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Nep1, a Schizosaccharomyces pombe deneddylating enzyme
Lihong Zhou1, Felicity Z Watts
1Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
The Biochemical Journal
|March 17, 2005
Summary
Nep1 is a deneddylating enzyme in fission yeast. While it can modify cullins in vitro, Nep1 likely targets other proteins in vivo, impacting cell-cycle progression.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nedd8 is a ubiquitin-like modifier crucial for E3 ubiquitin ligase function.
- Neddylation, the attachment of Nedd8, is a regulatory process.
- Recent findings indicate p53 can also be Nedd8-modified.
Purpose of the Study:
- Characterize Nep1, a deneddylating enzyme in fission yeast (Schizosaccharomyces pombe).
- Investigate the in vivo function of Nep1.
- Determine the substrates and cellular roles of Nep1.
Main Methods:
- Gene deletion (nep1Δ) in Schizosaccharomyces pombe.
- Cell viability and cell-cycle progression analysis.
- In vitro deneddylation assays and protein complex analysis.
Main Results:
- nep1Δ cells exhibit heterogeneous lengths and cell-cycle defects, dependent on the spindle checkpoint.
- Nep1 demonstrates in vitro deneddylating activity on cullins (Pcu1, Pcu3, Pcu4).
- Accumulation of Nedd8-modified proteins in nep1Δ cells, but not modified cullins, suggests non-culin targets in vivo.
Conclusions:
- Nep1 is a cysteine protease involved in deneddylation.
- While capable of deneddylating cullins in vitro, Nep1's primary in vivo function may target other proteins.
- Nep1 interacts with the signalosome subunit Csn5 and exists in a high-molecular-mass complex.