A mutually inhibitory feedback loop between the 20S proteasome and its regulator, NQO1
Oren Moscovitz1, Peter Tsvetkov, Nimrod Hazan
1Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Molecular Cell
|July 17, 2012
Summary
NAD(P)H:quinone-oxidoreductase-1 (NQO1) enzyme regulates protein degradation by the 20S proteasome. NQO1 stability is linked to FAD levels, connecting cellular metabolism to protein homeostasis.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Metabolism
Background:
- NAD(P)H:quinone-oxidoreductase-1 (NQO1) is a flavoprotein enzyme.
- NQO1 protects proteins like p53 from 20S proteasome degradation.
- The mechanism of NQO1-proteasome interaction was previously unknown.
Purpose of the Study:
- To elucidate the interaction between NQO1 and the 20S proteasome.
- To investigate the regulatory mechanisms controlling NQO1 stability.
- To explore the link between cellular metabolic state and protein turnover.
Main Methods:
- In vivo and in vitro assays were employed.
- Investigated the proteolytic activity of the 20S proteasome.
- Assessed the impact of flavin adenine dinucleotide (FAD) concentration on NQO1 levels.
Main Results:
- A double negative feedback loop exists between NQO1 and the 20S proteasome.
- NQO1 inhibits 20S proteasome activity.
- The 20S proteasome degrades the apo form of NQO1.
- NQO1 levels are significantly influenced by FAD concentration.
Conclusions:
- The NQO1-proteasome interaction represents a novel regulatory mechanism.
- Protein stability is modulated by cofactor availability, linking metabolism to protein levels.
- This finding suggests a broader principle of metabolic control over protein homeostasis.
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