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Updated: Jun 3, 2026
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Functional Characterization of RING-Type E3 Ubiquitin Ligases In Vitro and In Planta
Published on: December 5, 2019
Structure and function of a HECT domain ubiquitin-binding site
Hyung Cheol Kim1, Alanna M Steffen, Michael L Oldham
1Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA.
EMBO Reports
|March 15, 2011
Summary
The Rsp5 ubiquitin ligase uses a non-covalent ubiquitin binding site to regulate polyubiquitination. This interaction is critical for localizing ubiquitin chains and promoting further conjugation.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Rsp5 is a ubiquitin ligase with a HECT domain.
- Ubiquitin conjugation is a key post-translational modification.
- The HECT-ubiquitin interaction mechanism is not fully understood.
Purpose of the Study:
- To elucidate the structural basis of the Rsp5-ubiquitin interaction.
- To understand the role of the Rsp5 N-lobe binding site in polyubiquitination.
- To investigate the impact of mutations at the binding interface.
Main Methods:
- X-ray crystallography of the HECT-ubiquitin complex.
- Site-directed mutagenesis of ubiquitin and Rsp5.
- Analysis of polyubiquitination defects.
Main Results:
- The crystal structure of the HECT-ubiquitin complex revealed a non-covalent binding site on the Rsp5 N-lobe.
- Specific hydrophobic residues (L8, I44, V70) on ubiquitin are crucial for Rsp5 interaction.
- Mutations at the Rsp5-binding interface impaired polyubiquitination.
Conclusions:
- The Rsp5 N-lobe binding site serves to localize and orient ubiquitin for chain elongation.
- This mechanism is essential for efficient polyubiquitination.
- Structural insights into Rsp5 function provide a basis for understanding ubiquitin ligase mechanisms.
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