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Cullin 3 Recognition Is Not a Universal Property among KCTD Proteins
Giovanni Smaldone1, Luciano Pirone2, Nicole Balasco3
1Institute of Biostructures and Bioimaging, C.N.R., 80134, Napoli, Italy.
Plos One
|May 15, 2015
Summary
Not all KCTD proteins bind Cullin 3 (Cul3), despite structural similarities. KCTD6 and KCTD11 bind Cul3, while KCTD12 and KCTD15 do not, revealing evolutionary loss of this interaction.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Cullin 3 (Cul3) recognition by BTB domains is crucial for protein ubiquitination.
- KCTD proteins are key Cul3 binders involved in essential biological processes.
- The high similarity of BTB domains suggests a general Cul3-binding ability among KCTDs.
Purpose of the Study:
- To investigate the Cul3-binding capabilities of KCTD proteins.
- To differentiate between cullin-independent and cullin-mediated KCTD activities.
- To understand the structural basis of Cul3-KCTD recognition.
Main Methods:
- Quantification of Cul3 binding to KCTD BTB domains.
- Comparative sequence analysis of KCTD proteins.
- Characterization of chimeric KCTD variants.
Main Results:
- KCTD6(BTB) and KCTD11(BTB) exhibit high-affinity Cul3 binding with 4:4 stoichiometry.
- KCTD12(BTB) and KCTD15(BTB) do not interact with Cul3.
- Evolutionary analysis reveals multiple instances of lost Cul3-binding capability in KCTDs.
- Swapping of the α2β3 loop in KCTD11 abolished Cul3 binding.
Conclusions:
- Cul3-binding is not a universal property of all KCTD proteins.
- Structural determinants, particularly the α2β3 loop, are critical for Cul3 recognition.
- This study provides comprehensive insights into the Cul3-binding landscape of the KCTD family.
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