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Kubo S, Black CS, Joachimiak E, Yang SK, Legal T, Peri K, Khalifa AAZ, Ghanaeian A, McCafferty CL, Valente-Paterno M, De Bellis C, Huynh PM, Fan Z, Marcotte EM, Wloga D, Bui KH. Native doublet microtubules from Tetrahymena thermophila reveal the importance of outer junction proteins. Nat Commun 2023; 14:2168. [PMID: 37061538 PMCID: PMC10105768 DOI: 10.1038/s41467-023-37868-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 04/03/2023] [Indexed: 04/17/2023] Open
Abstract
Cilia are ubiquitous eukaryotic organelles responsible for cellular motility and sensory functions. The ciliary axoneme is a microtubule-based cytoskeleton consisting of two central singlets and nine outer doublet microtubules. Cryo-electron microscopy-based studies have revealed a complex network inside the lumen of both tubules composed of microtubule-inner proteins (MIPs). However, the functions of most MIPs remain unknown. Here, we present single-particle cryo-EM-based analyses of the Tetrahymena thermophila native doublet microtubule and identify 42 MIPs. These data shed light on the evolutionarily conserved and diversified roles of MIPs. In addition, we identified MIPs potentially responsible for the assembly and stability of the doublet outer junction. Knockout of the evolutionarily conserved outer junction component CFAP77 moderately diminishes Tetrahymena swimming speed and beat frequency, indicating the important role of CFAP77 and outer junction stability in cilia beating generation and/or regulation.
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Affiliation(s)
- Shintaroh Kubo
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Corbin S Black
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
| | - Shun Kai Yang
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Thibault Legal
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Katya Peri
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Ahmad Abdelzaher Zaki Khalifa
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Avrin Ghanaeian
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Caitlyn L McCafferty
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX, 78712, USA
| | - Melissa Valente-Paterno
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada
| | - Chelsea De Bellis
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - Phuong M Huynh
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - Zhe Fan
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - Edward M Marcotte
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX, 78712, USA
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland.
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada.
- Centre de Recherche en Biologie Structurale, McGill University, Montreal, QC, Canada.
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2
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Li S, Palo MZ, Zhang X, Pintilie G, Zhang K. Snapshots of the second-step self-splicing of Tetrahymena ribozyme revealed by cryo-EM. Nat Commun 2023; 14:1294. [PMID: 36928031 PMCID: PMC10020454 DOI: 10.1038/s41467-023-36724-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 02/13/2023] [Indexed: 03/18/2023] Open
Abstract
Group I introns are catalytic RNAs that coordinate two consecutive transesterification reactions for self-splicing. To understand how the group I intron promotes catalysis and coordinates self-splicing reactions, we determine the structures of L-16 Tetrahymena ribozyme in complex with a 5'-splice site analog product and a 3'-splice site analog substrate using cryo-EM. We solve six conformations from a single specimen, corresponding to different splicing intermediates after the first ester-transfer reaction. The structures reveal dynamics during self-splicing, including large conformational changes of the internal guide sequence and the J5/4 junction as well as subtle rearrangements of active-site metals and the hydrogen bond formed between the 2'-OH group of A261 and the N2 group of guanosine substrate. These results help complete a detailed structural and mechanistic view of this paradigmatic group I intron undergoing the second step of self-splicing.
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Affiliation(s)
- Shanshan Li
- Department of Urology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China.
| | - Michael Z Palo
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
| | - Xiaojing Zhang
- Department of Urology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China
| | - Grigore Pintilie
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Kaiming Zhang
- Department of Urology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China.
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Abstract
RNA-based machines are ubiquitous in Nature and increasingly important for medicines. They fold into complex, dynamic structures that process information and catalyze reactions, including reactions that generate new RNAs and proteins across biology. What are the experimental strategies and steps that are necessary to understand how these complex machines work? Two 1990 papers from Herschlag and Cech on "Catalysis of RNA Cleavage by the Tetrahymena thermophila Ribozyme" provide a master class in dissecting an RNA machine through kinetics approaches. By showing how to propose a kinetic framework, fill in the numbers, do cross-checks, and make comparisons across mutants and different RNA systems, the papers illustrate how to take a mechanistic approach and distill the results into general insights that are difficult to attain through other means.
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Affiliation(s)
- Rhiju Das
- Department
of Biochemistry, Stanford University School
of Medicine, Stanford, California 94305, United States
- Department
of Physics, Stanford University, Stanford, California 94305, United States
| | - Rick Russell
- Department
of Molecular Biosciences, The University
of Texas at Austin, Austin, Texas 78712, United States
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4
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Kong R, Sun Q, Cheng S, Fu J, Liu W, Letcher RJ, Liu C. Uptake, excretion and toxicity of titanate nanotubes in three stains of free-living ciliates of the genus Tetrahymena. Aquat Toxicol 2021; 233:105790. [PMID: 33662879 DOI: 10.1016/j.aquatox.2021.105790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 02/21/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
The potential exposure of titanate nanotubes (TNTs) to wildlife and humans may occur as a result of increased use and application as functional nanomaterials. However, there is a dearth of knowledge regarding the pathways of uptake and excretion of TNTs and their toxicity in cells. In this study, three strains of the Tetrahymena genus of free-living ciliates, including a wild type strain (SB210) and two mutant strains (SB255: mucocyst-deficient; NP1: temperature-sensitive "mouthless''), were used to study the pathways of uptake and excretion and evaluate the cytotoxicity of TNTs. The three Tetrahymena strains were separately exposed to 0, 0.01, 0.1, 1 or 10 mg/L of TNTs, and cells were collected at different time points for quantification of intracellular TNTs (e.g., 5, 10, 20, 40, 60, 90 and 120 min) and evaluation of cytotoxicity (12 and 24 h). TNT contents in NP1 and SB255 were greater or comparable to the contents in SB210 while exposure to 10 mg/L TNTs in 120 min. Furthermore, exposure to 10 mg/L TNTs for 24 h caused greater decreases in cell density of NP1 (38.2 %) and SB255 (36.8 %) compared with SB210 (26.5 %) and upregulated the expression of caspase 15 in SB210. Taken together, our results suggested that TNT uptake by pinocytosis and excretion by exocytosis in Tetrahymena, and the exposure could cause cytotoxicity which can offer novel insights into the accumulation kinetics of nanotubes and even nanomaterials in single cell.
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Affiliation(s)
- Ren Kong
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qian Sun
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shiyang Cheng
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jie Fu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Wen Liu
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, K1A 0H3, Canada
| | - Chunsheng Liu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Collaborative Innovation Centre for Efficient and Health Production of Fisheries in Hunan Province, Changde, 415000, China.
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Casler JC, Zajac AL, Valbuena FM, Sparvoli D, Jeyifous O, Turkewitz AP, Horne-Badovinac S, Green WN, Glick BS. ESCargo: a regulatable fluorescent secretory cargo for diverse model organisms. Mol Biol Cell 2020; 31:2892-2903. [PMID: 33112725 PMCID: PMC7927198 DOI: 10.1091/mbc.e20-09-0591] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/20/2020] [Accepted: 10/23/2020] [Indexed: 12/24/2022] Open
Abstract
Membrane traffic can be studied by imaging a cargo protein as it transits the secretory pathway. The best tools for this purpose initially block export of the secretory cargo from the endoplasmic reticulum (ER) and then release the block to generate a cargo wave. However, previously developed regulatable secretory cargoes are often tricky to use or specific for a single model organism. To overcome these hurdles for budding yeast, we recently optimized an artificial fluorescent secretory protein that exits the ER with the aid of the Erv29 cargo receptor, which is homologous to mammalian Surf4. The fluorescent secretory protein forms aggregates in the ER lumen and can be rapidly disaggregated by addition of a ligand to generate a nearly synchronized cargo wave. Here we term this regulatable secretory protein ESCargo (Erv29/Surf4-dependent secretory cargo) and demonstrate its utility not only in yeast cells, but also in cultured mammalian cells, Drosophila cells, and the ciliate Tetrahymena thermophila. Kinetic studies indicate that rapid export from the ER requires recognition by Erv29/Surf4. By choosing an appropriate ER signal sequence and expression vector, this simple technology can likely be used with many model organisms.
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Affiliation(s)
- Jason C. Casler
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Allison L. Zajac
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Fernando M. Valbuena
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Daniela Sparvoli
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Okunola Jeyifous
- Department of Neurobiology, University of Chicago, Chicago, IL 60637
- Marine Biological Laboratory, Woods Hole, MA 02543
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Sally Horne-Badovinac
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - William N. Green
- Department of Neurobiology, University of Chicago, Chicago, IL 60637
- Marine Biological Laboratory, Woods Hole, MA 02543
| | - Benjamin S. Glick
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
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6
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Joachimiak E, Waclawek E, Niziolek M, Osinka A, Fabczak H, Gaertig J, Wloga D. The LisH Domain-Containing N-Terminal Fragment is Important for the Localization, Dimerization, and Stability of Katnal2 in Tetrahymena. Cells 2020; 9:cells9020292. [PMID: 31991798 PMCID: PMC7072489 DOI: 10.3390/cells9020292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/14/2020] [Accepted: 01/22/2020] [Indexed: 12/12/2022] Open
Abstract
Katanin-like 2 protein (Katnal2) orthologs have a tripartite domain organization. Two highly conserved regions, an N-terminal LisH (Lis-homology) domain and a C-terminal AAA catalytic domain, are separated by a less conserved linker. The AAA domain of Katnal2 shares the highest amino acid sequence homology with the AAA domain of the canonical katanin p60. Katnal2 orthologs are present in a wide range of eukaryotes, from protists to humans. In the ciliate Tetrahymena thermophila, a Katnal2 ortholog, Kat2, co-localizes with the microtubular structures, including basal bodies and ciliary outer doublets, and this co-localization is sensitive to levels of microtubule glutamylation. The functional analysis of Kat2 domains suggests that an N-terminal fragment containing a LisH domain plays a role in the subcellular localization, dimerization, and stability of Kat2.
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Affiliation(s)
- Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
| | - Ewa Waclawek
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
| | - Michal Niziolek
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
| | - Anna Osinka
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
| | - Hanna Fabczak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA;
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur, 02-093 Warsaw, Poland; (E.J.); (E.W.); (M.N.); (A.O.); (H.F.)
- Correspondence: ; Tel.: +48-(22)-5892338
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7
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Jiang YY, Maier W, Baumeister R, Minevich G, Joachimiak E, Wloga D, Ruan Z, Kannan N, Bocarro S, Bahraini A, Vasudevan KK, Lechtreck K, Orias E, Gaertig J. LF4/MOK and a CDK-related kinase regulate the number and length of cilia in Tetrahymena. PLoS Genet 2019; 15:e1008099. [PMID: 31339880 PMCID: PMC6682161 DOI: 10.1371/journal.pgen.1008099] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/05/2019] [Accepted: 06/13/2019] [Indexed: 11/18/2022] Open
Abstract
The length of cilia is controlled by a poorly understood mechanism that involves members of the conserved RCK kinase group, and among them, the LF4/MOK kinases. The multiciliated protist model, Tetrahymena, carries two types of cilia (oral and locomotory) and the length of the locomotory cilia is dependent on their position with the cell. In Tetrahymena, loss of an LF4/MOK ortholog, LF4A, lengthened the locomotory cilia, but also reduced their number. Without LF4A, cilia assembled faster and showed signs of increased intraflagellar transport (IFT). Consistently, overproduced LF4A shortened cilia and downregulated IFT. GFP-tagged LF4A, expressed in the native locus and imaged by total internal reflection microscopy, was enriched at the basal bodies and distributed along the shafts of cilia. Within cilia, most LF4A-GFP particles were immobile and a few either diffused or moved by IFT. We suggest that the distribution of LF4/MOK along the cilium delivers a uniform dose of inhibition to IFT trains that travel from the base to the tip. In a longer cilium, the IFT machinery may experience a higher cumulative dose of inhibition by LF4/MOK. Thus, LF4/MOK activity could be a readout of cilium length that helps to balance the rate of IFT-driven assembly with the rate of disassembly at steady state. We used a forward genetic screen to identify a CDK-related kinase, CDKR1, whose loss-of-function suppressed the shortening of cilia caused by overexpression of LF4A, by reducing its kinase activity. Loss of CDKR1 alone lengthened both the locomotory and oral cilia. CDKR1 resembles other known ciliary CDK-related kinases: LF2 of Chlamydomonas, mammalian CCRK and DYF-18 of C. elegans, in lacking the cyclin-binding motif and acting upstream of RCKs. The new genetic tools we developed here for Tetrahymena have potential for further dissection of the principles of cilia length regulation in multiciliated cells.
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Affiliation(s)
- Yu-Yang Jiang
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Wolfgang Maier
- Bio 3/Bioinformatics and Molecular Genetics, Faculty of Biology and ZBMZ, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | - Ralf Baumeister
- Bio 3/Bioinformatics and Molecular Genetics, Faculty of Biology and ZBMZ, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | - Gregory Minevich
- Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, New York, United States of America
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Zheng Ruan
- Institute of Bioinformatics, University of Georgia, Athens, Georgia, United States of America
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, Georgia, United States of America
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Stephen Bocarro
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Anoosh Bahraini
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Krishna Kumar Vasudevan
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Eduardo Orias
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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8
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Xiong J, Yang W, Chen K, Jiang C, Ma Y, Chai X, Yan G, Wang G, Yuan D, Liu Y, Bidwell SL, Zafar N, Hadjithomas M, Krishnakumar V, Coyne RS, Orias E, Miao W. Hidden genomic evolution in a morphospecies-The landscape of rapidly evolving genes in Tetrahymena. PLoS Biol 2019; 17:e3000294. [PMID: 31158217 PMCID: PMC6564038 DOI: 10.1371/journal.pbio.3000294] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 06/13/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
A morphospecies is defined as a taxonomic species based wholly on morphology, but often morphospecies consist of clusters of cryptic species that can be identified genetically or molecularly. The nature of the evolutionary novelty that accompanies speciation in a morphospecies is an intriguing question. Morphospecies are particularly common among ciliates, a group of unicellular eukaryotes that separates 2 kinds of nuclei—the silenced germline nucleus (micronucleus [MIC]) and the actively expressed somatic nucleus (macronucleus [MAC])—within a common cytoplasm. Because of their very similar morphologies, members of the Tetrahymena genus are considered a morphospecies. We explored the hidden genomic evolution within this genus by performing a comprehensive comparative analysis of the somatic genomes of 10 species and the germline genomes of 2 species of Tetrahymena. These species show high genetic divergence; phylogenomic analysis suggests that the genus originated about 300 million years ago (Mya). Seven universal protein domains are preferentially included among the species-specific (i.e., the youngest) Tetrahymena genes. In particular, leucine-rich repeat (LRR) genes make the largest contribution to the high level of genome divergence of the 10 species. LRR genes can be sorted into 3 different age groups. Parallel evolutionary trajectories have independently occurred among LRR genes in the different Tetrahymena species. Thousands of young LRR genes contain tandem arrays of exactly 90-bp exons. The introns separating these exons show a unique, extreme phase 2 bias, suggesting a clonal origin and successive expansions of 90-bp–exon LRR genes. Identifying LRR gene age groups allowed us to document a Tetrahymena intron length cycle. The youngest 90-bp exon LRR genes in T. thermophila are concentrated in pericentromeric and subtelomeric regions of the 5 micronuclear chromosomes, suggesting that these regions act as genome innovation centers. Copies of a Tetrahymena Long interspersed element (LINE)-like retrotransposon are very frequently found physically adjacent to 90-bp exon/intron repeat units of the youngest LRR genes. We propose that Tetrahymena species have used a massive exon-shuffling mechanism, involving unequal crossing over possibly in concert with retrotransposition, to create the unique 90-bp exon array LRR genes. Genomic comparison of ten morphologically very similar species of ciliate from the genus Tetrahymena reveals how parallel microevolutionary processes have shaped their genomes and created unique genes through retrotransposition.
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Affiliation(s)
- Jie Xiong
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wentao Yang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Kai Chen
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chuanqi Jiang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang Ma
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaocui Chai
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guanxiong Yan
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guangying Wang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dongxia Yuan
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Yifan Liu
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Shelby L. Bidwell
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Nikhat Zafar
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | | | - Vivek Krishnakumar
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Robert S. Coyne
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Eduardo Orias
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, United States of America
| | - Wei Miao
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Animal Evolution and Genetics, Kunming, China
- State Key Laboratory of Freshwater Ecology and Biotechnology of China, Wuhan, China
- * E-mail:
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9
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Urbanska P, Joachimiak E, Bazan R, Fu G, Poprzeczko M, Fabczak H, Nicastro D, Wloga D. Ciliary proteins Fap43 and Fap44 interact with each other and are essential for proper cilia and flagella beating. Cell Mol Life Sci 2018; 75:4479-4493. [PMID: 29687140 PMCID: PMC6208767 DOI: 10.1007/s00018-018-2819-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/13/2018] [Accepted: 04/13/2018] [Indexed: 11/08/2022]
Abstract
Cilia beating is powered by the inner and outer dynein arms (IDAs and ODAs). These multi-subunit macrocomplexes are arranged in two rows on each outer doublet along the entire cilium length, except its distal end. To generate cilia beating, the activity of ODAs and IDAs must be strictly regulated locally by interactions with the dynein arm-associated structures within each ciliary unit and coordinated globally in time and space between doublets and along the axoneme. Here, we provide evidence of a novel ciliary complex composed of two conserved WD-repeat proteins, Fap43p and Fap44p. This complex is adjacent to another WD-repeat protein, Fap57p, and most likely the two-headed inner dynein arm, IDA I1. Loss of either protein results in altered waveform, beat stroke and reduced swimming speed. The ciliary localization of Fap43p and Fap44p is interdependent in the ciliate Tetrahymena thermophila.
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Affiliation(s)
- Paulina Urbanska
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland
| | - Rafał Bazan
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland
| | - Gang Fu
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX, USA
| | - Martyna Poprzeczko
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland
| | - Hanna Fabczak
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland
| | - Daniela Nicastro
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX, USA
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology PAS, Pasteur 3, 02-093, Warsaw, Poland.
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10
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Liu CB, Zhang L, Wu Q, Qu GB, Yin YG, Hu LG, Shi JB, Jiang GB. Mutual detoxification of mercury and selenium in unicellular Tetrahymena. J Environ Sci (China) 2018; 68:143-150. [PMID: 29908733 DOI: 10.1016/j.jes.2018.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 01/31/2018] [Accepted: 02/07/2018] [Indexed: 06/08/2023]
Abstract
Selenium (Se) is commonly recognized as a protective element with an antagonistic effect against mercury (Hg) toxicity. However, the mechanisms of this Hg-Se antagonism are complex and remain controversial. To gain insight into the Hg-Se antagonism, a type of unicellular eukaryotic protozoa (Tetrahymena malaccensis, T. malaccensis) was selected and individually or jointly exposed to two Hg and three Se species. We found that Se species showed different toxic effects on the proliferation of T. malaccensis with the toxicity following the order: selenite (Se(IV))>selenomethionine (SeMeth)>selenate (Se(VI)). The Hg-Se antagonism in Tetrahymena was observed because the joint toxicity significantly decreased under co-exposure to highly toxic dosages of Hg and Se versus individual toxicity. Unlike Se(IV) and Se(VI), non-toxic dosage of SeMeth significantly decreased the Hg toxicity, revealing the influence of the Se species and dosages on the Hg-Se antagonism. Unexpectedly, inorganic divalent Hg (Hg2+) and monomethylmercury (MeHg) also displayed detoxification towards extremely highly toxic dosages of Se, although their detoxifying efficiency was discrepant. These results suggested mutual Hg-Se detoxification in T. malaccensis, which was highly dependent on the dosages and species of both elements. As compared to other species, SeMeth and MeHg promoted the Hg-Se joint effects to a higher degree. Additionally, the Hg contents decreased for all the Hg-Se co-exposed groups, revealing a sequestering effect of Se towards Hg in T. malaccensis.
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Affiliation(s)
- Cheng-Bin Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Zhang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Institute of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Qi Wu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guang-Bo Qu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong-Guang Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li-Gang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian-Bo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Institute of Environment and Health, Jianghan University, Wuhan 430056, China.
| | - Gui-Bin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Seixas C, Gonçalves J, Melo LV, Soares H. Tetrahymena Cilia Cap is Built in a Multi-step Process: A Study by Atomic Force Microscopy. Protist 2017; 168:697-717. [PMID: 29149699 DOI: 10.1016/j.protis.2017.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 09/13/2017] [Accepted: 10/07/2017] [Indexed: 02/02/2023]
Abstract
Cilia are complex and dynamic organelles that have motility and sensory functions. Defects in cilia biogenesis and function are at the origin of human ciliopathies. In motile cilia, a basal body organizes the axoneme composed of nine microtubule doublets surrounding a central pair of singlet microtubules. The distal ends of axonemal microtubules are attached to the membrane by microtubule-capping structures. Little is known about the early steps of cilium assembly. Although cilia grow and resorb from their distal tips, it remains poorly understood where and when the components of the caps are first assembled. By using Atomic Force Microscopy in tapping mode, with resolution at the nanometer range and with minimum sample manipulation, we show that Tetrahymena cilia assembly requires transient assembly of structures, composed of three components that are placed asymmetrically on an early elongating axoneme. In small uncapped axonemes the microtubule central pair was never observed. Additionally, we show that cilia cap assembly is a multi-step process in which structures of different sizes and shapes are put together in close proximity before the axoneme appears capped. We propose that the cap modifies the axoneme microtubule rate of polymerization and present a model for Tetrahymena cilia cap assembly.
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Affiliation(s)
- Cecília Seixas
- Instituto Gulbenkian de Ciência, Apartado 14, 2781-901 Oeiras, Portugal
| | - João Gonçalves
- Instituto Gulbenkian de Ciência, Apartado 14, 2781-901 Oeiras, Portugal; Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, 1749-016 Lisboa, Portugal
| | - Luís Viseu Melo
- Physics Department, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; INESC-MN, Rua Alves Redol, 9, 1000-029, Lisboa, Portugal
| | - Helena Soares
- Instituto Gulbenkian de Ciência, Apartado 14, 2781-901 Oeiras, Portugal; Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, 1749-016 Lisboa, Portugal; Escola Superior de Tecnologia da Saúde de Lisboa, 1990-096 Lisboa, Instituto Politécnico de Lisboa, Portugal.
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12
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Farley BM, Collins K. Transgenerational function of Tetrahymena Piwi protein Twi8p at distinctive noncoding RNA loci. RNA 2017; 23:530-545. [PMID: 28053272 PMCID: PMC5340916 DOI: 10.1261/rna.060012.116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/29/2016] [Indexed: 06/06/2023]
Abstract
Transgenerational transmission of genome-regulatory epigenetic information can determine phenotypes in the progeny of sexual reproduction. Sequence specificity of transgenerational regulation derives from small RNAs assembled into Piwi-protein complexes. Known targets of transgenerational regulation are primarily transposons and transposon-derived sequences. Here, we extend the scope of Piwi-mediated transgenerational regulation to include unique noncoding RNA loci. Ciliates such as Tetrahymena have a phenotypically silent germline micronucleus and an expressed somatic macronucleus, which is differentiated anew from a germline genome copy in sexual reproduction. We show that the nuclear-localized Tetrahymena Piwi protein Twi8p shuttles from parental to zygotic macronuclei. Genetic elimination of Twi8p has no phenotype for cells in asexual growth. On the other hand, cells lacking Twi8p arrest in sexual reproduction with zygotic nuclei that retain the germline genome structure, without the DNA elimination and fragmentation required to generate a functional macronucleus. Twi8p-bound small RNAs originate from long-noncoding RNAs with a terminal hairpin, which become detectable in the absence of Twi8p. Curiously, the loci that generate Twi8p-bound small RNAs are essential for asexual cell growth, even though Twi8 RNPs are essential only in sexual reproduction. Our findings suggest the model that Twi8 RNPs act on silent germline chromosomes to permit their conversion to expressed macronuclear chromosomes. Overall this work reveals that a Piwi protein carrying small RNAs from long-noncoding RNA loci has transgenerational function in establishing zygotic nucleus competence for gene expression.
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MESH Headings
- Argonaute Proteins/genetics
- Argonaute Proteins/metabolism
- Chromosomes
- DNA, Protozoan/genetics
- DNA, Protozoan/metabolism
- Gene Rearrangement
- Genome, Protozoan
- Macronucleus/genetics
- Macronucleus/metabolism
- Micronucleus, Germline/genetics
- Micronucleus, Germline/metabolism
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Reproduction, Asexual/genetics
- Tetrahymena/genetics
- Tetrahymena/growth & development
- Tetrahymena/metabolism
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Affiliation(s)
- Brian M Farley
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720-3202, USA
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720-3202, USA
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13
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Zhang SW, Feng JN, Cao Y, Meng LP, Wang SL. Autophagy prevents autophagic cell death in Tetrahymena in response to oxidative stress. Zool Res 2015; 36:167-173. [PMID: 26018860 PMCID: PMC4790692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 05/07/2015] [Indexed: 06/04/2023] Open
Abstract
Autophagy is a major cellular pathway used to degrade long-lived proteins or organelles that may be damaged due to increased reactive oxygen species (ROS) generated by cellular stress. Autophagy typically enhances cell survival, but it may also act to promote cell death under certain conditions. The mechanism underlying this paradox, however, remains unclear. We showed that Tetrahymena cells exerted increased membrane-bound vacuoles characteristic of autophagy followed by autophagic cell death (referred to as cell death with autophagy) after exposure to hydrogen peroxide. Inhibition of autophagy by chloroquine or 3-methyladenine significantly augmented autophagic cell death induced by hydrogen peroxide. Blockage of the mitochondrial electron transport chain or starvation triggered activation of autophagy followed by cell death by inducing the production of ROS due to the loss of mitochondrial membrane potential. This indicated a regulatory role of mitochondrial ROS in programming autophagy and autophagic cell death in Tetrahymena. Importantly, suppression of autophagy enhanced autophagic cell death in Tetrahymena in response to elevated ROS production from starvation, and this was reversed by antioxidants. Therefore, our results suggest that autophagy was activated upon oxidative stress to prevent the initiation of autophagic cell death in Tetrahymena until the accumulation of ROS passed the point of no return, leading to delayed cell death in Tetrahymena.
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Affiliation(s)
- Si-Wei Zhang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jiang-Nan Feng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Yi Cao
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Li-Ping Meng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Shu-Lin Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, China.
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14
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Iwamoto M, Koujin T, Osakada H, Mori C, Kojidani T, Matsuda A, Asakawa H, Hiraoka Y, Haraguchi T. Biased assembly of the nuclear pore complex is required for somatic and germline nuclear differentiation in Tetrahymena. J Cell Sci 2015; 128:1812-23. [PMID: 25788697 PMCID: PMC4432229 DOI: 10.1242/jcs.167353] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/07/2015] [Indexed: 12/18/2022] Open
Abstract
Ciliates have two functionally distinct nuclei, a somatic macronucleus (MAC) and a germline micronucleus (MIC) that develop from daughter nuclei of the last postzygotic division (PZD) during the sexual process of conjugation. Understanding this nuclear dimorphism is a central issue in ciliate biology. We show, by live-cell imaging of Tetrahymena, that biased assembly of the nuclear pore complex (NPC) occurs immediately after the last PZD, which generates anterior-posterior polarized nuclei: MAC-specific NPCs assemble in anterior presumptive MACs but not in posterior presumptive MICs. MAC-specific NPC assembly in the anterior nuclei occurs much earlier than transport of Twi1p, which is required for MAC genome rearrangement. Correlative light-electron microscopy shows that addition of new nuclear envelope (NE) precursors occurs through the formation of domains of redundant NE, where the outer double membrane contains the newly assembled NPCs. Nocodazole inhibition of the second PZD results in assembly of MAC-specific NPCs in the division-failed zygotic nuclei, leading to failure of MIC differentiation. Our findings demonstrate that NPC type switching has a crucial role in the establishment of nuclear differentiation in ciliates.
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Affiliation(s)
- Masaaki Iwamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Takako Koujin
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Chie Mori
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Tomoko Kojidani
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Japan Women's University, Tokyo 112-8681, Japan
| | - Atsushi Matsuda
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Haruhiko Asakawa
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
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15
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Shodhan A, Lukaszewicz A, Novatchkova M, Loidl J. Msh4 and Msh5 function in SC-independent chiasma formation during the streamlined meiosis of Tetrahymena. Genetics 2014; 198:983-93. [PMID: 25217051 PMCID: PMC4224184 DOI: 10.1534/genetics.114.169698] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 09/06/2014] [Indexed: 11/25/2022] Open
Abstract
ZMM proteins have been defined in budding yeast as factors that are collectively involved in the formation of interfering crossovers (COs) and synaptonemal complexes (SCs), and they are a hallmark of the predominant meiotic recombination pathway of most organisms. In addition to this so-called class I CO pathway, a minority of crossovers are formed by a class II pathway, which involves the Mus81-Mms4 endonuclease complex. This is the only CO pathway in the SC-less meiosis of the fission yeast. ZMM proteins (including SC components) were always found to be co-occurring and hence have been regarded as functionally linked. Like the fission yeast, the protist Tetrahymena thermophila does not possess a SC, and its COs are dependent on Mus81-Mms4. Here we show that the ZMM proteins Msh4 and Msh5 are required for normal chiasma formation, and we propose that they have a pro-CO function outside a canonical class I pathway in Tetrahymena. Thus, the two-pathway model is not tenable as a general rule.
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Affiliation(s)
- Anura Shodhan
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, A-1030 Vienna, Austria
| | - Agnieszka Lukaszewicz
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, A-1030 Vienna, Austria
| | - Maria Novatchkova
- Research Institute of Molecular Pathology, A-130 Vienna, Austria IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, A-1030 Vienna, Austria
| | - Josef Loidl
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, A-1030 Vienna, Austria
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16
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Gilbert D, Jakobsen HH, Winding A, Mayer P. Co-transport of polycyclic aromatic hydrocarbons by motile microorganisms leads to enhanced mass transfer under diffusive conditions. Environ Sci Technol 2014; 48:4368-4375. [PMID: 24625194 DOI: 10.1021/es404793u] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The environmental chemodynamics of hydrophobic organic chemicals (HOCs) are often rate-limited by diffusion in stagnant boundary layers. This study investigated whether motile microorganisms can act as microbial carriers that enhance mass transfer of HOCs through diffusive boundary layers. A new experimental system was developed that allows (1) generation of concentration gradients of HOCs under the microscope, (2) exposure and direct observation of microorganisms in such gradients, and (3) quantification of HOC mass transfer. Silicone O-rings were integrated into a Dunn chemotaxis chamber to serve as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement with hydrophobicity indicated PAH co-transport with the motile organisms. Fluorescence microscopy confirmed such transport. The effective diffusivity of T. pyriformis, determined by video imaging microscopy, was found to exceed molecular diffusivities of the PAHs up to four-fold. Cell-bound PAH fractions were determined to range from 28% (naphthalene) to 92% (pyrene). Motile microorganisms can therefore function as effective carriers for HOCs under diffusive conditions and might significantly enhance mobility and availability of HOCs.
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Affiliation(s)
- Dorothea Gilbert
- Department of Environmental Science, Aarhus University , P.O. Box 358, 4000 Roskilde, Denmark
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17
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Zhang T, Li X, Lu Y, Wu C, Fang T, Liu P, Zhang C, Liang W. Acute toxicity of heavy metals to Tetrahymena in an in vitro experiment and envelope damage study. Bull Environ Contam Toxicol 2013; 91:62-68. [PMID: 23661168 DOI: 10.1007/s00128-013-1004-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Accepted: 04/17/2013] [Indexed: 06/02/2023]
Abstract
The toxicity of Cr³⁺, Cu²⁺ and Cd²⁺ to Tetrahymena growth metabolism was studied by microcalorimetry at 28°C, and the growth constant (k), peak time (T) and generation times (T(G)) were calculated. The metal ion concentrations that resulted in 50% inhibition (IC₅₀) of population growth were obtained through the dynamic parameters. The results indicated that the order of toxicity was Cd²⁺> Cr³⁺> Cu²⁺. Inductively coupled plasma-atomic emission spectrometry results suggested that the metal ions affected the permeability of the cell membrane. Observations of the Cd-exposed organisms by scanning electron microscopy revealed damage to the cell membrane in the form of an altered surface appearance. The cells suffered serious damage after sufficient acting time. Attenuated total reflection Fourier transform infrared spectra revealed that amide groups and PO₂⁻ of the phospholipid phospho-diester, both located in the hydrophobic end of the outer layer of the cell membrane, were most readily affected.
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Affiliation(s)
- Tian Zhang
- Department of Chemistry, School of Science, Wuhan University of Technology, Wuhan 430070, People's Republic of China
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18
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Malara A, Oleszczuk P. Application of a battery of biotests for the determination of leachate toxicity to bacteria and invertebrates from sewage sludge-amended soil. Environ Sci Pollut Res Int 2013; 20:3435-46. [PMID: 23132406 PMCID: PMC3633785 DOI: 10.1007/s11356-012-1268-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 10/16/2012] [Indexed: 05/13/2023]
Abstract
The objective of the study was to determine the leachates toxicity from sewage sludge-amended soils (sandy and loamy). Samples originated from a plot experiment realized over a period of 29 months. Two types of soil were fertilized with sewage sludges at the dose of 3 % (90 t/ha). Soil samples were taken after 0, 7, 17, and 29 months from the application of sewage sludges. Leachates were obtained according to the EN 12457-2 protocol. The following commercial tests were applied for the estimation of the toxicity: Microtox (Vibrio fischeri), Microbial assay for toxic risk assessment (ten bacteria and one yeast), Protoxkit F (Tetrahymena thermophila), Rotoxkit F (Brachionus calyciflorus), and Daphtoxkit F (Daphnia magna). The test organisms displayed varied toxicity with relation to the soils amended with sewage sludges. The toxicity of the leachates depended both on the soil type and on the kind of sewage sludge applied. Notable differences were also observed in the sensitivity of the test organisms to the presence of sewage sludge in the soil. The highest sensitivity was a characteristic of B. calyciflorus, while the lowest sensitivity to the presence of the sludges was revealed by the protozoa T. thermophila. Throughout the periods of the study, constant variations of toxicity were observed for most of the test organisms. The intensity as well as the range of those variations depended both on the kind of test organism and on the kind of sludge and soil type. In most cases, an increase of the toxicity of soils amended with the sewage sludges was observed after 29 months of the experiment.
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Affiliation(s)
- Anna Malara
- Faculty of Chemistry, Maria Curie-Skłodowska University, 3 Maria Curie-Skłodowska Square, 20-031 Lublin, Poland
| | - Patryk Oleszczuk
- Faculty of Chemistry, Maria Curie-Skłodowska University, 3 Maria Curie-Skłodowska Square, 20-031 Lublin, Poland
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19
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Schoeberl UE, Kurth HM, Noto T, Mochizuki K. Biased transcription and selective degradation of small RNAs shape the pattern of DNA elimination in Tetrahymena. Genes Dev 2012; 26:1729-42. [PMID: 22855833 PMCID: PMC3418590 DOI: 10.1101/gad.196493.112] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 06/21/2012] [Indexed: 01/05/2023]
Abstract
The ciliated protozoan Tetrahymena undergoes extensive programmed DNA elimination when the germline micronucleus produces the new macronucleus during sexual reproduction. DNA elimination is epigenetically controlled by DNA sequences of the parental macronuclear genome, and this epigenetic regulation is mediated by small RNAs (scan RNAs [scnRNAs]) of ∼28-30 nucleotides that are produced and function by an RNAi-related mechanism. Here, we examine scnRNA production and turnover by deep sequencing. scnRNAs are produced exclusively from the micronucleus and nonhomogeneously from a variety of chromosomal locations. scnRNAs are preferentially derived from the eliminated sequences, and this preference is mainly determined at the level of transcription. Despite this bias, a significant fraction of scnRNAs is also derived from the macronuclear-destined sequences, and these scnRNAs are degraded during the course of sexual reproduction. These results indicate that the pattern of DNA elimination in the new macronucleus is shaped by the biased transcription in the micronucleus and the selective degradation of scnRNAs in the parental macronucleus.
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Affiliation(s)
| | | | | | - Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), A-1030 Vienna, Austria
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20
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Frederiksen JK, Li NS, Das R, Herschlag D, Piccirilli JA. Metal-ion rescue revisited: biochemical detection of site-bound metal ions important for RNA folding. RNA 2012; 18:1123-1141. [PMID: 22539523 PMCID: PMC3358636 DOI: 10.1261/rna.028738.111] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 01/17/2012] [Indexed: 05/27/2023]
Abstract
Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of RNA structures. Metal-ion rescue experiments have provided a powerful approach to identify and distinguish catalytic metal ions within RNA active sites, but the ability of such experiments to identify metal ions that contribute to tertiary structure acquisition and structural stability is less developed and has been challenged. Herein, we use the well-defined P4-P6 RNA domain of the Tetrahymena group I intron to reevaluate prior evidence against the discriminatory power of metal-ion rescue experiments and to advance thermodynamic descriptions necessary for interpreting these experiments. The approach successfully identifies ligands within the RNA that occupy the inner coordination sphere of divalent metal ions and distinguishes them from ligands that occupy the outer coordination sphere. Our results underscore the importance of obtaining complete folding isotherms and establishing and evaluating thermodynamic models in order to draw conclusions from metal-ion rescue experiments. These results establish metal-ion rescue as a rigorous tool for identifying and dissecting energetically important metal-ion interactions in RNAs that are noncatalytic but critical for RNA tertiary structure.
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Affiliation(s)
- John K. Frederiksen
- The Pritzker School of Medicine
- Department of Biochemistry and Molecular Biology
| | - Nan-Sheng Li
- Department of Biochemistry and Molecular Biology
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
| | - Rhiju Das
- Department of Biochemistry, Beckman Center, Stanford University, Stanford, California 94305-5307, USA
| | - Daniel Herschlag
- Department of Biochemistry, Beckman Center, Stanford University, Stanford, California 94305-5307, USA
| | - Joseph A. Piccirilli
- Department of Biochemistry and Molecular Biology
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
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21
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Raju G, Srinivas R, Santhosh Reddy V, Idris MM, Kamal A, Nagesh N. Interaction of pyrrolobenzodiazepine (PBD) ligands with parallel intermolecular G-quadruplex complex using spectroscopy and ESI-MS. PLoS One 2012; 7:e35920. [PMID: 22558271 PMCID: PMC3338766 DOI: 10.1371/journal.pone.0035920] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 03/25/2012] [Indexed: 11/18/2022] Open
Abstract
Studies on ligand interaction with quadruplex DNA, and their role in stabilizing the complex at concentration prevailing under physiological condition, has attained high interest. Electrospray ionization mass spectrometry (ESI-MS) and spectroscopic studies in solution were used to evaluate the interaction of PBD and TMPyP4 ligands, stoichiometry and selectivity to G-quadruplex DNA. Two synthetic ligands from PBD family, namely pyrene-linked pyrrolo[2,1-c][1,4]benzodiazepine hybrid (PBD1), mixed imine-amide pyrrolobenzodiazepine dimer (PBD2) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP4) were studied. G-rich single-stranded oligonucleotide d(5'GGGGTTGGGG3') designated as d(T(2)G(8)), from the telomeric region of Tetrahymena Glaucoma, was considered for the interaction with ligands. ESI-MS and spectroscopic methods viz., circular dichroism (CD), UV-Visible, and fluorescence were employed to investigate the G-quadruplex structures formed by d(T(2)G(8)) sequence and its interaction with PBD and TMPyP4 ligands. From ESI-MS spectra, it is evident that the majority of quadruplexes exist as d(T(2)G(8))(2) and d(T(2)G(8))(4) forms possessing two to ten cations in the centre, thereby stabilizing the complex. CD band of PBD1 and PBD2 showed hypo and hyperchromicity, on interaction with quadruplex DNA, indicating unfolding and stabilization of quadruplex DNA complex, respectively. UV-Visible and fluorescence experiments suggest that PBD1 bind externally where as PBD2 intercalate moderately and bind externally to G-quadruplex DNA. Further, melting experiments using SYBR Green indicate that PBD1 unfolds and PBD2 stabilizes the G-quadruplex complex. ITC experiments using d(T(2)G(8)) quadruplex with PBD ligands reveal that PBD1 and PBD2 prefer external/loop binding and external/intercalative binding to quadruplex DNA, respectively. From experimental results it is clear that the interaction of PBD2 and TMPyP4 impart higher stability to the quadruplex complex.
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Affiliation(s)
- Gajjela Raju
- National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad, India
| | - Ragampeta Srinivas
- National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad, India
| | - Vangala Santhosh Reddy
- Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad, India
| | | | - Ahmed Kamal
- Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad, India
| | - Narayana Nagesh
- Centre for Cellular and Molecular Biology, Hyderabad, India
- * E-mail:
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22
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Elde NC, Roach KC, Yao MC, Malik HS. Absence of positive selection on centromeric histones in Tetrahymena suggests unsuppressed centromere: drive in lineages lacking male meiosis. J Mol Evol 2011; 72:510-20. [PMID: 21643829 PMCID: PMC3144370 DOI: 10.1007/s00239-011-9449-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 05/19/2011] [Indexed: 12/20/2022]
Abstract
Centromere-drive is a process where centromeres compete for transmission through asymmetric "female" meiosis for inclusion into the oocyte. In symmetric "male" meiosis, all meiotic products form viable germ cells. Therefore, the primary incentive for centromere-drive, a potential transmission bias, is believed to be missing from male meiosis. In this article, we consider whether male meiosis also bears the primary cost of centromere-drive. Because different taxa carry out different combinations of meiotic programs (symmetric + asymmetric, symmetric only, asymmetric only), it is possible to consider the evolutionary consequences of centromere-drive in the context of these differing systems. Groups with both types of meiosis have large, rapidly evolving centromeric regions, and their centromeric histones (CenH3s) have been shown to evolve under positive selection, suggesting roles as suppressors of centromere-drive. In contrast, taxa with only symmetric male meiosis have shown no evidence of positive selection in their centromeric histones. In this article, we present the first evolutionary analysis of centromeric histones in ciliated protozoans, a group that only undergoes asymmetric "female" meiosis. We find no evidence of positive selection acting on CNA1, the CenH3 of Tetrahymena species. Cytological observations of a panel of Tetrahymena species are consistent with dynamic karyotype evolution in this lineage. Our findings suggest that defects in male meiosis, and not mitosis or female meiosis, are the primary selective force behind centromere-drive suppression. Our study raises the possibility that taxa like ciliates, with only female meiosis, may therefore undergo unsuppressed centromere drive.
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Affiliation(s)
- Nels C. Elde
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N. A2-205, Seattle, WA 98109 USA
- Present Address: Department of Human Genetics, University of Utah, Salt Lake City, UT 84112 USA
| | - Kevin C. Roach
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N. A2-205, Seattle, WA 98109 USA
- Department of Genome Sciences, University of Washington, Seattle, WA 98195 USA
| | - Meng-Chao Yao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529
| | - Harmit S. Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N. A2-205, Seattle, WA 98109 USA
- HHMI, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N. A2-205, Seattle, WA 98109 USA
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23
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Abstract
Extensive programmed rearrangement of DNA, including DNA elimination, chromosome fragmentation, and DNA unscrambling, takes place in the newly developed macronucleus during the sexual reproduction of ciliated protozoa. Recent studies have revealed that two distant classes of ciliates use distinct types of non-coding RNAs to regulate such DNA rearrangement events. DNA elimination in Tetrahymena is regulated by small non-coding RNAs that are produced and utilized in an RNA interference (RNAi)-related process. It has been proposed that the small RNAs produced from the micronuclear genome are used to identify eliminated DNA sequences by whole-genome comparison between the parental macronucleus and the micronucleus. In contrast, DNA unscrambling in Oxytricha is guided by long non-coding RNAs that are produced from the parental macronuclear genome. These long RNAs are proposed to act as templates for the direct unscrambling events that occur in the developing macronucleus. Both cases provide useful examples to study epigenetic chromatin regulation by non-coding RNAs.
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Affiliation(s)
- Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, A-1030 Vienna, Austria.
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24
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Chaudhry R, Shakoori AR. Isolation and characterization of a novel copper-inducible metallothionein gene of a ciliate, Tetrahymena tropicalis lahorensis. J Cell Biochem 2010; 110:630-44. [PMID: 20512924 DOI: 10.1002/jcb.22573] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The two isoforms of copper metallothionein (CuMT) gene of a copper resistant ciliate, Tetrahymena tropicalis lahorensis (Ttl), have been isolated and characterized. The molecular cloning and nucleotide sequencing of cDNAs coding for the two CuMT isoforms revealed that TtlCuMT1 gene has 300, while TtlCuMT2 has 327 nucleotides, both with ATG as the initiation codon and TGA as the translational termination codon. TAG codes for glutamine in TtlCuMT2 gene which is peculiar to Tetrahymena. The deduced or translated TtlCuMT1 and TtlCuMT2 peptide sequences contain 100 and 108 amino acid residues including 28 and 32 cysteine residues, respectively. The amino acid sequences of TtlCuMT1 and TtlCuMT2 have special features of two and three CXCXXCXCXXCXC intragenic tandem repeats with a conserved structural pattern of cysteine, respectively. The predicted tertiary structures of these two isoforms indicate two domains. Domain I and the initial part of domain II showed >98% homology with other Tetrahymena CuMT. On the basis of the differences in the domain II, the metallothionein subfamily 7b can be divided into two groups, one (TtlCuMT1) comprising >100 amino acids and the other (TtlCuMT2) comprising <100 amino acids. This is a novel finding of the present study as no such report on this type of classification exists at the moment. TtlCuMT1 has 95%, while TtlCuMT2 has 97% resemblance with the previously reported CuMT genes of Tetrahymena spp. SDS-PAGE analysis using fluorescent probe as well as coomassie brilliant blue staining also confirmed the presence of metallothionein.
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Affiliation(s)
- Raheela Chaudhry
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
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25
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Seixas C, Cruto T, Tavares A, Gaertig J, Soares H. CCTalpha and CCTdelta chaperonin subunits are essential and required for cilia assembly and maintenance in Tetrahymena. PLoS One 2010; 5:e10704. [PMID: 20502701 PMCID: PMC2872681 DOI: 10.1371/journal.pone.0010704] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 04/23/2010] [Indexed: 12/24/2022] Open
Abstract
Background The eukaryotic cytosolic chaperonin CCT is a hetero-oligomeric complex formed by two rings connected back-to-back, each composed of eight distinct subunits (CCTα to CCTζ). CCT complex mediates the folding, of a wide range of newly synthesised proteins including tubulin (α, β and γ) and actin, as quantitatively major substrates. Methodology/Principal Findings We disrupted the genes encoding CCTα and CCTδ subunits in the ciliate Tetrahymena. Cells lacking the zygotic expression of either CCTα or CCTδ showed a loss of cell body microtubules, failed to assemble new cilia and died within 2 cell cycles. We also show that loss of CCT subunit activity leads to axoneme shortening and splaying of tips of axonemal microtubules. An epitope-tagged CCTα rescued the gene knockout phenotype and localized primarily to the tips of cilia. A mutation in CCTα, G346E, at a residue also present in the related protein implicated in the Bardet Biedel Syndrome, BBS6, also caused defects in cilia and impaired CCTα localization in cilia. Conclusions/Significance Our results demonstrate that the CCT subunits are essential and required for ciliary assembly and maintenance of axoneme structure, especially at the tips of cilia.
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Affiliation(s)
- Cecilia Seixas
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Teresa Cruto
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Helena Soares
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Escola Superior de Tecnologia da Saúde de Lisboa, Lisboa, Portugal
- * E-mail:
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26
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Frederiksen JK, Piccirilli JA. Identification of catalytic metal ion ligands in ribozymes. Methods 2009; 49:148-66. [PMID: 19651216 DOI: 10.1016/j.ymeth.2009.07.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 07/20/2009] [Accepted: 07/29/2009] [Indexed: 01/05/2023] Open
Abstract
Site-bound metal ions participate in the catalytic mechanisms of many ribozymes. Understanding these mechanisms therefore requires knowledge of the specific ligands on both substrate and ribozyme that coordinate these catalytic metal ions. A number of different structural and biochemical strategies have been developed and refined for identifying metal ion binding sites within ribozymes, and for assessing the catalytic contributions of the metal ions bound at those sites. We review these approaches and provide examples of their application, focusing in particular on metal ion rescue experiments and their roles in the construction of the transition state models for the Tetrahymena group I and RNase P ribozymes.
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Affiliation(s)
- John K Frederiksen
- The Pritzker School of Medicine, The University of Chicago, Chicago, IL 60637, USA
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27
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Abstract
Posttranslational modifications of tubulin likely generate the functional diversity of microtubules. In this issue of Developmental Cell, Loktev and colleagues (2008) describe a novel protein BBIP10 with dual roles: it is required for ciliogenesis as well as acetylation and stabilization of microtubules.
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Affiliation(s)
- Anna Diaz-Font
- Molecular Medicine Unit, Institute of Child Health, University College London, London, UK
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28
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Rico D, Martín-González A, Díaz S, de Lucas P, Gutiérrez JC. Heavy metals generate reactive oxygen species in terrestrial and aquatic ciliated protozoa. Comp Biochem Physiol C Toxicol Pharmacol 2009; 149:90-6. [PMID: 18725323 DOI: 10.1016/j.cbpc.2008.07.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 07/21/2008] [Accepted: 07/21/2008] [Indexed: 10/21/2022]
Abstract
Reactive oxygen species (ROS) induction by exposure to heavy metals (Cd, Cu or Zn) in diverse free-living ciliated protozoa (Tetrahymena sp. and three strains of Colpoda steinii, isolated from freshwater and soils with different level of metal pollution) has been evaluated. Using specific fluorophores, such as 2',7'-dichlorofluorescein diacetate, hydroethidine and dihydrorhodamine 123, and a fluorescence microscope with the program MetaMorph Imaging System 4.0, we have analyzed both the average fluorescence emission and the heterogeneous distribution of fluorescence in control and treated cells. This is the first time that these fluorophores are used to detect ROS production in ciliated protozoa. All metals generate ROS, mainly superoxide and peroxides, showing a remarkable inter- and intra-specific variations. Likewise, resistance against each metal was also very diverse. Cu and specially Cd, the most toxic heavy metal for these ciliates, are the best oxidative stress inducers. However, a correlation between fluorescence emission intensity and cellular metal sensitivity for each strain cannot be established. Results are discussed and compared with similar findings previously published in other unicellular and pluricellular organisms.
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Affiliation(s)
- Daniel Rico
- Departamento Microbiología-III, Facultad de Biología, Universidad Complutense (UCM), Madrid, Spain
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29
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Kirk KE, Christ C, McGuire JM, Paul AG, Vahedi M, Stuart KR, Cole ES. Abnormal micronuclear telomeres lead to an unusual cell cycle checkpoint and defects in Tetrahymena oral morphogenesis. Eukaryot Cell 2008; 7:1712-23. [PMID: 18469136 PMCID: PMC2568063 DOI: 10.1128/ec.00393-07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Accepted: 04/16/2008] [Indexed: 11/20/2022]
Abstract
Telomere mutants have been well studied with respect to telomerase and the role of telomere binding proteins, but they have not been used to explore how a downstream morphogenic event is related to the mutated telomeric DNA. We report that alterations at the telomeres can have profound consequences on organellar morphogenesis. Specifically, a telomerase RNA mutation termed ter1-43AA results in the loss of germ line micronuclear telomeres in the binucleate protozoan Tetrahymena thermophila. These cells also display a micronuclear mitotic arrest, characterized by an extreme delay in anaphase with an elongated, condensed chromatin and a mitotic spindle apparatus. This anaphase defect suggests telomere fusions and consequently a spindle rather than a DNA damage checkpoint. Most surprisingly, these mutants exhibit unique, dramatic defects in the formation of the cell's oral apparatus. We suggest that micronuclear telomere loss leads to a "dynamic pause" in the program of cortical development, which may reveal an unusual cell cycle checkpoint.
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Affiliation(s)
- Karen E Kirk
- Department of Biology, Lake Forest College, Lake Forest, Illinois 60045, USA.
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30
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Amaro F, del Pilar de Lucas M, Martín-González A, Gutiérrez JC. Two new members of the Tetrahymena multi-stress-inducible metallothionein family: characterization and expression analysis of T. rostrata Cd/Cu metallothionein genes. Gene 2008; 423:85-91. [PMID: 18675326 DOI: 10.1016/j.gene.2008.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 06/17/2008] [Accepted: 07/03/2008] [Indexed: 11/19/2022]
Abstract
We report the cloning and characterization of two new metallothionein (MT) genes (TrosMTT1 and TrosMTT2), isolated as cDNAs, from the ciliated protozoa Tetrahymena rostrata. The TrosMTT1 inferred protein has been identified as a CdMT and included into the 7a subfamily of Tetrahymena MTs, while TrosMTT2 has been identified as a CuMT (including it into 7b subfamily), due to its similarity to TpigMT-2 and its significant induction by copper. TrosMTT1 protein sequence reveals a remarkably regular and hierarchical modular organization, as it is known for other Tetrahymena CdMTs, showing a bi-modular structure. TrosMTT2 presents a structural organization based on CKCX(2-5)CKC repeats, like it occurs in other Tetrahymena CuMTs, indicating that an evolutionary history based on intra-gene duplications might be also possible. Both are also multi-stress-inducible genes because they are induced by other heavy metals and stressors, as it has been shown by quantitative real-time RT-PCR. It is the first time that the gene expression of a putative Tetrahymena CuMT is analyzed by quantitative PCR, confirming it as a CuMT. These two new Tetrahymena MTs complete, at present, the actual view of this protein superfamily, and corroborate the unique features of ciliate MTs. Furthermore, both, a comparative analysis of relative gene expression values obtained by quantitative RT-PCR on other Tetrahymena MT genes and an analysis of the different Tetrahymena MTs based on the different Cys clusters of these proteins are carried out, which show an update view of Tetrahymena MT gene family.
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Affiliation(s)
- Francisco Amaro
- Departamento de Microbiología-III, Facultad de Biología, C/, José Antonio Novais, 2, Universidad Complutense (UCM), 28040 Madrid, Spain
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31
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Mochizuki K, Novatchkova M, Loidl J. DNA double-strand breaks, but not crossovers, are required for the reorganization of meiotic nuclei in Tetrahymena. J Cell Sci 2008; 121:2148-58. [PMID: 18522989 PMCID: PMC3184542 DOI: 10.1242/jcs.031799] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
During meiosis, the micronuclei of the ciliated protist Tetrahymena thermophila elongate dramatically. Within these elongated nuclei, chromosomes are arranged in a bouquet-like fashion and homologous pairing and recombination takes place. We studied meiotic chromosome behavior in Tetrahymena in the absence of two genes, SPO11 and a homolog of HOP2 (HOP2A), which have conserved roles in the formation of meiotic DNA double-strand breaks (DSBs) and their repair, respectively. Single-knockout mutants for each gene display only a moderate reduction in chromosome pairing, but show a complete failure to form chiasmata and exhibit chromosome missegregation. The lack of SPO11 prevents the elongation of meiotic nuclei, but it is restored by the artificial induction of DSBs. In the hop2ADelta mutant, the transient appearance of gamma-H2A.X and Rad51p signals indicates the formation and efficient repair of DSBs; but this repair does not occur by interhomolog crossing over. In the absence of HOP2A, the nuclei are elongated, meaning that DSBs but not their conversion to crossovers are required for the development of this meiosis-specific morphology. In addition, by in silico homology searches, we compiled a list of likely Tetrahymena meiotic proteins as the basis for further studies of the unusual synaptonemal complex-less meiosis in this phylogenetically remote model organism.
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Affiliation(s)
- Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), A-1030 Vienna, Austria
| | - Maria Novatchkova
- Research Institute of Molecular Pathology (IMP), A-1030 Vienna, Austria
| | - Josef Loidl
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr Bohr Gasse 1, A-1030 Vienna, Austria
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32
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Cole ES, Anderson PC, Fulton RB, Majerus ME, Rooney MG, Savage JM, Chalker D, Honts J, Welch ME, Wentland AL, Zweifel E, Beussman DJ. A proteomics approach to cloning fenestrin from the nuclear exchange junction of tetrahymena. J Eukaryot Microbiol 2008; 55:245-56. [PMID: 18681839 DOI: 10.1111/j.1550-7408.2008.00337.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We set out to find the "fenestrin" gene, a gene whose protein is associated with numerous cellular apertures, including the nuclear exchange junction in mating Tetrahymena thermophila. First we developed protocols for imaging and isolating intact nuclear exchange junctions from conjugating cells. Proteins from these junctions were purified using SDS-PAGE, subjected to limited proteolysis, and precise molecular weights were determined by mass spectrometry. Using Protein Prospector software and the published Tetrahymena Genome Database, genes for 15 of the most abundant proteins found in our extracts were identified. The most promising candidate was cloned by PCR, fused to yellow fluorescent protein (YFP), and placed under the control of an inducible metallothionein promoter. YFP-localization within live Tetrahymena transformants strongly suggested that one of these genes encoded the fenestrin protein, a result that was subsequently confirmed by Western blotting.
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Affiliation(s)
- Eric S Cole
- Biology Department, St. Olaf College, Northfield, Minnesota 55057, USA.
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33
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Abstract
The structure and activity of nucleic acids depend on their interactions with metal ions. Fundamental to these interactions is the degree of specificity observed between the metal ions and nucleic acids, and a complete description of nucleic acid folding requires that we understand the nature of the interactions with metal ions, including specificity. The prior demonstration that high concentrations of monovalent cations prevent nonspecific association of divalent ions with nucleic acids provides a novel and powerful means to examine site-specific metal ion binding isolated from complicating effects of the ion atmosphere. Using these high monovalent cation solution conditions we have monitored the affinity of a series of divalent metal ions for two site-specific metal ion binding sites in the P4-P6 domain of the Tetrahymena group I intron ribozyme. The metal ion core of this highly structured RNA binds two divalent metal ions under these conditions. Despite multiple metal ion-RNA interactions observed in the X-ray crystallographic structure of P4-P6 RNA at the metal ion binding sites, these sites exhibit low specificity among Mn(2+), Mg(2+), Ca(2+), Ni(2+), and Zn(2+). Nevertheless, the largest divalent metal ions tested, Sr(2+) and Ba(2+), were excluded from binding, exhibiting affinities at least two orders of magnitude weaker than observed for the other metal ions. Thus, a picture emerges of two metal ion binding sites, each with a high tolerance for metal ions with different properties but also with limits to accommodation. These limits presumably arise from steric or electrostatic features of the metal ion binding sites.
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Affiliation(s)
- Kevin J Travers
- Department of Biochemistry, Stanford University, Stanford, CA 94305-5307, USA
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34
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Abstract
Microtubules in neurites undergo multiple post-translational modifications. Recent work shows that neurites enriched in acetylated microtubules selectively support kinesin-mediated transport of the JNK regulator JIP-1 to growth cones.
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Affiliation(s)
- J Chloë Bulinski
- Biological Sciences and Pathology & Cell Biology, Columbia University, 804A Sherman Fairchild Center, MC 2450, 1212 Amsterdam Avenue, New York, New York 10027-2450, USA.
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35
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Abstract
RNA molecules are exquisitely sensitive to the properties of counterions. The folding equilibrium of the Tetrahymena ribozyme is measured by nondenaturing gel electrophoresis in the presence of divalent group IIA metal cations. The stability of the folded ribozyme increases with the charge density (zeta) of the cation. Similar scaling is found when the free energy of the RNA folded in small and large metal cations is measured by urea denaturation. Brownian dynamics simulations of a polyelectrolyte show that the experimental observations can be explained by nonspecific ion-RNA interactions in the absence of site-specific metal chelation. The experimental and simulation results establish that RNA stability is largely determined by a combination of counterion charge and the packing efficiency of condensed cations that depends on the excluded volume of the cations.
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Affiliation(s)
- Eda Koculi
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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36
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Noseda DG, Gentili HG, Nani ML, Nusblat A, Tiedtke A, Florin-Christensen J, Nudel CB. A bioreactor model system specifically designed for Tetrahymena growth and cholesterol removal from milk. Appl Microbiol Biotechnol 2007; 75:515-20. [PMID: 17294184 DOI: 10.1007/s00253-007-0843-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 01/09/2007] [Accepted: 01/10/2007] [Indexed: 11/28/2022]
Abstract
This work describes the configuration and operation of a bioreactor system especially designed for Tetrahymena cultivation and its use for milk improvement, particularly cholesterol elimination by the action of this cell. An advantage of the proposed method is the re-use of the growth medium; thus, the medium is used twice to provide two batches of Tetrahymena biomass without the need of further inoculation. This makes the procedure of producing the cell biomass faster and more economical. Cells are concentrated in the culture vessels by sedimentation at room temperature and then transferred to milk suspensions, where they can further grow for at least one generation with the benefit of reducing steeply cholesterol level. Milk treated according to this process is separated from the biomass by centrifugation. Under these conditions, less than 5% of the cells remain in the milk, and cholesterol elimination amounts to 75 +/- 10% of that initially present. No changes in sensorial properties of the milk, such as clotting or butyric odor, were observed as a result of this treatment. In addition, the bioreactor allows the aseptic recovery of the spent growth medium, which contains diverse enzymes of interest, and the cell pellets, to exploit particular lipids like phosphonolipids, abundant poly-unsaturated fatty acids and co-enzyme Q(8).
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Affiliation(s)
- D G Noseda
- Laboratorio de Desarrollo e Investigaciones Aplicadas de Medipharma S.A., 1056, Buenos Aires, Argentina.
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37
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Abstract
Telomerase is a ribonucleoprotein complex that reverse transcribes a portion of its RNA subunit during the synthesis of G-rich DNA at the 3' end of each chromosome in most eukaryotes. This activity compensates for the inability of the normal DNA replication machinery to fully replicate chromosome termini. The roles of telomerase in cellular immortality and tumor biology have catalyzed a significant interest in this unusual polymerase. Recently the first structures of two domains, the CR4/CR5 and pseudoknot, of human telomerase RNA (hTR) were reported, offering a structural basis for interpreting biochemical studies and possible roles of hTR mutations in human diseases. Structures of the stem II and stem IV domains of Tetrahymena thermophila TR as well as the N-terminal domain of the T. thermophila telomerase reverse transcriptase have also been determined. These studies complement previous biochemical studies, providing rich insight into the structural basis for telomerase activity.
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Affiliation(s)
- Jason D Legassie
- Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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38
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Garcia BA, Hake SB, Diaz RL, Kauer M, Morris SA, Recht J, Shabanowitz J, Mishra N, Strahl BD, Allis CD, Hunt DF. Organismal differences in post-translational modifications in histones H3 and H4. J Biol Chem 2006; 282:7641-55. [PMID: 17194708 DOI: 10.1074/jbc.m607900200] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Post-translational modifications (PTMs) of histones play an important role in many cellular processes, notably gene regulation. Using a combination of mass spectrometric and immunobiochemical approaches, we show that the PTM profile of histone H3 differs significantly among the various model organisms examined. Unicellular eukaryotes, such as Saccharomyces cerevisiae (yeast) and Tetrahymena thermophila (Tet), for example, contain more activation than silencing marks as compared with mammalian cells (mouse and human), which are generally enriched in PTMs more often associated with gene silencing. Close examination reveals that many of the better-known modified lysines (Lys) can be either methylated or acetylated and that the overall modification patterns become more complex from unicellular eukaryotes to mammals. Additionally, novel species-specific H3 PTMs from wild-type asynchronously grown cells are also detected by mass spectrometry. Our results suggest that some PTMs are more conserved than previously thought, including H3K9me1 and H4K20me2 in yeast and H3K27me1, -me2, and -me3 in Tet. On histone H4, methylation at Lys-20 showed a similar pattern as H3 methylation at Lys-9, with mammals containing more methylation than the unicellular organisms. Additionally, modification profiles of H4 acetylation were very similar among the organisms examined.
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Affiliation(s)
- Benjamin A Garcia
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
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39
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Xie R, Clark KM, Gorovsky MA. Endoplasmic reticulum retention signal-dependent glycylation of the Hsp70/Grp170-related Pgp1p in Tetrahymena. Eukaryot Cell 2006; 6:388-97. [PMID: 17189490 PMCID: PMC1828932 DOI: 10.1128/ec.00366-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycylation is an uncommon posttranslational modification. It has been found that tubulin glycylation is essential for cell survival in Tetrahymena. Here we describe PGP1, a Tetrahymena gene encoding an Hsp70 homologue that is a novel glycylated protein. Pgp1p is a conserved glycoprotein that localizes within the lumen of the endoplasmic reticulum (ER). We demonstrate that PGP1 is essential for viability and present evidence that both glycosylation and ER retention are necessary but not sufficient for glycylation.
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Affiliation(s)
- Rong Xie
- Department of Biology, University of Rochester, 425 Hutchison Hall, Rochester, NY 14627, USA
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Csaba G, Kovács P, Tóthfalusi L, Pállinger E. Effects of extremely low concentrations of hormones on the insulin binding of Tetrahymena. Cell Biol Int 2006; 30:957-62. [PMID: 16889990 DOI: 10.1016/j.cellbi.2006.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 06/06/2006] [Accepted: 06/26/2006] [Indexed: 10/24/2022]
Abstract
FITC-insulin binding to previously hormone-treated Tetrahymena was studied by flow cytometry and confocal microscopy. Hormones produced by Tetrahymena were chosen for study and the hormone concentrations were administered between 10(-6) and 10(-21)M for 30 min. Endorphin, serotonin and insulin significantly reduced the hormone binding however histamine did not influence it at all. Endorphin, serotonin and insulin were significantly effective down to 10(-18)M and the effect of insulin and endorphin suggest a similar mechanism. The results call attention to the efficacy of very low hormone concentrations, which can influence the hormone content (earlier experiments) and receptor binding capacity (present study) of a unicellular organism. This seems to be very important, as in wild (natural) conditions the dilution of signaling materials secreted by a water-living protozoan is very high. In addition, the results point to the selectivity of response, as not all of the hormones that deeply influence other physiological indices (e.g. histamine) have an effect on insulin content or insulin receptors.
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Affiliation(s)
- G Csaba
- Department of Genetics, Cell and Immunobiology, Semmelweis University, Budapest, Hungary.
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41
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Abstract
Calmodulin (CaM) is an axonemal component. To examine the pathway of Ca(2+)/CaM signaling in cilia, using Ca(2+)/CaM-affinity column, we identified seven Ca(2+)/CaM-associated proteins from a crude dynein fraction and isolated 62 kDa (p62) and 66 kDa (p66) Ca(2+)/CaM-associated proteins in Tetrahymena cilia. The amino acid sequences deduced from the p62 and p66 cDNA sequences suggested that these proteins were similar to Chlamydomonas radial spoke proteins 4 and 6 (RSP4 and RSP6), components of the radial spoke head, and sea urchin sperm p63, which is a homologue of RSP4/6, and isolated as a key component that affect flagellar bending patterns. Although p62 and p66 do not have a conventional CaM-binding site, those have consecutive sequences which showed high normalized scores (>or= 5) from a CaM target database. These consecutive sequences were also found in RSP4, RSP6, and p63. These radial spoke heads proteins have a high similarity region composed of 15 amino acids between the five proteins. Immunoelectron microscopy using anti-CaM antibody showed that CaM was localized along the outer edge of the curved central pair microtubules in axoneme. Therefore, it is possible that the interaction between Ca(2+)/CaM and radial spoke head control axonemal curvature in the ciliary and flagellar waveform.
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Affiliation(s)
- Hironori Ueno
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572
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42
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Bunai F, Ando K, Ueno H, Numata O. Tetrahymena Eukaryotic Translation Elongation Factor 1A (eEF1A) Bundles Filamentous Actin through Dimer Formation. ACTA ACUST UNITED AC 2006; 140:393-9. [PMID: 16877446 DOI: 10.1093/jb/mvj169] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Eukaryotic translation elongation factor 1A (eEF1A) is known to be a multifunctional protein. In Tetrahymena, eEF1A is localized to the division furrow and has the character to bundle filamentous actin (F-actin). eEF1A binds F-actin and the ratio of eEF1A and actin is approximately 1:1 (Kurasawa et al., 1996). In this study, we revealed that eEF1A itself exists as monomer and dimer, using gel filtration column chromatography. Next, eEF1A monomer and eEF1A dimer were separated using gel filtration column, and their interaction with F-actin was examined with cosedimentation assay and electron microscopy. In the absence of Ca2+/calmodulin (CaM), eEF1A dimer bundled F-actin and coprecipitated with F-actin at low-speed centrifugation, but eEF1A monomer did not. In the presence of Ca2+/CaM, eEF1A monomer increased, while dimer decreased. To examine that Ca2+/CaM alters eEF1A dimer into monomer and inhibits bundle formation of F-actin, Ca2+/CaM was added to F-actin bundles formed by eEF1A dimer. Ca2+/CaM separated eEF1A dimer to monomer, loosened F-actin bundles and then dispersed actin filaments. Simultaneously, Ca2+/CaM/ eEF1A monomer complexes were dissociated from actin filaments. Therefore, Ca2+/CaM reversibly regulates the F-actin bundling activity of eEF1A.
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Affiliation(s)
- Fumihide Bunai
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572
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43
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Russell R, Das R, Suh H, Travers KJ, Laederach A, Engelhardt MA, Herschlag D. The paradoxical behavior of a highly structured misfolded intermediate in RNA folding. J Mol Biol 2006; 363:531-44. [PMID: 16963081 DOI: 10.1016/j.jmb.2006.08.024] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 07/29/2006] [Accepted: 08/09/2006] [Indexed: 11/27/2022]
Abstract
Like many structured RNAs, the Tetrahymena group I ribozyme is prone to misfolding. Here we probe a long-lived misfolded species, referred to as M, and uncover paradoxical aspects of its structure and folding. Previous work indicated that a non-native local secondary structure, termed alt P3, led to formation of M during folding in vitro. Surprisingly, hydroxyl radical footprinting, fluorescence measurements with site-specifically incorporated 2-aminopurine, and functional assays indicate that the native P3, not alt P3, is present in the M state. The paradoxical behavior of alt P3 presumably arises because alt P3 biases folding toward M, but, after commitment to this folding pathway and before formation of M, alt P3 is replaced by P3. Further, structural and functional probes demonstrate that the misfolded ribozyme contains extensive native structure, with only local differences between the two states, and the misfolded structure even possesses partial catalytic activity. Despite the similarity of these structures, re-folding of M to the native state is very slow and is strongly accelerated by urea, Na+, and increased temperature and strongly impeded by Mg2+ and the presence of native peripheral contacts. The paradoxical observations of extensive native structure within the misfolded species but slow conversion of this species to the native state are readily reconciled by a model in which the misfolded state is a topological isomer of the native state, and computational results support the feasibility of this model. We speculate that the complex topology of RNA secondary structures and the inherent rigidity of RNA helices render kinetic traps due to topological isomers considerably more common for RNA than for proteins.
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Affiliation(s)
- Rick Russell
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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44
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Joubert LM, Wolfaardt GM, Botha A. Microbial exopolymers link predator and prey in a model yeast biofilm system. Microb Ecol 2006; 52:187-97. [PMID: 16897306 DOI: 10.1007/s00248-006-9063-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 12/30/2005] [Accepted: 01/03/2006] [Indexed: 05/11/2023]
Abstract
Protistan grazing on biofilms is potentially an important conduit enabling energy flow between microbial trophic levels. Contrary to the widely held assumption that protistan feeding primarily involves ingestion of biofilm cells, with negative consequences for the biofilm, this study demonstrated preferential grazing on the noncellular biofilm matrix by a ciliate, with selective ingestion of yeast and bacterial cells of planktonic origin over attached and biofilm-derived planktonic cells. Introducing a ciliate to two biofilm-forming Cryptococcus species, as well as two bacterial species in a model biofilm system, fluorescent probes were applied to determine ingestion of cellular and noncellular biofilm fractions. Fluoromicroscopy, as well as photometric quantification, confirmed that protistan grazing enhanced yeast biofilm metabolism, and an increase in biofilm biomass and viability. We propose that the extracellular polymeric matrix of biofilms may act as an interface regulating interaction between predator and prey, while serving as source of nutrients and energy for protists.
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Affiliation(s)
- L-M Joubert
- Department of Microbiology, University of Stellenbosch, Stellenbosch, South Africa
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45
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Grishchuk EL, Molodtsov MI, Ataullakhanov FI, McIntosh JR. Force production by disassembling microtubules. Nature 2005; 438:384-8. [PMID: 16292315 DOI: 10.1038/nature04132] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Accepted: 08/08/2005] [Indexed: 11/09/2022]
Abstract
Microtubules (MTs) are important components of the eukaryotic cytoskeleton: they contribute to cell shape and movement, as well as to the motions of organelles including mitotic chromosomes. MTs bind motor enzymes that drive many such movements, but MT dynamics can also contribute to organelle motility. Each MT polymer is a store of chemical energy that can be used to do mechanical work, but how this energy is converted to motility remains unknown. Here we show, by conjugating glass microbeads to tubulin polymers through strong inert linkages, such as biotin-avidin, that depolymerizing MTs exert a brief tug on the beads, as measured with laser tweezers. Analysis of these interactions with a molecular-mechanical model of MT structure and force production shows that a single depolymerizing MT can generate about ten times the force that is developed by a motor enzyme; thus, this mechanism might be the primary driving force for chromosome motion. Because even the simple coupler used here slows MT disassembly, physiological couplers may modulate MT dynamics in vivo.
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46
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Netzeva TI, Schultz TW. QSARs for the aquatic toxicity of aromatic aldehydes from Tetrahymena data. Chemosphere 2005; 61:1632-43. [PMID: 15950260 DOI: 10.1016/j.chemosphere.2005.04.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/29/2005] [Accepted: 04/11/2005] [Indexed: 05/02/2023]
Abstract
The aim of the study was to develop quantitative structure-activity relationships (QSARs) for a large group of 77 aromatic aldehydes tested for acute toxicity to the ciliate Tetrahymena pyriformis using mechanistically interpretable descriptors. The resulting QSARs revealed that the 1-octanol/water partition coefficient (log K(ow)), is the most important descriptor of aldehyde aquatic toxic potency. The model with log K(ow) was improved by adding electronic descriptor (the maximum acceptor superdelocalizability in a molecule--A(max)) based on calculations with the semi-empirical AM1 model. The two descriptors reflect the two main processes responsible for demonstration of acute aquatic toxicity, namely penetration through cell membranes (log K(ow)) and interaction with the biomacromolecules (A(max)) into the cells. Results showed that generally the studied group of aldehydes could be modeled by this simple two-descriptor approach. However, the group of 2- and/or 4-hydroxylated aldehydes demonstrates enhanced toxicity compared to the other aldehydes. Transformation to quinone-like structures is proposed as the explanation for this enhanced potency. The 2- and/or 4-hydroxylated aldehydes are modeled successfully by [log(1/IGC50) = 0.540(0.038) log K(ow) + 8.30(2.88)A(max) - 3.11(0.92), n = 25, R2 = 0.916, R(CV)2 = 0.896, s = 0.141, F = 120], while the other aldehydes are modeled by the relationship [log(1/IGC50) = 0.583 (0.034)log K(ow) + 9.80(2.62)A(max) - 4.04 (0.85), n = 52, R2 = 0.864, R(CV)2 = 0.844, s = 0.203, F = 156], which is similar to the general benzene model.
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Affiliation(s)
- Tatiana I Netzeva
- European Chemicals Bureau (ECB), Institute for Health and Consumer Protection, Joint Research Centre, 21020 Ispra (VA), Italy.
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Bowman GR, Elde NC, Morgan G, Winey M, Turkewitz AP. Core formation and the acquisition of fusion competence are linked during secretory granule maturation in Tetrahymena. Traffic 2005; 6:303-23. [PMID: 15752136 PMCID: PMC4708285 DOI: 10.1111/j.1600-0854.2005.00273.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The formation of dense core secretory granules is a multistage process beginning in the trans Golgi network and continuing during a period of granule maturation. Direct interactions between proteins in the membrane and those in the forming dense core may be important for sorting during this process, as well as for organizing membrane proteins in mature granules. We have isolated two mutants in dense core granule formation in the ciliate Tetrahymena thermophila, an organism in which this pathway is genetically accessible. The mutants lie in two distinct genes but have similar phenotypes, marked by accumulation of a set of granule cargo markers in intracellular vesicles resembling immature secretory granules. Sorting to these vesicles appears specific, since they do not contain detectable levels of an extraneous secretory marker. The mutants were initially identified on the basis of aberrant proprotein processing, but also showed defects in the docking of the immature granules. These defects, in core assembly and docking, were similarly conditional with respect to growth conditions, and therefore are likely to be tightly linked. In starved cells, the processing defect was less severe, and the immature granules could dock but still did not undergo stimulated exocytosis. We identified a lumenal protein that localizes to the docking-competent end of wildtype granules, but which is delocalized in the mutants. Our results suggest that dense cores have functionally distinct domains that may be important for organizing membrane proteins involved in docking and fusion.
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Affiliation(s)
- Grant R Bowman
- Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
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48
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Abstract
Telomerase is a ribonucleoprotein reverse transcriptase responsible for the maintenance of one strand of the telomere terminal repeats. It consists minimally of a catalytic protein component (TERT) and an RNA subunit that provides the template. Compared with prototypical reverse transcriptases, telomerase is unique in possessing a DNA binding domain (anchor site) that is distinct from the catalytic site. Yeast TERT mutants bearing deletion or point mutations in an N-terminal domain (known as N-GQ) were found to be selectively impaired in extending primers that form short hybrids with telomerase RNA. The mutants also suffered a significant loss of repeat addition processivity but displayed an enhancement in nucleotide addition processivity. Furthermore, the mutants manifested altered primer utilization properties for oligonucleotides containing non-telomeric residues in the 5'-region. Cross-linking studies indicate that the N-GQ domain physically contacts the 5'-region of the DNA substrate in the context of a telomerase-telomere complex. Together, these results implicate the N-GQ domain of TERT as a physical and functional constituent of the telomerase anchor site. Coupled with previous genetic analysis, our data confirm that anchor site interaction is indeed important for telomerase function in vivo.
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Affiliation(s)
- Neal F Lue
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College of Cornell University, New York, New York 10021, USA.
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Zhang L, Xiao M, Lu C, Zhang Y. Fast formation of the P3-P7 pseudoknot: a strategy for efficient folding of the catalytically active ribozyme. RNA 2005; 11:59-69. [PMID: 15574515 PMCID: PMC1370691 DOI: 10.1261/rna.7145105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Accepted: 10/02/2004] [Indexed: 05/23/2023]
Abstract
Formation of the P3-P7 pseudoknot structure, the core of group I ribozymes, requires long-range base pairing. Study of the Tetrahymena ribozyme appreciates the hierarchical folding of the large, multidomain RNA, in which the P3-P7 core folds significantly slower than do the other domains. Here we explored the formation of the P3-P7 pseudoknot of the Candida ribozyme that has been reported to concertedly fold to the catalytically active structure with a rate constant of 2 min(-1). We demonstrate that pseudoknot formation occurs during the rapid ribozyme compaction, coincident with formation of many tertiary interactions of the ribozyme. A low physiological concentration of magnesium (1.5 mM) is sufficient to fully support the pseudoknot formation. The presence of nonnative intermediates containing an unfolded P3-P7 region is evident. However, catalysis-based analysis shows these nonnative intermediates are stable and fail to convert to the catalytically active structure, suggesting that rapid pseudoknot formation is essential for folding of the active ribozyme. Interestingly, RNAstructure predicts no stable Alt P3 structure for the Candida ribozyme, but two stable Alt P3s for the Tetrahymena ribozyme, explaining the dramatic difference in folding of the P3-P7 core of these two ribozymes. We propose that rapid formation of the P3-P7 pseudoknot represents a folding strategy ensuring efficient production of the catalytically active structure of group I ribozymes, which sheds new light on the mechanism of effective ribozyme folding in vivo.
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Affiliation(s)
- Libin Zhang
- Key Laboratory of Virology of the Ministry of Education, Department of Biotechnology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China
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Yoshioka W, Ikawa Y, Jaeger L, Shiraishi H, Inoue T. Generation of a catalytic module on a self-folding RNA. RNA 2004; 10:1900-6. [PMID: 15525711 PMCID: PMC1370678 DOI: 10.1261/rna.7170304] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Accepted: 09/27/2004] [Indexed: 05/18/2023]
Abstract
It is theoretically possible to obtain a catalytic site of an artificial ribozyme from a random sequence consisting of a limited numbers of nucleotides. However, this strategy has been inadequately explored. Here, we report an in vitro selection technique that exploits modular construction of a structurally constrained RNA to acquire a catalytic site for RNA ligation from a short random sequence. To practice the selection, a sequence of 30 nucleotides was located close to the putative reaction site in a derivative of a naturally occurring self-folding RNA whose crystal structure is known. RNAs whose activity depended on the starting three-dimensional structure were selected with 3'-5' ligation specificity, indicating that the strategy can be used to acquire a variety of catalytic sites and other functional RNA modules.
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Affiliation(s)
- Wataru Yoshioka
- Graduate School of Biostudies, Kyoto University, 606-8502 Japan
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