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Barrero DJ, Wijeratne SS, Zhao X, Cunningham GF, Rui Y, Nelson CR, Yasuhiro A, Funabiki H, Asbury CL, Yu Z, Subramanian R, Biggins S. Architecture and flexibility of native kinetochores revealed by structural studies utilizing a thermophilic yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582571. [PMID: 38464254 PMCID: PMC10925344 DOI: 10.1101/2024.02.28.582571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Eukaryotic chromosome segregation requires kinetochores, multi-megadalton protein machines that assemble on the centromeres of chromosomes and mediate attachments to dynamic spindle microtubules. Kinetochores are built from numerous complexes, and understanding how they are arranged is key to understanding how kinetochores perform their multiple functions. However, an integrated understanding of kinetochore architecture has not yet been established. To address this, we purified functional, native kinetochores from Kluyveromyces marxianus and examined them by electron microscopy, cryo-electron tomography and atomic force microscopy. The kinetochores are extremely large, flexible assemblies that exhibit features consistent with prior models. We assigned kinetochore polarity by visualizing their interactions with microtubules and locating the microtubule binder Ndc80c. This work shows that isolated kinetochores are more dynamic and complex than what might be anticipated based on the known structures of recombinant subassemblies, and provides the foundation to study the global architecture and functions of kinetochores at a structural level.
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Affiliation(s)
- Daniel J. Barrero
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
- Molecular and Cellular Biology Program, University of Washington, 1705 NE Pacific Street, Seattle, WA 98195, USA
| | - Sithara S. Wijeratne
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Xiaowei Zhao
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Grace F. Cunningham
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yan Rui
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Christian R. Nelson
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
| | - Arimura Yasuhiro
- The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | | | - Charles L. Asbury
- Department of Physiology and Biophysics, 1959 NE Pacific Street, University of Washington, Seattle, WA 98195, USA
| | - Zhiheng Yu
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
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Mehta G, Sanyal K, Abhishek S, Rajakumara E, Ghosh SK. Minichromosome maintenance proteins in eukaryotic chromosome segregation. Bioessays 2021; 44:e2100218. [PMID: 34841543 DOI: 10.1002/bies.202100218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 01/02/2023]
Abstract
Minichromosome maintenance (Mcm) proteins are well-known for their functions in DNA replication. However, their roles in chromosome segregation are yet to be reviewed in detail. Following the discovery in 1984, a group of Mcm proteins, known as the ARS-nonspecific group consisting of Mcm13, Mcm16-19, and Mcm21-22, were characterized as bonafide kinetochore proteins and were shown to play significant roles in the kinetochore assembly and high-fidelity chromosome segregation. This review focuses on the structure, function, and evolution of this group of Mcm proteins. Our in silico analysis of the physical interactors of these proteins reveals that they share non-overlapping functions despite being copurified in biochemically stable complexes. We have discussed the contrasting results reported in the literature and experimental strategies to address them. Taken together, this review focuses on the structure-function of the ARS-nonspecific Mcm proteins and their evolutionary flexibility to maintain genome stability in various organisms.
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Affiliation(s)
- Gunjan Mehta
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, India
| | - Suman Abhishek
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India
| | - Eerappa Rajakumara
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
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Katheeja MN, Das SP, Laha S. The budding yeast protein Chl1p is required for delaying progression through G1/S phase after DNA damage. Cell Div 2021; 16:4. [PMID: 34493312 PMCID: PMC8424871 DOI: 10.1186/s13008-021-00072-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022] Open
Abstract
Background The budding yeast protein Chl1p is a nuclear protein required for sister-chromatid cohesion, transcriptional silencing, rDNA recombination, ageing and plays an instrumental role in chromatin remodeling. This helicase is known to preserve genome integrity and spindle length in S-phase. Here we show additional roles of Chl1p at G1/S phase of the cell cycle following DNA damage. Results G1 arrested cells when exposed to DNA damage are more sensitive and show bud emergence with faster kinetics in chl1 mutants compared to wild-type cells. Also, more damage to DNA is observed in chl1 cells. The viability falls synergistically in rad24chl1 cells. The regulation of Chl1p on budding kinetics in G1 phase falls in line with Rad9p/Chk1p and shows a synergistic effect with Rad24p/Rad53p. rad9chl1 and chk1chl1 shows similar bud emergence as the single mutants chl1, rad9 and chk1. Whereas rad24chl1 and rad53chl1 shows faster bud emergence compared to the single mutants rad24, rad53 and chl1. In presence of MMS induced damage, synergistic with Rad24p indicates Chl1p’s role as a checkpoint at G1/S acting parallel to damage checkpoint pathway. The faster movement of DNA content through G1/S phase and difference in phosphorylation profile of Rad53p in wild type and chl1 cells confirms the checkpoint defect in chl1 mutant cells. Further, we have also confirmed that the checkpoint defect functions in parallel to the damage checkpoint pathway of Rad24p. Conclusion Chl1p shows Rad53p independent bud emergence and Rad53p dependent checkpoint activity in presence of damage. This confirms its requirement in two different pathways to maintain the G1/S arrest when cells are exposed to damaging agents. The bud emergence kinetics and DNA segregation were similar to wild type when given the same damage in nocodazole treated chl1 cells which establishes the absence of any role of Chl1p at the G2/M phase. The novelty of this paper lies in revealing the versatile role of Chl1p in checkpoints as well as repair towards regulating G1/S transition. Chl1p thus regulates the G1/S phase by affecting the G1 replication checkpoint pathway and shows an additive effect with Rad24p for Rad53p activation when damaging agents perturb the DNA. Apart from checkpoint activation, it also regulates the budding kinetics as a repair gene. Supplementary Information The online version contains supplementary material available at 10.1186/s13008-021-00072-x.
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Affiliation(s)
- Muhseena N Katheeja
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India
| | - Shankar Prasad Das
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India. .,Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VII M, 700 054, Kolkata, India.
| | - Suparna Laha
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India. .,Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VII M, 700 054, Kolkata, India.
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A Computational Approach to Estimating Nondisjunction Frequency in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2016; 6:669-82. [PMID: 26747203 PMCID: PMC4777129 DOI: 10.1534/g3.115.024380] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Errors segregating homologous chromosomes during meiosis result in aneuploid gametes and are the largest contributing factor to birth defects and spontaneous abortions in humans. Saccharomyces cerevisiae has long served as a model organism for studying the gene network supporting normal chromosome segregation. Measuring homolog nondisjunction frequencies is laborious, and involves dissecting thousands of tetrads to detect missegregation of individually marked chromosomes. Here we describe a computational method (TetFit) to estimate the relative contributions of meiosis I nondisjunction and random-spore death to spore inviability in wild type and mutant strains. These values are based on finding the best-fit distribution of 4, 3, 2, 1, and 0 viable-spore tetrads to an observed distribution. Using TetFit, we found that meiosis I nondisjunction is an intrinsic component of spore inviability in wild-type strains. We show proof-of-principle that the calculated average meiosis I nondisjunction frequency determined by TetFit closely matches empirically determined values in mutant strains. Using these published data sets, TetFit uncovered two classes of mutants: Class A mutants skew toward increased nondisjunction death, and include those with known defects in establishing pairing, recombination, and/or synapsis of homologous chromosomes. Class B mutants skew toward random spore death, and include those with defects in sister-chromatid cohesion and centromere function. Epistasis analysis using TetFit is facilitated by the low numbers of tetrads (as few as 200) required to compare the contributions to spore death in different mutant backgrounds. TetFit analysis does not require any special strain construction, and can be applied to previously observed tetrad distributions.
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Meyer RE, Chuong HH, Hild M, Hansen CL, Kinter M, Dawson DS. Ipl1/Aurora-B is necessary for kinetochore restructuring in meiosis I in Saccharomyces cerevisiae. Mol Biol Cell 2015; 26:2986-3000. [PMID: 26157162 PMCID: PMC4551314 DOI: 10.1091/mbc.e15-01-0032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/30/2015] [Indexed: 11/11/2022] Open
Abstract
In mitosis, the centromeres of sister chromosomes are pulled toward opposite poles of the spindle. In meiosis I, the opposite is true: the sister centromeres move together to the same pole, and the homologous chromosomes are pulled apart. This change in segregation patterns demands that between the final mitosis preceding meiosis and the first meiotic division, the kinetochores must be restructured. In budding yeast, unlike mammals, kinetochores are largely stable throughout the mitotic cycle. In contrast, previous work with budding and fission yeast showed that some outer kinetochore proteins are lost in early meiosis. We use quantitative mass spectrometry methods and imaging approaches to explore the kinetochore restructuring process that occurs in meiosis I in budding yeast. The Ndc80 outer kinetochore complex, but not other subcomplexes, is shed upon meiotic entry. This shedding is regulated by the conserved protein kinase Ipl1/Aurora-B and promotes the subsequent assembly of a kinetochore that will confer meiosis-specific segregation patterns on the chromosome.
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Affiliation(s)
- Régis E Meyer
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Hoa H Chuong
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Marrett Hild
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Christina L Hansen
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Michael Kinter
- Program in Free Radical Biology and Aging, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Dean S Dawson
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104 Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
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Agarwal M, Mehta G, Ghosh SK. Role of Ctf3 and COMA subcomplexes in meiosis: Implication in maintaining Cse4 at the centromere and numeric spindle poles. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:671-84. [PMID: 25562757 DOI: 10.1016/j.bbamcr.2014.12.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 12/16/2022]
Abstract
During mitosis and meiosis, kinetochore, a conserved multi-protein complex, connects microtubule with the centromere and promotes segregation of the chromosomes. In budding yeast, central kinetochore complex named Ctf19 has been implicated in various functions and is believed to be made up of three biochemically distinct subcomplexes: COMA, Ctf3 and Iml3-Chl4. In this study, we aimed to identify whether Ctf3 and COMA subcomplexes have any unshared function at the kinetochore. Our data suggests that both these subcomplexes may work as a single functional unit without any unique functions, which we tested. Analysis of severity of the defects in the mutants suggests that COMA is epistatic to Ctf3 subcomplex. Interestingly, we noticed that these subcomplexes affect the organization of mitotic and meiotic kinetochores with subtle differences and they promote maintenance of Cse4 at the centromeres specifically during meiosis which is similar to the role of Mis6 (Ctf3 homolog) in fission yeast during mitosis. Interestingly, analysis of ctf3Δ and ctf19Δ mutants revealed a novel role of Ctf19 complex in regulation of SPB cohesion and duplication in meiosis.
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Affiliation(s)
- Meenakshi Agarwal
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 40076, India
| | - Gunjan Mehta
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 40076, India
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 40076, India.
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7
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Sau S, Sutradhar S, Paul R, Sinha P. Budding yeast kinetochore proteins, Chl4 and Ctf19, are required to maintain SPB-centromere proximity during G1 and late anaphase. PLoS One 2014; 9:e101294. [PMID: 25003500 PMCID: PMC4086815 DOI: 10.1371/journal.pone.0101294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/05/2014] [Indexed: 12/23/2022] Open
Abstract
In the budding yeast, centromeres stay clustered near the spindle pole bodies (SPBs) through most of the cell cycle. This SPB-centromere proximity requires microtubules and functional kinetochores, which are protein complexes formed on the centromeres and capable of binding microtubules. The clustering is suggested by earlier studies to depend also on protein-protein interactions between SPB and kinetochore components. Previously it has been shown that the absence of non-essential kinetochore proteins of the Ctf19 complex weakens kinetochore-microtubule interaction, but whether this compromised interaction affects centromere/kinetochore positioning inside the nucleus is unknown. We found that in G1 and in late anaphase, SPB-centromere proximity was disturbed in mutant cells lacking Ctf19 complex members,Chl4p and/or Ctf19p, whose centromeres lay further away from their SPBs than those of the wild-type cells. We unequivocally show that the SPB-centromere proximity and distances are not dependent on physical interactions between SPB and kinetochore components, but involve microtubule-dependent forces only. Further insight on the positional difference between wild-type and mutant kinetochores was gained by generating computational models governed by (1) independently regulated, but constant kinetochore microtubule (kMT) dynamics, (2) poleward tension on kinetochore and the antagonistic polar ejection force and (3) length and force dependent kMT dynamics. Numerical data obtained from the third model concurs with experimental results and suggests that the absence of Chl4p and/or Ctf19p increases the penetration depth of a growing kMT inside the kinetochore and increases the rescue frequency of a depolymerizing kMT. Both the processes result in increased distance between SPB and centromere.
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Affiliation(s)
- Soumitra Sau
- Department of Biochemistry, Bose Institute, Kolkata, India
| | - Sabyasachi Sutradhar
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
- * E-mail: (PS); (RP)
| | - Pratima Sinha
- Department of Biochemistry, Bose Institute, Kolkata, India
- * E-mail: (PS); (RP)
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8
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Mehta GD, Agarwal M, Ghosh SK. Functional characterization of kinetochore protein, Ctf19 in meiosis I: an implication of differential impact of Ctf19 on the assembly of mitotic and meiotic kinetochores in Saccharomyces cerevisiae. Mol Microbiol 2014; 91:1179-99. [PMID: 24446862 DOI: 10.1111/mmi.12527] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2014] [Indexed: 11/29/2022]
Abstract
Meiosis is a specialized cell division process through which chromosome numbers are reduced by half for the generation of gametes. Kinetochore, a multiprotein complex that connects centromeres to microtubules, plays essential role in chromosome segregation. Ctf19 is the key central kinetochore protein that recruits all the other non-essential proteins of the Ctf19 complex in budding yeast. Earlier studies have shown the role of Ctf19 complex in enrichment of cohesin around the centromeres both during mitosis and meiosis, leading to sister chromatid cohesion and meiosis II disjunction. Here we show that Ctf19 is also essential for the proper execution of the meiosis I specific unique events, such as non-homologous centromere coupling, homologue pairing, chiasmata resolution and proper orientation of homologues and sister chromatids with respect to the spindle poles. Additionally, this investigation reveals that proper kinetochore function is required for faithful chromosome condensation in meiosis. Finally, this study suggests that absence of Ctf19 affects the integrity of meiotic kinetochore differently than that of the mitotic kinetochore. Consequently, absence of Ctf19 leads to gross chromosome missegregation during meiosis as compared with mitosis. Hence, this study reports for the first time the differential impact of a non-essential kinetochore protein on the mitotic and meiotic kinetochore ensembles and hence chromosome segregation.
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Affiliation(s)
- Gunjan D Mehta
- Department of Biosciences and Bioengineering, Wadhawani Research Centre of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 40076, India
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Hinshaw SM, Harrison SC. An Iml3-Chl4 heterodimer links the core centromere to factors required for accurate chromosome segregation. Cell Rep 2013; 5:29-36. [PMID: 24075991 PMCID: PMC3888643 DOI: 10.1016/j.celrep.2013.08.036] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 07/21/2013] [Accepted: 08/16/2013] [Indexed: 01/12/2023] Open
Abstract
Accurate segregation of genetic material in eukaryotes relies on the kinetochore, a multiprotein complex that connects centromeric DNA with microtubules. In yeast and humans, two proteins-Mif2/CENP-C and Chl4/CNEP-N-interact with specialized centromeric nucleosomes and establish distinct but cross-connecting axes of chromatin-microtubule linkage. Proteins recruited by Chl4/CENP-N include a subset that regulates chromosome transmission fidelity. We show that Chl4 and a conserved member of this subset, Iml3, both from Saccharomyces cerevisiae, form a stable protein complex that interacts with Mif2 and Sgo1. We have determined the structures of an Iml3 homodimer and an Iml3-Chl4 heterodimer, which suggest a mechanism for regulating the assembly of this functional axis of the kinetochore. We propose that at the core centromere, the Chl4-Iml3 complex participates in recruiting factors, such as Sgo1, that influence sister chromatid cohesion and encourage sister kinetochore biorientation.
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Affiliation(s)
- Stephen M Hinshaw
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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10
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Hamza A, Baetz K. Iron-responsive transcription factor Aft1 interacts with kinetochore protein Iml3 and promotes pericentromeric cohesin. J Biol Chem 2012; 287:4139-47. [PMID: 22157760 PMCID: PMC3281692 DOI: 10.1074/jbc.m111.319319] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/06/2011] [Indexed: 12/27/2022] Open
Abstract
The Saccharomyces cerevisiae iron-responsive transcription factor, Aft1, has a well established role in regulating iron homeostasis through the transcriptional induction of iron-regulon genes. However, recent studies have implicated Aft1 in other cellular processes independent of iron regulation such as chromosome stability. In addition, chromosome spreads and two-hybrid data suggest that Aft1 interacts with and co-localizes with kinetochore proteins; however, the cellular implications of this have not been established. Here, we demonstrate that Aft1 associates with the kinetochore complex through Iml3. Furthermore, like Iml3, Aft1 is required for the increased association of cohesin with pericentric chromatin, which is required to resist microtubule tension, and aft1Δ cells display chromosome segregation defects in meiosis. Our work defines a new role for Aft1 in chromosome stability and transmission.
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Affiliation(s)
- Akil Hamza
- From the Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Kristin Baetz
- From the Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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11
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Laha S, Das SP, Hajra S, Sanyal K, Sinha P. Functional characterization of the Saccharomyces cerevisiae protein Chl1 reveals the role of sister chromatid cohesion in the maintenance of spindle length during S-phase arrest. BMC Genet 2011; 12:83. [PMID: 21943249 PMCID: PMC3190345 DOI: 10.1186/1471-2156-12-83] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 09/23/2011] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Metaphase cells have short spindles for efficient bi-orientation of chromosomes. The cohesin proteins hold sister chromatids together, creating Sister Chromatid Cohesion (SCC) that helps in the maintenance of short spindle lengths in metaphase. The budding yeast protein Chl1p, which has human homologs, is required for DNA damage repair, recombination, transcriptional silencing and aging. This protein is also needed to establish SCC between sister chromatids in S-phase. RESULTS In the present study we have further characterized Chl1p for its role in the yeast Saccharomyces cerevisiae when cells are under replication stress. We show that when DNA replication is arrested by hydroxyurea (HU), the chl1 mutation causes growth deficiency and a mild loss in cell viability. Although both mutant and wild-type cells remained arrested with undivided nuclei, mutant cells had mitotic spindles, which were about 60-80% longer than wild-type spindles. Spindle extension occurred in S-phase in the presence of an active S-phase checkpoint pathway. Further, the chl1 mutant did not show any kinetochore-related defect that could have caused spindle extension. These cells were affected in the retention of SCC in that they had only about one-fourth of the normal levels of the cohesin subunit Scc1p at centromeres, which was sufficient to bi-orient the chromosomes. The mutant cells showed defects in SCC, both during its establishment in S-phase and in its maintenance in G2. Mutants with partial and pericentromeric cohesion defects also showed spindle elongation when arrested in S-phase by HU. CONCLUSIONS Our work shows that Chl1p is required for normal growth and cell viability in the presence of the replication block caused by HU. The absence of this protein does not, however, compromize the replication checkpoint pathway. Even though the chl1 mutation gives synthetic lethal interactions with kinetochore mutations, its absence does not affect kinetochore function; kinetochore-microtubule interactions remain unperturbed. Further, chl1 cells were found to lose SCC at centromeres in both S- and G2 phases, showing the requirement of Chl1p for the maintenance of cohesion in G2 phase of these cells. This work documents for the first time that SCC is an important determinant of spindle size in the yeast Saccharomyces cerevisiae when genotoxic agents cause S-phase arrest of cells.
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Affiliation(s)
| | - Shankar P Das
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA-01604, USA
| | - Sujata Hajra
- R&D Manager (Molecular Biology), HiMedia Laboratories Pvt. Ltd., Mumbai, India
| | - Kaustuv Sanyal
- Molecular Biology & Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064, India
| | - Pratima Sinha
- Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VII M, Kolkata
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12
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Fernius J, Marston AL. Establishment of cohesion at the pericentromere by the Ctf19 kinetochore subcomplex and the replication fork-associated factor, Csm3. PLoS Genet 2009; 5:e1000629. [PMID: 19730685 PMCID: PMC2727958 DOI: 10.1371/journal.pgen.1000629] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 08/04/2009] [Indexed: 12/20/2022] Open
Abstract
The cohesin complex holds sister chromatids together from the time of their duplication in S phase until their separation during mitosis. Although cohesin is found along the length of chromosomes, it is most abundant at the centromere and surrounding region, the pericentromere. We show here that the budding yeast Ctf19 kinetochore subcomplex and the replication fork-associated factor, Csm3, are both important mediators of pericentromeric cohesion, but they act through distinct mechanisms. We show that components of the Ctf19 complex direct the increased association of cohesin with the pericentromere. In contrast, Csm3 is dispensable for cohesin enrichment in the pericentromere but is essential in ensuring its functionality in holding sister centromeres together. Consistently, cells lacking Csm3 show additive cohesion defects in combination with mutants in the Ctf19 complex. Furthermore, delaying DNA replication rescues the cohesion defect observed in cells lacking Ctf19 complex components, but not Csm3. We propose that the Ctf19 complex ensures additional loading of cohesin at centromeres prior to passage of the replication fork, thereby ensuring its incorporation into functional linkages through a process requiring Csm3. During cell division, chromosomes must be distributed accurately to daughter cells to protect against aneuploidy, a state in which cells have too few or too many chromosomes, and which is associated with diseases such as cancer and birth defects. This process begins with the generation of an exact copy of each chromosome and the establishment of tight linkages that hold the newly duplicated sister chromosomes together. These linkages, generated by the cohesin complex, are essential to resist the pulling forces of the spindle, which will pull the sister chromosomes apart into the two new daughter cells. Here we examine the establishment of cohesin at the pericentromere, the region surrounding the site of spindle attachment and where its forces are strongest. We find that a dedicated pathway promotes cohesin establishment in this region through a two-step mechanism. In the first step, a group of proteins, known as the Ctf19 complex, promote the association of cohesin with this region. In the second step, the Csm3 protein, which is coupled to the DNA replication machinery, ensures its conversion into functional linkages. We demonstrate the importance of this process for accurate chromosome segregation during cell division.
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Affiliation(s)
- Josefin Fernius
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Adele L. Marston
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Laha S, Das SP, Hajra S, Sau S, Sinha P. The budding yeast protein Chl1p is required to preserve genome integrity upon DNA damage in S-phase. Nucleic Acids Res 2006; 34:5880-91. [PMID: 17062629 PMCID: PMC1635322 DOI: 10.1093/nar/gkl749] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The budding yeast protein, Chl1p, is required for sister-chromatid cohesion, transcriptional silencing, rDNA recombination and aging. In this work, we show that Chl1p is also required for viability when DNA replication is stressed, either due to mutations or if cells are treated with genotoxic agents like methylmethane sulfonate (MMS) and ultraviolet (UV) rays. The chl1 mutation caused synthetic growth defects with mutations in DNA replication genes. At semi-permissive temperatures, the double mutants grew poorly, were less viable and showed nuclear fragmentation. They were, however, not limited in their bulk DNA synthesis. When chl1 cells were treated with relatively low levels of MMS in S-phase, they lost viability. The S-phase DNA damage checkpoint pathway, however, remained active in these cells. Agarose gel electrophoresis of genomic DNA isolated from wild-type and chl1 cells, after recovery from MMS treatment, suggested that the wild-type was more proficient in the repair of DNA damage than the mutant. Our work suggests that Chl1p is required for genome integrity when cells suffer endogenously or exogenously induced DNA damage.
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Affiliation(s)
| | | | | | | | - Pratima Sinha
- To whom correspondence should be addressed. Tel: 91 33 23550256; Fax: 91 33 23343886;
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