Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase.
Turnover of cyclin E is controlled by SCF(Fbw7). Three isoforms of Fbw7 are produced by alternative splicing. Whereas Fbw7alpha and -gamma are nuclear and the beta-isoform is cytoplasmic in 293T cells, all three isoforms induce cyclin E destruction in an in vivo degradation assay. Cyclin E is phosph...
| Main Authors: | , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2004
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| _version_ | 1797082172678471680 |
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| author | Ye, X Nalepa, G Welcker, M Kessler, B Spooner, E Qin, J Elledge, S Clurman, B Harper, J |
| author_facet | Ye, X Nalepa, G Welcker, M Kessler, B Spooner, E Qin, J Elledge, S Clurman, B Harper, J |
| author_sort | Ye, X |
| collection | OXFORD |
| description | Turnover of cyclin E is controlled by SCF(Fbw7). Three isoforms of Fbw7 are produced by alternative splicing. Whereas Fbw7alpha and -gamma are nuclear and the beta-isoform is cytoplasmic in 293T cells, all three isoforms induce cyclin E destruction in an in vivo degradation assay. Cyclin E is phosphorylated on Thr(62), Ser(88), Ser(372), Thr(380), and Ser(384) in vivo. To examine the roles of phosphorylation in cyclin E turnover, a series of alanine point mutations in each of these sites were analyzed for Fbw7-driven degradation. As expected, mutation of the previously characterized residue Thr(380) to alanine led to profound defects of cyclin E turnover, and largely abolished association with Fbw7. Mutation of Thr(62) to alanine led to a dramatic reduction in the extent of Thr(380) phosphorylation, suggesting an indirect effect of this mutation on cyclin E turnover. Nevertheless, phosphopeptides centered at Thr(62) associated with Fbw7, and residual binding of cyclin E(T380A) to Fbw7 was abolished upon mutation of Thr(62), suggesting a minor role for this residue in direct association with Fbw7. Mutation of Ser(384) to alanine also rendered cyclin E resistant to degradation by Fbw7, with the largest effects being observed with Fbw7beta. Cyclin E(S384A) associated more weakly with Fbw7alpha and -beta isoforms but was not defective in Thr(380) phosphorylation. Analysis of the localization of cyclin E mutant proteins indicated selective accumulation of cyclin E(S384A) in the nucleus, which may contribute to the inability of cytoplasmic Fbw7beta to promote turnover of this cyclin E mutant protein. |
| first_indexed | 2024-03-07T01:24:26Z |
| format | Journal article |
| id | oxford-uuid:917a13eb-94ca-435b-83f0-04411dd6c893 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T01:24:26Z |
| publishDate | 2004 |
| record_format | dspace |
| spelling | oxford-uuid:917a13eb-94ca-435b-83f0-04411dd6c8932022-03-26T23:19:01ZRecognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:917a13eb-94ca-435b-83f0-04411dd6c893EnglishSymplectic Elements at Oxford2004Ye, XNalepa, GWelcker, MKessler, BSpooner, EQin, JElledge, SClurman, BHarper, JTurnover of cyclin E is controlled by SCF(Fbw7). Three isoforms of Fbw7 are produced by alternative splicing. Whereas Fbw7alpha and -gamma are nuclear and the beta-isoform is cytoplasmic in 293T cells, all three isoforms induce cyclin E destruction in an in vivo degradation assay. Cyclin E is phosphorylated on Thr(62), Ser(88), Ser(372), Thr(380), and Ser(384) in vivo. To examine the roles of phosphorylation in cyclin E turnover, a series of alanine point mutations in each of these sites were analyzed for Fbw7-driven degradation. As expected, mutation of the previously characterized residue Thr(380) to alanine led to profound defects of cyclin E turnover, and largely abolished association with Fbw7. Mutation of Thr(62) to alanine led to a dramatic reduction in the extent of Thr(380) phosphorylation, suggesting an indirect effect of this mutation on cyclin E turnover. Nevertheless, phosphopeptides centered at Thr(62) associated with Fbw7, and residual binding of cyclin E(T380A) to Fbw7 was abolished upon mutation of Thr(62), suggesting a minor role for this residue in direct association with Fbw7. Mutation of Ser(384) to alanine also rendered cyclin E resistant to degradation by Fbw7, with the largest effects being observed with Fbw7beta. Cyclin E(S384A) associated more weakly with Fbw7alpha and -beta isoforms but was not defective in Thr(380) phosphorylation. Analysis of the localization of cyclin E mutant proteins indicated selective accumulation of cyclin E(S384A) in the nucleus, which may contribute to the inability of cytoplasmic Fbw7beta to promote turnover of this cyclin E mutant protein. |
| spellingShingle | Ye, X Nalepa, G Welcker, M Kessler, B Spooner, E Qin, J Elledge, S Clurman, B Harper, J Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title | Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title_full | Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title_fullStr | Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title_full_unstemmed | Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title_short | Recognition of phosphodegron motifs in human cyclin E by the SCF(Fbw7) ubiquitin ligase. |
| title_sort | recognition of phosphodegron motifs in human cyclin e by the scf fbw7 ubiquitin ligase |
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