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Chen D, Li H. Mannitol improves Monascus pigment biosynthesis with rice bran as a substrate in Monascus purpureus. Front Microbiol 2023; 14:1300461. [PMID: 38156009 PMCID: PMC10753769 DOI: 10.3389/fmicb.2023.1300461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/09/2023] [Indexed: 12/30/2023] Open
Abstract
To reduce the production cost of Monascus pigments (MPs), the utilization of rice bran (RB), an agricultural waste product, as a substrate in submerged fermentation was conducted in this study. To improve MP production, different nutritional ingredients including mannitol (Man), NH4NO3 (AN), ZnSO4 (Zn), and optimization (Opti), which was a synthesis of the three above ones, were added in rice bran (RB) medium. The yields of MPs, pigment constituents, and growth and development of Monascus purpureus M9 were investigated in this study. Man had the maximum color value of 3,532 U/g, which was 18.69 times more than that of RB and reached up to 76.65% of the value of rice (Rice) fermentation. Man significantly increased the production of two orange pigments, monascorubrin and rubropunctatin, of which the yields were 69.49 and 95.36% of the counterpart of Rice. The biomass and colony diameter of Opti presented the maximum value among different groups. AN and RB induced more asexual spore formation, whereas Opti and Man promoted sexual spore production. Comparative transcriptomic analysis showed that different nutritional ingredients led to changes in pigment production, promoting the growth and development of M. purpureus M9 through the regulation of related gene expression. Man and Opti improved MP production by regulating the primary metabolism, including the Embden-Meyerhof pathway (EMP), the pentose phosphate (PP) pathway, the tricarboxylic (TCA) cycle, fatty acid degradation (FAD), fatty acid biosynthesis (FAB), amino acid metabolism (AAM), and fructose and mannose metabolism (FMM), to provide the precursors (acetyl-CoA and malonyl-CoA) for MP biosynthesis. This study presents a low-cost method for increasing MP production and explains the molecular mechanisms of different nutritional ingredients for enhancing MP biosynthesis.
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Affiliation(s)
- Di Chen
- College of Biological Engineering, Henan University of Technology, Zhengzhou, China
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2
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Leontiou I, London N, May KM, Ma Y, Grzesiak L, Medina-Pritchard B, Amin P, Jeyaprakash AA, Biggins S, Hardwick KG. The Bub1-TPR Domain Interacts Directly with Mad3 to Generate Robust Spindle Checkpoint Arrest. Curr Biol 2019; 29:2407-2414.e7. [PMID: 31257143 PMCID: PMC6657678 DOI: 10.1016/j.cub.2019.06.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 01/30/2019] [Accepted: 06/04/2019] [Indexed: 12/14/2022]
Abstract
The spindle checkpoint monitors kinetochore-microtubule interactions and generates a “wait anaphase” delay when any defects are apparent [1, 2, 3]. This provides time for cells to correct chromosome attachment errors and ensure high-fidelity chromosome segregation. Checkpoint signals are generated at unattached chromosomes during mitosis. To activate the checkpoint, Mps1Mph1 kinase phosphorylates the kinetochore component KNL1Spc105/Spc7 on conserved MELT motifs to recruit Bub3-Bub1 complexes [4, 5, 6] via a direct Bub3 interaction with phospho-MELT motifs [7, 8]. Mps1Mph1 then phosphorylates Bub1, which strengthens its interaction with Mad1-Mad2 complexes to produce a signaling platform [9, 10]. The Bub1-Mad1 platform is thought to recruit Mad3, Cdc20, and Mad2 to produce the mitotic checkpoint complex (MCC), which is the diffusible wait anaphase signal [9, 11, 12]. The MCC binds and inhibits the mitotic E3 ubiquitin ligase, known as Cdc20-anaphase promoting complex/cyclosome (APC/C), and stabilizes securin and cyclin to delay anaphase onset [13, 14, 15, 16, 17]. Here we demonstrate, in both budding and fission yeast, that kinetochores and KNL1Spc105/Spc7 can be bypassed; simply inducing heterodimers of Mps1Mph1 kinase and Bub1 is sufficient to trigger metaphase arrest that is dependent on Mad1, Mad2, and Mad3. We use this to dissect the domains of Bub1 necessary for arrest, highlighting the need for Bub1-CD1, which binds Mad1 [9], and Bub1’s highly conserved N-terminal tetratricopeptide repeat (TPR) domain [18, 19]. We demonstrate that the Bub1 TPR domain is both necessary and sufficient to bind and recruit Mad3. We propose that this brings Mad3 into close proximity to Mad1-Mad2 and Mps1Mph1 kinase, enabling efficient generation of MCC complexes. Heterodimers of Mps1 and Bub1 generate robust spindle checkpoint arrest in yeasts This arrest is independent of kinetochores but requires Bub1-CD1 and the Bub1-TPR The Bub1-TPR is both necessary and sufficient for Mad3 interaction and recruitment Recombinant fission yeast Bub1-TPR and Mad3 form a stable complex
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Affiliation(s)
- Ioanna Leontiou
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Nitobe London
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Karen M May
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Yingrui Ma
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Lucile Grzesiak
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Bethan Medina-Pritchard
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Priya Amin
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - A Arockia Jeyaprakash
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Kevin G Hardwick
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK.
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3
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The molecular mechanisms of Monascus purpureus M9 responses to blue light based on the transcriptome analysis. Sci Rep 2017; 7:5537. [PMID: 28717254 PMCID: PMC5514072 DOI: 10.1038/s41598-017-05990-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 06/16/2017] [Indexed: 01/14/2023] Open
Abstract
Light is an important environmental factor that regulates various physiological processes of fungi. To thoroughly study the responses of Monascus to blue light, transcriptome sequencing was performed on mRNAs isolated from samples of Monascus purpureus M9 cultured under three conditions: darkness (D); exposure to blue light for 15 min/d (B15); and exposure to blue light for 60 min/d over 8 days (B60). The number of differentially expressed genes between the three pairs of samples-B15 vs D, B60 vs B15, and B60 vs D-was 1167, 1172, and 220, respectively. KEGG analysis showed the genes involved in primary metabolism including carbon and nitrogen metabolism were downregulated by B15 light treatment, whereas B15 upregulated expression of genes involved with aromatic amino acid metabolism, which associated with development, and branched chain amino acid metabolism, and fatty acid degradation, which can produce the biosynthetic precursors of pigments. When exposed to B60 conditions, genes with roles in carbohydrate metabolism and protein synthesis were upregulated as part of a stress response to blue light. Based on this study, we propose a predicted light-stimulated signal transduction pathway in Monascus. Our work is the first comprehensive investigation concerning the mechanism of Monascus responses to blue light.
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Edgerton H, Paolillo V, Oakley BR. Spatial regulation of the spindle assembly checkpoint and anaphase-promoting complex in Aspergillus nidulans. Mol Microbiol 2014; 95:442-57. [PMID: 25417844 DOI: 10.1111/mmi.12871] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2014] [Indexed: 11/29/2022]
Abstract
The spindle assembly checkpoint (SAC) plays a critical role in preventing mitotic errors by inhibiting anaphase until all kinetochores are correctly attached to spindle microtubules. In spite of the economic and medical importance of filamentous fungi, relatively little is known about the behavior of SAC proteins in these organisms. In our efforts to understand the role of γ-tubulin in cell cycle regulation, we have created functional fluorescent protein fusions of four SAC proteins in Aspergillus nidulans, the homologs of Mad2, Mps1, Bub1/BubR1 and Bub3. Time-lapse imaging reveals that SAC proteins are in distinct compartments of the cell until early mitosis when they co-localize at the spindle pole body. SAC activity is, thus, spatially regulated in A. nidulans. Likewise, Cdc20, an activator of the anaphase-promoting complex/cyclosome, is excluded from interphase nuclei, but enters nuclei at mitotic onset and accumulates to a higher level in mitotic nuclei than in the surrounding nucleoplasm before leaving in anaphase/telophase. The activity of this critical cell cycle regulatory complex is likely regulated by the location of Cdc20. Finally, the γ-tubulin mutation mipAD159 causes a nuclear-specific failure of nuclear localization of Mps1 and Bub1/R1 but not of Cdc20, Bub3 or Mad2.
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Affiliation(s)
- Heather Edgerton
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave., Lawrence, KS, 66045, USA
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5
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London N, Biggins S. Signalling dynamics in the spindle checkpoint response. Nat Rev Mol Cell Biol 2014; 15:736-47. [PMID: 25303117 DOI: 10.1038/nrm3888] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The spindle checkpoint ensures proper chromosome segregation during cell division. Unravelling checkpoint signalling has been a long-standing challenge owing to the complexity of the structures and forces that regulate chromosome segregation. New reports have now substantially advanced our understanding of checkpoint signalling mechanisms at the kinetochore, the structure that connects microtubules and chromatin. In contrast to the traditional view of a binary checkpoint response - either completely on or off - new findings indicate that the checkpoint response strength is variable. This revised perspective provides insight into how checkpoint bypass can lead to aneuploidy and informs strategies to exploit these errors for cancer treatments.
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Affiliation(s)
- Nitobe London
- 1] Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., PO Box 19024, Seattle, Washington 98109, USA. [2] Molecular and Cellular Biology Program, University of Washington/Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Sue Biggins
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., PO Box 19024, Seattle, Washington 98109, USA
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6
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Bolanos-Garcia VM. Formation of multiprotein assemblies in the nucleus: the spindle assembly checkpoint. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 307:151-74. [PMID: 24380595 DOI: 10.1016/b978-0-12-800046-5.00006-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Specific interactions within the cell must occur in a crowded environment and often in a narrow time-space framework to ensure cell survival. In the light that up to 10% of individual protein molecules present at one time in mammalian cells mediate signal transduction, the establishment of productive, specific interactions is a remarkable achievement. The spindle assembly checkpoint (SAC) is an evolutionarily conserved and essential self-monitoring system of the eukaryotic cell cycle that ensures the high fidelity of chromosome segregation by delaying the onset of anaphase until all chromosomes are properly bi-oriented on the mitotic spindle. The function of the SAC involves communication with the kinetochore, an essential multiprotein complex crucial for chromosome segregation that assembles on mitotic or meiotic centromeres to link centromeric DNA with microtubules. Interactions in the SAC and kinetochore-microtubule network often involve the reversible assembly of large multiprotein complexes in which regions of the polypeptide chain that exhibit low structure complexity undergo a disorder-to-order transition. The confinement and high density of protein molecules in the cell has a profound effect on the stability, folding rate, and biological functions of individual proteins and protein assemblies. Here, I discuss the role of large and highly flexible surfaces that mediate productive intermolecular interactions in SAC signaling and postulate that macromolecular crowding contributes to the exquisite regulation that is required for the timely and accurate segregation of chromosomes in higher organisms.
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Affiliation(s)
- Victor M Bolanos-Garcia
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom.
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Primorac I, Weir JR, Chiroli E, Gross F, Hoffmann I, van Gerwen S, Ciliberto A, Musacchio A. Bub3 reads phosphorylated MELT repeats to promote spindle assembly checkpoint signaling. eLife 2013; 2:e01030. [PMID: 24066227 PMCID: PMC3779320 DOI: 10.7554/elife.01030] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 08/21/2013] [Indexed: 12/31/2022] Open
Abstract
Regulation of macromolecular interactions by phosphorylation is crucial in signaling networks. In the spindle assembly checkpoint (SAC), which enables errorless chromosome segregation, phosphorylation promotes recruitment of SAC proteins to tensionless kinetochores. The SAC kinase Mps1 phosphorylates multiple Met-Glu-Leu-Thr (MELT) motifs on the kinetochore subunit Spc105/Knl1. The phosphorylated MELT motifs (MELTP) then promote recruitment of downstream signaling components. How MELTP motifs are recognized is unclear. In this study, we report that Bub3, a 7-bladed β-propeller, is the MELTP reader. It contains an exceptionally well-conserved interface that docks the MELTP sequence on the side of the β-propeller in a previously unknown binding mode. Mutations targeting the Bub3 interface prevent kinetochore recruitment of the SAC kinase Bub1. Crucially, they also cause a checkpoint defect, showing that recognition of phosphorylated targets by Bub3 is required for checkpoint signaling. Our data provide the first detailed mechanistic insight into how phosphorylation promotes recruitment of checkpoint proteins to kinetochores. DOI:http://dx.doi.org/10.7554/eLife.01030.001 The cell cycle is the process by which a cell divides to produce two near-identical daughter cells. Two crucial parts of the cell cycle are the duplication of the chromosomes in the original cell, and the segregation of these chromosomes between the two daughter cells. These and other parts of the cell cycle are strictly regulated to prevent errors, which can lead to cancer and other diseases. After chromosome duplication has taken place, the pairs of identical chromosomes, known as sister chromatids, remain tightly bound to each other. These sister chromatids line up in the middle of the cell, with protein filaments called microtubules connecting them to a bipolar structure called the spindle. For the cell to divide correctly, the sister chromatids in each pair must be connected to opposite poles of the spindle. A signalling network known as the spindle assembly checkpoint (SAC) ensures that the sister chromatids have enough time to line up correctly and to correct possible problems. Once everything is in place, the SAC releases its ‘break’, and the microtubules then pull the sister chromatids away from each other. This way, each daughter cell receives the same complement of chromosomes that was present in the mother cell. The microtubules are not directly attached to the sister chromatids but to protein complexes called kinetochores that assemble on each sister chromatid. In particular, each microtubule binds to a very large protein complex called the KMN network. Knl1, which is part of this network, recruits two SAC proteins–Bub1 and Bub3–to the kinetochore. It is known that a phosphate group is added to Knl1 when the SAC is active, and that Knl1 can only recruit Bub1 and Bub3 after it has been phosphorylated. However, the details of the interactions between Knl1, Bub1 and Bub3 are not understood, and it is not clear whether these interactions are essential for the SAC. Now Primorac et al. have shown that Bub3 binds directly to Knl1 through a region that contains multiple MELT motifs (where M, E, L and T are all amino acids), and that this interaction only happens if these ‘MELT repeats’ have been phosphorylated. Moreover, once bound to the Knl1, Bub3 then recruits Bub1 to the kinetochore. By showing that the recognition of phosphorylated Knl1 by the Bub1-Bub3 complex has a central role in the spindle assembly checkpoint, these results highlight the importance of phosphorylation as a way of regulating the timing of events during the cell cycle. DOI:http://dx.doi.org/10.7554/eLife.01030.002
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Affiliation(s)
- Ivana Primorac
- Department of Mechanistic Cell Biology , Max Planck Institute of Molecular Physiology , Dortmund , Germany
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8
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Heinrich S, Windecker H, Hustedt N, Hauf S. Mph1 kinetochore localization is crucial and upstream in the hierarchy of spindle assembly checkpoint protein recruitment to kinetochores. J Cell Sci 2012; 125:4720-7. [DOI: 10.1242/jcs.110387] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) blocks entry into anaphase until all chromosomes have stably attached to the mitotic spindle through their kinetochores. The checkpoint signal originates from unattached kinetochores, where SAC proteins enrich. Whether the enrichment of all SAC proteins is crucial for SAC signalling is unclear. Here we provide evidence that in fission yeast, recruitment of the kinase Mph1 is of vital importance for a stable SAC arrest. An Mph1 mutant that eliminates kinetochore enrichment abolishes SAC signalling, whereas forced recruitment of this mutant to kinetochores restores SAC signalling. In bub3Δ cells, the SAC is functional with only Mph1 and the Aurora kinase Ark1, but no other SAC proteins, enriched at kinetochores. We analysed the network of dependencies for SAC protein localization to kinetochores and identify a three-layered hierarchy with Ark1 and Mph1 on top, Bub1 and Bub3 in the middle, and Mad3 as well as the Mad1-Mad2 complex at the lower end of the hierarchy. If Mph1 is artificially recruited to kinetochores, Ark1 becomes dispensable for SAC activity. Our results highlight the critical role of Mph1 at kinetochores and suggest that the Mad1-Mad2 complex does not necessarily need to enrich at kinetochores for functional SAC signalling.
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9
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Vanoosthuyse V, Meadows JC, van der Sar SJA, Millar JBA, Hardwick KG. Bub3p facilitates spindle checkpoint silencing in fission yeast. Mol Biol Cell 2010; 20:5096-105. [PMID: 19846658 DOI: 10.1091/mbc.e09-09-0762] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Although critical for spindle checkpoint signaling, the role kinetochores play in anaphase promoting complex (APC) inhibition remains unclear. Here we show that spindle checkpoint proteins are severely depleted from unattached kinetochores in fission yeast cells lacking Bub3p. Surprisingly, a robust mitotic arrest is maintained in the majority of bub3 Delta cells, yet they die, suggesting that Bub3p is essential for successful checkpoint recovery. During recovery, two defects are observed: (1) cells mis-segregate chromosomes and (2) anaphase onset is significantly delayed. We show that Bub3p is required to activate the APC upon inhibition of Aurora kinase activity in checkpoint-arrested cells, suggesting that Bub3p is required for efficient checkpoint silencing downstream of Aurora kinase. Together, these results suggest that spindle checkpoint signals can be amplified in the nucleoplasm, yet kinetochore localization of spindle checkpoint components is required for proper recovery from a spindle checkpoint-dependent arrest.
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Affiliation(s)
- Vincent Vanoosthuyse
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3JR, United Kingdom.
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10
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Checkpoint kinase 1 modulates sensitivity to cisplatin after spindle checkpoint activation in SW620 cells. Int J Biochem Cell Biol 2010; 42:318-28. [DOI: 10.1016/j.biocel.2009.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 10/30/2009] [Accepted: 11/10/2009] [Indexed: 01/17/2023]
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11
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Windecker H, Langegger M, Heinrich S, Hauf S. Bub1 and Bub3 promote the conversion from monopolar to bipolar chromosome attachment independently of shugoshin. EMBO Rep 2009; 10:1022-8. [PMID: 19680287 PMCID: PMC2728212 DOI: 10.1038/embor.2009.183] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 07/09/2009] [Accepted: 07/10/2009] [Indexed: 11/09/2022] Open
Abstract
The eukaryotic spindle assembly checkpoint (SAC) delays anaphase in the presence of chromosome attachment errors. Bub3 has been reported to be required for SAC activity in all eukaryotes examined so far. We find that Bub3, unlike its binding partner Bub1, is not essential for the SAC in fission yeast. As Bub3 is needed for the efficient kinetochore localization of Bub1, and of Mad1, Mad2 and Mad3, this implies that most SAC proteins do not need to be enriched at the kinetochores for the SAC to function. We find that Bub3 is also dispensable for shugoshin localization to the centromeres, which is the second known function of Bub1. Instead, Bub3, together with Bub1, has a specific function in promoting the conversion from chromosome mono-orientation to bi-orientation.
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Affiliation(s)
- Hanna Windecker
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstrasse 39, 72076 Tuebingen, Germany
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12
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Saitoh S, Kobayashi Y, Ogiyama Y, Takahashi K. Dual regulation of Mad2 localization on kinetochores by Bub1 and Dam1/DASH that ensure proper spindle interaction. Mol Biol Cell 2008; 19:3885-97. [PMID: 18632983 DOI: 10.1091/mbc.e08-03-0298] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The spindle assembly checkpoint monitors the state of spindle-kinetochore interaction to prevent premature onset of anaphase. Although checkpoint proteins, such as Mad2, are localized on kinetochores that do not interact properly with the spindle, it remains unknown how the checkpoint proteins recognize abnormalities in spindle-kinetochore interaction. Here, we report that Mad2 localization on kinetochores in fission yeast is regulated by two partially overlapping but distinct pathways: the Dam1/DASH and the Bub1 pathways. We show that Mad2 is localized on "unattached" as well as "tensionless" kinetochores. Our observations suggest that Bub1 is required for Mad2 to detect tensionless kinetochores, whereas Dam1/DASH is crucial for Mad2 to detect unattached kinetochores. In cells lacking both Bub1 and Dam1/DASH, Mad2 localization on kinetochores is diminished, and mitotic progression appears to be accelerated despite the frequent occurrence of abnormal chromosome segregation. Furthermore, we found that Dam1/DASH is required for promotion of spindle association with unattached kinetochores. In contrast, there is accumulating evidence that Bub1 is involved in resolution of erroneous spindle attachment on tensionless kinetochores. These pathways may act as molecular sensors determining the state of spindle association on each kinetochore, enabling proper regulation of the checkpoint activation as well as promotion/resolution of spindle attachment.
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Affiliation(s)
- Shigeaki Saitoh
- Division of Cell Biology, Institute of Life Science, Kurume University, Kurume, Fukuoka 839-0864, Japan.
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Sczaniecka M, Feoktistova A, May KM, Chen JS, Blyth J, Gould KL, Hardwick KG. The spindle checkpoint functions of Mad3 and Mad2 depend on a Mad3 KEN box-mediated interaction with Cdc20-anaphase-promoting complex (APC/C). J Biol Chem 2008; 283:23039-47. [PMID: 18556659 PMCID: PMC2516979 DOI: 10.1074/jbc.m803594200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mitotic progression is driven by proteolytic destruction of securin and cyclins. These proteins are labeled for destruction by an ubiquitin-protein isopeptide ligase (E3) known as the anaphase-promoting complex or cyclosome (APC/C). The APC/C requires activators (Cdc20 or Cdh1) to efficiently recognize its substrates, which are specified by destruction (D box) and/or KEN box signals. The spindle assembly checkpoint responds to unattached kinetochores and to kinetochores lacking tension, both of which reflect incomplete biorientation of chromosomes, by delaying the onset of anaphase. It does this by inhibiting Cdc20-APC/C. Certain checkpoint proteins interact directly with Cdc20, but it remains unclear how the checkpoint acts to efficiently inhibit Cdc20-APC/C activity. In the fission yeast, Schizosaccharomyces pombe, we find that the Mad3 and Mad2 spindle checkpoint proteins interact stably with the APC/C in mitosis. Mad3 contains two KEN boxes, conserved from yeast Mad3 to human BubR1, and mutation of either of these abrogates the spindle checkpoint. Strikingly, mutation of the N-terminal KEN box abolishes incorporation of Mad3 into the mitotic checkpoint complex (Mad3-Mad2-Slp1 in S. pombe, where Slp1 is the Cdc20 homolog that we will refer to as Cdc20 hereafter) and stable association of both Mad3 and Mad2 with the APC/C. Our findings demonstrate that this Mad3 KEN box is a critical mediator of Cdc20-APC/C inhibition, without which neither Mad3 nor Mad2 can associate with the APC/C or inhibit anaphase onset.
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Affiliation(s)
- Matylda Sczaniecka
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3JR, United Kingdom
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14
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Beaufils S, Grossmann JG, Renault A, Bolanos-Garcia VM. Characterization of the tetratricopeptide-containing domain of BUB1, BUBR1, and PP5 proves that domain amphiphilicity over amino acid sequence specificity governs protein adsorption and interfacial activity. J Phys Chem B 2008; 112:7984-91. [PMID: 18547097 DOI: 10.1021/jp711222s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The tetratricopeptide motif repeat (TPR) is an alpha-helix-turn-alpha-helix motif that typically mediates protein-protein and, in some cases, protein-lipid interactions. Because of its success, this motif has been preserved through evolution and can be identified in proteins of a wide range of functions in lower and higher organisms. The N-terminal region of BUB1, BUBR1, and protein phosphatase 5 (PP5) contains tandem arrangements of the TPR motif. BUB1 and BUBR1 are conserved multidomain protein kinases that play a key role in the mitotic checkpoint, the mechanism that ensures the synchrony of chromosome segregation. PP5 is an enzyme that targets a wide range of protein substrates including single transmembrane receptors and mammalian cryptochromes. The N-terminal TPR domain of PP5 regulates the activity of the C-terminal catalytic domain through direct interaction with protein and lipid molecules. We portray the biophysical and biochemical properties of the tandem arrangements of the TPR motif of BUB1, BUBR1, and PP5 using far-UV spectroscopy, solution X-ray scattering, null ellipsometry, surface rheology measurements, and Brewster angle microscopy (BAM) observations. We show that, despite the low amino acid sequence conservation and different function, the TPR motif repeats of the three proteins exhibit similar interfacial properties including adsorption kinetics, high surface activity, and the formation of stable, rigid films at the air/water interface. Our studies demonstrate that domain amphiphilicity is of higher importance than amino acid sequence specificity in the determination of protein adsorption and interfacial activity.
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Affiliation(s)
- Sylvie Beaufils
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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15
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Tange Y, Niwa O. Schizosaccharomyces pombe Bub3 is dispensable for mitotic arrest following perturbed spindle formation. Genetics 2008; 179:785-92. [PMID: 18505884 PMCID: PMC2429874 DOI: 10.1534/genetics.107.081695] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 04/07/2008] [Indexed: 11/18/2022] Open
Abstract
The core proteins of the spindle assembly checkpoint (SAC), Mads, Bubs, and Mps1, first identified in the budding yeast, are thought to be functionally and structurally conserved through evolution. We found that fission yeast Bub3 is dispensable for SAC, as bub3 null mutants blocked mitotic progression when spindle formation was disrupted. Consistently, the bub3 mutation only weakly affected the stability of minichromosome Ch16 compared with other SAC mutants. Fission yeast Rae1 has sequence homology with Bub3. The bub3 rae1 double mutant and rae1 single mutant did not have defective SAC, suggesting that these genes do not have overlapping roles for SAC. Observations of living cells revealed that the duration of the mitotic prometaphase/metaphase was longer in the bub3 mutant and was Mad2 dependent. Further, the bub3 mutant was defective in sister centromere association during metaphase. Together, these findings suggest that fission yeast Bub3 is required for normal spindle dynamics, but not for SAC.
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Affiliation(s)
- Yoshie Tange
- Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
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Rischitor PE, May KM, Hardwick KG. Bub1 is a fission yeast kinetochore scaffold protein, and is sufficient to recruit other spindle checkpoint proteins to ectopic sites on chromosomes. PLoS One 2007; 2:e1342. [PMID: 18094750 PMCID: PMC2147072 DOI: 10.1371/journal.pone.0001342] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 11/25/2007] [Indexed: 11/18/2022] Open
Abstract
The spindle checkpoint delays anaphase onset until all chromosomes have attached in a bi-polar manner to the mitotic spindle. Mad and Bub proteins are recruited to unattached kinetochores, and generate diffusible anaphase inhibitors. Checkpoint models propose that Mad1 and Bub1 act as stable kinetochore-bound scaffolds, to enhance recruitment of Mad2 and Mad3/BubR1, but this remains untested for Bub1. Here, fission yeast FRAP experiments confirm that Bub1 stably binds kinetochores, and by tethering Bub1 to telomeres we demonstrate that it is sufficient to recruit anaphase inhibitors in a kinase-independent manner. We propose that the major checkpoint role for Bub1 is as a signalling scaffold.
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Affiliation(s)
- Patricia E. Rischitor
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Karen M. May
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kevin G. Hardwick
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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Murakami H, Goto DB, Toda T, Chen ES, Grewal SI, Martienssen RA, Yanagida M. Ribonuclease activity of Dis3 is required for mitotic progression and provides a possible link between heterochromatin and kinetochore function. PLoS One 2007; 2:e317. [PMID: 17380189 PMCID: PMC1820850 DOI: 10.1371/journal.pone.0000317] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 03/05/2007] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Cellular RNA metabolism has a broad range of functional aspects in cell growth and division, but its role in chromosome segregation during mitosis is only poorly understood. The Dis3 ribonuclease is a key component of the RNA-processing exosome complex. Previous isolation of the dis3-54 cold-sensitive mutant of fission yeast Schizosaccharomyces pombe suggested that Dis3 is also required for correct chromosome segregation. METHODOLOGY/PRINCIPAL FINDINGS We show here that the progression of mitosis is arrested in dis3-54, and that segregation of the chromosomes is blocked by activation of the mitotic checkpoint control. This block is dependent on the Mad2 checkpoint protein. Double mutant and inhibitor analyses revealed that Dis3 is required for correct kinetochore formation and function, and that this activity is monitored by the Mad2 checkpoint. Dis3 is a member of the highly conserved RNase II family and is known to be an essential subunit of the exosome complex. The dis3-54 mutation was found to alter the RNaseII domain of Dis3, which caused a reduction in ribonuclease activity in vitro. This was associated with loss of silencing of an ura4(+) reporter gene inserted into the outer repeats (otr) and central core (cnt and imr) regions of the centromere. On the other hand, centromeric siRNA maturation and formation of the RITS RNAi effector complex was normal in the dis3-54 mutant. Micrococcal nuclease assay also suggested the overall chromatin structure of the centromere was not affected in dis3-54 mutant. CONCLUSIONS/SIGNIFICANCE RNase activity of Dis3, a core subunit of exosome, was found to be required for proper kinetochore formation and establishment of kinetochore-microtubule interactions. Moreover, Dis3 was suggested to contribute to kinetochore formation through an involvement in heterochromatic silencing at both outer centromeric repeats and within the central core region. This activity is likely monitored by the mitotic checkpoint, and distinct from that of RNAi-mediated heterochromatin formation directly targeting outer centromeric repeats.
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Affiliation(s)
- Hiroaki Murakami
- CREST Research Program, Japan Science and Technology Corporation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, Japan
| | - Derek B. Goto
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
| | - Ee Sin Chen
- Laboratory of Molecular Cell Biology, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Shiv I. Grewal
- Laboratory of Molecular Cell Biology, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert A. Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Mitsuhiro Yanagida
- CREST Research Program, Japan Science and Technology Corporation, Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, Japan
- * To whom correspondence should be addressed. E-mail:
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Vaur S, Cubizolles F, Plane G, Genier S, Rabitsch PK, Gregan J, Nasmyth K, Vanoosthuyse V, Hardwick KG, Javerzat JP. Control of Shugoshin function during fission-yeast meiosis. Curr Biol 2006; 15:2263-70. [PMID: 16360688 DOI: 10.1016/j.cub.2005.11.034] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Revised: 10/20/2005] [Accepted: 11/01/2005] [Indexed: 10/25/2022]
Abstract
Meiosis consists of a single round of DNA replication followed by two consecutive nuclear divisions. During the first division (MI), sister kinetochores must orient toward the same pole to favor reductional segregation. Correct chromosome segregation during the second division (MII) requires the retention of centromeric cohesion until anaphase II. The spindle checkpoint protein Bub1 is essential for both processes in fission yeast . When bub1 is deleted, the Shugoshin protein Sgo1 is not recruited to centromeres, cohesin Rec8 does not persist at centromeres, and sister-chromatid cohesion is lost by the end of MI. Deletion of bub1 also affects kinetochore orientation because sister centromeres can move to opposite spindle poles in approximately 30% of MI divisions. We show here that these two functions are separable within the Bub1 protein. The N terminus of Bub1 is necessary and sufficient for Sgo1 targeting to centromeres and the protection of cohesion, whereas the C-terminal kinase domain acts together with Sgo2, the second fission-yeast Shugoshin protein, to promote sister-kinetochore co-orientation during MI. Additional analyses suggest that the protection of centromeric cohesion does not operate when sister kinetochores attach to opposite spindle poles during MI. Sgo1-mediated protection of centromere cohesion might therefore be regulated by the mode of kinetochore attachment.
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Affiliation(s)
- Sabine Vaur
- Centre National de la Recherche Scientifique, Institut de Biochimie et Génétique Cellulaires, Unité mixte de recherche 5095, Bordeaux, F-33077, France
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Asakawa K, Kume K, Kanai M, Goshima T, Miyahara K, Dhut S, Tee WW, Hirata D, Toda T. The V260I mutation in fission yeast alpha-tubulin Atb2 affects microtubule dynamics and EB1-Mal3 localization and activates the Bub1 branch of the spindle checkpoint. Mol Biol Cell 2006; 17:1421-35. [PMID: 16394105 PMCID: PMC1382329 DOI: 10.1091/mbc.e05-08-0802] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 12/13/2005] [Accepted: 12/27/2005] [Indexed: 11/11/2022] Open
Abstract
We have identified a novel temperature-sensitive mutant of fission yeast alpha-tubulin Atb2 (atb2-983) that contains a single amino acid substitution (V260I). Atb2-983 is incorporated into the microtubules, and their overall structures are not altered noticeably, but microtubule dynamics is compromised during interphase. atb2-983 displays a high rate of chromosome missegregation and is synthetically lethal with deletions in a subset of spindle checkpoint genes including bub1, bub3, and mph1, but not with mad1, mad2, and mad3. During early mitosis in this mutant, Bub1, but not Mad2, remains for a prolonged period in the kinetochores that are situated in proximity to one of the two SPBs (spindle pole bodies). High dosage mal3(+), encoding EB1 homologue, rescues atb2-983, suggesting that Mal3 function is compromised. Consistently, Mal3 localization and binding between Mal3 and Atb2-983 are impaired significantly, and a mal3 single mutant, such as atb2-983, displays prolonged Bub1 kinetochore localization. Furthermore in atb2-983 back-and-forth centromere oscillation during prometaphase is abolished. Intriguingly, this oscillation still occurs in the mal3 mutant, indicating that there is another defect independent of Mal3. These results show that microtubule dynamics is important for coordinated execution of mitotic events, in which Mal3 plays a vital role.
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Affiliation(s)
- Kazuhide Asakawa
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3PX, UK
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Asakawa K, Toya M, Sato M, Kanai M, Kume K, Goshima T, Garcia MA, Hirata D, Toda T. Mal3, the fission yeast EB1 homologue, cooperates with Bub1 spindle checkpoint to prevent monopolar attachment. EMBO Rep 2006; 6:1194-200. [PMID: 16179942 PMCID: PMC1369205 DOI: 10.1038/sj.embor.7400540] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 08/22/2005] [Accepted: 08/24/2005] [Indexed: 11/09/2022] Open
Abstract
Bipolar microtubule attachment is central to genome stability. Here, we investigate the mitotic role of the fission yeast EB1 homologue Mal3. Mal3 shows dynamic inward movement along the spindle, initial emergence at the spindle pole body (SPB) and translocation towards the equatorial plane, followed by sudden disappearance. Deletion of Mal3 results in early mitotic delay, which is dependent on the Bub1, but not the Mad2, spindle checkpoint. Consistently, Bub1, but not Mad2, shows prolonged kinetochore localization. Double mutants between mal3 and a subset of checkpoint mutants, including bub1, bub3, mad3 and mph1, but not mad1 or mad2, show massive chromosome mis-segregation defects. In mal3bub1 mutants, both sister centromeres tend to remain in close proximity to one of the separating SPBs. Further analysis indicates that mis-segregated centromeres are exclusively associated with the mother SPB. Mal3, therefore, has a role in preventing monopolar attachment in cooperation with the Bub1/Bub3/Mad3/Mph1-dependent checkpoint.
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Affiliation(s)
- Kazuhide Asakawa
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Mika Toya
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Masamitsu Sato
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Muneyoshi Kanai
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Kazunori Kume
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Tetsuya Goshima
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Miguel Angel Garcia
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Dai Hirata
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
- Tel: +44 20 7269 3535; Fax: 44 20 7269 3258; E-mail:
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Kadura S, Sazer S. SAC-ing mitotic errors: how the spindle assembly checkpoint (SAC) plays defense against chromosome mis-segregation. ACTA ACUST UNITED AC 2005; 61:145-60. [PMID: 15887295 DOI: 10.1002/cm.20072] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sheila Kadura
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Current awareness on yeast. Yeast 2005; 22:745-52. [PMID: 16106592 DOI: 10.1002/yea.1165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Umeda M, Izaddoost S, Cushman I, Moore MS, Sazer S. The fission yeast Schizosaccharomyces pombe has two importin-alpha proteins, Imp1p and Cut15p, which have common and unique functions in nucleocytoplasmic transport and cell cycle progression. Genetics 2005; 171:7-21. [PMID: 15937127 PMCID: PMC1456536 DOI: 10.1534/genetics.105.042598] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nuclear import of classical nuclear localization signal-containing proteins depends on importin-alpha transport receptors. In budding yeast there is a single importin-alpha gene and in higher eukaryotes there are multiple importin-alpha-like genes, but in fission yeast there are two: the previously characterized cut15 and the more recently identified imp1. Like other importin-alpha family members, Imp1p supports nuclear protein import in vitro. In contrast to cut15, imp1 is not essential for viability, but imp1delta mutant cells exhibit a telophase delay and mild temperature-sensitive lethality. Differences in the cellular functions that depend on Imp1p and Cut15p indicate that they each have unique physiological roles. They also have common roles because the imp1delta and the cut15-85 temperature-sensitive mutations are synthetically lethal; overexpression of cut15 partially suppresses the temperature sensitivity, but not the mitotic delay in imp1delta cells; and overexpression of imp1 partially suppresses the mitotic defect in cut15-85 cells but not the loss of viability. Both Imp1p and Cut15p are required for the efficient nuclear import of both an SV40 nuclear localization signal-containing reporter protein and the Pap1p component of the stress response MAP kinase pathway. Imp1p and Cut15p are essential for efficient nuclear protein import in S. pombe.
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Affiliation(s)
- Makoto Umeda
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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