed beta-sheet surface.
- Mutations at this interface disrupted PAS domain interactions in vitro and impaired HIF function in cells.
- This beta-sheet interaction motif appears conserved across various PAS-containing signaling proteins.
Conclusions:
- The PAS domain beta-sheet interface is critical for HIF complex assembly and hypoxia response.
- This finding provides insights into the specificity and regulation of PAS domain-mediated signaling.
- The study suggests a common mechanism for PAS domain interactions in diverse signaling pathways.