Abstract
Cohesin's Smc1, Smc3, and kleisin subunits create a tripartite ring within which sister DNAs are entrapped. Evidence suggests that DNA enters through a gate created by transient dissociation of the Smc1/3 interface. Release at the onset of anaphase is triggered by proteolytic cleavage of kleisin. Less well understood is the mechanism of release at other stages of the cell cycle, in particular during prophase when most cohesin dissociates from chromosome arms in a process dependent on the regulatory subunit Wapl. We show here that Wapl-dependent release from salivary gland polytene chromosomes during interphase and from neuroblast chromosome arms during prophase is blocked by translational fusion of Smc3's C-terminus to kleisin's N-terminus. Our findings imply that proteolysis-independent release of cohesin from chromatin is mediated by Wapl-dependent escape of DNAs through a gate created by transient dissociation of the Smc3/kleisin interface. Thus, cohesin's DNA entry and exit gates are distinct.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Genetically Modified
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Blotting, Western
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Chromatin / genetics
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism*
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DNA / genetics
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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism*
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Drosophila melanogaster / genetics
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Drosophila melanogaster / growth & development
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Drosophila melanogaster / metabolism
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Female
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Immunoenzyme Techniques
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Interphase / physiology*
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Male
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Mitosis / physiology*
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Neurons / cytology
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Neurons / metabolism
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Polytene Chromosomes / genetics*
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Polytene Chromosomes / metabolism
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RNA, Messenger / genetics
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Real-Time Polymerase Chain Reaction
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Reverse Transcriptase Polymerase Chain Reaction
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Salivary Glands / cytology
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Salivary Glands / metabolism
Substances
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C(2)M protein, Drosophila
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Cell Cycle Proteins
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Chromatin
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Chromosomal Proteins, Non-Histone
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Drosophila Proteins
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RNA, Messenger
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Wapl protein, Drosophila
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cohesin protein complex, Drosophila
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DNA