13 results on '"Michiko HIRANO"'
Search Results
2. Precise compositional analysis of liquid crystalline aromatic polyesters containing aromatic amide linkages by thermally assisted hydrolysis and methylation-gas chromatography
- Author
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Hajime Ohtnai, Toshiaki Yokota, Noriaki Sugimoto, Kohichi Katoh, and Michiko Hirano
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Polyester ,chemistry.chemical_compound ,Hydrolysis ,Tetramethylammonium hydroxide ,Fuel Technology ,Monomer ,chemistry ,Amide ,Organic chemistry ,Methanol ,Gas chromatography ,Pyrolysis ,Analytical Chemistry - Abstract
Multi-component liquid crystalline aromatic polyesters (LCPs) containing 4-aminophenol (PAP) units to form amide linkages were characterized by thermally assisted hydrolysis and methylation-gas chromatography (THM-GC). Under the given THM conditions (300 °C; in the presence of 25 wt% tetramethylammonium hydroxide in methanol), the aromatic amide linkages in the LCP chains were only methylated but hardly cleaved, whereas the ester bonds almost quantitatively decomposed into methyl esters and methyl ethers. Thus dimeric and trimeric products consisting of PAP and another monomer unit linked through methylated amide linkage(s) were observed in the THM chromatograms along with dimethyl derivatives of the monomer units other than PAP. The compositions of the LCP samples containing PAP units were then determined from the relative peak intensities observed in the THM chromatograms, and showed quite good agreement with the original monomer compositions in feed with superior reproducibility; less than 1% relative standard deviation.
- Published
- 2007
3. Opening Closed Arms: Long-Distance Activation of SMC ATPase by Hinge-DNA Interactions
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Michiko Hirano and Tatsuya Hirano
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Models, Molecular ,Conformational change ,Chromosomal Proteins, Non-Histone ,Archaeal Proteins ,Molecular Sequence Data ,Protein design ,Hinge ,In Vitro Techniques ,Biology ,Models, Biological ,chemistry.chemical_compound ,Adenosine Triphosphate ,Protein structure ,Bacterial Proteins ,ATP hydrolysis ,Humans ,Point Mutation ,Amino Acid Sequence ,Molecular Biology ,Adenosine Triphosphatases ,Binding Sites ,Sequence Homology, Amino Acid ,SMC protein ,DNA ,Cell Biology ,Recombinant Proteins ,Protein Structure, Tertiary ,Enzyme Activation ,Kinetics ,chemistry ,Biochemistry ,Biophysics ,Binding domain - Abstract
Structural maintenance of chromosomes (SMC) proteins form a V-shaped dimer in which a central hinge domain connects two coiled-coil arms, each having an ATP binding head domain at its distal end. Here, we show that the hinge domain plays essential roles in modulating the mechanochemical cycle of SMC proteins. An initial interaction of the hinge domain with DNA leads to opening of the arms by triggering hydrolysis of ATP bound to the head domains, which are located approximately 50 nm away from the hinge. This conformational change allows the inner surface of the hinge domain to stably interact with DNA by an ATP-independent mechanism and primes ATP-driven engagement between the liberated head domains either intramolecularly or intermolecularly. Consistently, a variety of hinge mutations drastically alter DNA binding properties of SMC proteins through distinct mechanisms. Our results suggest that SMC proteins possess an intrinsic property to change their own conformations upon binding to DNA.
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- 2006
- Full Text
- View/download PDF
4. Differential Contributions of Condensin I and Condensin II to Mitotic Chromosome Architecture in Vertebrate Cells
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Andrew F. Neuwald, Michael P. Myers, Michiko Hirano, Tatsuya Hirano, Ana Losada, and Takao Ono
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Macromolecular Substances ,Condensin ,Molecular Sequence Data ,Xenopus ,Mitosis ,macromolecular substances ,Chromosomes ,General Biochemistry, Genetics and Molecular Biology ,Mitotic chromosome condensation ,Xenopus laevis ,03 medical and health sciences ,Condensin complex ,0302 clinical medicine ,Animals ,Humans ,Protein Isoforms ,RNA, Small Interfering ,030304 developmental biology ,Adenosine Triphosphatases ,Genetics ,0303 health sciences ,biology ,Biochemistry, Genetics and Molecular Biology(all) ,SMC protein ,Nuclear Proteins ,Chromosome ,biology.organism_classification ,Condensin I complex ,Cell biology ,DNA-Binding Proteins ,Protein Subunits ,Multiprotein Complexes ,Oocytes ,biology.protein ,030217 neurology & neurosurgery ,HeLa Cells - Abstract
The canonical condensin complex (henceforth condensin I) plays an essential role in mitotic chromosome assembly and segregation from yeast to humans. We report here the identification of a second condensin complex (condensin II) from vertebrate cells. Condensins I and II share the same pair of structural maintenance of chromosomes (SMC) subunits but contain different sets of non-SMC subunits. siRNA-mediated depletion of condensin I- or condensin II-specific subunits in HeLa cells produces a distinct, highly characteristic defect in chromosome morphology. Simultaneous depletion of both complexes causes the severest defect. In Xenopus egg extracts, condensin I function is predominant, but lack of condensin II results in the formation of irregularly shaped chromosomes. Condensins I and II show different distributions along the axis of chromosomes assembled in vivo and in vitro. We propose that the two condensin complexes make distinct mechanistic contributions to mitotic chromosome architecture in vertebrate cells.
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- 2003
5. Hinge-mediated dimerization of SMC protein is essential for its dynamic interaction with DNA
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Tatsuya Hirano and Michiko Hirano
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Protein Conformation ,Mutant ,Cell Cycle Proteins ,Biology ,Antiparallel (biochemistry) ,DNA-binding protein ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Protein structure ,Bacterial Proteins ,Molecular Biology ,Adenosine Triphosphatases ,Coiled coil ,General Immunology and Microbiology ,General Neuroscience ,Point mutation ,SMC protein ,Articles ,DNA-Binding Proteins ,chemistry ,Biochemistry ,Mutagenesis, Site-Directed ,Biophysics ,Dimerization ,DNA ,Bacillus subtilis - Abstract
Structural maintenance of chromosomes (SMC) proteins play central roles in regulating higher order chromosome dynamics from bacteria to humans. As judged by electron microscopy, the SMC homodimer from Bacillus subtilis (BsSMC) is composed of two antiparallel, coiled-coil arms with a flexible hinge. Site-directed cross-linking experiments show here that dimerization of BsSMC is mediated by a hinge-hinge interaction between self-folded monomers. This architecture is conserved in the eukaryotic SMC2-SMC4 heterodimer. Analysis of different deletion mutants of BsSMC unexpectedly reveals that the major DNA-binding activity does not reside in the catalytic ATPase domains located at the ends of a dimer. Instead, point mutations in the hinge domain that disturb dimerization of BsSMC drastically reduce its ability to interact with DNA. Proper hinge function is essential for BsSMC to recognize distinct DNA topology, and mutant proteins with altered hinge angles cross-link double-stranded DNA in a nucleotide-dependent manner. We propose that the hinge domain of SMC proteins is not a simple dimerization site, but rather it acts as an essential determinant of dynamic SMC-DNA interactions.
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- 2002
6. ATP-dependent aggregation of single-stranded DNA by a bacterial SMC homodimer
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Tatsuya Hirano and Michiko Hirano
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ATPase ,Molecular Sequence Data ,DNA, Single-Stranded ,Bacillus subtilis ,Biology ,DNA-binding protein ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Adenosine Triphosphate ,Bacterial Proteins ,Endopeptidases ,Amino Acid Sequence ,Molecular Biology ,Adenosine Triphosphatases ,Dosage compensation ,General Immunology and Microbiology ,General Neuroscience ,Circular bacterial chromosome ,SMC protein ,biology.organism_classification ,DNA-Binding Proteins ,chemistry ,Biochemistry ,Premature chromosome condensation ,biology.protein ,Dimerization ,DNA ,Research Article - Abstract
SMC (structural maintenance of chromosomes) proteins are putative ATPases that are highly conserved among Bacteria, Archaea and Eucarya. Eukaryotic SMC proteins are implicated in a diverse range of chromosome dynamics including chromosome condensation, dosage compensation and recombinational repair. In eukaryotes, two different SMC proteins form a heterodimer, which in turn acts as the core component of a large protein complex. Despite recent progress, no ATP-dependent activity has been found in individual SMC subunits. We report here the first biochemical characterization of a bacterial SMC protein from Bacillus subtilis. Unlike eukaryotic versions, the B.subtilis SMC protein (BsSMC) is a simple homodimer with no associated subunits. It binds preferentially to single-stranded DNA (ssDNA) and has a ssDNA-stimulated ATPase activity. In the presence of ATP, BsSMC forms large nucleoprotein aggregates in a ssDNA-specific manner. Proteolytic cleavage of BsSMC is changed upon binding to ATP and ssDNA. The energy-dependent aggregation of ssDNA might represent a primitive type of chromosome condensation that occurs during segregation of bacterial chromosomes.
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- 1998
7. Identification of Xenopus SMC protein complexes required for sister chromatid cohesion
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Michiko Hirano, Ana Losada, and Tatsuya Hirano
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DNA Replication ,Cohesin complex ,Chromosomal Proteins, Non-Histone ,Macromolecular Substances ,Nuclear Envelope ,Condensin ,Molecular Sequence Data ,Mitosis ,Cell Cycle Proteins ,Chromatids ,Xenopus Proteins ,Biology ,Fungal Proteins ,Mitotic chromosome condensation ,Xenopus laevis ,Genetics ,Animals ,Amino Acid Sequence ,Cloning, Molecular ,Interphase ,Adenosine Triphosphatases ,Cohesin loading ,Sequence Homology, Amino Acid ,Cohesin ,SMC protein ,Chromatin ,Cell biology ,DNA-Binding Proteins ,Molecular Weight ,Establishment of sister chromatid cohesion ,Multiprotein Complexes ,biology.protein ,Chromatid ,biological phenomena, cell phenomena, and immunity ,Research Paper ,Developmental Biology - Abstract
The structural maintenance of chromosomes (SMC) family is a growing family of chromosomal ATPases. The founding class of SMC protein complexes, condensins, plays a central role in mitotic chromosome condensation. We report here a new class of SMC protein complexes containing XSMC1 and XSMC3, Xenopus homologs of yeast Smc1p and Smc3p, respectively. The protein complexes (termed cohesins) exist as two major forms with sedimentation coefficients of 9S and 14S. 9S cohesin is a heterodimer of XSMC1 and XSMC3, whereas 14S cohesin contains three additional subunits. One of them has been identified as a Xenopus homolog of the Schizosaccharomyces pombeRad21p implicated in DNA repair and the Saccharomyces cerevisiae Scc1p/Mcd1p implicated in sister chromatid cohesion. 14S cohesin binds to interphase chromatin independently of DNA replication and dissociates from it at the onset of mitosis. Immunodepletion of cohesins during interphase causes defects in sister chromatid cohesion in subsequent mitosis, whereas condensation is unaffected. These results suggest that proper assembly of mitotic chromosomes is regulated by two distinct classes of SMC protein complexes, cohesins and condensins.
- Published
- 1998
8. Condensins, Chromosome Condensation Protein Complexes Containing XCAP-C, XCAP-E and a Xenopus Homolog of the Drosophila Barren Protein
- Author
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Ryuji Kobayashi, Michiko Hirano, and Tatsuya Hirano
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Chromosomal Proteins, Non-Histone ,Macromolecular Substances ,Protein Conformation ,Condensin ,Xenopus ,Molecular Sequence Data ,Mitosis ,Cell Cycle Proteins ,macromolecular substances ,Xenopus Proteins ,General Biochemistry, Genetics and Molecular Biology ,Chromosomes ,Mitotic chromosome condensation ,Chromosome segregation ,Condensin complex ,Species Specificity ,Antigens, Neoplasm ,Centrifugation, Density Gradient ,Animals ,Drosophila Proteins ,Amino Acid Sequence ,Phosphorylation ,Ovum ,Adenosine Triphosphatases ,biology ,Sequence Homology, Amino Acid ,Biochemistry, Genetics and Molecular Biology(all) ,SMC protein ,Cell Cycle ,Nuclear Proteins ,Molecular biology ,Cell biology ,Condensin I complex ,DNA-Binding Proteins ,Isoenzymes ,DNA Topoisomerases, Type II ,Premature chromosome condensation ,Multiprotein Complexes ,biology.protein ,Drosophila ,Female ,Carrier Proteins ,Dimerization ,Drosophila Protein - Abstract
We report here purification and characterization of chro- mosome condensation protein complexes (termed condensins) containing XCAP-C and XCAP-E, two Xenopus members of the SMC family. Sucrose density gradient centrifugation reveals two major forms of condensins. The 8S form is a heterodimer of XCAP-C and XCAP-E, whereas the 13S form contains three additional subunits. One of them is identified as a homolog of the Drosophila Barren protein whose mutation shows a defect in chromosome segregation. Chromosomal targeting of condensins is mitosis-specific and is independent of topoisomerase IIα. 13S condensin is required for condensation, as demonstrated by immunodepletion and rescue experiments. Our results suggest that the condensin complexes represent the most abundant structural components of mitotic chromosomes and play a central role in driving chromosome condensation.
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- 1997
- Full Text
- View/download PDF
9. Cpk Is a Novel Class of Drosophila PtdIns 3-Kinase Containing a C2 Domain
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Lewis T. Williams, Lisa Molz, Yen-Wen Chen, and Michiko Hirano
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DNA, Complementary ,Molecular Sequence Data ,Genes, Insect ,Phosphatidylinositol 3-Kinases ,Biology ,Phosphatidylinositols ,Biochemistry ,Substrate Specificity ,Mice ,chemistry.chemical_compound ,Phosphatidylinositol Phosphates ,Animals ,Amino Acid Sequence ,Phosphatidylinositol ,Tyrosine ,Kinase activity ,Molecular Biology ,Peptide sequence ,DNA Primers ,C2 domain ,Base Sequence ,Molecular Structure ,Sequence Homology, Amino Acid ,Kinase ,fungi ,Cell Biology ,Phosphotransferases (Alcohol Group Acceptor) ,Drosophila melanogaster ,chemistry ,Phosphorylation ,Carrier Proteins - Abstract
We report the identification of a novel class of phosphatidylinositol (PtdIns) 3-kinases whose members contain C-terminal C2 domains. We have isolated Drosophila and murine genes (termed cpk and cpk-m respectively) by polymerase chain reaction amplification of cDNA libraries with degenerate primers corresponding to conserved regions of PtdIns kinases. The amino acid sequences of Cpk and Cpk-m are most similar to that of p110, a family of PtdIns 3-kinases that mediates the responses of cells to mitogenic stimuli. The Cpk and Cpk-m sequences are similar to a large, central region of p110, but differ from p110 at their N and C termini. The N termini of the Cpk proteins do not contain any recognizable protein motif, while the C termini contain "C2 domains," a feature unique among PtdIns kinases. Cpk has an intrinsic PtdIns kinase activity and can phosphorylate PtdIns and PtdIns-4-P, but not PtdIns(4,5)P2, at the D3 position of the inositol ring. Cpk is the first PtdIns 3-kinase identified with this particular substrate specificity. We have identified two potential Cpk-binding proteins, p90 and p190, and have determined that both Cpk and p190 may be tyrosine phosphorylated. This finding suggests that Cpk function may be regulated by tyrosine kinases.
- Published
- 1996
10. Reconstitution and subunit geometry of human condensin complexes
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Itay Onn, Nobuki Aono, Tatsuya Hirano, and Michiko Hirano
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Cell Extracts ,Models, Molecular ,Protein Conformation ,Protein subunit ,Condensin ,Xenopus ,Molecular Sequence Data ,Mitosis ,Geometry ,Cell Cycle Proteins ,macromolecular substances ,General Biochemistry, Genetics and Molecular Biology ,Article ,Chromosome segregation ,Condensin complex ,Protein structure ,Chromosome Segregation ,Animals ,Humans ,Amino Acid Sequence ,Molecular Biology ,Ovum ,Adenosine Triphosphatases ,General Immunology and Microbiology ,Cohesin ,biology ,General Neuroscience ,SMC protein ,Genetic Complementation Test ,Nuclear Proteins ,DNA-Binding Proteins ,Protein Subunits ,Multiprotein Complexes ,biology.protein ,Carrier Proteins - Abstract
Vertebrate cells possess two different condensin complexes, known as condensin I and condensin II, that play a fundamental role in chromosome assembly and segregation during mitosis. Each complex contains a pair of structural maintenance of chromosomes (SMC) ATPases, a kleisin subunit and two HEAT-repeat subunits. Here we use recombinant human condensin subunits to determine their geometry within each complex. We show that both condensin I and condensin II have a pseudo-symmetrical structure, in which the N-terminal half of kleisin links the first HEAT subunit to SMC2, whereas its C-terminal half links the second HEAT subunit to SMC4. No direct interactions are detectable between the SMC dimer and the HEAT subunits, indicating that the kleisin subunit acts as the linchpin in holocomplex assembly. ATP has little, if any, effects on the assembly and integrity of condensin. Cleavage pattern of SMC2 by limited proteolysis is changed upon its binding to ATP or DNA. Our results shed new light on the architecture and dynamics of this highly elaborate machinery designed for chromosome assembly.
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- 2007
11. Positive and negative regulation of SMC–DNA interactions by ATP and accessory proteins
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Michiko Hirano and Tatsuya Hirano
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DNA, Bacterial ,Protein Conformation ,Dimer ,Condensin ,Mutant ,medicine.disease_cause ,Models, Biological ,General Biochemistry, Genetics and Molecular Biology ,Article ,chemistry.chemical_compound ,Protein structure ,Bacterial Proteins ,Catalytic Domain ,medicine ,Centrifugation, Density Gradient ,Molecular Biology ,Adenosine Triphosphatases ,Mutation ,General Immunology and Microbiology ,Cohesin ,biology ,General Neuroscience ,SMC protein ,Chromosomes, Bacterial ,Precipitin Tests ,chemistry ,Biochemistry ,Biophysics ,biology.protein ,Dimerization ,DNA ,Bacillus subtilis - Abstract
Structural maintenance of chromosomes (SMC) proteins are central regulators of higher-order chromosome dynamics from bacteria to humans. The Bacillus subtilis SMC (BsSMC) homodimer adopts a V-shaped structure with an ATP-binding catalytic domain at each end. We report here that two small proteins, ScpA and ScpB, associate with the catalytic domains of BsSMC in an ordered fashion and suppress its ATPase activity. When combined with a 'transition state' mutant of BsSMC that poorly hydrolyzes ATP, ScpA promotes stable engagement of two catalytic domains in an ATP-dependent manner. In solution, this occurs intramolecularly and closes the DNA-entry gate of an SMC dimer. ScpB further stabilizes this conformation and prevents BsSMC from binding to double-stranded DNA (dsDNA). In contrast, when the mutant BsSMC is first allowed to interact with dsDNA, subsequent addition of ScpA leads to assembly of large nucleoprotein complexes, possibly by stabilizing intermolecular engagement of the catalytic domains from different SMC dimers. We propose that the ATP-modulated engagement/disengagement cycle of SMC proteins plays both positive and negative roles in their dynamic interactions with dsDNA.
- Published
- 2004
12. Cohesin release is required for sister chromatid resolution, but not for condensin-mediated compaction, at the onset of mitosis
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Michiko Hirano, Tatsuya Hirano, and Ana Losada
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Chromosomal Proteins, Non-Histone ,Condensin ,Xenopus ,Cell Cycle Proteins ,macromolecular substances ,Biology ,Protein Serine-Threonine Kinases ,Xenopus Proteins ,Chromosomes ,Fungal Proteins ,Prophase ,Aurora Kinases ,Genetics ,Sister chromatids ,Animals ,Phosphorylation ,Metaphase ,Ovum ,Adenosine Triphosphatases ,Cohesin ,Kinetochore ,Nuclear Proteins ,Spindle apparatus ,Cell biology ,Establishment of sister chromatid cohesion ,DNA-Binding Proteins ,Multiprotein Complexes ,biology.protein ,Female ,Separase ,biological phenomena, cell phenomena, and immunity ,Developmental Biology ,Research Paper - Abstract
The establishment of metaphase chromosomes is an essential prerequisite of sister chromatid separation in anaphase. It involves the coordinated action of cohesin and condensin, protein complexes that mediate cohesion and condensation, respectively. In metazoans, most cohesin dissociates from chromatin at prophase, coincident with association of condensin. Whether loosening of cohesion at the onset of mitosis facilitates the compaction process, resolution of the sister chromatids, or both, remains unknown. We have found that the prophase release of cohesin is completely blocked when two mitotic kinases, aurora B and polo-like kinase (Plx1), are simultaneously depleted fromXenopus egg extracts. Condensin loading onto chromatin is not affected under this condition, and rod-shaped chromosomes are produced that show an apparently normal level of compaction. However, the resolution of sister chromatids within these chromosomes is severely compromised. This is not because of inhibition of topoisomerase II activity that is also required for the resolution process. We propose that aurora B and Plx1 cooperate to destabilize the sister chromatid linkage through distinct mechanisms that may involve phosphorylation of histone H3 and cohesin, respectively. More importantly, our results strongly suggest that cohesin release at the onset of mitosis is essential for sister chromatid resolution but not for condensin-mediated compaction.
- Published
- 2002
13. Phosphorylation and activation of 13S condensin by Cdc2 in vitro
- Author
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Ryuji Kobayashi, Michiko Hirano, Keiji Kimura, and Tatsuya Hirano
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Condensin ,Xenopus ,Molecular Sequence Data ,Mitosis ,macromolecular substances ,Biology ,Peptide Mapping ,Chromosomes ,Mitotic chromosome condensation ,Condensin complex ,chemistry.chemical_compound ,CDC2 Protein Kinase ,Animals ,Amino Acid Sequence ,Phosphorylation ,Interphase ,Adenosine Triphosphatases ,Multidisciplinary ,DNA, Superhelical ,biology.organism_classification ,DNA-Binding Proteins ,Enzyme Activation ,Biochemistry ,chemistry ,Premature chromosome condensation ,Multiprotein Complexes ,biology.protein ,DNA supercoil ,Nucleic Acid Conformation ,DNA, Circular ,Adenosine triphosphate - Abstract
13 S condensin is a multisubunit protein complex essential for mitotic chromosome condensation in Xenopus egg extracts. Purified 13 S condensin introduces positive supercoils into DNA in the presence of topoisomerase I and adenosine triphosphate in vitro. The supercoiling activity of 13 S condensin was regulated by mitosis-specific phosphorylation. Immunodepletion, in vitro phosphorylation, and peptide-mapping experiments indicated that Cdc2 is likely to be the kinase that phosphorylates and activates 13 S condensin. Multiple Cdc2 phosphorylation sites are clustered in the carboxyl-terminal domain of the XCAP-D2 ( Xenopus chromosome-associated polypeptide D2) subunit. These results suggest that phosphorylation of 13 S condensin by Cdc2 may trigger mitotic chromosome condensation in vitro.
- Published
- 1998
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