Abstract | BACKGROUND: RESULTS: Inhibition of separase expression in human cells by RNA interference causes the formation of polyploid cells with large lobed nuclei. In mitosis, many of these cells contain abnormal chromosome plates with unseparated sister chromatids. Inhibitor binding experiments in vitro reveal that securin prevents the access of substrate analogs to the active site of separase. Upon securin degradation, the active site of full-length separase becomes accessible, allowing rapid autocatalytic cleavage of separase at one of three sites. The resulting N- and C-terminal fragments remain associated and can be reinhibited by securin. A noncleavable separase mutant retains its ability to cleave cohesin in vitro. CONCLUSIONS: Our results suggest that separase is required for sister chromatid separation during mitosis in human cells. Our data further indicate that securin inhibits separase by blocking the access of substrates to the active site of separase. Securin proteolysis allows autocatalytic processing of separase into a cleaved form, but separase cleavage is not essential for separase activation.
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Authors | Irene Waizenegger, Juan F Giménez-Abián, Dominik Wernic, Jan-Michael Peters |
Journal | Current biology : CB
(Curr Biol)
Vol. 12
Issue 16
Pg. 1368-78
(Aug 20 2002)
ISSN: 0960-9822 [Print] England |
PMID | 12194817
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Cell Cycle Proteins
- Chromosomal Proteins, Non-Histone
- Enzyme Inhibitors
- Fungal Proteins
- MCD1 protein, S cerevisiae
- Neoplasm Proteins
- Nuclear Proteins
- Peptides
- Phosphoproteins
- Saccharomyces cerevisiae Proteins
- Securin
- Trans-Activators
- pituitary tumor-transforming protein 1, human
- Endopeptidases
- ESP1 protein, S cerevisiae
- ESPL1 protein, human
- Separase
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Topics |
- Amino Acid Sequence
- Animals
- Cell Cycle Proteins
(antagonists & inhibitors, metabolism)
- Cell Nucleus
(metabolism)
- Chromosomal Proteins, Non-Histone
- Chromosomes
(metabolism)
- Endopeptidases
- Enzyme Activation
- Enzyme Inhibitors
(metabolism)
- Fungal Proteins
(genetics, metabolism)
- HeLa Cells
- Humans
- Mitosis
(genetics)
- Models, Biological
- Molecular Structure
- Neoplasm Proteins
(metabolism)
- Nuclear Proteins
- Peptides
(metabolism)
- Phosphoproteins
- Polyploidy
- Protein Binding
- RNA Interference
- Saccharomyces cerevisiae Proteins
- Securin
- Separase
- Sequence Alignment
- Trans-Activators
(metabolism)
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