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Chen H, Wang J, Niu C, Zheng F, Liu C, Li Q. Genetic Strategies and Mechanisms for Improving Ribonucleic Acid Levels of Saccharomyces pastorianus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:18552-18560. [PMID: 39129495 DOI: 10.1021/acs.jafc.4c05096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Developing microorganisms with a high ribonucleic acid (RNA) content is crucial for the RNA industry. Numerous studies have been conducted to enhance RNA production in yeast cells through genetic engineering, yet precise mechanisms remain elusive. Previously, upregulation of TAL1 or PGM2 and deleting PRS5 or DBP8 individually could increase the RNA content in Saccharomyces pastorianus. In this study, within these genetically modified strains, the intracellular nucleotide levels notably increased following cell fragmentation. Deletion of PRS5 and DBP8 within the strain prompted the upregulation of genes sharing similar functions, consequently augmenting the flow of the gene pathway. Furthermore, the upregulation of genes encoding cell-cycle-dependent protein kinases (CDK) was observed in the G03-△PRS5 strain. The influence of TAL1 and PGM2 on RNA content was attributed to the pentose phosphate pathway (PPP). The RNA content of polygenic recombinant strains, G03-△PRS5+△DBP8 and G03-△PRS5+△DBP8+PGM2, displayed the most significant improvement, increasing by 71.8 and 80.1% when compared to the parental strain. Additionally, the maximum specific growth rate of cells increased in these strains. This study contributes valuable insights into the genetic mechanisms underlying high nucleic acid synthesis in S. pastorianus.
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Affiliation(s)
- Hao Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Jinjing Wang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Chengtuo Niu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Feiyun Zheng
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Chunfeng Liu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Qi Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Laboratory of Brewing Science and Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, No. 1800, Lihu Avenue, Wuxi 214122, Jiangsu, China
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2
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Mitterer V, Pertschy B. RNA folding and functions of RNA helicases in ribosome biogenesis. RNA Biol 2022; 19:781-810. [PMID: 35678541 PMCID: PMC9196750 DOI: 10.1080/15476286.2022.2079890] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic ribosome biogenesis involves the synthesis of ribosomal RNA (rRNA) and its stepwise folding into the unique structure present in mature ribosomes. rRNA folding starts already co-transcriptionally in the nucleolus and continues when pre-ribosomal particles further maturate in the nucleolus and upon their transit to the nucleoplasm and cytoplasm. While the approximate order of folding of rRNA subdomains is known, especially from cryo-EM structures of pre-ribosomal particles, the actual mechanisms of rRNA folding are less well understood. Both small nucleolar RNAs (snoRNAs) and proteins have been implicated in rRNA folding. snoRNAs hybridize to precursor rRNAs (pre-rRNAs) and thereby prevent premature folding of the respective rRNA elements. Ribosomal proteins (r-proteins) and ribosome assembly factors might have a similar function by binding to rRNA elements and preventing their premature folding. Besides that, a small group of ribosome assembly factors are thought to play a more active role in rRNA folding. In particular, multiple RNA helicases participate in individual ribosome assembly steps, where they are believed to coordinate RNA folding/unfolding events or the release of proteins from the rRNA. In this review, we summarize the current knowledge on mechanisms of RNA folding and on the specific function of the individual RNA helicases involved. As the yeast Saccharomyces cerevisiae is the organism in which ribosome biogenesis and the role of RNA helicases in this process is best studied, we focused our review on insights from this model organism, but also make comparisons to other organisms where applicable.
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Affiliation(s)
- Valentin Mitterer
- Biochemistry Center, Heidelberg University, Im Neuenheimer Feld 328, Heidelberg, Germany
- BioTechMed-Graz, Graz, Austria
| | - Brigitte Pertschy
- BioTechMed-Graz, Graz, Austria
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, Graz, Austria
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3
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Anders U, Gulotti-Georgieva M, Zelger-Paulus S, Hibti FE, Frydman C, Suckau D, Sigel RKO, Zenobi R. Screening for potential interaction partners with surface plasmon resonance imaging coupled to MALDI mass spectrometry. Anal Biochem 2021; 624:114195. [PMID: 33857502 DOI: 10.1016/j.ab.2021.114195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/14/2021] [Accepted: 04/02/2021] [Indexed: 11/29/2022]
Abstract
We coupled SPR imaging (SPRi) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) to identify new potential RNA binders. Here, we improve this powerful method, especially by optimizing the proteolytic digestion (type of reducing agent, its concentration, and incubation time), to work with complex mixtures, specifically a lysate of the rough mitochondrial fraction from yeast. The advantages of this hyphenated method compared to column-based or separate analyses are (i) rapid and direct visual readout from the SPRi array, (ii) possibility of high-throughput analysis of different interactions in parallel, (iii) high sensitivity, and (iv) no sample loss or contamination due to elution or micro-recovery procedures. The model system used is a catalytically active RNA (group IIB intron from Saccharomyces cerevisiae, Sc.ai5γ) and its cofactor Mss116. The protein supports the RNA folding process and thereby the subsequent excision of the intronic RNA from the coding part. Using the novel approach of coupling SPR with MALDI MS, we report the identification of potential RNA-binding proteins from a crude yeast mitochondrial lysate in a non-targeted approach. Our results show that proteins other than the well-known cofactor Mss116 interact with Sc.ai5γ (Dbp8, Prp8, Mrp13, and Cullin-3), suggesting that the intron folding and splicing are regulated by more than one cofactor in vivo.
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Affiliation(s)
- Ulrike Anders
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 3, CH-8093, Zurich, Switzerland
| | - Maya Gulotti-Georgieva
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Susann Zelger-Paulus
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Fatima-Ezzahra Hibti
- Horiba France S.A.S, Avenue de La Vauve, Passage Jobin Yvon, CS 45002 - F-91120 Palaiseau, France
| | - Chiraz Frydman
- Horiba France S.A.S, Avenue de La Vauve, Passage Jobin Yvon, CS 45002 - F-91120 Palaiseau, France
| | - Detlev Suckau
- Bruker Daltonics, Fahrenheitstr. 4, D-28359 Bremen, Germany
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 3, CH-8093, Zurich, Switzerland.
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4
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Weis BL, Kovacevic J, Missbach S, Schleiff E. Plant-Specific Features of Ribosome Biogenesis. TRENDS IN PLANT SCIENCE 2015; 20:729-740. [PMID: 26459664 DOI: 10.1016/j.tplants.2015.07.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/19/2015] [Accepted: 07/15/2015] [Indexed: 05/03/2023]
Abstract
The biogenesis of eukaryotic ribosomes is a fundamental process involving hundreds of ribosome biogenesis factors (RBFs) in three compartments of the cell, namely the nucleolus, nucleus, and cytoplasm. Many RBFs are involved in the processing of the primary ribosomal (r)RNA transcript, in which three of the four rRNAs are imbedded. While pre-rRNA processing is well described for yeast and mammals, a detailed processing scheme for plants is lacking. Here, we discuss the emerging scheme of pre-rRNA processing in Arabidopsis thaliana in comparison to other eukaryotes, with a focus on plant characteristics. In addition, we highlight the impact of the ribosome and its biogenesis on developmental processes because common phenotypes can be observed for ribosomal protein and RBF mutants.
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Affiliation(s)
- Benjamin L Weis
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Jelena Kovacevic
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Sandra Missbach
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany; Current address: Sanofi-Aventis GmbH, Industriepark Höchst, K703, 65926 Frankfurt am Main, Germany
| | - Enrico Schleiff
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany; Cluster of Excellence Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany; Buchman Institute for Molecular Life Sciences, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany.
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5
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Abstract
RNA helicases of the DEAD-box family are found in all eukaryotes, most bacteria and many archaea. They play important roles in rearranging RNA-RNA and RNA-protein interactions. DEAD-box proteins are ATP-dependent RNA binding proteins and RNA-dependent ATPases. The first helicases of this large family of proteins were described in the 1980s. Since then our perception of these proteins has dramatically changed. From bona fide helicases, they became RNA binding proteins that separate duplex RNAs, in a local manner, by binding and bending the target RNA. In the present review we describe some of the experiments that were important milestones in the life of DEAD-box proteins since their birth 25 years ago.
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Affiliation(s)
- Patrick Linder
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, Genève 4, 1211, Switzerland,
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6
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Abstract
DEAD-box proteins, a large class of RNA-dependent ATPases, regulate all aspects of gene expression and RNA metabolism. They can facilitate dissociation of RNA duplexes and remodeling of RNA-protein complexes, serve as ATP-dependent RNA-binding proteins, or even anneal duplexes. These proteins have highly conserved sequence elements that are contained within two RecA-like domains; consequently, their structures are nearly identical. Furthermore, crystal structures of DEAD-box proteins with bound RNA reveal interactions exclusively between the protein and the RNA backbone. Together, these findings suggest that DEAD-box proteins interact with their substrates in a nonspecific manner, which is confirmed in biochemical experiments. Nevertheless, this contrasts with the need to target these enzymes to specific substrates in vivo. Using the DEAD-box protein Rok1 and its cofactor Rrp5, which both function during maturation of the small ribosomal subunit, we show here that Rrp5 provides specificity to the otherwise nonspecific biochemical activities of the Rok1 DEAD-domain. This finding could reconcile the need for specific substrate binding of some DEAD-box proteins with their nonspecific binding surface and expands the potential roles of cofactors to specificity factors. Identification of helicase cofactors and their RNA substrates could therefore help define the undescribed roles of the 19 DEAD-box proteins that function in ribosome assembly.
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7
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Rodríguez-Galán O, García-Gómez JJ, de la Cruz J. Yeast and human RNA helicases involved in ribosome biogenesis: current status and perspectives. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:775-90. [PMID: 23357782 DOI: 10.1016/j.bbagrm.2013.01.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/15/2013] [Accepted: 01/16/2013] [Indexed: 11/17/2022]
Abstract
Ribosome biogenesis is a fundamental process that is conserved in eukaryotes. Although spectacular progress has been made in understanding mammalian ribosome synthesis in recent years, by far, this process has still been best characterised in the yeast Saccharomyces cerevisiae. In yeast, besides the rRNAs, the ribosomal proteins and the 75 small nucleolar RNAs, more than 250 non-ribosomal proteins, generally referred to as trans-acting factors, are involved in ribosome biogenesis. These factors include nucleases, RNA modifying enzymes, ATPases, GTPases, kinases and RNA helicases. Altogether, they likely confer speed, accuracy and directionality to the ribosome synthesis process, however, the precise functions for most of them are still largely unknown. This review summarises our current knowledge on eukaryotic RNA helicases involved in ribosome biogenesis, particularly focusing on the most recent advances with respect to the molecular roles of these enzymes and their co-factors in yeast and human cells. This article is part of a Special Issue entitled: The Biology of RNA helicases-Modulation for life.
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8
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Martin R, Straub AU, Doebele C, Bohnsack MT. DExD/H-box RNA helicases in ribosome biogenesis. RNA Biol 2012; 10:4-18. [PMID: 22922795 DOI: 10.4161/rna.21879] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Ribosome synthesis requires a multitude of cofactors, among them DExD/H-box RNA helicases. Bacterial RNA helicases involved in ribosome assembly are not essential, while eukaryotes strictly require multiple DExD/H-box proteins that are involved in the much more complex ribosome biogenesis pathway. Here, RNA helicases are thought to act in structural remodeling of the RNPs including the modulation of protein binding, and they are required for allowing access or the release of specific snoRNPs from pre-ribosomes. Interestingly, helicase action is modulated by specific cofactors that can regulate recruitment and enzymatic activity. This review summarizes the current knowledge and focuses on recent findings and open questions on RNA helicase function and regulation in ribosome synthesis.
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Affiliation(s)
- Roman Martin
- Centre for Biochemistry and Molecular Cell Biology, Göttingen University, Göttingen, Germany
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9
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Rawling DC, Baserga SJ. In vivo approaches to dissecting the function of RNA helicases in eukaryotic ribosome assembly. Methods Enzymol 2012; 511:289-321. [PMID: 22713326 DOI: 10.1016/b978-0-12-396546-2.00014-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In eukaryotes, ribosome biogenesis involves the nucleolar transcription and processing of pre-ribosomal RNA molecules (pre-rRNA) in a complex pathway requiring the participation of myriad protein and ribonucleoprotein factors. Through efforts aimed at categorizing and characterizing these factors, at least 20 RNA helicases have been shown to interact with or participate in the activities of the major ribosome biogenesis complexes. Unfortunately, little is known about the enzymatic properties of most of these helicases, and less is known about their roles in ribosome biogenesis and pre-rRNA maturation. This chapter presents approaches for characterizing RNA helicases involved in ribosome biogenesis. Included are methods for depletion of specific protein targets, with standard protocols for assaying the typical ribosome biogenesis defects that may result. Procedures and rationales for mutagenic studies of target proteins are discussed, as well as several approaches for identifying protein-protein interactions in order to determine functional context and potential cofactors of RNA helicases.
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Affiliation(s)
- David C Rawling
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, USA
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10
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Daugeron MC, Prouteau M, Lacroute F, Séraphin B. The highly conserved eukaryotic DRG factors are required for efficient translation in a manner redundant with the putative RNA helicase Slh1. Nucleic Acids Res 2010; 39:2221-33. [PMID: 21076151 PMCID: PMC3064805 DOI: 10.1093/nar/gkq898] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Eukaryotic and archaeal DRG factors are highly conserved proteins with characteristic GTPase motifs. This suggests their implication in a central biological process, which has so far escaped detection. We show here that the two Saccharomyces cerevisiae DRGs form distinct complexes, RBG1 and RBG2, and that the former co-fractionate with translating ribosomes. A genetic screen for triple synthetic interaction demonstrates that yeast DRGs have redundant function with Slh1, a putative RNA helicase also associating with translating ribosomes. Translation and cell growth are severely impaired in a triple mutant lacking both yeast DRGs and Slh1, but not in double mutants. This new genetic assay allowed us to characterize the roles of conserved motifs present in these proteins for efficient translation and/or association with ribosomes. Altogether, our results demonstrate for the first time a direct role of the highly conserved DRG factors in translation and indicate that this function is redundantly shared by three factors. Furthermore, our data suggest that important cellular processes are highly buffered against external perturbation and, consequently, that redundantly acting factors may escape detection in current high-throughput binary genetic interaction screens.
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Affiliation(s)
- Marie-Claire Daugeron
- Equipe Labellisée La Ligue, CGM, CNRS FRE3144, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, Univ Paris-Sud, Orsay F-91405, France
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Liu M, Shi DQ, Yuan L, Liu J, Yang WC. SLOW WALKER3, encoding a putative DEAD-box RNA helicase, is essential for female gametogenesis in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:817-28. [PMID: 20738726 DOI: 10.1111/j.1744-7909.2010.00972.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
RNA helicases are adenosine tri-phosphatases that unwind the secondary structures of RNAs and are required in almost any aspect of RNA metabolism. They are highly conserved from prokaryotic to eukaryotic organisms. However, their precise roles in plant physiology and development remain to be clarified. Here we report that the mutation in the gene SLOW WALKER3 (SWA3) results in the slow and retarded progression of mitosis during megagametogenesis in Arabidopsis. SWA3 is a putative RNA helicase of the DEAD-box subfamily. Mutant megagametophyte development is arrested at four- or eight-nucleate stages, furthermore, one of the synergids in about half of the mutant embryo sacs displays abnormal polarity, with its nucleus locating at the chalazal end, instead of the micropylar end in the wild-type. Transmission of the mutation through female gametophytes is severely reduced in swa3. However, a small portion of mutant embryo sacs are able to develop into mature and functional female gametophytes when pollination was postponed. The SWA3 in Arabidopsis is a homolog of Dbp8 in yeast. Dbp8 interacts with Efs2 and is essential for biogenesis of 18S rRNA in yeast. Our data suggest that SWA3 may form a complex with AtEfs2 and take roles in ribosomal biogenesis as RNA helicase during megagametogenesis in Arabidopsis.
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Affiliation(s)
- Man Liu
- Key Laboratory of Molecular and Developmental Biology, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, Beijing, China
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Huang CK, Yu SM, Lu CA. A rice DEAD-box protein, OsRH36, can complement an Arabidopsis atrh36 mutant, but cannot functionally replace its yeast homolog Dbp8p. PLANT MOLECULAR BIOLOGY 2010; 74:119-28. [PMID: 20607362 DOI: 10.1007/s11103-010-9659-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 06/18/2010] [Indexed: 05/25/2023]
Abstract
DEAD-box proteins comprise a large family and function in RNA metabolism. Although DEAD-box proteins are highly conserved among eukaryotes, little is known about the role of DEAD-box proteins in rice. In this study, we identified a rice DEAD-box protein, OsRH36, and demonstrated that OsRH36 and AtRH36 are functional orthologs. OsRH36 was expressed ubiquitously throughout the plant and the OsRH36-GFP fusion protein was localized to the nucleus and nucleolus. Furthermore, functional complementation tests among three homologous DEAD-box protein genes indicated that OsRH36 can restore segregation distortion in the Arabidopsis atrh36-1 mutant, but cannot complement the lethal phenotype in the yeast dbp8p mutant. Moreover, mutation of osrh36 also led to defective transmission of the osrh36 allele, as shown for the atrh36 mutants of Arabidopsis. Previously, we have shown that AtRH36 is involved at an early stage of rRNA maturation and is required for synchronous development of female gametophytes in Arabidopsis. Therefore, we suggest that OsRH36 is required for rRNA biogenesis and megagametogenesis in rice, consistent with the function of AtRH36 in Arabidopsis.
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Affiliation(s)
- Chun-Kai Huang
- Department of Life Science, National Central University, Zhongli, Taoyuan County, Taiwan, ROC
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13
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Huang CK, Huang LF, Huang JJ, Wu SJ, Yeh CH, Lu CA. A DEAD-box protein, AtRH36, is essential for female gametophyte development and is involved in rRNA biogenesis in Arabidopsis. PLANT & CELL PHYSIOLOGY 2010; 51:694-706. [PMID: 20378763 DOI: 10.1093/pcp/pcq045] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
DEAD-box RNA helicases are involved in RNA metabolism, including pre-mRNA splicing, ribosome biogenesis, RNA decay and gene expression. In this study, we identified a homolog of the RH36 gene, AtRH36, which encodes a DEAD-box protein in Arabidopsis thaliana. The gene was expressed ubiquitously throughout the plant. The AtRH36 fused to green fluorescent protein was localized in the nucleus. Homozygosity for the Arabidopsis atrh36 mutants, atrh36-1 and atrh36-2, could not be obtained. Progeny of selfed Arabidopsis atrh36 heterozygote plants were obtained at a heterozygote to wild-type ratio of 1 : 1, which suggested that the AtRH36 gene was involved in gametogenesis. Therefore, we performed a reciprocal cross to determine whether AtRH36 was involved in female gametophyte development. Female gametogenesis was delayed in atrh36-1, and asynchronous development of the female gametophytes was found within a single pistil. Knock-down of AtRH36 gave a pleiotropic phenotype and led to the accumulation of unprocessed 18S pre-rRNA. These results suggest that AtRH36 is essential for mitotic division during female gametogenesis and plays an important role in rRNA biogenesis in Arabidopsis.
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Affiliation(s)
- Chun-Kai Huang
- Department of Life Science, National Central University, Jhongli City, Taoyuan County 320, Taiwan, ROC
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14
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Banroques J, Doère M, Dreyfus M, Linder P, Tanner NK. Motif III in superfamily 2 "helicases" helps convert the binding energy of ATP into a high-affinity RNA binding site in the yeast DEAD-box protein Ded1. J Mol Biol 2009; 396:949-66. [PMID: 20026132 DOI: 10.1016/j.jmb.2009.12.025] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 12/08/2009] [Accepted: 12/14/2009] [Indexed: 01/09/2023]
Abstract
Motif III in the putative helicases of superfamily 2 is highly conserved in both its sequence and its structural context. It typically consists of the sequence alcohol-alanine-alcohol (S/T-A-S/T). Historically, it was thought to link ATPase activity with a "helicase" strand displacement activity that disrupts RNA or DNA duplexes. DEAD-box proteins constitute the largest family of superfamily 2; they are RNA-dependent ATPases and ATP-dependent RNA binding proteins that, in some cases, are able to disrupt short RNA duplexes. We made mutations of motif III (S-A-T) in the yeast DEAD-box protein Ded1 and analyzed in vivo phenotypes and in vitro properties. Moreover, we made a tertiary model of Ded1 based on the solved structure of Vasa. We used Ded1 because it has relatively high ATPase and RNA binding activities; it is able to displace moderately stable duplexes at a large excess of substrate. We find that the alanine and the threonine in the second and third positions of motif III are more important than the serine, but that mutations of all three residues have strong phenotypes. We purified the wild-type and various mutants expressed in Escherichia coli. We found that motif III mutations affect the RNA-dependent hydrolysis of ATP (k(cat)), but not the affinity for ATP (K(m)). Moreover, mutations alter and reduce the affinity for single-stranded RNA and subsequently reduce the ability to disrupt duplexes. We obtained intragenic suppressors of the S-A-C mutant that compensate for the mutation by enhancing the affinity for ATP and RNA. We conclude that motif III and the binding energy of gamma-PO(4) of ATP are used to coordinate motifs I, II, and VI and the two RecA-like domains to create a high-affinity single-stranded RNA binding site. It also may help activate the beta,gamma-phosphoanhydride bond of ATP.
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Affiliation(s)
- Josette Banroques
- Institut de Biologie Physico-chimique, CNRS UPR 9073 in association with the Université Paris VII, Paris 75005, France
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15
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Abstract
Ribosome assembly is required for cell growth in all organisms. Classic in vitro work in bacteria has led to a detailed understanding of the biophysical, thermodynamic, and structural basis for the ordered and correct assembly of ribosomal proteins on ribosomal RNA. Furthermore, it has enabled reconstitution of active subunits from ribosomal RNA and proteins in vitro. Nevertheless, recent work has shown that eukaryotic ribosome assembly requires a large macromolecular machinery in vivo. Many of these assembly factors such as ATPases, GTPases, and kinases hydrolyze nucleotide triphosphates. Because these enzymes are likely regulatory proteins, much work to date has focused on understanding their role in the assembly process. Here, we review these factors, as well as other sources of energy, and their roles in the ribosome assembly process. In addition, we propose roles of energy-releasing enzymes in the assembly process, to explain why energy is used for a process that occurs largely spontaneously in bacteria. Finally, we use literature data to suggest testable models for how these enzymes could be used as targets for regulation of ribosome assembly.
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Affiliation(s)
- Bethany S Strunk
- Chemical Biology Doctoral Program, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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16
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Acencio ML, Lemke N. Towards the prediction of essential genes by integration of network topology, cellular localization and biological process information. BMC Bioinformatics 2009; 10:290. [PMID: 19758426 PMCID: PMC2753850 DOI: 10.1186/1471-2105-10-290] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 09/16/2009] [Indexed: 11/21/2022] Open
Abstract
Background The identification of essential genes is important for the understanding of the minimal requirements for cellular life and for practical purposes, such as drug design. However, the experimental techniques for essential genes discovery are labor-intensive and time-consuming. Considering these experimental constraints, a computational approach capable of accurately predicting essential genes would be of great value. We therefore present here a machine learning-based computational approach relying on network topological features, cellular localization and biological process information for prediction of essential genes. Results We constructed a decision tree-based meta-classifier and trained it on datasets with individual and grouped attributes-network topological features, cellular compartments and biological processes-to generate various predictors of essential genes. We showed that the predictors with better performances are those generated by datasets with integrated attributes. Using the predictor with all attributes, i.e., network topological features, cellular compartments and biological processes, we obtained the best predictor of essential genes that was then used to classify yeast genes with unknown essentiality status. Finally, we generated decision trees by training the J48 algorithm on datasets with all network topological features, cellular localization and biological process information to discover cellular rules for essentiality. We found that the number of protein physical interactions, the nuclear localization of proteins and the number of regulating transcription factors are the most important factors determining gene essentiality. Conclusion We were able to demonstrate that network topological features, cellular localization and biological process information are reliable predictors of essential genes. Moreover, by constructing decision trees based on these data, we could discover cellular rules governing essentiality.
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Affiliation(s)
- Marcio L Acencio
- Department of Physics and Biophysics, São Paulo State University, Botucatu, São Paulo, Brazil.
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Garcia I, Uhlenbeck OC. Differential RNA-dependent ATPase activities of four rRNA processing yeast DEAD-box proteins. Biochemistry 2008; 47:12562-73. [PMID: 18975973 PMCID: PMC2649780 DOI: 10.1021/bi8016119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
S. cerevisiae ribosome biogenesis is a highly ordered and dynamic process that involves over 100 accessory proteins, including 18 DExD/H-box proteins that act at discrete steps in the pathway. Although often termed RNA helicases, the biochemical functions of individual DExD/H-box proteins appear to vary considerably. Four DExD/H-box proteins, Dbp3p, Dbp4p, Rok1p, and Rrp3p, involved in yeast ribosome assembly were expressed in E. coli, and all were found to be active RNA-dependent ATPases with k(cat) values ranging from 13 to 170 min(-1) and K(M)(ATP) values ranging from 0.24 to 2.3 mM. All four proteins are activated by single-stranded oligonucleotides, but they require different chain lengths for maximal ATPase activity, ranging from 10 to >40 residues. None of the four proteins shows significant specificity for yeast rRNA, compared to nonspecific control RNAs since these large RNAs contain multiple binding sites that appear to be catalytically similar. This systematic comparison of four members of the DExD/H-box family demonstrates a range of biochemical properties and lays the foundation for relating the activities of proteins to their biological functions.
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Affiliation(s)
- Ivelitza Garcia
- Department of Biochemistry Molecular Biology, and Cellular Biology, Northwestern University, 2205 Tech Drive, Hogan 2-100, Evanston, IL 60208
| | - Olke C. Uhlenbeck
- Department of Biochemistry Molecular Biology, and Cellular Biology, Northwestern University, 2205 Tech Drive, Hogan 2-100, Evanston, IL 60208
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18
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Elles LMS, Uhlenbeck OC. Mutation of the arginine finger in the active site of Escherichia coli DbpA abolishes ATPase and helicase activity and confers a dominant slow growth phenotype. Nucleic Acids Res 2007; 36:41-50. [PMID: 17986459 PMCID: PMC2248767 DOI: 10.1093/nar/gkm926] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Escherichia coli DEAD-box protein A (DbpA) is an ATP-dependent RNA helicase with specificity for 23S ribosomal RNA. Although DbpA has been extensively characterized biochemically, its biological function remains unknown. Previous work has shown that a DbpA deletion strain is viable with little or no effect on growth rate. In attempt to elucidate a phenotype for DbpA, point mutations were made at eleven conserved residues in the ATPase active site, which have exhibited dominant-negative phenotypes in other DExD/H proteins. Biochemical analysis of these DbpA mutants shows the expected decrease in RNA-dependent ATPase activity and helix unwinding activity. Only the least biochemically active mutation, R331A, produces small colony phenotype and a reduced growth rate. This dominant slow growth mutant will be valuable to determine the cellular function of DbpA.
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Affiliation(s)
- Lisa M Sharpe Elles
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA
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19
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Linder P. Dead-box proteins: a family affair--active and passive players in RNP-remodeling. Nucleic Acids Res 2006; 34:4168-80. [PMID: 16936318 PMCID: PMC1616962 DOI: 10.1093/nar/gkl468] [Citation(s) in RCA: 347] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 06/19/2006] [Accepted: 06/20/2006] [Indexed: 11/23/2022] Open
Abstract
DEAD-box proteins are characterized by nine conserved motifs. According to these criteria, several hundreds of these proteins can be identified in databases. Many different DEAD-box proteins can be found in eukaryotes, whereas prokaryotes have small numbers of different DEAD-box proteins. DEAD-box proteins play important roles in RNA metabolism, and they are very specific and cannot mutually be replaced. In vitro, many DEAD-box proteins have been shown to have RNA-dependent ATPase and ATP-dependent RNA helicase activities. From the genetic and biochemical data obtained mainly in yeast, it has become clear that these proteins play important roles in remodeling RNP complexes in a temporally controlled fashion. Here, I shall give a general overview of the DEAD-box protein family.
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Affiliation(s)
- Patrick Linder
- Department of Microbiology and Molecular Medicine, CMU 1, rue Michel Servet, CH-1211 Genève 4, Switzerland.
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20
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Tuteja R, Pradhan A. Unraveling the 'DEAD-box' helicases of Plasmodium falciparum. Gene 2006; 376:1-12. [PMID: 16713133 PMCID: PMC7127577 DOI: 10.1016/j.gene.2006.03.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 03/06/2006] [Accepted: 03/07/2006] [Indexed: 11/16/2022]
Abstract
The causative agent for the most fatal form of malaria, Plasmodium falciparum, has developed insecticide and drug resistance with time. Therefore combating this disease is becoming increasingly difficult and this calls for finding alternate ways to control malaria. One of the feasible ways could be to find out inhibitors/drugs specific for the indispensable enzymes of malaria parasite such as helicases. These helicases, which contain intrinsic nucleic acid-dependent ATPase activity, are capable of enzymatically unwinding energetically stable duplex nucleic acids into single-stranded templates and are required for all the nucleic acid transactions. Most of the helicases contain a set of nine extremely conserved amino acid sequences, which are called 'helicase motifs'. Due to the presence of the DEAD (Asp-Glu-Ala-Asp) in one of the conserved motifs, this family is also known as the 'DEAD-box' family. In this review, using bioinformatic approach, we describe the 'DEAD-box' helicases of malaria parasite P. falciparum. An in depth analysis shows that the parasite contains 22 full-length genes, some of which are homologues of well-characterized helicases of this family from other organisms. Recently we have cloned and characterized the first member of this family, which is a homologue of p68 and is expressed during the schizont stage of the development of the parasite [Pradhan, A., Chauhan, V.S., Tuteja, R., 2005a. A novel 'DEAD-box' DNA helicase from Plasmodium falciparum is homologous to p68. Mol. Biochem. Parasitol. 140, 55-60.; Pradhan A., Chauhan V.S., Tuteja R., 2005b. Plasmodium falciparum DNA helicase 60 is a schizont stage specific, bipolar and dual helicase stimulated by PKC phosphorylation. Mol. Biochem. Parasitol. 144, 133-141.]. It will be really interesting to clone and characterize other members of the 'DEAD-box' family and understand their role in the replication and transmission of the parasite. These detailed studies may help to identify a parasite-specific enzyme, which could be a potential drug target to treat malaria. The various steps at which this probable drug can act are also discussed.
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Affiliation(s)
- Renu Tuteja
- Malaria Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box 10504, Aruna Asaf Ali Marg, New Delhi-110067, India.
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21
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Granneman S, Lin C, Champion EA, Nandineni MR, Zorca C, Baserga SJ. The nucleolar protein Esf2 interacts directly with the DExD/H box RNA helicase, Dbp8, to stimulate ATP hydrolysis. Nucleic Acids Res 2006; 34:3189-99. [PMID: 16772403 PMCID: PMC1483223 DOI: 10.1093/nar/gkl419] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While 18 putative RNA helicases are involved in ribosome biogenesis in Saccharomyces cerevisiae, their enzymatic properties have remained largely biochemically uncharacterized. To better understand their function, we examined the enzymatic properties of Dpb8, a DExD/H box protein previously shown to be required for the synthesis of the 18S rRNA. As expected for an RNA helicase, we demonstrate that recombinant Dbp8 has ATPase activity in vitro, and that this activity is dependent on an intact ATPase domain. Strikingly, we identify Esf2, a nucleolar putative RNA binding protein, as a binding partner for Dbp8, and show that it enhances Dbp8 ATPase activity by decreasing the K(M) for ATP. Thus, we have uncovered Esf2 as the first example of a protein co-factor that has a stimulatory effect on a nucleolar RNA helicase. We show that Esf2 can bind to pre-rRNAs and speculate that it may function to bring Dbp8 to the pre-rRNA, thereby both regulating its enzymatic activity and guiding Dbp8 to its site of action.
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Affiliation(s)
- Sander Granneman
- Departments of Molecular Biophysics and Biochemistry, Yale University School of MedicineNew Haven, Connecticut 06520, USA
| | - ChieYu Lin
- Departments of Molecular Biophysics and Biochemistry, Yale University School of MedicineNew Haven, Connecticut 06520, USA
| | - Erica A. Champion
- Genetics, Yale University School of MedicineNew Haven, Connecticut 06520, USA
| | - Madhusudan R. Nandineni
- Departments of Molecular Biophysics and Biochemistry, Yale University School of MedicineNew Haven, Connecticut 06520, USA
| | - Cornelia Zorca
- Departments of Molecular Biophysics and Biochemistry, Yale University School of MedicineNew Haven, Connecticut 06520, USA
| | - Susan J. Baserga
- Departments of Molecular Biophysics and Biochemistry, Yale University School of MedicineNew Haven, Connecticut 06520, USA
- Genetics, Yale University School of MedicineNew Haven, Connecticut 06520, USA
- Therapeutic Radiology, Yale University School of MedicineNew Haven, Connecticut 06520, USA
- To whom correspondence should be addressed at Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, SHM C-114, 06520-8024, USA. Tel: 203 785 4618; Fax: 203 785 6404;
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Granneman S, Bernstein KA, Bleichert F, Baserga SJ. Comprehensive mutational analysis of yeast DEXD/H box RNA helicases required for small ribosomal subunit synthesis. Mol Cell Biol 2006; 26:1183-94. [PMID: 16449634 PMCID: PMC1367182 DOI: 10.1128/mcb.26.4.1183-1194.2006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 17 putative RNA helicases required for pre-rRNA processing are predicted to play a crucial role in ribosome biogenesis by driving structural rearrangements within preribosomes. To better understand the function of these proteins, we have generated a battery of mutations in five putative RNA helicases involved in 18S rRNA synthesis and analyzed their effects on cell growth and pre-rRNA processing. Our results define functionally important residues within conserved motifs and demonstrate that lethal mutations in predicted ATP binding-hydrolysis motifs often confer a dominant negative phenotype in vivo when overexpressed in a wild-type background. We show that dominant negative mutants delay processing of the 35S pre-rRNA and cause accumulation of pre-rRNA species that normally have low steady-state levels. Our combined results establish that not all conserved domains function identically in each protein, suggesting that the RNA helicases may have distinct biochemical properties and diverse roles in ribosome biogenesis.
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Affiliation(s)
- Sander Granneman
- Molecular Biophysics & Biochemistry Department, Yale University School of Medicine, 333 Cedar St., SHM C-114, New Haven, CT 06520-8024, USA
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23
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Bernstein KA, Granneman S, Lee AV, Manickam S, Baserga SJ. Comprehensive mutational analysis of yeast DEXD/H box RNA helicases involved in large ribosomal subunit biogenesis. Mol Cell Biol 2006; 26:1195-208. [PMID: 16449635 PMCID: PMC1367183 DOI: 10.1128/mcb.26.4.1195-1208.2006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DEXD/H box putative RNA helicases are required for pre-rRNA processing in Saccharomyces cerevisiae, although their exact roles and substrates are unknown. To characterize the significance of the conserved motifs for helicase function, a series of five mutations were created in each of the eight essential RNA helicases (Has1, Dbp6, Dbp10, Mak5, Mtr4, Drs1, Spb4, and Dbp9) involved in 60S ribosomal subunit biogenesis. Each mutant helicase was screened for the ability to confer dominant negative growth defects and for functional complementation. Different mutations showed different degrees of growth inhibition among the helicases, suggesting that the conserved regions do not function identically in vivo. Mutations in motif I and motif II (the DEXD/H box) often conferred dominant negative growth defects, indicating that these mutations do not interfere with substrate binding. In addition, mutations in the putative unwinding domains (motif III) demonstrated that conserved amino acids are often not essential for function. Northern analysis of steady-state RNA from strains expressing mutant helicases showed that the dominant negative mutations also altered pre-rRNA processing. Coimmunoprecipitation experiments indicated that some RNA helicases associated with each other. In addition, we found that yeasts disrupted in expression of the two nonessential RNA helicases, Dbp3 and Dbp7, grew worse than when either one alone was disrupted.
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Affiliation(s)
- Kara A Bernstein
- Molecular Biophysics & Biochemistry Department, Yale University School of Medicine, 333 Cedar St., SHM C-114, New Haven, CT 06520-8024, USA
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24
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Lebaron S, Froment C, Fromont-Racine M, Rain JC, Monsarrat B, Caizergues-Ferrer M, Henry Y. The splicing ATPase prp43p is a component of multiple preribosomal particles. Mol Cell Biol 2005; 25:9269-82. [PMID: 16227579 PMCID: PMC1265834 DOI: 10.1128/mcb.25.21.9269-9282.2005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prp43p is a putative helicase of the DEAH family which is required for the release of the lariat intron from the spliceosome. Prp43p could also play a role in ribosome synthesis, since it accumulates in the nucleolus. Consistent with this hypothesis, we find that depletion of Prp43p leads to accumulation of 35S pre-rRNA and strongly reduces levels of all downstream pre-rRNA processing intermediates. As a result, the steady-state levels of mature rRNAs are greatly diminished following Prp43p depletion. We present data arguing that such effects are unlikely to be solely due to splicing defects. Moreover, we demonstrate by a combination of a comprehensive two-hybrid screen, tandem-affinity purification followed by mass spectrometry, and Northern analyses that Prp43p is associated with 90S, pre-60S, and pre-40S ribosomal particles. Prp43p seems preferentially associated with Pfa1p, a novel specific component of pre-40S ribosomal particles. In addition, Prp43p interacts with components of the RNA polymerase I (Pol I) transcription machinery and with mature 18S and 25S rRNAs. Hence, Prp43p might be delivered to nascent 90S ribosomal particles during pre-rRNA transcription and remain associated with preribosomal particles until their final maturation steps in the cytoplasm. Our data also suggest that the ATPase activity of Prp43p is required for early steps of pre-rRNA processing and normal accumulation of mature rRNAs.
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Affiliation(s)
- Simon Lebaron
- Laboratoire de Biologie Moléculaire Eucaryote, UMR5099 CNRS-Université Paul Sabatier, IFR109, 118 route de Narbonne, 31062 Toulouse cedex 09, France
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25
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Rocak S, Emery B, Tanner NK, Linder P. Characterization of the ATPase and unwinding activities of the yeast DEAD-box protein Has1p and the analysis of the roles of the conserved motifs. Nucleic Acids Res 2005; 33:999-1009. [PMID: 15718299 PMCID: PMC549409 DOI: 10.1093/nar/gki244] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The yeast DEAD-box protein Has1p is required for the maturation of 18S rRNA, the biogenesis of 40S r-subunits and for the processing of 27S pre-rRNAs during 60S r-subunit biogenesis. We purified recombinant Has1p and characterized its biochemical activities. We show that Has1p is an RNA-dependent ATPase in vitro and that it is able to unwind RNA/DNA duplexes in an ATP-dependent manner. We also report a mutational analysis of the conserved residues in motif I (86AKTGSGKT93), motif III (228SAT230) and motif VI (375HRVGRTARG383). The in vivo lethal K92A substitution in motif I abolishes ATPase activity in vitro. The mutations S228A and T230A partially dissociate ATPase and helicase activities, and they have cold-sensitive and lethal growth phenotypes, respectively. The H375E substitution in motif VI significantly decreased helicase but not ATPase activity and was lethal in vivo. These results suggest that both ATPase and unwinding activities are required in vivo. Has1p possesses a Walker A-like motif downstream of motif VI (383GTKGKGKS390). K389A substitution in this motif significantly increases the Has1p activity in vitro, which indicates it potentially plays a role as a negative regulator. Finally, rRNAs and poly(A) RNA serve as the best stimulators of the ATPase activity of Has1p among the tested RNAs.
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Affiliation(s)
| | | | | | - Patrick Linder
- To whom correspondence should be addressed. Tel: +41 22 379 54 84; Fax: +41 22 379 55 02;
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26
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Emery B, de la Cruz J, Rocak S, Deloche O, Linder P. Has1p, a member of the DEAD-box family, is required for 40S ribosomal subunit biogenesis in Saccharomyces cerevisiae. Mol Microbiol 2004; 52:141-58. [PMID: 15049817 DOI: 10.1111/j.1365-2958.2003.03973.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Has1 protein, a member of the DEAD-box family of ATP-dependent RNA helicases in Saccharomyces cerevisiae, has been found by different proteomic approaches to be associated with 90S and several pre-60S ribosomal complexes. Here, we show that Has1p is an essential trans-acting factor involved in 40S ribosomal subunit biogenesis. Polysome analyses of strains genetically depleted of Has1p or carrying a temperature-sensitive has1-1 mutation show a clear deficit in 40S ribosomal subunits. Analyses of pre-rRNA processing by pulse-chase labelling, Northern hybridization and primer extension indicate that these strains form less 18S rRNA because of inhibition of processing of the 35S pre-rRNA at the early cleavage sites A0, A1 and A2. Moreover, processing of the 27SA3 and 27SB pre-rRNAs is delayed in these strains. Therefore, in addition to its role in the biogenesis of 40S ribosomal subunits, Has1p is required for the optimal synthesis of 60S ribosomal subunits. Consistent with a role in ribosome biogenesis, Has1p is localized to the nucleolus. On sucrose gradients, Has1p is associated with a high-molecular-weight complex sedimenting at positions equivalent to 60S and pre-60S ribosomal particles. A mutation in the ATP-binding motif of Has1p does not support growth of a has1 null strain, suggesting that the enzymatic activity of Has1p is required in ribosome biogenesis. Finally, sequence comparisons suggest that Has1p homologues exist in all eukaryotes, and we show that a has1 null strain can be fully complemented by the Candida albicans homologue.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Candida albicans/genetics
- Cell Nucleolus/metabolism
- Centrifugation, Density Gradient
- DEAD-box RNA Helicases
- Genes, Essential
- Genes, Fungal
- Genetic Complementation Test
- Molecular Sequence Data
- Mutation
- Polyribosomes/metabolism
- RNA Helicases/chemistry
- RNA Helicases/genetics
- RNA Helicases/metabolism
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal/analysis
- RNA, Ribosomal/biosynthesis
- RNA, Ribosomal, 18S/analysis
- RNA, Ribosomal, 18S/biosynthesis
- Ribosomes/metabolism
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Alignment
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Affiliation(s)
- Bertrand Emery
- Département de Biochimie Médicale, Centre Médical Universitaire, 1, rue Michel Servet, CH-1211 Genève 4, Switzerland
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Abstract
Ribosome synthesis is a highly complex and coordinated process that occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells. Based on the protein composition of several ribosomal subunit precursors recently characterized in yeast, a total of more than 170 factors are predicted to participate in ribosome biogenesis and the list is still growing. So far the majority of ribosomal factors have been implicated in RNA maturation (nucleotide modification and processing). Recent advances gave insight into the process of ribosome export and assembly. Proteomic approaches have provided the first indications for a ribosome assembly pathway in eukaryotes and confirmed the dynamic character of the whole process.
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Abstract
Structural analyses of the large and small ribosomal subunits have allowed us to think about how they work in more detail than ever before. The mechanisms that underlie ribosomal synthesis, translocation and catalysis are now being unravelled, with practical implications for the design of antibiotics.
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Affiliation(s)
- D L Lafontaine
- FNRS, Université Libre de Bruxelles, Département de Biologie Moléculaire, IRMW - Campus CERIA, Avenue Emile Gryson 1, B-1070 Brussels, Belgium.
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29
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Current Awareness. Yeast 2001. [DOI: 10.1002/yea.686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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