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Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism
Published on: December 18, 2013
Biological regulation via ankyrin repeat folding.
1T. C. Jenkins Department of Biophysics, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA. barrick@jhu.edu
ACS Chemical Biology
|January 17, 2009
Summary
Phosphorylation of tumor suppressor p19(INK4d) destabilizes its native state, creating a partly folded intermediate. This intermediate is rapidly ubiquitinated, suggesting dual regulation of cell-cycle progression via proteasomal and biophysical mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- p19(INK4d) is a tumor suppressor protein characterized by five ankyrin repeats.
- Protein phosphorylation is a key post-translational modification regulating protein function and stability.
- Understanding the biophysical mechanisms of tumor suppressor regulation is crucial for cancer research.
Purpose of the Study:
- To investigate how mimicking the phosphorylation of p19(INK4d) affects its native state stability.
- To determine the impact of phosphorylation on the ubiquitination rate of p19(INK4d).
- To elucidate the combined biochemical and biophysical mechanisms by which p19(INK4d) regulates cell-cycle progression.
Main Methods:
- Mimicking phosphorylation of p19(INK4d) to induce destabilization of its native state.
- Characterizing the populated state at physiological temperature.
- Assessing the ubiquitination rate of the native and partially folded states.
- Analyzing the role of folding intermediates in protein regulation.
Main Results:
- Mimicking p19(INK4d) phosphorylation destabilizes the native state, populating a partially folded intermediate at physiological temperature.
- This intermediate lacks structure in ankyrin repeats 1 and 2, resembling an on-pathway folding intermediate.
- The partially folded state exhibits a significantly higher ubiquitination rate compared to the parent construct.
Conclusions:
- Phosphorylation of p19(INK4d) likely regulates cell-cycle progression through both biochemical (proteasomal degradation) and biophysical (altered folding and cyclin-dependent kinase binding) pathways.
- The study reveals a novel mechanism where protein folding intermediates are targeted for degradation.
- These findings provide insights into the multifaceted regulation of tumor suppressors.
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