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Structural Basis for the Functional Diversity of Centrins: A Focus on Calcium Sensing Properties and Target Recognition. Int J Mol Sci 2021; 22:ijms222212173. [PMID: 34830049 PMCID: PMC8622359 DOI: 10.3390/ijms222212173] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 11/23/2022] Open
Abstract
Centrins are a family of small, EF hand-containing proteins that are found in all eukaryotes and are often complexed with centrosome-related structures. Since their discovery, centrins have attracted increasing interest due to their multiple, diverse cellular functions. Centrins are similar to calmodulin (CaM) in size, structure and domain organization, although in contrast to CaM, the majority of centrins possess at least one calcium (Ca2+) binding site that is non-functional, thus displaying large variance in Ca2+ sensing abilities that could support their functional versatility. In this review, we summarize current knowledge on centrins from both biophysical and structural perspectives with an emphasis on centrin-target interactions. In-depth analysis of the Ca2+ sensing properties of centrins and structures of centrins complexed with target proteins can provide useful insight into the mechanisms of the different functions of centrins and how these proteins contribute to the complexity of the Ca2+ signaling cascade. Moreover, it can help to better understand the functional redundancy of centrin isoforms and centrin-binding proteins.
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2
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Zhao J, Yang Y, Fan Y, Yi J, Zhang C, Gu Z, Pan W, Gu J, Liao W, Fang W. Ribosomal Protein L40e Fused With a Ubiquitin Moiety Is Essential for the Vegetative Growth, Morphological Homeostasis, Cell Cycle Progression, and Pathogenicity of Cryptococcus neoformans. Front Microbiol 2020; 11:570269. [PMID: 33224112 PMCID: PMC7674629 DOI: 10.3389/fmicb.2020.570269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/20/2020] [Indexed: 11/13/2022] Open
Abstract
Ubiquitin is a highly conserved protein required for various fundamental cellular processes in eukaryotes. Herein, we first report the contribution of the ubiquitin fusion protein Ubi1 (a ubiquitin monomer fused with the ribosome protein L40e, Rpl40e) in the growth and pathogenicity of Cryptococcus neoformans. UBI1 deletion resulted in severe growth restriction of C. neoformans, whose growth rate was positively correlated with UBI1 expression level. The growth defect of the ubi1Δ strain could be closely associated with its morphological abnormalities, such as its reduced ribosome particles. In addition, the ubi1Δ mutant also displayed increased cell ploidy, cell cycle arrest, and decreased intracellular survival inside macrophages. All these phenotypes were reversed by the reconstitution of the full-length UBI1 gene or RPL40a domain. Mouse survival and fungal burden assays further revealed a severely attenuated pathogenicity for the ubi1Δ mutant, which is probably associated with its reduced stress tolerance and the induction of T-helper 1-type immune response. Taken together, Ubi1 is required for maintaining the vegetative growth, morphological homeostasis, cell cycle progression, and pathogenicity in vivo of C. neoformans. The pleiotropic roles of Ubi1 are dependent on the presence of Rpl40e and associated with its regulation of cryptococcal ribosome biogenesis.
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Affiliation(s)
- Jingyu Zhao
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China.,Department of Dermatology, Shanghai Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Yali Yang
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China.,Department of Dermatology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yibin Fan
- Department of Dermatology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Jiu Yi
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Chao Zhang
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Zhongkai Gu
- The Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Weihua Pan
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Julin Gu
- Department of Dermatology, Shanghai Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Wanqing Liao
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Wei Fang
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
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3
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Calcium and phosphorylation double-regulating caltractin initiating target protein XPC function. Int J Biol Macromol 2019; 136:503-511. [DOI: 10.1016/j.ijbiomac.2019.06.095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 01/22/2023]
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4
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Shan F, Yang X, Diwu Y, Ma H, Tu X. Trypanosoma brucei centrin5 is enriched in the flagellum and interacts with other centrins in a calcium-dependent manner. FEBS Open Bio 2019; 9:1421-1431. [PMID: 31161731 PMCID: PMC6668372 DOI: 10.1002/2211-5463.12683] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/24/2019] [Accepted: 05/31/2019] [Indexed: 11/21/2022] Open
Abstract
Centrin is an evolutionarily conserved EF‐hand‐containing protein, which is present in eukaryotic organisms as diverse as algae, yeast, and humans. Centrins are associated with the microtubule‐organizing center and with centrosome‐related structures, such as basal bodies in flagellar and ciliated cells, and the spindle pole body in yeast. Five centrin genes have been identified in Trypanosoma brucei (T. brucei), a protozoan parasite that causes sleeping sickness in humans and nagana in cattle in sub‐Saharan Africa. In the present study, we identified that centrin5 of T. brucei (TbCentrin5) is localized throughout the cytosol and nucleus and enriched in the flagellum. We further identified that TbCentrin5 binds Ca2+ ions with a high affinity and constructed a model of TbCentrin5 bound by Ca2+ ions. Meanwhile, we observed that TbCentrin5 interacts with TbCentrin1, TbCentrin3, and TbCentrin4 and that the interactions are Ca2+‐dependent, suggesting that TbCentrin5 is able to form different complexes with other TbCentrins to participate in relevant cellular processes. Our study provides a foundation for better understanding of the biological roles of TbCentrin5.
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Affiliation(s)
- Fangzhen Shan
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, China
| | - Xiao Yang
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, China
| | - Yating Diwu
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, China
| | - Haoyu Ma
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, China
| | - Xiaoming Tu
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, China
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5
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Solution structure of TbCentrin4 from Trypanosoma brucei and its interactions with Ca 2+ and other centrins. Biochem J 2018; 475:3763-3778. [PMID: 30389845 DOI: 10.1042/bcj20180752] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/30/2018] [Accepted: 11/01/2018] [Indexed: 12/17/2022]
Abstract
Centrin is a conserved calcium-binding protein that plays an important role in diverse cellular biological processes such as ciliogenesis, gene expression, DNA repair and signal transduction. In Trypanosoma brucei, TbCentrin4 is mainly localized in basal bodies and bi-lobe structure, and is involved in the processes coordinating karyokinesis and cytokinesis. In the present study, we solved the solution structure of TbCentrin4 using NMR (nuclear magnetic resonance) spectroscopy. TbCentrin4 contains four EF-hand motifs consisting of eight α-helices. Isothermal titration calorimetry experiment showed that TbCentrin4 has a strong Ca2+ binding ability. NMR chemical shift perturbation indicated that TbCentrin4 binds to Ca2+ through its C-terminal domain composed of EF-hand 3 and 4. Meanwhile, we revealed that TbCentrin4 undergoes a conformational change and self-assembly induced by high concentration of Ca2+ Intriguingly, localization of TbCentrin4 was dispersed or disappeared from basal bodies and the bi-lobe structure when the cells were treated with Ca2+ in vivo, implying the influence of Ca2+ on the cellular functions of TbCentrin4. Besides, we observed the interactions between TbCentrin4 and other Tbcentrins and revealed that the interactions are Ca2+ dependent. Our findings provide a structural basis for better understanding the biological functions of TbCentrin4 in the relevant cellular processes.
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Chen L, Bian S, Li H, Madura K. A role for Saccharomyces cerevisiae Centrin (Cdc31) in mitochondrial function and biogenesis. Mol Microbiol 2018; 110:831-846. [PMID: 30251372 DOI: 10.1111/mmi.14128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 08/24/2018] [Accepted: 09/09/2018] [Indexed: 11/28/2022]
Abstract
Centrins belong to a family of proteins containing calcium-binding EF-hand motifs that perform well-established roles in centrosome and spindle pole body (SPB) duplication. Yeast encodes a single Centrin protein (Cdc31) that binds components in the SPB. However, further studies revealed a role for Centrins in mRNA export, and interactions with contractile filaments and photoreceptors. In addition, human Centrin-2 can bind the DNA-lesion recognition factor XPC, and improve the efficiency of nucleotide excision repair. Similarly, we reported that yeast Cdc31 binds Rad4, a functional counterpart of the XPC DNA repair protein. We also found that Cdc31 is involved in the ubiquitin/proteasome system, and mutations interfere with intracellular protein turnover. In this report, we describe new findings that indicate a role for Cdc31 in the energy metabolism pathway. Cdc31 and cdc31 mutant proteins showed distinct interactions with proteins in energy metabolism, and mutants showed sensitivity to oxidative stress and poor growth on non-fermentable carbon. Significant alteration in mitochondrial morphology was also detected. Although it is unclear how Cdc31 contributes to so many unrelated mechanisms, we propose that by controlling SPB duplication Centrin proteins might link the cellular responses to DNA damage, oxidative load and proteotoxic stresses to growth control.
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Affiliation(s)
- Li Chen
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, 683 Hoes Lane, SPH-383, Piscataway, NJ, 08854, USA
| | - Shengjie Bian
- Center for Advanced Proteomics Research, New Jersey Medical School, Rutgers University, 185 S. Orange Ave., Newark, NJ, 07103, USA
| | - Hong Li
- Center for Advanced Proteomics Research, New Jersey Medical School, Rutgers University, 185 S. Orange Ave., Newark, NJ, 07103, USA
| | - Kiran Madura
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, 683 Hoes Lane, SPH-383, Piscataway, NJ, 08854, USA
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Abstract
Myers and Payne discuss work by De et al. describing the unique structure of Vps13 and its role in trafficking Yeast Vps13 is a member of a conserved protein family that includes human homologues associated with neurodegenerative and developmental disorders. In this issue, De et al. (2017. J. Cell Biol.https://doi.org/10.1083/jcb.201606078) establish direct roles for Vps13 and its surprising binding partner, the calcium-binding centrin Cdc31, in trans-Golgi network (TGN) to endosome traffic and TGN homotypic fusion.
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Affiliation(s)
- Margaret D Myers
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - Gregory S Payne
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
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De M, Oleskie AN, Ayyash M, Dutta S, Mancour L, Abazeed ME, Brace EJ, Skiniotis G, Fuller RS. The Vps13p-Cdc31p complex is directly required for TGN late endosome transport and TGN homotypic fusion. J Cell Biol 2017; 216:425-439. [PMID: 28122955 PMCID: PMC5294781 DOI: 10.1083/jcb.201606078] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 11/04/2016] [Accepted: 01/11/2017] [Indexed: 01/09/2023] Open
Abstract
VPS13 proteins are widely conserved in eukaryotes and associated with human neurodegenerative and neurodevelopmental diseases. De et al. describe the lipid specificity and structure of yeast Vps13p, providing insight into its role in both TGN late endosome transport and TGN homotypic fusion. Yeast VPS13 is the founding member of a eukaryotic gene family of growing interest in cell biology and medicine. Mutations in three of four human VPS13 genes cause autosomal recessive neurodegenerative or neurodevelopmental disease, making yeast Vps13p an important structural and functional model. Using cell-free reconstitution with purified Vps13p, we show that Vps13p is directly required both for transport from the trans-Golgi network (TGN) to the late endosome/prevacuolar compartment (PVC) and for TGN homotypic fusion. Vps13p must be in complex with the small calcium-binding protein Cdc31p to be active. Single-particle electron microscopic analysis of negatively stained Vps13p indicates that this 358-kD protein is folded into a compact rod-shaped density (20 × 4 nm) with a loop structure at one end with a circular opening ∼6 nm in diameter. Vps13p exhibits ATP-stimulated binding to yeast membranes and specific interactions with phosphatidic acid and phosphorylated forms of phosphatidyl inositol at least in part through the binding affinities of conserved N- and C-terminal domains.
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Affiliation(s)
- Mithu De
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Austin N Oleskie
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Mariam Ayyash
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Somnath Dutta
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Liliya Mancour
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Mohamed E Abazeed
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109.,Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Eddy J Brace
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Georgios Skiniotis
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Robert S Fuller
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109
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9
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Xiaojuan Guo YZ, Yang B. Regulation of centrin self-assembly investigated by fluorescence resonance light scattering. RSC Adv 2017. [DOI: 10.1039/c6ra26865j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Centrin is primarily involved in fiber contraction, which is associated with the cell division cycle and ciliogenesis.
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Affiliation(s)
- Yaqin Zhao Xiaojuan Guo
- Institute of Molecular Science
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education
- Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province
- Shanxi University
- Taiyuan 030006
| | - Binsheng Yang
- Institute of Molecular Science
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education
- Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province
- Shanxi University
- Taiyuan 030006
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10
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Martinez-Sanz J, Assairi L. New insights into the interaction of centrin with Sfi1. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:319-30. [PMID: 26779587 DOI: 10.1016/j.bbapap.2016.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/03/2015] [Accepted: 01/08/2016] [Indexed: 10/22/2022]
Abstract
Centrin binds to Rad4(XPC) and Sfi1 through the hydrophobic motif W(1)xxL(4)xxxL(8) in the opposite orientation. Rad4 has one motif, but Sfi1 has approximately 20 repeats, each of which interacts with a centrin molecule. To investigate the parameters involved in centrin binding, we purified a ScSfi1 domain containing 6 repeats complexed with either yeast centrin Cdc31 or human centrin 1. The present study was performed using mutagenesis of centrin and of Sfi1 residues involved in centrin binding and the stability of the centrin-centrin complexes was assessed using thermal denaturation and CD. Calcium stabilized these complexes, as indicated by the Tm increases measured by circular dichroism. The complexes, which were composed of Sfi1 variants and yeast centrin, were analysed in the presence of EDTA. The replacement of W with F within the repeat region yielded a functional repeat (Tm 45°C). The replacement of W with A in two adjacent Sfi1 repeats reduced the thermal stability of the Sfi1-centrin complexes (40°C). We analysed three HsCen1 variants that were homologous to the yeast mutants and induced cell cycle arrest during the G2/M transition. The HsCen1 variants E105K and F113L reduced the thermal stability (50°C, 50°C) of the ScSfi1-HsCen1 complexes; in contrast, the A109T variant exhibited no change in thermal stability relative to the wild-type (60°C). Conversely to ScCdc31, there were no apparent centrin-centrin interactions with wild-type HsCen1, but they did occur for the S170D mutation that mimics PKA phosphorylation at the S170 residue.
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Affiliation(s)
- Juan Martinez-Sanz
- Institut Curie-Centre de Recherche, F-91405 Orsay Cédex, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U759, F-91405 Orsay Cédex, France
| | - Liliane Assairi
- Institut Curie-Centre de Recherche, F-91405 Orsay Cédex, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U759, F-91405 Orsay Cédex, France.
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11
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Plattner H, Verkhratsky A. The ancient roots of calcium signalling evolutionary tree. Cell Calcium 2015; 57:123-32. [DOI: 10.1016/j.ceca.2014.12.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 12/05/2014] [Indexed: 12/26/2022]
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12
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Santos-Pereira JM, García-Rubio ML, González-Aguilera C, Luna R, Aguilera A. A genome-wide function of THSC/TREX-2 at active genes prevents transcription-replication collisions. Nucleic Acids Res 2014; 42:12000-14. [PMID: 25294824 PMCID: PMC4231764 DOI: 10.1093/nar/gku906] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The THSC/TREX-2 complex of Saccharomyces cerevisiae mediates the anchoring of transcribed genes to the nuclear pore, linking transcription elongation with mRNA export and genome stability, as shown for specific reporters. However, it is still unknown whether the function of TREX-2 is global and the reason for its relevant role in genome integrity. Here, by studying two TREX-2 representative subunits, Thp1 and Sac3, we show that TREX-2 has a genome-wide role in gene expression. Both proteins show similar distributions along the genome, with a gradient disposition at active genes that increases towards the 3′ end. Thp1 and Sac3 have a relevant impact on the expression of long, G+C-rich and highly transcribed genes. Interestingly, replication impairment detected by the genome-wide accumulation of the replicative Rrm3 helicase is increased preferentially at highly expressed genes in the thp1Δ and sac3Δ mutants analyzed. Therefore, our work provides evidence of a function of TREX-2 at the genome-wide level and suggests a role for TREX-2 in preventing transcription–replication conflicts, as a source of genome instability derived from a defective messenger ribonucleoprotein particle (mRNP) biogenesis.
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Affiliation(s)
- José M Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain
| | - María L García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain
| | - Cristina González-Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain
| | - Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain
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13
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Lee IJ, Wang N, Hu W, Schott K, Bähler J, Giddings TH, Pringle JR, Du LL, Wu JQ. Regulation of spindle pole body assembly and cytokinesis by the centrin-binding protein Sfi1 in fission yeast. Mol Biol Cell 2014; 25:2735-49. [PMID: 25031431 PMCID: PMC4161509 DOI: 10.1091/mbc.e13-11-0699] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A previous model suggested doubling of Sfi1 as the first step of SPB assembly. Here it is shown that Sfi1 is gradually recruited to SPBs throughout the cell cycle. Conserved tryptophans in Sfi1 are required for its equal partitioning during mitosis, and unequal partitioning of Sfi1 underlies SPB assembly and mitotic defects in the next cell cycle. Centrosomes play critical roles in the cell division cycle and ciliogenesis. Sfi1 is a centrin-binding protein conserved from yeast to humans. Budding yeast Sfi1 is essential for the initiation of spindle pole body (SPB; yeast centrosome) duplication. However, the recruitment and partitioning of Sfi1 to centrosomal structures have never been fully investigated in any organism, and the presumed importance of the conserved tryptophans in the internal repeats of Sfi1 remains untested. Here we report that in fission yeast, instead of doubling abruptly at the initiation of SPB duplication and remaining at a constant level thereafter, Sfi1 is gradually recruited to SPBs throughout the cell cycle. Like an sfi1Δ mutant, a Trp-to-Arg mutant (sfi1-M46) forms monopolar spindles and exhibits mitosis and cytokinesis defects. Sfi1-M46 protein associates preferentially with one of the two daughter SPBs during mitosis, resulting in a failure of new SPB assembly in the SPB receiving insufficient Sfi1. Although all five conserved tryptophans tested are involved in Sfi1 partitioning, the importance of the individual repeats in Sfi1 differs. In summary, our results reveal a link between the conserved tryptophans and Sfi1 partitioning and suggest a revision of the model for SPB assembly.
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Affiliation(s)
- I-Ju Lee
- Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Ning Wang
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Wen Hu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Kersey Schott
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Thomas H Giddings
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado-Boulder, Boulder, CO 80309
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Li-Lin Du
- National Institute of Biological Sciences, Beijing 102206, China
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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14
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Grecu D, Blouquit Y, Assairi L. The E144 residue of Scherffelia dubia centrin discriminates between the DNA repair protein XPC and the centrosomal protein Sfi1. FEBS Open Bio 2013; 4:33-42. [PMID: 24371720 PMCID: PMC3871271 DOI: 10.1016/j.fob.2013.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 11/27/2022] Open
Abstract
Centrins are members of the EF-hand family of calcium-binding proteins, which are highly conserved among eukaryotes. Centrins bind to several cellular targets, through a hydrophobic triad. However, the W(1)xxL(4)xxxL(8) triad in XPC (Xeroderma Pigmentosum Group C protein) is found in the reverse orientation, as in the L(8)xxxL(4)xxW(1) triad in Sfi1 (Suppressor of Fermentation-Induced loss of stress resistance protein 1). As shown by previous NMR studies of human centrin 2 in complex with XPC or Sfi1, the E148 residue of human centrin 2 is in contact with XPC but is pushed away from the triad of Sfi1. We corroborated these findings using site-directed mutagenesis to generate mutations in Scherffelia dubia centrin (SdCen) and by using isothermal titration calorimetry to analyze the binding affinity of these mutants to XPC and Sfi1. We mutated the F109 residue, which is the main residue involved in target binding regardless of triad orientation, and the E144 residue, which was thought to be involved only in XPC binding. The F109L mutation reduced the binding of SdCen to XPC and Sfi1 and the negative effect was greater upon temperature increase. By contrast, the E144A mutation reduced the binding to XPC but had no effect on Sfi1 binding. The F109L-E144A mutation enhanced the negative effect of the two single mutations on XPC binding. Sfi1 proteins from Ostreococcus lucimarinus and Ostreococcus tauri, which belong to the same clade as S. dubia, were also investigated. A comparative analysis shows that the triad residues are more conserved than those in human Sfi1.
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Affiliation(s)
- Dora Grecu
- Institut Curie, Centre de Recherche, Orsay Cédex F-91405, France
| | - Yves Blouquit
- Institut Curie, Centre de Recherche, Orsay Cédex F-91405, France
| | - Liliane Assairi
- Institut Curie, Centre de Recherche, Orsay Cédex F-91405, France
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15
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Cunningham CN, Schmidt CA, Schramm NJ, Gaylord MR, Resendes KK. Human TREX2 components PCID2 and centrin 2, but not ENY2, have distinct functions in protein export and co-localize to the centrosome. Exp Cell Res 2013; 320:209-18. [PMID: 24291146 DOI: 10.1016/j.yexcr.2013.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 11/15/2022]
Abstract
TREX-2 is a five protein complex, conserved from yeast to humans, involved in linking mRNA transcription and export. The centrin 2 subunit of TREX-2 is also a component of the centrosome and is additionally involved in a distinctly different process of nuclear protein export. While centrin 2 is a known multifunctional protein, the roles of other human TREX-2 complex proteins other than mRNA export are not known. In this study, we found that human TREX-2 member PCID2 but not ENY2 is involved in some of the same cellular processes as those of centrin 2 apart from the classical TREX-2 function. PCID2 is present at the centrosome in a subset of HeLa cells and this localization is centrin 2 dependent. Furthermore, the presence of PCID2 at the centrosome is prevalent throughout the cell cycle as determined by co-staining with cyclins E, A and B. PCID2 but not ENY2 is also involved in protein export. Surprisingly, siRNA knockdown of PCID2 delayed the rate of nuclear protein export, a mechanism distinct from the effects of centrin 2, which when knocked down inhibits export. Finally we showed that co-depletion of centrin 2 and PCID2 leads to blocking rather than delaying nuclear protein export, indicating the dominance of the centrin 2 phenotype. Together these results represent the first discovery of specific novel functions for PCID2 other than mRNA export and suggest that components of the TREX-2 complex serve alternative shared roles in the regulation of nuclear transport and cell cycle progression.
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Affiliation(s)
- Corey N Cunningham
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Casey A Schmidt
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Nathaniel J Schramm
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Michelle R Gaylord
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California - San Diego, 9500 Gilman Drive, #0347, La Jolla, CA 92093-0347, USA
| | - Karen K Resendes
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA.
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16
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Abstract
Productive cell proliferation involves efficient and accurate splitting of the dividing cell into two separate entities. This orderly process reflects coordination of diverse cytological events by regulatory systems that drive the cell from mitosis into G1. In the budding yeast Saccharomyces cerevisiae, separation of mother and daughter cells involves coordinated actomyosin ring contraction and septum synthesis, followed by septum destruction. These events occur in precise and rapid sequence once chromosomes are segregated and are linked with spindle organization and mitotic progress by intricate cell cycle control machinery. Additionally, critical paarts of the mother/daughter separation process are asymmetric, reflecting a form of fate specification that occurs in every cell division. This chapter describes central events of budding yeast cell separation, as well as the control pathways that integrate them and link them with the cell cycle.
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17
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Zhao YQ, Yan J, Chao JB, Liang AH, Yang BS. The biochemical effect of Ser166 phosphorylation on Euplotes octocarinatus centrin. J Biol Inorg Chem 2012. [DOI: 10.1007/s00775-012-0957-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Role of centrins 2 and 3 in organelle segregation and cytokinesis in Trypanosoma brucei. PLoS One 2012; 7:e45288. [PMID: 23028908 PMCID: PMC3448667 DOI: 10.1371/journal.pone.0045288] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/15/2012] [Indexed: 11/19/2022] Open
Abstract
Centrins are calcium binding proteins involved in cell division in eukaryotes. Previously, we have shown that depletion of centrin1 in Trypanosoma brucei (T. brucei) displayed arrested organelle segregation resulting in loss of cytokinesis. In this study we analyzed the role of T. brucei centrin2 (TbCen2) and T. brucei 3 (TbCen3) in the early events of T. brucei procyclic cell cycle. Both the immunofluorescence assay and electron microscopy showed that TbCen2 and 3-deficient cells were enlarged in size with duplicated basal bodies, multinuclei and new flagella that are detached along the length of the cell body. In both TbCen2 and TbCen3 depleted cells segregation of the organelles i.e. basal bodies, kinetoplast and nucleus was disrupted. Further analysis of the cells with defective organelle segregation identified three different sub configurations of organelle mis-segregations (Type 1-3). In addition, in majority of the TbCen2 depleted cells and in nearly half of the TbCen3 depleted cells, the kinetoplasts were enlarged and undivided. The abnormal segregations ultimately led to aborted cytokinesis and hence affected growth in these cells. Therefore, both centrin2 and 3 are involved in organelle segregation similar to centrin1 as was previously observed. In addition, we identified their role in kinetoplast division which may be also linked to overall mis-segregation.
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19
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Dantas TJ, Daly OM, Morrison CG. Such small hands: the roles of centrins/caltractins in the centriole and in genome maintenance. Cell Mol Life Sci 2012; 69:2979-97. [PMID: 22460578 PMCID: PMC11114748 DOI: 10.1007/s00018-012-0961-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/20/2012] [Accepted: 03/12/2012] [Indexed: 01/11/2023]
Abstract
Centrins are small, highly conserved members of the EF-hand superfamily of calcium-binding proteins that are found throughout eukaryotes. They play a major role in ensuring the duplication and appropriate functioning of the ciliary basal bodies in ciliated cells. They have also been localised to the centrosome, which is the major microtubule organising centre in animal somatic cells. We describe the identification, cloning and characterisation of centrins in multiple eukaryotic species. Although centrins have been implicated in centriole biogenesis, recent results have indicated that centrosome duplication can, in fact, occur in the absence of centrins. We discuss these data and the non-centrosomal functions that are emerging for the centrins. In particular, we discuss the involvement of centrins in nucleotide excision repair, a process that repairs the DNA lesions that are induced primarily by ultraviolet irradiation. We discuss how centrin may be involved in these diverse processes and contribute to nuclear and cytoplasmic events.
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Affiliation(s)
- Tiago J. Dantas
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, University Road, Galway, Ireland
| | - Owen M. Daly
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, University Road, Galway, Ireland
| | - Ciaran G. Morrison
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, University Road, Galway, Ireland
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20
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Zhang Y, He CY. Centrins in unicellular organisms: functional diversity and specialization. PROTOPLASMA 2012; 249:459-467. [PMID: 21786168 DOI: 10.1007/s00709-011-0305-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 07/10/2011] [Indexed: 05/31/2023]
Abstract
Centrins (also known as caltractins) are conserved, EF hand-containing proteins ubiquitously found in eukaryotes. Similar to calmodulins, the calcium-binding EF hands in centrins fold into two structurally similar domains separated by an alpha-helical linker region, shaping like a dumbbell. The small size (15-22 kDa) and domain organization of centrins and their functional diversity/specialization make them an ideal system to study protein structure-function relationship. Here, we review the work on centrins with a focus on their structures and functions characterized in unicellular organisms.
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Affiliation(s)
- Yu Zhang
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
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21
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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22
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Zhao Y, Yan J, Song L, Feng Y, Liang A, Yang B. The interaction between lanthanide (III) and N-terminal domain of Euplotes octocarinatus centrin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 87:163-170. [PMID: 22154266 DOI: 10.1016/j.saa.2011.11.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 11/13/2011] [Indexed: 05/31/2023]
Abstract
Centrin, a member of calcium-binding proteins, is an essential component for microtubule-organizing center (MTOC). Lanthanide (Ln) ions can increase amounts, enhance stability and orderliness of microtubules which is an important component of cytoskeleton. To investigate the structural basis of the effect of Ln ions on orderliness of microtubules, we focused on the interactions between the isolated N-terminal domain of Euplotes centrin (N-EoCen) and Ln by some combined biophysical and biochemical methods. Our results suggest that Ln ions may bind to the canonical calcium binding sites on N-EoCen. Taking advantage of ligand competition, we first determined the metal-binding affinities of Nd(3+), Eu(3+), Gd(3+) and Tm(3+) with N-EoCen. Major changes of N-EoCen in secondary and tertiary structure are noted while Ln ions bind with N-EoCen through CD spectra and 2-p-toluidinylnaphthalene-6-sulfonate (TNS) fluorescence. N-EoCen exists in the form of monomer and dimer in the presence of Ln ions. These results can provide some insights into the structural basis of how Ln ions achieve biological effect in cell through the centrin protein.
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Affiliation(s)
- Yaqin Zhao
- Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
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23
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Wang M, Gheiratmand L, He CY. An interplay between Centrin2 and Centrin4 on the bi-lobed structure in Trypanosoma brucei. Mol Microbiol 2012; 83:1153-61. [PMID: 22324849 DOI: 10.1111/j.1365-2958.2012.07998.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Centrins are conserved calcium-binding proteins important for various regulatory functions. In procyclic Trypanosoma brucei, TbCentrin2 and TbCentrin4 have distinct effects on cell division but both localize to the basal bodies that seed the flagellum, and a bi-lobed structure important for organelle duplication and cell division. Here we show that TbCentrin2 and TbCentrin4 both bind to the basal bodies and bi-lobed structure through the conserved C-terminal domain. Molecular genetic manipulation of TbCentrin4 levels greatly affects TbCentrin2 association with the bi-lobed structure. Using established synchronization methods, TbCentrin2 expression level is shown to be relatively constant throughout the cell cycle while TbCentrin4 level fluctuates, decreasing most during early S-phase when the bi-lobe undergoes duplication. These results thus suggest a co-ordinated action between these two centrin proteins, where the cell cycle-dependent TbCentrin4 expression could regulate the abundance of TbCentrin2 on the bi-lobed structure.
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Affiliation(s)
- Min Wang
- Department of Biological Sciences, National University of Singapore, Singapore
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24
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Analysis of Lanthanide-Induced Conformational Change of the C-Terminal Domain on Centrin. J Fluoresc 2011; 22:485-94. [DOI: 10.1007/s10895-011-0982-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 09/16/2011] [Indexed: 10/17/2022]
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25
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Vonderfecht T, Stemm-Wolf AJ, Hendershott M, Giddings TH, Meehl JB, Winey M. The two domains of centrin have distinct basal body functions in Tetrahymena. Mol Biol Cell 2011; 22:2221-34. [PMID: 21562224 PMCID: PMC3128525 DOI: 10.1091/mbc.e11-02-0151] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/15/2011] [Accepted: 04/29/2011] [Indexed: 11/11/2022] Open
Abstract
The basal body is a microtubule-organizing center responsible for organizing the cilium, a structure important for cell locomotion and sensing of the surrounding environment. A widely conserved basal body component is the Ca(2+)-binding protein centrin. Analyses of centrin function suggest a role in basal body assembly and stability; however, its molecular mechanisms remain unclear. Here we describe a mutagenic strategy to study the function and essential nature of the various structural features of Cen1 in the ciliate Tetrahymena. We find that the two domains of Cen1 are both essential, and examination of strains containing mutant CEN1 alleles indicates that there are two predominant basal body phenotypes: misorientation of newly assembled basal bodies and stability defects. The results also show that the two domains of Cen1 are able to bind Ca(2+) and that perturbation of Ca(2+) binding affects Cen1 function. In all, the data suggest that the two domains of Cen1 have distinct functions.
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Affiliation(s)
- Tyson Vonderfecht
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | - Alexander J. Stemm-Wolf
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | | | - Thomas H. Giddings
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | - Janet B. Meehl
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | - Mark Winey
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
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26
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Keller LC, Wemmer KA, Marshall WF. Influence of centriole number on mitotic spindle length and symmetry. Cytoskeleton (Hoboken) 2010; 67:504-18. [PMID: 20540087 DOI: 10.1002/cm.20462] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The functional role of centrioles or basal bodies in mitotic spindle assembly and function is currently unclear. Although supernumerary centrioles have been associated with multipolar spindles in cancer cells, suggesting centriole number might dictate spindle polarity, bipolar spindles are able to assemble in the complete absence of centrioles, suggesting a level of centriole-independence in the spindle assembly pathway. In this report we perturb centriole number using mutations in Chlamydomonas reinhardtii, and measure the response of the mitotic spindle to these perturbations in centriole number. Although altered centriole number increased the frequency of monopolar and multipolar spindles, the majority of spindles remained bipolar regardless of the centriole number. But even when spindles were bipolar, abnormal centriole numbers led to asymmetries in tubulin distribution, half-spindle length and spindle pole focus. Half spindle length correlated directly with number of centrioles at a pole, such that an imbalance in centriole number between the two poles of a bipolar spindle correlated with increased asymmetry between half spindle lengths. These results are consistent with centrioles playing an active role in regulating mitotic spindle length. Mutants with centriole number alteration also show increased cytokinesis defects, but these do not correlate with centriole number in the dividing cell and may therefore reflect downstream consequences of defects in preceding cell divisions.
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Affiliation(s)
- Lani C Keller
- Department of Biochemistry and Biophysics, UCSF, San Francisco, California 94158, USA
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27
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Araki Y, Gombos L, Migueleti SPS, Sivashanmugam L, Antony C, Schiebel E. N-terminal regions of Mps1 kinase determine functional bifurcation. ACTA ACUST UNITED AC 2010; 189:41-56. [PMID: 20368617 PMCID: PMC2854372 DOI: 10.1083/jcb.200910027] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Spindle pole body components Spc29 and Cdc31 are identified as targets of Mps1 kinase, which, when phosphorylated, regulate protein–protein interactions in the spindle pole body. Mps1 is a conserved kinase that in budding yeast functions in duplication of the spindle pole body (SPB), spindle checkpoint activation, and kinetochore biorientation. The identity of Mps1 targets and the subdomains that convey specificity remain largely unexplored. Using a novel combination of systematic deletion analysis and chemical biology, we identified two regions within the N terminus of Mps1 that are essential for either SPB duplication or kinetochore biorientation. Suppression analysis of the MPS1 mutants defective in SPB duplication and biochemical enrichment of Mps1 identified the essential SPB components Spc29 and the yeast centrin Cdc31 as Mps1 targets in SPB duplication. Our data suggest that phosphorylation of Spc29 by Mps1 in G1/S recruits the Mps2–Bbp1 complex to the newly formed SPB to facilitate its insertion into the nuclear envelope. Mps1 phosphorylation of Cdc31 at the conserved T110 residue controls substrate binding to Kar1 protein. These findings explain the multiple SPB duplication defects of mps1 mutants on a molecular level.
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Affiliation(s)
- Yasuhiro Araki
- Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-ZMBH Allianz, 69120 Heidelberg, Germany
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28
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Dictyostelium discoideum CenB is a bona fide centrin essential for nuclear architecture and centrosome stability. EUKARYOTIC CELL 2009; 8:1106-17. [PMID: 19465563 DOI: 10.1128/ec.00025-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Centrins are a family of proteins within the calcium-binding EF-hand superfamily. In addition to their archetypical role at the microtubule organizing center (MTOC), centrins have acquired multiple functionalities throughout the course of evolution. For example, centrins have been linked to different nuclear activities, including mRNA export and DNA repair. Dictyostelium discoideum centrin B is a divergent member of the centrin family. At the amino acid level, DdCenB shows 51% identity with its closest relative and only paralog, DdCenA. Phylogenetic analysis revealed that DdCenB and DdCenA form a well-supported monophyletic and divergent group within the centrin family of proteins. Interestingly, fluorescently tagged versions of DdCenB were not found at the centrosome (in whole cells or in isolated centrosomes). Instead, DdCenB localized to the nuclei of interphase cells. This localization disappeared as the cells entered mitosis, although Dictyostelium cells undergo a closed mitosis in which the nuclear envelope (NE) does not break down. DdCenB knockout cells exhibited aberrant nuclear architecture, characterized by enlarged and deformed nuclei and loss of proper centrosome-nucleus anchoring (observed as NE protrusions). At the centrosome, loss of DdCenB resulted in defects in the organization and morphology of the MTOC and supernumerary centrosomes and centrosome-related bodies. The multiple defects that the loss of DdCenB generated at the centrosome can be explained by its atypical division cycle, transitioning into the NE as it divides at mitosis. On the basis of these findings, we propose that DdCenB is required at interphase to maintain proper nuclear architecture, and before delocalizing from the nucleus, DdCenB is part of the centrosome duplication machinery.
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29
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Jani D, Lutz S, Marshall NJ, Fischer T, Köhler A, Ellisdon AM, Hurt E, Stewart M. Sus1, Cdc31, and the Sac3 CID region form a conserved interaction platform that promotes nuclear pore association and mRNA export. Mol Cell 2009; 33:727-37. [PMID: 19328066 PMCID: PMC2726291 DOI: 10.1016/j.molcel.2009.01.033] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 01/19/2009] [Accepted: 01/30/2009] [Indexed: 11/25/2022]
Abstract
The yeast Sac3:Cdc31:Sus1:Thp1 (TREX-2) complex facilitates the repositioning and association of actively transcribing genes with nuclear pores (NPCs)—“gene gating”—that is central to integrating transcription, processing, and mRNA nuclear export. We present here the crystal structure of Sus1 and Cdc31 bound to a central region of Sac3 (the CID domain) that is crucial for its function. Sac3CID forms a long, gently undulating α helix around which one Cdc31 and two Sus1 chains are wrapped. Sus1 has an articulated helical hairpin fold that facilitates its wrapping around Sac3. In vivo studies using engineered mutations that selectively disrupted binding of individual chains to Sac3 indicated that Sus1 and Cdc31 function synergistically to promote NPC association of TREX-2 and mRNA nuclear export. These data indicate Sac3CID provides a scaffold within TREX-2 to integrate interactions between protein complexes to facilitate the coupling of transcription and mRNA export during gene expression.
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Affiliation(s)
- Divyang Jani
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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30
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González-Aguilera C, Tous C, Gómez-González B, Huertas P, Luna R, Aguilera A. The THP1-SAC3-SUS1-CDC31 complex works in transcription elongation-mRNA export preventing RNA-mediated genome instability. Mol Biol Cell 2008; 19:4310-8. [PMID: 18667528 DOI: 10.1091/mbc.e08-04-0355] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The eukaryotic THO/TREX complex, involved in mRNP biogenesis, plays a key role in the maintenance of genome integrity in yeast. mRNA export factors such as Thp1-Sac3 also affect genome integrity, but their mutations have other phenotypes different from those of THO/TREX. Sus1 is a novel component of SAGA transcription factor that also associates with Thp1-Sac3, but little is known about its effect on genome instability and transcription. Here we show that Thp1, Sac3, and Sus1 form a functional unit with a role in mRNP biogenesis and maintenance of genome integrity that is independent of SAGA. Importantly, the effects of ribozyme-containing transcription units, RNase H, and the action of human activation-induced cytidine deaminase on transcription and genome instability are consistent with the possibility that R-loops are formed in Thp1-Sac3-Sus1-Cdc31 as in THO mutants. Our data reveal that Thp1-Sac3-Sus1-Cdc31, together with THO/TREX, define a specific pathway connecting transcription elongation with export via an RNA-dependent dynamic process that provides a feedback mechanism for the control of transcription and the preservation of genetic integrity of transcribed DNA regions.
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Affiliation(s)
- Cristina González-Aguilera
- Centro Andaluz de Biologia Molecular y Medicina Regenerativa, Universidad de Sevilla-CSIC, 41092 Sevilla, Spain
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31
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Trojan P, Krauss N, Choe HW, Giessl A, Pulvermüller A, Wolfrum U. Centrins in retinal photoreceptor cells: regulators in the connecting cilium. Prog Retin Eye Res 2008; 27:237-59. [PMID: 18329314 DOI: 10.1016/j.preteyeres.2008.01.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Changes in the intracellular Ca2+ concentration regulate the visual signal transduction cascade directly or more often indirectly through Ca2+-binding proteins. Here we focus on centrins, which are members of a highly conserved subgroup of the EF-hand superfamily of Ca2+-binding proteins in photoreceptor cells of the vertebrate retina. Centrins are commonly associated with centrosome-related structures. In mammalian retinal photoreceptor cells, four centrin isoforms are expressed as prominent components in the connecting cilium linking the light-sensitive outer segment compartment with the metabolically active inner segment compartment. Our data indicate that Ca2+-activated centrin isoforms assemble into protein complexes with the visual heterotrimeric G-protein transducin. This interaction of centrins with transducin is mediated by binding to the betagamma-dimer of the heterotrimeric G-protein. More recent findings show that these interactions of centrins with transducin are reciprocally regulated via site-specific phosphorylations mediated by the protein kinase CK2. The assembly of centrin/G-protein complexes is a novel aspect of translocation regulation of signalling proteins in sensory cells, and represents a potential link between molecular trafficking and signal transduction in general.
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Affiliation(s)
- Philipp Trojan
- Institut für Zoologie, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
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32
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Centrin 2 localizes to the vertebrate nuclear pore and plays a role in mRNA and protein export. Mol Cell Biol 2008; 28:1755-69. [PMID: 18172010 DOI: 10.1128/mcb.01697-07] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Centrins in vertebrates have traditionally been associated with microtubule-nucleating centers such as the centrosome. Unexpectedly, we found centrin 2 to associate biochemically with nucleoporins, including the Xenopus laevis Nup107-160 complex, a critical subunit of the vertebrate nuclear pore in interphase and of the kinetochores and spindle poles in mitosis. Immunofluorescence of Xenopus cells and in vitro reconstituted nuclei indeed revealed centrin 2 localized at the nuclear pores. Use of the mild detergent digitonin in immunofluorescence also allowed centrin 2 to be clearly visualized at the nuclear pores of human cells. Disruption of nuclear pores using RNA interference of the pore assembly protein ELYS/MEL-28 resulted in a specific decrease of centrin 2 at the nuclear rim of HeLa cells. Functionally, excess expression of either the N- or C-terminal calcium-binding domains of human centrin 2 caused a dominant-negative effect on both mRNA and protein export, leaving protein import intact. The mRNA effect mirrors that found for the Saccharomyes cerevisiae centrin Cdc31p at the yeast nuclear pore, a role until now thought to be unique to yeast. We conclude that in vertebrates, centrin 2 interacts with major subunits of the nuclear pore, exhibits nuclear pore localization, and plays a functional role in multiple nuclear export pathways.
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Charbonnier JB, Renaud E, Miron S, Le Du MH, Blouquit Y, Duchambon P, Christova P, Shosheva A, Rose T, Angulo JF, Craescu CT. Structural, Thermodynamic, and Cellular Characterization of Human Centrin 2 Interaction with Xeroderma Pigmentosum Group C Protein. J Mol Biol 2007; 373:1032-46. [PMID: 17897675 DOI: 10.1016/j.jmb.2007.08.046] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 08/17/2007] [Accepted: 08/20/2007] [Indexed: 11/25/2022]
Abstract
Human centrin 2 (HsCen2), an EF-hand calcium binding protein, plays a regulatory role in the DNA damage recognition during the first steps of the nucleotide excision repair. This biological action is mediated by the binding to a short fragment (N847-R863) from the C-terminal region of xeroderma pigmentosum group C (XPC) protein. This work presents a detailed structural and energetic characterization of the HsCen2/XPC interaction. Using a truncated form of HsCen2 we obtained a high resolution (1.8 A) X-ray structure of the complex with the peptide N847-R863 from XPC. Structural and thermodynamic analysis of the interface revealed the existence of both electrostatic and apolar inter-molecular interactions, but the binding energy is mainly determined by the burial of apolar bulky side-chains into the hydrophobic pocket of the HsCen2 C-terminal domain. Binding studies with various peptide variants showed that XPC residues W848 and L851 constitute the critical anchoring side-chains. This enabled us to define a minimal centrin binding peptide variant of five residues, which accounts for about 75% of the total free energy of interaction between the two proteins. Immunofluorescence imaging in HeLa cells demonstrated that HsCen2 binding to the integral XPC protein may be observed in living cells, and is determined by the same interface residues identified in the X-ray structure of the complex. Overexpression of XPC perturbs the cellular distribution of HsCen2, by inducing a translocation of centrin molecules from the cytoplasm to the nucleus. The present data confirm that the in vitro structural features of the centrin/XPC peptide complex are highly relevant to the cellular context.
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Affiliation(s)
- Jean-Baptiste Charbonnier
- Laboratoire de Biologie Structurale et Radiobiologie, iBiTec-S, CEA, Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France
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34
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Selvapandiyan A, Kumar P, Morris JC, Salisbury JL, Wang CC, Nakhasi HL. Centrin1 is required for organelle segregation and cytokinesis in Trypanosoma brucei. Mol Biol Cell 2007; 18:3290-301. [PMID: 17567955 PMCID: PMC1951761 DOI: 10.1091/mbc.e07-01-0022] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Centrin is a calcium-binding centrosome/basal body-associated protein involved in duplication and segregation of these organelles in eukaryotes. We had shown that disruption of one of the centrin genes (centrin1) in Leishmania amastigotes resulted in failure of both basal body duplication and cytokinesis. Here, we undertook to define the role of centrin1 (TbCen1) in the duplication and segregation of basal body and its associated organelles kinetoplast and Golgi, as well as its role in cytokinesis of the procyclic form of Trypanosoma brucei by depleting its protein using RNA inhibition methodology. TbCen1-depleted cells showed significant reduction in growth compared with control cells. Morphological analysis of these cells showed they were large and pleomorphic with multiple detached flagella. Both immunofluorescence assays using organelle-specific antibodies and electron microscopic analysis showed that TbCen1-deficient cells contained multiple basal bodies, kinetoplasts, Golgi, and nuclei. These multiple organelles were, however, closely clustered together, indicating duplication without segregation in the absence of centrin. This failure in organelle segregation may be the likely cause of inhibition of cytokinesis, suggesting for the first time a new and unique role for centrin in the segregation of organelles without affecting their multiplication in the procyclic form of T. brucei.
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Affiliation(s)
- Angamuthu Selvapandiyan
- *Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892
| | - Praveen Kumar
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143
| | - James C. Morris
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634; and
| | | | - Ching C. Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143
| | - Hira L. Nakhasi
- *Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892
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Abstract
The structure of the yeast Sfi1-centrin complex, and its asymmetric position within the yeast centrosome, suggest a model for the initiation of centrosome duplication and provides a target for licensing this event.
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Affiliation(s)
- Michele H Jones
- MCD Biology, University of Colorado - Boulder, 347 UCB, Boulder, Colorado 80309-0347, USA
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36
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Li S, Sandercock AM, Conduit P, Robinson CV, Williams RL, Kilmartin JV. Structural role of Sfi1p-centrin filaments in budding yeast spindle pole body duplication. ACTA ACUST UNITED AC 2006; 173:867-77. [PMID: 16785321 PMCID: PMC2063913 DOI: 10.1083/jcb.200603153] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Centrins are calmodulin-like proteins present in centrosomes and yeast spindle pole bodies (SPBs) and have essential functions in their duplication. The Saccharomyces cerevisiae centrin, Cdc31p, binds Sfi1p on multiple conserved repeats; both proteins localize to the SPB half-bridge, where the new SPB is assembled. The crystal structures of Sfi1p–centrin complexes containing several repeats show Sfi1p as an α helix with centrins wrapped around each repeat and similar centrin–centrin contacts between each repeat. Electron microscopy (EM) shadowing of an Sfi1p–centrin complex with 15 Sfi1 repeats and 15 centrins bound showed filaments 60 nm long, compatible with all the Sfi1 repeats as a continuous α helix. Immuno-EM localization of the Sfi1p N and C termini showed Sfi1p–centrin filaments spanning the length of the half-bridge with the Sfi1p N terminus at the SPB. This suggests a model for SPB duplication where the half-bridge doubles in length by association of the Sfi1p C termini, thereby providing a new Sfi1p N terminus to initiate SPB assembly.
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Affiliation(s)
- Sam Li
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, England, UK
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Meyn SM, Seda C, Campbell M, Weiss KL, Hu H, Pastrana-Rios B, Chazin WJ. The biochemical effect of Ser167 phosphorylation on Chlamydomonas reinhardtii centrin. Biochem Biophys Res Commun 2006; 342:342-8. [PMID: 16480960 DOI: 10.1016/j.bbrc.2006.01.155] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Accepted: 01/29/2006] [Indexed: 11/19/2022]
Abstract
Centrin is an EF-hand calcium-binding protein found in microtubule organizing centers of organisms ranging from algae and yeast to man. Phosphorylation in the centrin C-terminal domain occurs in mitosis and is associated with alterations in contractile fibers. To obtain insight into the structural basis for the functional effect of phosphorylation, Chlamydomonas reinhardtii centrin C-terminal domain phosphorylated at Ser167 (pCRC-C) has been produced and characterized. The structure of pCRC-C was compared to the unmodified protein by NMR spectroscopy. The effect of phosphorylation on target binding was examined for the complex of pCRC-C and a 19 residue centrin-binding fragment of Kar1. Remarkably, the efficient and selective phosphorylation by PKA was suppressed in the complex. Moreover, comparisons of NMR chemical shift differences induced by phosphorylation reveal a greater effect from phosphorylation in the context of the Kar1 complex than for the free protein. These results directly demonstrate that phosphorylation modulates the structure and biochemical activities of centrin.
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Affiliation(s)
- Susan M Meyn
- Department of Biochemistry, Center for Structural Biology, 5140 BIOSCI/MRBIII, Vanderbilt University, Nashville, TN 37232-8725, USA
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Sheehan JH, Bunick CG, Hu H, Fagan PA, Meyn SM, Chazin WJ. Structure of the N-terminal Calcium Sensor Domain of Centrin Reveals the Biochemical Basis for Domain-specific Function. J Biol Chem 2006; 281:2876-81. [PMID: 16317001 DOI: 10.1074/jbc.m509886200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Centrin is an essential component of microtubule-organizing centers in organisms ranging from algae and yeast to humans. It is an EF-hand calcium-binding protein with homology to calmodulin but distinct calcium binding properties. In a previously proposed model, the C-terminal domain of centrin serves as a constitutive anchor to target proteins, and the N-terminal domain serves as the sensor of calcium signals. The three-dimensional structure of the N-terminal domain of Chlamydomonas rheinhardtii centrin has been determined in the presence of calcium by solution NMR spectroscopy. The domain is found to occupy an open conformation typical of EF-hand calcium sensors. Comparison of the N- and C-terminal domains of centrin reveals a structural and biochemical basis for the domain specificity of interactions with its cellular targets and the distinct nature of centrin relative to other EF-hand proteins. An NMR titration of the centrin N-terminal domain with a fragment of the known centrin target Sfi1 reveals binding of the peptide to a discrete site on the protein, which supports the proposal that the N-terminal domain serves as a calcium sensor in centrin.
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Affiliation(s)
- Jonathan H Sheehan
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232-8725, USA
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Ribichich KF, Gomes SL. Blastocladiella emersoniiexpresses a centrin similar toChlamydomonas reinhardtiiisoform not found in late-diverging fungi. FEBS Lett 2005; 579:4355-60. [PMID: 16051227 DOI: 10.1016/j.febslet.2005.06.075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2005] [Revised: 06/27/2005] [Accepted: 06/27/2005] [Indexed: 11/25/2022]
Abstract
Centrins are members of the calcium-binding EF-hand protein superfamily which can be divided into two subfamilies, probably associated with different functions: one related to Chlamydomonas reinhardtii centrin, CrCenp, and the other, represented by Saccharomyces cerevisiae isoform, ScCdc31p. ESTs encoding the two isoforms (BeCen1 and BeCen3) from the chytridiomycete Blastocladiella emersonii were isolated, and expression of the CrCenp-type centrin, BeCen1, was analyzed throughout the fungus life cycle. Becen1 mRNA levels increase transiently during sporulation and protein levels present a similar pattern. Immunolocalization studies seem to localize BeCen1 at the basal body zone and in the cytoplasm surrounding the nuclear cap, a zoospore organelle.
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Affiliation(s)
- Karina Fabiana Ribichich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil
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Zamora I, Marshall WF. A mutation in the centriole-associated protein centrin causes genomic instability via increased chromosome loss in Chlamydomonas reinhardtii. BMC Biol 2005; 3:15. [PMID: 15927066 PMCID: PMC1174865 DOI: 10.1186/1741-7007-3-15] [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] [Received: 04/15/2005] [Accepted: 05/31/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The role of centrioles in mitotic spindle function remains unclear. One approach to investigate mitotic centriole function is to ask whether mutation of centriole-associated proteins can cause genomic instability. RESULTS We addressed the role of the centriole-associated EF-hand protein centrin in genomic stability using a Chlamydomonas reinhardtii centrin mutant that forms acentriolar bipolar spindles and lacks the centrin-based rhizoplast structures that join centrioles to the nucleus. Using a genetic assay for loss of heterozygosity, we found that this centrin mutant showed increased genomic instability compared to wild-type cells, and we determined that the increase in genomic instability was due to a 100-fold increase in chromosome loss rates compared to wild type. Live cell imaging reveals an increased rate in cell death during G1 in haploid cells that is consistent with an elevated rate of chromosome loss, and analysis of cell death versus centriole copy number argues against a role for multipolar spindles in this process. CONCLUSION The increased chromosome loss rates observed in a centrin mutant that forms acentriolar spindles suggests a role for centrin protein, and possibly centrioles, in mitotic fidelity.
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Affiliation(s)
- Ivan Zamora
- Dept. of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, California, 9414, USA
| | - Wallace F Marshall
- Dept. of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, California, 9414, USA
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Muller EGD, Snydsman BE, Novik I, Hailey DW, Gestaut DR, Niemann CA, O'Toole ET, Giddings TH, Sundin BA, Davis TN. The organization of the core proteins of the yeast spindle pole body. Mol Biol Cell 2005; 16:3341-52. [PMID: 15872084 PMCID: PMC1165416 DOI: 10.1091/mbc.e05-03-0214] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The spindle pole body (SPB) is the microtubule organizing center of Saccharomyces cerevisiae. Its core includes the proteins Spc42, Spc110 (kendrin/pericentrin ortholog), calmodulin (Cmd1), Spc29, and Cnm67. Each was tagged with CFP and YFP and their proximity to each other was determined by fluorescence resonance energy transfer (FRET). FRET was measured by a new metric that accurately reflected the relative extent of energy transfer. The FRET values established the topology of the core proteins within the architecture of SPB. The N-termini of Spc42 and Spc29, and the C-termini of all the core proteins face the gap between the IL2 layer and the central plaque. Spc110 traverses the central plaque and Cnm67 spans the IL2 layer. Spc42 is a central component of the central plaque where its N-terminus is closely associated with the C-termini of Spc29, Cmd1, and Spc110. When the donor-acceptor pairs were ordered into five broad categories of increasing FRET, the ranking of the pairs specified a unique geometry for the positions of the core proteins, as shown by a mathematical proof. The geometry was integrated with prior cryoelectron tomography to create a model of the interwoven network of proteins within the central plaque. One prediction of the model, the dimerization of the calmodulin-binding domains of Spc110, was confirmed by in vitro analysis.
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Affiliation(s)
- Eric G D Muller
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7350, USA.
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42
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Abstract
Nucleation of microtubules by eukaryotic microtubule organizing centers (MTOCs) is required for a variety of functions, including chromosome segregation during mitosis and meiosis, cytokinesis, fertilization, cellular morphogenesis, cell motility, and intracellular trafficking. Analysis of MTOCs from different organisms shows that the structure of these organelles is widely varied even though they all share the function of microtubule nucleation. Despite their morphological diversity, many components and regulators of MTOCs, as well as principles in their assembly, seem to be conserved. This review focuses on one of the best-characterized MTOCs, the budding yeast spindle pole body (SPB). We review what is known about its structure, protein composition, duplication, regulation, and functions. In addition, we discuss how studies of the yeast SPB have aided investigation of other MTOCs, most notably the centrosome of animal cells.
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Affiliation(s)
- Sue L Jaspersen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA.
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43
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Abstract
Centrin is an EF-hand calcium-binding protein closely related to the prototypical calcium sensor protein calmodulin. It is found in microtubule-organizing centers of organisms ranging from algae and yeast to man. In vitro, the C-terminal domain of centrin binds to the yeast centrosomal protein Kar1p in a calcium-dependent manner, whereas the N-terminal domain does not show any appreciable affinity for Kar1p. To obtain deeper insights into the structural basis for centrin's function, we have characterized the affinities of the C-terminal domain of Chlamydomonas reinhardtii centrin for calcium and for a peptide fragment of Kar1p using CD, fluorescence, and NMR spectroscopy. Calcium binding site IV in C. reinhardtii centrin was found to bind Ca2+ approximately 100-fold more strongly than site III. In the absence of Ca2+, the protein occupies a mixture of closed conformations. Binding of a single ion in site IV is sufficient to radically alter the conformational equilibrium, promoting occupancy of an open conformation. However, an exchange between closed and open conformations remains even at saturating levels of Ca2+. The population of the open conformation is substantially stabilized by the presence of the target peptide Kar1p-(239-257) to a point where a single ion bound in site IV is sufficient to completely shift the conformational equilibrium to the open conformation. This is reflected in the enhancement of the Ca2+ affinity in this site by more than an order of magnitude. These data confirm the direct coupling of the Ca2+ binding-induced shift in the equilibrium between the closed and open conformations to the binding of the peptide. Combined with the common localization of the two proteins in the microtubule organizing center, our results suggest that centrin is constitutively bound to Kar1p through its C-terminal domain and that centrin's calcium sensor activities are mediated by the N-terminal domain.
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Affiliation(s)
- Haitao Hu
- Departments of Biochemistry and Physics and the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-8725, USA
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44
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Fischer T, Rodríguez-Navarro S, Pereira G, Rácz A, Schiebel E, Hurt E. Yeast centrin Cdc31 is linked to the nuclear mRNA export machinery. Nat Cell Biol 2004; 6:840-8. [PMID: 15311284 DOI: 10.1038/ncb1163] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 07/27/2004] [Indexed: 11/09/2022]
Abstract
Centrins are calmodulin-like proteins that function in the duplication of microtubule-organizing centres. Here we describe a new function of the yeast centrin Cdc31. We show that overproduction of a sequence, termed CID, in the carboxy-terminal domain of the nuclear export factor Sac3 titrates Cdc31, causing a dominant-lethal phenotype and a block in spindle pole body (SPB) duplication. Under normal conditions, the CID motif recruits Cdc31 and Sus1 (a subunit of the SAGA transcription complex) to the Sac3-Thp1 complex, which functions in mRNA export together with specific nucleoporins at the nuclear basket. A previously reported cdc31 temperature-sensitive allele, which is neither defective in SPB duplication nor Kic1 kinase activation, induces mRNA export defects. Thus, Cdc31 has an unexpected link to the mRNA export machinery.
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Affiliation(s)
- Tamás Fischer
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
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45
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Popescu A, Miron S, Blouquit Y, Duchambon P, Christova P, Craescu CT. Xeroderma pigmentosum group C protein possesses a high affinity binding site to human centrin 2 and calmodulin. J Biol Chem 2003; 278:40252-61. [PMID: 12890685 DOI: 10.1074/jbc.m302546200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human centrin 2 (HsCen2), a member of the EF-hand superfamily of Ca2+-binding proteins, is commonly associated with centrosome-related structures. The protein is organized in two domains, each containing two EF-hand motifs, but only the C-terminal half exhibits Ca2+ sensor properties. A significant fraction of HsCen2 is localized in the nucleus, where it was recently found associated with the xeroderma pigmentosum group C protein (XPC), a component of the nuclear excision repair pathway. Analysis of the XPC sequence (940 residues), using a calmodulin target recognition software, enabled us to predict two putative binding sites. The binding properties of the two corresponding peptides were investigated by isothermal titration calorimetry. Only one of the peptides (P1-XPC) interacts strongly (Ka = 2.2 x 10(8) m-1, stoichiometry 1:1) with HsCen2 in a Ca2+-dependent manner. This peptide also binds, with a similar affinity (Ka = 1.1 x 10(8) m-1) to a C-terminal construct of HsCen2, indicating that the interaction with the integral protein is mainly the result of the contribution of the C-terminal half. The second peptide (P2-XPC) failed to show any detectable binding either to HsCen2 or to its C-terminal lobe. The two peptides interact with different affinities and mechanisms with calmodulin. Circular dichroism and nuclear magnetic resonance were used to structurally characterize the complex formed by the C-terminal domain of HsCen2 with P1-XPC.
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Affiliation(s)
- Aurel Popescu
- INSERM U350 and Institut Curie-Recherche, Centre Universitaire, Batiments 110-112, 91405 Orsay, France
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46
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Wolfrum U, Giessl A, Pulvermüller A. Centrins, a novel group of Ca2+-binding proteins in vertebrate photoreceptor cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 514:155-78. [PMID: 12596921 DOI: 10.1007/978-1-4615-0121-3_10] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Changes in the intracellular Ca2+-concentration affect the visual signal transduction cascade directly or more often indirectly through Ca2+-binding proteins. Here we review recent findings on centrins in photoreceptor cells of the mammalian retina. Centrins are members of a highly conserved subgroup of the EF-hand superfamily of Ca2+-binding proteins commonly associated with centrosome-related structures. In vertebrate photoreceptor cells, centrins are also prominent components in the connecting cilium linking the light sensitive outer segment with the biosynthetically active inner segment compartment. Recent findings demonstrate that Ca2+-activated centrin forms a complex with the visual G-protein transducin in photoreceptor cells. This Ca2+-dependent assembly of G-proteins with centrin is a novel aspect of the supply of signaling proteins in sensory cells, and a potential link between molecular translocations and signal transduction in general.
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Affiliation(s)
- Uwe Wolfrum
- Institut für Zoologie, Johannes Gutenberg-Universitit Mainz, 55099 Mainz, Germany.
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47
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Abstract
Caltractin (centrin) is a member of the calmodulin (CaM) superfamily of EF-hand calcium-binding proteins. It is an essential component of the centrosomal structures in a wide range of organisms. Caltractin and calmodulin apparently function in distinct calcium signaling pathways despite substantial sequence similarity. In an effort to understand the structural basis for such differences, the high-resolution three-dimensional solution structure of the complex between the Ca(2+)-activated C-terminal domain of Chlamydomonas reinhardtii caltractin (CRC-C) and a 19 residue peptide fragment comprising the putative cdc31p-binding region of Kar1p (K(19)) has been determined by multi-dimensional heteronuclear NMR spectroscopy. Formation of the complex is calcium-dependent and is stabilized by extensive interactions between CRC-C and three key hydrophobic anchors (Trp10, Leu13 and Leu14) in the peptide as well as favorable electrostatic interactions at the protein-peptide interface. In-depth comparisons have been made to the structure of the complex of Ca(2+)-activated calmodulin and R(20), the CaM-binding domain of smooth muscle myosin light-chain kinase. Although the overall structures of CRC and CaM domains in their respective complexes are very similar, differences in critical regions in the sequences of these proteins and their targets lead to clear differences in the complementarity of their respective binding surfaces. These subtle differences reveal the structural basis for the Ca(2+)-dependent regulation of distinct cellular signaling events by CRC and CaM.
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Affiliation(s)
- Haitao Hu
- Departments of Biochemistry and Physics, Center for Structural Biology, Vanderbilt University, 5142 BIOSCI/MRBIII, Nashville, TN 37232-8725, USA
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48
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Koblenz B, Schoppmeier J, Grunow A, Lechtreck KF. Centrin deficiency in Chlamydomonas causes defects in basal body replication, segregation and maturation. J Cell Sci 2003; 116:2635-46. [PMID: 12746491 DOI: 10.1242/jcs.00497] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Centrin, a 20 kDa calcium-binding protein, is a constituent of contractile basal body-associated fibers in protists and of various centrosomal structures. A construct inducing centrin RNAi was used to study the effect of centrin deficiency in Chlamydomonas. Transformants contained variable amounts of residual centrin (down to 5% of wild-type) and lacked centrin fibers. They displayed a variable flagellar number phenotype with mostly nonflagellate cells, suggesting that centrin is required for basal body assembly. Furthermore, basal bodies often failed to dock to the plasma membrane and to assemble flagella, and displayed defects in the flagellar root system indicating that centrin deficiency interferes with basal body development. Multiple basal bodies caused the formation of additional microtubular asters, whereas the microtubular cytoskeleton was disordered in most cells without basal bodies. The number of multinucleated cells was increased, indicating that aberrant numbers of basal bodies interfered with the cytokinesis of Chlamydomonas. In contrast to wild-type cells, basal bodies in centrin-RNAi cells were separated from the spindle poles, suggesting a role of centrin in tethering basal bodies to the spindle. To test whether an association with the spindle poles is required for correct basal body segregation, we disrupted centrin fibers in wild-type cells by over-expressing a nonfunctional centrin-GFP. In these cells, basal bodies were disconnected from the spindle but segregation errors were not observed. We propose that basal body segregation in Chlamydomonas depends on an extranuclear array of microtubules independent of the mitotic spindle.
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Affiliation(s)
- Bettina Koblenz
- Department of Botany, University of Cologne, Gyrhofstr. 15, D-50931 Cologne, Germany
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49
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Paoletti A, Bordes N, Haddad R, Schwartz CL, Chang F, Bornens M. Fission yeast cdc31p is a component of the half-bridge and controls SPB duplication. Mol Biol Cell 2003; 14:2793-808. [PMID: 12857865 PMCID: PMC165677 DOI: 10.1091/mbc.e02-10-0661] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The fission yeast spindle pole body (SPB) is a nucleus-associated organelle that duplicates once each cell cycle during interphase. Duplicated SPBs serve as the poles of an intranuclear mitotic spindle after their insertion into the nuclear envelope in mitosis (Ding et al., Mol. Biol. Cell 8, 1461-1479). Here, we report the identification and characterization of Schizosaccharomyces pombe cdc31p, a member of the conserved calcium-binding centrin/CDC31 family. Immunofluorescence and immunoelectron microscopy show that cdc31p is a SPB component localized at the half-bridge structure of the SPB. cdc31 is an essential gene and Deltacdc31 cells and cdc31 conditional mutant cells arrest in mitosis with a monopolar mitotic spindle organized from a single SPB. EM analysis demonstrates that mutant cdc31 cells fail to duplicate the SPB. In addition, cdc31p exhibits genetic interactions with the SPB component sad1p and is required for sad1p localization. Finally, cdc31 mutant can undergo single or multiple rounds of septation before the exit from mitosis, suggesting that cdc31p activity or SPB duplication may be required for the proper coordination between the exit from mitosis and the initiation of septation.
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Gavet O, Alvarez C, Gaspar P, Bornens M. Centrin4p, a novel mammalian centrin specifically expressed in ciliated cells. Mol Biol Cell 2003; 14:1818-34. [PMID: 12802058 PMCID: PMC165080 DOI: 10.1091/mbc.e02-11-0709] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Centriole assembly plays an important role in centrosome duplication during the cell cycle and is a prerequisite for cilia formation during the differentiation of ciliated cells. In spite of numerous investigations, the molecular machinery that governs centriole/basal body formation remains enigmatic. Recent reports suggest that the ubiquitously expressed mammalian centrins, centrin2p and centrin3p, could be involved in the centriole duplication process. To better understand the specific functions of these proteins, we performed a systematic search for novel mammalian centrins. We isolated a cDNA and the corresponding gene coding for a novel murine centrin, centrin4p, which is more closely related to centrin2p. Like centrin2p, centrin4p accumulates to centrioles and procentrioles when ectopically expressed in HeLa cells. However, centrin4p possesses two splice variants that do not localize to centrioles, suggesting a posttranscriptional regulation mechanism. We also observed that centrin4p does not share the same centriolar targeting properties with centrin2p and 3p, indicating that these proteins could recognize different centriolar partners. Centrin4 mRNA possesses a restricted expression profile and is only detected in brain, kidney, lung, and ovary. In brain, centrin4p is exclusively expressed in ependymal and choroidal ciliated cells where it is localized to basal bodies. Together, our present data suggest that centrin4p could be more specifically involved in basal bodies assembly or in a subsequent step of ciliogenesis.
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Affiliation(s)
- Olivier Gavet
- Institut Curie, Section Recherche, Unité Mixte Recherche 144 du Centre National de la Recherche Scientifique, 75248 Paris, France
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