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Clark ZS, O'Connor M. Suppressor analysis links trans-translation and ribosomal protein uS7 to RluD function in Escherichia coli. Biochem Biophys Res Commun 2024; 700:149584. [PMID: 38295647 PMCID: PMC10878134 DOI: 10.1016/j.bbrc.2024.149584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 01/25/2024] [Indexed: 02/17/2024]
Abstract
The pseudouridine (ψ) synthase, RluD is responsible for three ψ modifications in the helix 69 (H69) of bacterial 23S rRNA. While normally dispensable, rluD becomes critical for rapid cell growth in bacteria that are defective in translation-termination. In slow-growing rluD- bacteria, suppressors affecting termination factors RF2 and RF3 arise frequently and restore normal termination and rapid cell growth. Here we describe two weaker suppressors, affecting rpsG, encoding ribosomal protein uS7 and ssrA, encoding tmRNA. In K-12 strains of E. coli, rpsG terminates at a TGA codon. In the suppressor strain, alteration of an upstream CAG to a TAG stop codon results in a shortened uS7 and partial alleviation of slow growth, likely by replacing an inefficient TGA stop codon with the more efficient TAG. Inefficient termination events, such as occurs in some rluD- strains, are targeted by trans-translation. Inactivation of the ssrA gene in slow-growing, termination-defective mutants lacking RluD and RF3, also partially restores robust growth, most probably by preventing destruction of completed polypeptides on ribosomes at slow-terminating stop codons. Finally, an additional role for RluD has been proposed, independent of its pseudouridine synthase activity. This is based on the observation that plasmids expressing catalytically dead (D139N or D139T) RluD proteins could nonetheless restore robust growth to an E. coli K-12 rluD- mutant. However, newly constructed D139N and D139T rluD plasmids do not have any growth-restoring activity and the original observations were likely due to the appearance of suppressors.
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Affiliation(s)
- Zachary S Clark
- Division of Biology and Biomedical Systems, School of Science and Engineering, 306 Spencer Hall, University of Missouri-Kansas City, 5007 Rockhill Rd., Kansas City, MO, 64110, USA
| | - Michael O'Connor
- Division of Biology and Biomedical Systems, School of Science and Engineering, 306 Spencer Hall, University of Missouri-Kansas City, 5007 Rockhill Rd., Kansas City, MO, 64110, USA.
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2
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Chabronova A, van den Akker G, Housmans BAC, Caron MMJ, Cremers A, Surtel DAM, Peffers MJ, van Rhijn LW, Marchand V, Motorin Y, Welting TJM. Depletion of SNORA33 Abolishes ψ of 28S-U4966 and Affects the Ribosome Translational Apparatus. Int J Mol Sci 2023; 24:12578. [PMID: 37628759 PMCID: PMC10454564 DOI: 10.3390/ijms241612578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
Eukaryotic ribosomes are complex molecular nanomachines translating genetic information from mRNAs into proteins. There is natural heterogeneity in ribosome composition. The pseudouridylation (ψ) of ribosomal RNAs (rRNAs) is one of the key sources of ribosome heterogeneity. Nevertheless, the functional consequences of ψ-based ribosome heterogeneity and its relevance for human disease are yet to be understood. Using HydraPsiSeq and a chronic disease model of non-osteoarthritic primary human articular chondrocytes exposed to osteoarthritic synovial fluid, we demonstrated that the disease microenvironment is capable of instigating site-specific changes in rRNA ψ profiles. To investigate one of the identified differential rRNA ψ sites (28S-ψ4966), we generated SNORA22 and SNORA33 KO SW1353 cell pools using LentiCRISPRv2/Cas9 and evaluated the ribosome translational capacity by 35S-Met/Cys incorporation, assessed the mode of translation initiation and ribosomal fidelity using dual luciferase reporters, and assessed cellular and ribosomal proteomes by LC-MS/MS. We uncovered that the depletion of SNORA33, but not SNORA22, reduced 28S-ψ4966 levels. The resulting loss of 28S-ψ4966 affected ribosomal protein composition and function and led to specific changes in the cellular proteome. Overall, our pioneering findings demonstrate that cells dynamically respond to disease-relevant changes in their environment by altering their rRNA pseudouridylation profiles, with consequences for ribosome function and the cellular proteome relevant to human disease.
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Affiliation(s)
- Alzbeta Chabronova
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Guus van den Akker
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Bas A. C. Housmans
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Marjolein M. J. Caron
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Andy Cremers
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Don A. M. Surtel
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Mandy J. Peffers
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L8 7TX, UK
| | - Lodewijk W. van Rhijn
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
| | - Virginie Marchand
- UAR2008 IBSLor CNRS-INSERM-Université de Lorraine, F54000 Nancy, France
| | - Yuri Motorin
- UAR2008 IBSLor CNRS-INSERM-Université de Lorraine, F54000 Nancy, France
- UMR7365 IMOPA, CNRS-Université de Lorraine, F54000 Nancy, France
| | - Tim J. M. Welting
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, 6229 HX Maastricht, The Netherlands; (A.C.); (B.A.C.H.)
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University Medical Center+ (MUMC+), 6229 HX Maastricht, The Netherlands
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3
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Fatkhullin BF, Gabdulkhakov AG, Yusupov MM. Is RsfS a Hibernation Factor or a Ribosome Biogenesis Factor? BIOCHEMISTRY. BIOKHIMIIA 2022; 87:500-510. [PMID: 35790407 DOI: 10.1134/s0006297922060025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/20/2022] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
Solving the structures of bacterial, archaeal, and eukaryotic ribosomes by crystallography and cryo-electron microscopy has given an impetus for studying intracellular regulatory proteins affecting various stages of protein translation. Among them are ribosome hibernation factors, which have been actively investigated during the last decade. These factors are involved in the regulation of protein biosynthesis under stressful conditions. The main role of hibernation factors is the reduction of energy consumption for protein biosynthesis and preservation of existing functional ribosomes from degradation, which increases cell survival under unfavorable conditions. Despite a broad interest in this topic, only a few articles have been published on the ribosomal silencing factor S (RsfS). According to the results of these studies, RsfS can be assigned to the group of hibernation factors. However, recent structural studies of the 50S ribosomal subunit maturation demonstrated that RsfS has the features inherent to biogenesis factors for example, ability to bind to the immature ribosomal subunit (similar to the RsfS mitochondrial ortholog MALSU1, mitochondrial assembly of ribosomal large subunit 1). In this review, we summarized the information on the function and structural features RsfS, as well as compared RsfS with MALSU1 in order to answer the emerging question on whether RsfS is a hibernation factor or a ribosome biogenesis factor. We believe that this review might promote future studies of the RsfS-involving molecular mechanisms, which so far remain completely unknown.
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Affiliation(s)
- Bulat F Fatkhullin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
- Institute of Genetics and Molecular and Cellular Biology, Illkirsch-Graffenstaden, F-67400, France
| | - Azat G Gabdulkhakov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Marat M Yusupov
- Institute of Genetics and Molecular and Cellular Biology, Illkirsch-Graffenstaden, F-67400, France
- Laboratory of Structural Analyze of Biomacromolecules, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Kazan, 420111, Russia
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4
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Lahry K, Gopal A, Kumar Sahu A, Nora Marbaniang C, Ahmad Shah R, Mehta A, Varshney U. An alternative role of RluD in the fidelity of translation initiation in Escherichia coli. J Mol Biol 2022; 434:167588. [DOI: 10.1016/j.jmb.2022.167588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/21/2022] [Accepted: 04/10/2022] [Indexed: 10/18/2022]
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5
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Antoine L, Bahena-Ceron R, Devi Bunwaree H, Gobry M, Loegler V, Romby P, Marzi S. RNA Modifications in Pathogenic Bacteria: Impact on Host Adaptation and Virulence. Genes (Basel) 2021; 12:1125. [PMID: 34440299 PMCID: PMC8394870 DOI: 10.3390/genes12081125] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 12/19/2022] Open
Abstract
RNA modifications are involved in numerous biological processes and are present in all RNA classes. These modifications can be constitutive or modulated in response to adaptive processes. RNA modifications play multiple functions since they can impact RNA base-pairings, recognition by proteins, decoding, as well as RNA structure and stability. However, their roles in stress, environmental adaptation and during infections caused by pathogenic bacteria have just started to be appreciated. With the development of modern technologies in mass spectrometry and deep sequencing, recent examples of modifications regulating host-pathogen interactions have been demonstrated. They show how RNA modifications can regulate immune responses, antibiotic resistance, expression of virulence genes, and bacterial persistence. Here, we illustrate some of these findings, and highlight the strategies used to characterize RNA modifications, and their potential for new therapeutic applications.
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Affiliation(s)
| | | | | | | | | | | | - Stefano Marzi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, F-67000 Strasbourg, France; (L.A.); (R.B.-C.); (H.D.B.); (M.G.); (V.L.); (P.R.)
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6
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Chen J, Wang L, Jin X, Wan J, Zhang L, Je BI, Zhao K, Kong F, Huang J, Tian M. Oryza sativa ObgC1 Acts as a Key Regulator of DNA Replication and Ribosome Biogenesis in Chloroplast Nucleoids. RICE (NEW YORK, N.Y.) 2021; 14:65. [PMID: 34251486 PMCID: PMC8275814 DOI: 10.1186/s12284-021-00498-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 05/30/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The Spo0B-associated GTP-binding protein (Obg) GTPase, has diverse and important functions in bacteria, including morphological development, DNA replication and ribosome maturation. Homologs of the Bacillus subtilis Obg have been also found in chloroplast of Oryza sativa, but their primary roles remain unknown. RESULTS We clarify that OsObgC1 is a functional homolog of AtObgC. The mutant obgc1-d1 exhibited hypersensitivity to the DNA replication inhibitor hydroxyurea. Quantitative PCR results showed that the ratio of chloroplast DNA to nuclear DNA in the mutants was higher than that of the wild-type plants. After DAPI staining, OsObgC1 mutants showed abnormal nucleoid architectures. The specific punctate staining pattern of OsObgC1-GFP signal suggests that this protein localizes to the chloroplast nucleoids. Furthermore, loss-of-function mutation in OsObgC1 led to a severe suppression of protein biosynthesis by affecting plastid rRNA processing. It was also demonstrated through rRNA profiling that plastid rRNA processing was decreased in obgc1-d mutants, which resulted in impaired ribosome biogenesis. The sucrose density gradient profiles revealed a defective chloroplast ribosome maturation of obgc1-d1 mutants. CONCLUSION Our findings here indicate that the OsObgC1 retains the evolutionarily biological conserved roles of prokaryotic Obg, which acts as a signaling hub that regulates DNA replication and ribosome biogenesis in chloroplast nucleoids.
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Affiliation(s)
- Ji Chen
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
- Division of Applied Life Sciences (BK21+), Graduate School of Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Li Wang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Xiaowan Jin
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Jian Wan
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Lang Zhang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Byoung Il Je
- College of Ecology and Environment, Chengdu University of Technology, Chengdu, 61005, China
| | - Ke Zhao
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Fanlei Kong
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Jin Huang
- Division of Applied Life Sciences (BK21+), Graduate School of Gyeongsang National University, Jinju, 660-701, Republic of Korea.
- College of Ecology and Environment, Chengdu University of Technology, Chengdu, 61005, China.
| | - Mengliang Tian
- Institute for New Rural Development, Sichuan Agricultural University, Yaan, 625000, China.
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7
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Tobiasson V, Gahura O, Aibara S, Baradaran R, Zíková A, Amunts A. Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit. EMBO J 2021; 40:e106292. [PMID: 33576519 PMCID: PMC7957421 DOI: 10.15252/embj.2020106292] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/18/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022] Open
Abstract
Mitoribosomes consist of ribosomal RNA and protein components, coordinated assembly of which is critical for function. We used mitoribosomes from Trypanosoma brucei with reduced RNA and increased protein mass to provide insights into the biogenesis of the mitoribosomal large subunit. Structural characterization of a stable assembly intermediate revealed 22 assembly factors, some of which have orthologues/counterparts/homologues in mammalian genomes. These assembly factors form a protein network that spans a distance of 180 Å, shielding the ribosomal RNA surface. The central protuberance and L7/L12 stalk are not assembled entirely and require removal of assembly factors and remodeling of the mitoribosomal proteins to become functional. The conserved proteins GTPBP7 and mt‐EngA are bound together at the subunit interface in proximity to the peptidyl transferase center. A mitochondrial acyl‐carrier protein plays a role in docking the L1 stalk, which needs to be repositioned during maturation. Additional enzymatically deactivated factors scaffold the assembly while the exit tunnel is blocked. Together, this extensive network of accessory factors stabilizes the immature sites and connects the functionally important regions of the mitoribosomal large subunit.
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Affiliation(s)
- Victor Tobiasson
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Ondřej Gahura
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Shintaro Aibara
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Rozbeh Baradaran
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.,Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
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8
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Loss of Pseudouridine Synthases in the RluA Family Causes Hypersensitive Nociception in Drosophila. G3-GENES GENOMES GENETICS 2020; 10:4425-4438. [PMID: 33028630 PMCID: PMC7718762 DOI: 10.1534/g3.120.401767] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Nociceptive neurons of Drosophila melanogaster larvae are characterized by highly branched dendritic processes whose proper morphogenesis relies on a large number of RNA-binding proteins. Post-transcriptional regulation of RNA in these dendrites has been found to play an important role in their function. Here, we investigate the neuronal functions of two putative RNA modification genes, RluA-1 and RluA-2, which are predicted to encode pseudouridine synthases. RluA-1 is specifically expressed in larval sensory neurons while RluA-2 expression is ubiquitous. Nociceptor-specific RNAi knockdown of RluA-1 caused hypersensitive nociception phenotypes, which were recapitulated with genetic null alleles. These were rescued with genomic duplication and nociceptor-specific expression of UAS- RluA-1 -cDNA As with RluA-1, RluA-2 loss of function mutants also displayed hyperalgesia. Interestingly, nociceptor neuron dendrites showed a hyperbranched morphology in the RluA-1 mutants. The latter may be a cause or a consequence of heightened sensitivity in mutant nociception behaviors.
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9
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Pletnev P, Guseva E, Zanina A, Evfratov S, Dzama M, Treshin V, Pogorel'skaya A, Osterman I, Golovina A, Rubtsova M, Serebryakova M, Pobeguts OV, Govorun VM, Bogdanov AA, Dontsova OA, Sergiev PV. Comprehensive Functional Analysis of Escherichia coli Ribosomal RNA Methyltransferases. Front Genet 2020; 11:97. [PMID: 32174967 PMCID: PMC7056703 DOI: 10.3389/fgene.2020.00097] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 01/29/2020] [Indexed: 11/13/2022] Open
Abstract
Ribosomal RNAs in all organisms are methylated. The functional role of the majority of modified nucleotides is unknown. We systematically questioned the influence of rRNA methylation in Escherichia coli on a number of characteristics of bacterial cells with the help of a set of rRNA methyltransferase (MT) gene knockout strains from the Keio collection. Analysis of ribosomal subunits sedimentation profiles of the knockout strains revealed a surprisingly small number of rRNA MT that significantly affected ribosome assembly. Accumulation of the assembly intermediates was observed only for the rlmE knockout strain whose growth was retarded most significantly among other rRNA MT knockout strains. Accumulation of the 17S rRNA precursor was observed for rsmA(ksgA) knockout cells as well as for cells devoid of functional rsmB and rlmC genes. Significant differences were found among the WT and the majority of rRNA MT knockout strains in their ability to sustain exogenous protein overexpression. While the majority of the rRNA MT knockout strains supported suboptimal reporter gene expression, the strain devoid of the rsmF gene demonstrated a moderate increase in the yield of ectopic gene expression. Comparative 2D protein gel analysis of rRNA MT knockout strains revealed only minor perturbations of the proteome.
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Affiliation(s)
- Philipp Pletnev
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia
| | - Ekaterina Guseva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Anna Zanina
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Sergey Evfratov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Margarita Dzama
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Vsevolod Treshin
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Alexandra Pogorel'skaya
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Ilya Osterman
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Anna Golovina
- Belozersky Institute of Physico-Chemical Biololgy, Lomonosov Moscow State University, Moscow, Russia
| | - Maria Rubtsova
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Marina Serebryakova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Belozersky Institute of Physico-Chemical Biololgy, Lomonosov Moscow State University, Moscow, Russia
| | - Olga V Pobeguts
- Federal Research and Clinical Centre of Physical-Chemical Medicine, Moscow, Russia
| | - Vadim M Govorun
- Federal Research and Clinical Centre of Physical-Chemical Medicine, Moscow, Russia
| | - Alexey A Bogdanov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Belozersky Institute of Physico-Chemical Biololgy, Lomonosov Moscow State University, Moscow, Russia
| | - Olga A Dontsova
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia.,Belozersky Institute of Physico-Chemical Biololgy, Lomonosov Moscow State University, Moscow, Russia
| | - Petr V Sergiev
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Belozersky Institute of Physico-Chemical Biololgy, Lomonosov Moscow State University, Moscow, Russia.,Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, Russia
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10
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Choi E, Jeon H, Oh JI, Hwang J. Overexpressed L20 Rescues 50S Ribosomal Subunit Assembly Defects of bipA-Deletion in Escherichia coli. Front Microbiol 2020; 10:2982. [PMID: 31998269 PMCID: PMC6962249 DOI: 10.3389/fmicb.2019.02982] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/10/2019] [Indexed: 11/13/2022] Open
Abstract
The BipA (BPI-inducible protein A) protein is highly conserved in a large variety of bacteria and belongs to the translational GTPases, based on sequential and structural similarities. Despite its conservation in bacteria, bipA is not essential for cell growth under normal growth conditions. However, at 20°C, deletion of bipA causes not only severe growth defects but also several phenotypic changes such as capsule production, motility, and ribosome assembly, indicating that it has global regulatory properties. Our recent studies revealed that BipA is a novel ribosome-associating GTPase, whose expression is cold-shock-inducible and involved in the incorporation of the ribosomal protein (r-protein) L6. However, the precise mechanism of BipA in 50S ribosomal subunit assembly is not completely understood. In this study, to demonstrate the role of BipA in the 50S ribosomal subunit and possibly to find an interplaying partner(s), a genomic library was constructed and suppressor screening was conducted. Through screening, we found a suppressor gene, rplT, encoding r-protein L20, which is assembled at the early stage of ribosome assembly and negatively regulates its own expression at the translational level. We demonstrated that the exogenous expression of rplT restored the growth of bipA-deleted strain at low temperature by partially recovering the defects in ribosomal RNA processing and ribosome assembly. Our findings suggest that the function of BipA is pivotal for 50S ribosomal subunit biogenesis at a low temperature and imply that BipA and L20 may exert coordinated actions for proper ribosome assembly under cold-shock conditions.
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Affiliation(s)
- Eunsil Choi
- Department of Microbiology, Pusan National University, Busan, South Korea
| | - Hyerin Jeon
- Department of Microbiology, Pusan National University, Busan, South Korea
| | - Jeong-Il Oh
- Department of Microbiology, Pusan National University, Busan, South Korea
| | - Jihwan Hwang
- Department of Microbiology, Pusan National University, Busan, South Korea
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11
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Song S, Wood TK. Persister cells resuscitate via ribosome modification by 23S rRNA pseudouridine synthase RluD. Environ Microbiol 2019; 22:850-857. [DOI: 10.1111/1462-2920.14828] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 10/07/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Sooyeon Song
- Department of Chemical EngineeringPennsylvania State University University Park Pennsylvania 16802‐4400 USA
| | - Thomas K. Wood
- Department of Chemical EngineeringPennsylvania State University University Park Pennsylvania 16802‐4400 USA
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12
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Maiti P, Kim HJ, Tu YT, Barrientos A. Human GTPBP10 is required for mitoribosome maturation. Nucleic Acids Res 2018; 46:11423-11437. [PMID: 30321378 PMCID: PMC6265488 DOI: 10.1093/nar/gky938] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 09/18/2018] [Accepted: 10/05/2018] [Indexed: 01/07/2023] Open
Abstract
Most steps on the biogenesis of the mitochondrial ribosome (mitoribosome) occur near the mitochondrial DNA nucleoid, in RNA granules, which contain dedicated RNA metabolism and mitoribosome assembly factors. Here, analysis of the RNA granule proteome identified the presence of a set of small GTPases that belong to conserved families of ribosome assembly factors. We show that GTPBP10, a member of the conserved Obg family of P-loop small G proteins, is a mitochondrial protein and have used gene-editing technologies to create a HEK293T cell line KO for GTPBP10. The absence of GTPBP10 leads to attenuated mtLSU and mtSSU levels and the virtual absence of the 55S monosome, which entirely prevents mitochondrial protein synthesis. We show that a fraction of GTPBP10 cosediments with the large mitoribosome subunit and the monosome. GTPBP10 physically interacts with the 16S rRNA, but not with the 12S rRNA, and crosslinks with several mtLSU proteins. Additionally, GTPBP10 is indirectly required for efficient processing of the 12S-16S rRNA precursor transcript, which could explain the mtSSU accumulation defect. We propose that GTPBP10 primarily ensures proper mtLSU maturation and ultimately serves to coordinate mtSSU and mtLSU accumulation then providing a quality control check-point function during mtLSU assembly that minimizes premature subunit joining.
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Affiliation(s)
- Priyanka Maiti
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Hyun-Jung Kim
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Ya-Ting Tu
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Antoni Barrientos
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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13
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Jiang Y, Yu H, Li F, Cheng L, Zhu L, Shi Y, Gong Q. Unveiling the structural features that determine the dual methyltransferase activities of Streptococcus pneumoniae RlmCD. PLoS Pathog 2018; 14:e1007379. [PMID: 30388185 PMCID: PMC6235398 DOI: 10.1371/journal.ppat.1007379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/14/2018] [Accepted: 10/03/2018] [Indexed: 12/03/2022] Open
Abstract
Methyltransferase RlmCD was previously shown to be responsible for the introduction of C5 methylation at both U747 and U1939 of the 23S ribosomal RNA in Streptococcus pneumoniae. Intriguingly, its structural homologue, RumA, can only catalyze the methylation of U1939, while RlmC is the dedicated enzyme for m5U747 in Escherichia coli. In this study, we describe the structure of RlmCD in complex with its cofactor and the RNA substrate containing U747 at 2.00 Å or U1939 at 3.10 Å. We demonstrate that multiple structural features collaborate to establish the dual enzymatic activities of RlmCD. Of them, the side-chain rearrangement of F145 was observed to be an unusual mechanism through which RlmCD can discriminate between U747- and U1939-containing RNA substrate by switching the intermolecular aromatic stacking between protein and RNA on/off. An in-vitro methyltransferase assay and electrophoretic mobility shift assay were performed to validate these findings. Overall, our complex structures allow for a better understanding of the dual-functional mechanism of RlmCD, suggesting useful implications for the evolution of the RumA-type enzyme and the potential development of antibiotic drugs against S. pneumoniae.
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Affiliation(s)
- Yiyang Jiang
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Hailong Yu
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Fudong Li
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Lin Cheng
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Lingru Zhu
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Yunyu Shi
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Qingguo Gong
- Hefei National Laboratory for Physical Science at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
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14
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Investigation on the Evolutionary Relation of Diverse Polyhydroxyalkanoate Gene Clusters in Betaproteobacteria. J Mol Evol 2018; 86:470-483. [PMID: 30062554 DOI: 10.1007/s00239-018-9859-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 07/24/2018] [Indexed: 10/28/2022]
Abstract
Products of numerous genes (phaC, phaA, phaB, phaP, phaR, and phaZ) are involved in the synthesis and degradation processes of the ubiquitous prokaryotic polyhydroxyalkanoate (PHA) intracellular reserve storage system. In this study, we performed a bioinformatics analysis to identify PHA-related genes and proteins in the genome of 66 selected organisms (class: Betaproteobacteria) that occur in various habitats; besides, evolutionary trajectories of the PHA system are reported here. The identified PHA-related genes were organized into clusters, and the gene arrangement was highly diverse. The occurrence and distribution of PHA-related clusters revealed that a single cluster was primarily segmented into small gene groups among various genomes, which were further reorganized as novel clusters based on various functional genes. The individual phylogenies of gene and protein sequences supported that the clusters were assembled through the relocation of native orthologous genes that underwent insertion, deletion, and elongation events. Furthermore, the neighboring genes provided valuable evolutionary and functional cues regarding the conservation and maintenance of PHA-related genes in the genome. Overall, the aforementioned results strongly indicate the influence of horizontal gene transfer on the organization of PHA-related gene clusters. Therefore, our results reveal new insights into the organization, evolutionary history, and cluster conservation of the PHA-related gene inventories among Betaproteobacterial organisms.
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15
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16
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Leppik M, Liiv A, Remme J. Random pseuoduridylation in vivo reveals critical region of Escherichia coli 23S rRNA for ribosome assembly. Nucleic Acids Res 2017; 45:6098-6108. [PMID: 28334881 PMCID: PMC5449589 DOI: 10.1093/nar/gkx160] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 02/20/2017] [Accepted: 02/27/2017] [Indexed: 12/18/2022] Open
Abstract
Pseudouridine is the most common modified nucleoside in RNA, which is found in stable RNA species and in eukaryotic mRNAs. Functional analysis of pseudouridine is complicated by marginal effect of its absence. We demonstrate that excessive pseudouridines in rRNA inhibit ribosome assembly. Ten-fold increase of pseudouridines in the 16S and 23S rRNA made by a chimeric pseudouridine synthase leads to accumulation of the incompletely assembled large ribosome subunits. Hyper modified 23S rRNA is found in the r-protein assembly defective particles and are selected against in the 70S and polysome fractions showing modification interference. Eighteen positions of 23S rRNA were identified where isomerization of uridines interferes with ribosome assembly. Most of the interference sites are located in the conserved core of the large subunit, in the domain 0 of 23S rRNA, around the peptide exit tunnel. A plausible reason for pseudouridine-dependent inhibition of ribosome assembly is stabilization of rRNA structure, which leads to the folding traps of rRNA and to the retardation of the ribosome assembly.
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Affiliation(s)
- Margus Leppik
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Aivar Liiv
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Jaanus Remme
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
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17
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Abstract
All types of nucleic acids in cells undergo naturally occurring chemical modifications, including DNA, rRNA, mRNA, snRNA, and most prominently tRNA. Over 100 different modifications have been described and every position in the purine and pyrimidine bases can be modified; often the sugar is also modified [1]. In tRNA, the function of modifications varies; some modulate global and/or local RNA structure, and others directly impact decoding and may be essential for viability. Whichever the case, the overall importance of modifications is highlighted by both their evolutionary conservation and the fact that organisms use a substantial portion of their genomes to encode modification enzymes, far exceeding what is needed for the de novo synthesis of the canonical nucleotides themselves [2]. Although some modifications occur at exactly the same nucleotide position in tRNAs from the three domains of life, many can be found at various positions in a particular tRNA and their location may vary between and within different tRNAs. With this wild array of chemical diversity and substrate specificities, one of the big challenges in the tRNA modification field has been to better understand at a molecular level the modes of substrate recognition by the different modification enzymes; in this realm RNA binding rests at the heart of the problem. This chapter will focus on several examples of modification enzymes where their mode of RNA binding is well understood; from these, we will try to draw general conclusions and highlight growing themes that may be applicable to the RNA modification field at large.
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18
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Mundus J, Flyvbjerg KF, Kirpekar F. Identification of the methyltransferase targeting C2499 in Deinococcus radiodurans 23S ribosomal RNA. Extremophiles 2016; 20:91-9. [PMID: 26590840 PMCID: PMC4690841 DOI: 10.1007/s00792-015-0800-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/29/2015] [Indexed: 01/11/2023]
Abstract
The bacterium Deinococcus radiodurans-like all other organisms-introduces nucleotide modifications into its ribosomal RNA. We have previously found that the bacterium contains a Carbon-5 methylation on cytidine 2499 of its 23S ribosomal RNA, which is so far the only modified version of cytidine 2499 reported. Using homology search, we identified the open reading frame DR_0049 as the primary candidate gene for the methyltransferase that modifies cytidine 2499. Mass spectrometric analysis demonstrated that recombinantly expressed DR0049 protein methylates E. coli cytidine 2499 both in vitro and in vivo. We also inactivated the DR_0049 gene in D. radiodurans through insertion of a chloramphenicol resistance cassette. This resulted in complete absence of the cytidine 2499 methylation, which all together demonstrates that DR_0049 encodes the methyltransferase producing m(5)C2499 in D. radiodurans 23S rRNA. Growth experiments disclosed that inactivation of DR_0049 is associated with a severe growth defect, but available ribosome structures show that cytidine 2499 is positioned very similar in D. radiodurans harbouring the modification and E. coli without the modification. Hence there is no obvious structure-based explanation for the requirement for the C2499 posttranscriptional modification in D. radiodurans.
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Affiliation(s)
- Julie Mundus
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Karen Freund Flyvbjerg
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Finn Kirpekar
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
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19
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High-resolution structure of the Escherichia coli ribosome. Nat Struct Mol Biol 2015; 22:336-41. [PMID: 25775265 PMCID: PMC4429131 DOI: 10.1038/nsmb.2994] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 02/19/2015] [Indexed: 01/21/2023]
Abstract
Protein synthesis by the ribosome is highly dependent on the ionic conditions in the cellular environment, but the roles of ribosome solvation remain poorly understood. Moreover, the function of modifications to ribosomal RNA and ribosomal proteins are unclear. Here we present the structure of the Escherichia coli 70S ribosome to 2.4 Å resolution. The structure reveals details of the ribosomal subunit interface that are conserved in all domains of life, and suggest how solvation contributes to ribosome integrity and function. The structure also suggests how the conformation of ribosomal protein uS12 likely impacts its contribution to messenger RNA decoding. This structure helps to explain the phylogenetic conservation of key elements of the ribosome, including posttranscriptional and posttranslational modifications and should serve as a basis for future antibiotic development.
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20
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Popova AM, Williamson JR. Quantitative analysis of rRNA modifications using stable isotope labeling and mass spectrometry. J Am Chem Soc 2014; 136:2058-69. [PMID: 24422502 PMCID: PMC3985470 DOI: 10.1021/ja412084b] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Post-transcriptional RNA modifications
that are introduced during
the multistep ribosome biogenesis process are essential for protein
synthesis. The current lack of a comprehensive method for a fast quantitative
analysis of rRNA modifications significantly limits our understanding
of how individual modification steps are coordinated during biogenesis
inside the cell. Here, an LC-MS approach has been developed and successfully
applied for quantitative monitoring of 29 out of 36 modified residues
in the 16S and 23S rRNA from Escherichia coli. An isotope labeling strategy is described for efficient identification
of ribose and base methylations, and a novel metabolic labeling approach
is presented to allow identification of MS-silent pseudouridine modifications.
The method was used to measure relative abundances of modified residues
in incomplete ribosomal subunits compared to a mature 15N-labeled rRNA standard, and a number of modifications in both 16S
and 23S rRNA were present in substoichiometric amounts in the preribosomal
particles. The RNA modification levels correlate well with previously
obtained profiles for the ribosomal proteins, suggesting that RNA
is modified in a schedule comparable to the association of the ribosomal
proteins. Importantly, this study establishes an efficient workflow
for a global monitoring of ribosomal modifications that will contribute
to a better understanding of mechanisms of RNA modifications and their
impact on intracellular processes in the future.
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Affiliation(s)
- Anna M Popova
- Department of Integrative Structural and Computational Biology and ‡Department of Chemistry, The Scripps Research Institute , La Jolla, California 92037, United States
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21
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Spenkuch F, Motorin Y, Helm M. Pseudouridine: still mysterious, but never a fake (uridine)! RNA Biol 2014; 11:1540-54. [PMID: 25616362 PMCID: PMC4615568 DOI: 10.4161/15476286.2014.992278] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/23/2014] [Accepted: 10/10/2014] [Indexed: 01/15/2023] Open
Abstract
Pseudouridine (Ψ) is the most abundant of >150 nucleoside modifications in RNA. Although Ψ was discovered as the first modified nucleoside more than half a century ago, neither the enzymatic mechanism of its formation, nor the function of this modification are fully elucidated. We present the consistent picture of Ψ synthases, their substrates and their substrate positions in model organisms of all domains of life as it has emerged to date and point out the challenges that remain concerning higher eukaryotes and the elucidation of the enzymatic mechanism.
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MESH Headings
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Humans
- Intramolecular Transferases/genetics
- Intramolecular Transferases/metabolism
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Nucleic Acid Conformation
- Pseudouridine/metabolism
- RNA/genetics
- RNA/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Mitochondrial
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Transfer, Amino Acid-Specific/chemistry
- RNA, Transfer, Amino Acid-Specific/genetics
- RNA, Transfer, Amino Acid-Specific/metabolism
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Uridine/metabolism
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Felix Spenkuch
- Institute of Pharmacy and Biochemistry; Johannes Gutenberg-University of Mainz; Mainz, Germany
| | - Yuri Motorin
- Laboratoire IMoPA; Ingénierie Moléculaire et Physiopathologie Articulaire; BioPôle de l'Université de Lorraine; Campus Biologie-Santé; Faculté de Médecine; Vandoeuvre-les-Nancy Cedex, France
| | - Mark Helm
- Institute of Pharmacy and Biochemistry; Johannes Gutenberg-University of Mainz; Mainz, Germany
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22
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Russell SP, Limbach PA. Evaluating the reproducibility of quantifying modified nucleosides from ribonucleic acids by LC-UV-MS. J Chromatogr B Analyt Technol Biomed Life Sci 2013; 923-924:74-82. [PMID: 23500350 DOI: 10.1016/j.jchromb.2013.02.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 02/07/2013] [Accepted: 02/11/2013] [Indexed: 11/26/2022]
Abstract
Post-transcriptional chemical covalent modification of adenosine, guanosine, uridine and cytidine occurs frequently in all types of ribonucleic acids (RNAs). In ribosomal RNA (rRNA) and transfer RNA (tRNA) these modifications make important contributions to RNA structure and stability and to the accuracy and efficiency of protein translation. The functional dynamics, synergistic nature and regulatory roles of these posttranscriptional nucleoside modifications within the cell are not well characterized. These modifications are present at very low levels and isolation of individual nucleosides for analysis requires a complex multi-step approach. The focus of this study is to characterize the reproducibility of a liquid chromatography method used to isolate and quantitatively characterize modified nucleosides in tRNA and rRNA when nucleoside detection is performed using ultraviolet and mass spectrometric detection (UV and MS, respectively). Despite the analytical challenges of sample isolation and dynamic range, quantitative profiling of modified nucleosides obtained from bacterial tRNAs and rRNAs is feasible at relative standard deviations of 5% RSD or less.
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Affiliation(s)
- Susan P Russell
- Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221-0172, United States
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23
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Jiang J, Sakakibara Y, Chow CS. Helix 69: A Multitasking RNA Motif as a Novel Drug Target. Isr J Chem 2013. [DOI: 10.1002/ijch.201300012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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24
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Francisella tularensis live vaccine strain folate metabolism and pseudouridine synthase gene mutants modulate macrophage caspase-1 activation. Infect Immun 2012; 81:201-8. [PMID: 23115038 DOI: 10.1128/iai.00991-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Francisella tularensis is a Gram-negative bacterium and the causative agent of the disease tularemia. Escape of F. tularensis from the phagosome into the cytosol of the macrophage triggers the activation of the AIM2 inflammasome through a mechanism that is not well understood. Activation of the AIM2 inflammasome results in autocatalytic cleavage of caspase-1, resulting in the processing and secretion of interleukin-1β (IL-1β) and IL-18, which play a crucial role in innate immune responses to F. tularensis. We have identified the 5-formyltetrahydrofolate cycloligase gene (FTL_0724) as being important for F. tularensis live vaccine strain (LVS) virulence. Infection of mice in vivo with a F. tularensis LVS FTL_0724 mutant resulted in diminished mortality compared to infection of mice with wild-type LVS. The FTL_0724 mutant also induced increased inflammasome-dependent IL-1β and IL-18 secretion and cytotoxicity in macrophages in vitro. In contrast, infection of macrophages with a F. tularensis LVS rluD pseudouridine synthase (FTL_0699) mutant resulted in diminished IL-1β and IL-18 secretion from macrophages in vitro compared to infection of macrophages with wild-type LVS. In addition, the FTL_0699 mutant was not attenuated in vivo. These findings further illustrate that F. tularensis LVS possesses numerous genes that influence its ability to activate the inflammasome, which is a key host strategy to control infection with this pathogen in vivo.
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25
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Golovina AY, Dzama MM, Osterman IA, Sergiev PV, Serebryakova MV, Bogdanov AA, Dontsova OA. The last rRNA methyltransferase of E. coli revealed: the yhiR gene encodes adenine-N6 methyltransferase specific for modification of A2030 of 23S ribosomal RNA. RNA (NEW YORK, N.Y.) 2012; 18:1725-1734. [PMID: 22847818 PMCID: PMC3425786 DOI: 10.1261/rna.034207.112] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/16/2012] [Indexed: 06/01/2023]
Abstract
The ribosomal RNA (rRNA) of Escherichia coli contains 24 methylated residues. A set of 22 methyltransferases responsible for modification of 23 residues has been described previously. Herein we report the identification of the yhiR gene as encoding the enzyme that modifies the 23S rRNA nucleotide A2030, the last methylated rRNA nucleotide whose modification enzyme was not known. YhiR prefers protein-free 23S rRNA to ribonucleoprotein particles containing only part of the 50S subunit proteins and does not methylate the assembled 50S subunit. We suggest renaming the yhiR gene to rlmJ according to the rRNA methyltransferase nomenclature. The phenotype of yhiR knockout gene is very mild under various growth conditions and at the stationary phase, except for a small growth advantage at anaerobic conditions. Only minor changes in the total E. coli proteome could be observed in a cell devoid of the 23S rRNA nucleotide A2030 methylation.
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Affiliation(s)
- Anna Y. Golovina
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Margarita M. Dzama
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Ilya A. Osterman
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Petr V. Sergiev
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Marina V. Serebryakova
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Alexey A. Bogdanov
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
| | - Olga A. Dontsova
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia
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26
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Leppik M, Ero R, Liiv A, Kipper K, Remme J. Different sensitivity of H69 modification enzymes RluD and RlmH to mutations in Escherichia coli 23S rRNA. Biochimie 2012; 94:1080-9. [PMID: 22586702 DOI: 10.1016/j.biochi.2012.02.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nucleoside modifications are introduced into the ribosomal RNA during the assembly of the ribosome. The number and the localization of the modified nucleosides in rRNAs are known for several organisms. In bacteria, rRNA modified nucleosides are synthesized by a set of specific enzymes, the majority of which have been identified in Escherichia coli. Each rRNA modification enzyme recognizes its substrate nucleoside(s) at a specific stage of ribosome assembly. Not much is known about the specificity determinants involved in the substrate recognition of the modification enzymes. In order to shed light on the substrate specificity of RluD and RlmH, the enzymes responsible for the introduction of modifications into the stem-loop 69 (H69), we monitored the formation of H69 pseudouridines (Ψ) and methylated pseudouridine (m3Ψ) in vitro on ribosomes with alterations in 23S rRNA. While the synthesis of Ψs in H69 by RluD is relatively insensitive to the point mutations at neighboring positions, methylation of one of the Ψs by RlmH exhibited a much stronger sensitivity. Apparently, in spite of synthesizing modifications in the same region or even at the same position of rRNA, the two enzymes employ different substrate recognition mechanisms.
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Affiliation(s)
- Margus Leppik
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
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27
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Bang WY, Chen J, Jeong IS, Kim SW, Kim CW, Jung HS, Lee KH, Kweon HS, Yoko I, Shiina T, Bahk JD. Functional characterization of ObgC in ribosome biogenesis during chloroplast development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 71:122-34. [PMID: 22380942 DOI: 10.1111/j.1365-313x.2012.04976.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The Spo0B-associated GTP-binding protein (Obg) GTPase, essential for bacterial viability, is also conserved in eukaryotes, but its primary role in eukaryotes remains unknown. Here, our functional characterization of Arabidopsis and rice obgc mutants strongly underlines the evolutionarily conserved role of eukaryotic Obgs in organellar ribosome biogenesis. The mutants exhibited a chlorotic phenotype, caused by retarded chloroplast development. A plastid DNA macroarray revealed a plastid-encoded RNA polymerase (PEP) deficiency in an obgc mutant, caused by incompleteness of the PEP complex, as its western blot exhibited reduced levels of RpoA protein, a component of PEP. Plastid rRNA profiling indicated that plastid rRNA processing is defective in obgc mutants, probably resulting in impaired ribosome biogenesis and, in turn, in reduced levels of RpoA protein. RNA co-immunoprecipitation revealed that ObgC specifically co-precipitates with 23S rRNA in vivo. These findings indicate that ObgC functions primarily in plastid ribosome biogenesis during chloroplast development. Furthermore, complementation analysis can provide new insights into the functional modes of three ObgC domains, including the Obg fold, G domain and OCT.
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Affiliation(s)
- Woo Young Bang
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology-GNTECH, Jinju 660-758, Korea
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28
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Kimura S, Ikeuchi Y, Kitahara K, Sakaguchi Y, Suzuki T, Suzuki T. Base methylations in the double-stranded RNA by a fused methyltransferase bearing unwinding activity. Nucleic Acids Res 2012; 40:4071-85. [PMID: 22210896 PMCID: PMC3351187 DOI: 10.1093/nar/gkr1287] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 11/28/2011] [Accepted: 12/14/2011] [Indexed: 12/18/2022] Open
Abstract
Modifications of rRNAs are clustered in functional regions of the ribosome. In Helix 74 of Escherichia coli 23S rRNA, guanosines at positions 2069 and 2445 are modified to 7-methylguanosine(m(7)G) and N(2)-methylguanosine(m(2)G), respectively. We searched for the gene responsible for m(7)G2069 formation, and identified rlmL, which encodes the methyltransferase for m(2)G2445, as responsible for the biogenesis of m(7)G2069. In vitro methylation of rRNA revealed that rlmL encodes a fused methyltransferase responsible for forming both m(7)G2069 and m(2)G2445. We renamed the gene rlmKL. The N-terminal RlmL activity for m(2)G2445 formation was significantly enhanced by the C-terminal RlmK. Moreover, RlmKL had an unwinding activity of Helix 74, facilitating cooperative methylations of m(7)G2069 and m(2)G2445 during biogenesis of 50S subunit. In fact, we observed that RlmKL was involved in the efficient assembly of 50S subunit in a mutant strain lacking an RNA helicase deaD.
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MESH Headings
- Escherichia coli/enzymology
- Escherichia coli/genetics
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/metabolism
- Guanosine/analogs & derivatives
- Guanosine/metabolism
- Methylation
- Methyltransferases/chemistry
- Methyltransferases/metabolism
- Models, Molecular
- Protein Structure, Tertiary
- RNA Helicases/metabolism
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/metabolism
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/metabolism
- Ribosome Subunits, Large, Bacterial/metabolism
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Affiliation(s)
| | | | | | | | | | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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29
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Sergiev PV, Golovina AY, Sergeeva OV, Osterman IA, Nesterchuk MV, Bogdanov AA, Dontsova OA. How much can we learn about the function of bacterial rRNA modification by mining large-scale experimental datasets? Nucleic Acids Res 2012; 40:5694-705. [PMID: 22411911 PMCID: PMC3384335 DOI: 10.1093/nar/gks219] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Modification of ribosomal RNA is ubiquitous among living organisms. Its functional role is well established for only a limited number of modified nucleotides. There are examples of rRNA modification involvement in the gene expression regulation in the cell. There is a need for large data set analysis in the search for potential functional partners for rRNA modification. In this study, we extracted phylogenetic profile, genome neighbourhood, co-expression and phenotype profile and co-purification data regarding Escherichia coli rRNA modification enzymes from public databases. Results were visualized as graphs using Cytoscape and analysed. Majority linked genes/proteins belong to translation apparatus. Among co-purification partners of rRNA modification enzymes are several candidates for experimental validation. Phylogenetic profiling revealed links of pseudouridine synthetases with RF2, RsmH with translation factors IF2, RF1 and LepA and RlmM with RdgC. Genome neighbourhood connections revealed several putative functionally linked genes, e.g. rlmH with genes coding for cell wall biosynthetic proteins and others. Comparative analysis of expression profiles (Gene Expression Omnibus) revealed two main associations, a group of genes expressed during fast growth and association of rrmJ with heat shock genes. This study might be used as a roadmap for further experimental verification of predicted functional interactions.
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Affiliation(s)
- Petr V Sergiev
- Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow 119992, Russia.
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30
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Abstract
The assembly of ribosomes from a discrete set of components is a key aspect of the highly coordinated process of ribosome biogenesis. In this review, we present a brief history of the early work on ribosome assembly in Escherichia coli, including a description of in vivo and in vitro intermediates. The assembly process is believed to progress through an alternating series of RNA conformational changes and protein-binding events; we explore the effects of ribosomal proteins in driving these events. Ribosome assembly in vivo proceeds much faster than in vitro, and we outline the contributions of several of the assembly cofactors involved, including Era, RbfA, RimJ, RimM, RimP, and RsgA, which associate with the 30S subunit, and CsdA, DbpA, Der, and SrmB, which associate with the 50S subunit.
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Affiliation(s)
- Zahra Shajani
- Departments of Molecular Biology and Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
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Sumita M, Jiang J, SantaLucia J, Chow CS. Comparison of solution conformations and stabilities of modified helix 69 rRNA analogs from bacteria and human. Biopolymers 2011; 97:94-106. [PMID: 21858779 DOI: 10.1002/bip.21706] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/31/2011] [Indexed: 12/20/2022]
Abstract
The helix 69 (H69) region of the large subunit (28S) ribosomal RNA (rRNA) of Homo sapiens contains five pseudouridine (Ψ) residues out of 19 total nucleotides, three of which are highly conserved. In this study, the effects of this abundant modified nucleotide on the structure and stability of H69 were compared with those of uridine in double-stranded (stem) regions. These results were compared with previous hairpin (stem plus single-stranded loop) studies to understand the contributions of the loop sequences to H69 structure and stability. The role of a loop nucleotide substitution from an A in bacteria (position 1918 in Escherichia coli 23S rRNA) to a G in eukaryotes (position 3734 in H. sapiens 28S rRNA) was examined. Thermodynamic parameters for the duplex RNAs were obtained through UV melting studies, and differences in the modified and unmodified RNA structures were examined by circular dichroism spectroscopy. The overall folded structure of human H69 appears to be similar to the bacterial RNA, consistent with the idea that ribosome structure and function are highly conserved; however, our results reveal subtle differences in structure and stability between the bacterial and human H69 RNAs in both the stem and loop regions. These findings may be significant with respect to H69 as a potential drug target site.
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Affiliation(s)
- Minako Sumita
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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Small RNAs endow a transcriptional activator with essential repressor functions for single-tier control of a global stress regulon. Proc Natl Acad Sci U S A 2011; 108:12875-80. [PMID: 21768388 DOI: 10.1073/pnas.1109379108] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Escherichia coli σ(E) envelope stress response monitors and repairs the outer membrane, a function central to the life of Gram-negative bacteria. The σ(E) stress response was characterized as a single-tier activation network comprised of ~100 genes, including the MicA and RybB noncoding sRNAs. These highly expressed sRNAs were thought to carry out the specialized function of halting de novo synthesis of several abundant porins when envelope homeostasis was perturbed. Using a systematic target profiling and validation approach we discovered that MicA and RybB are each global mRNA repressors of both distinct and shared targets, and that the two sRNAs constitute a posttranscriptional repression arm whose regulatory scope rivals that of the protein-based σ(E) activation arm. Intriguingly, porin mRNAs constitute only ~1/3 of all targets and new nonporin targets predict roles for MicA and RybB in crosstalk with other regulatory responses. This work also provides an example of evolutionarily unrelated sRNAs that are coinduced and bind the same targets, but at different sites. Our finding that expression of either MicA or RybB sRNA protects the cell from the loss of viability experienced when σ(E) activity is inadequate illustrates the importance of the posttranscriptional repression arm of the response. σ(E) is a paradigm of a single-tier stress response with a clear division of labor in which highly expressed noncoding RNAs (MicA, RybB) endow a transcriptional factor intrinsically restricted to gene activation (σ(E)) with the opposite repressor function.
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Kumar A, Saigal K, Malhotra K, Sinha KM, Taneja B. Structural and functional characterization of Rv2966c protein reveals an RsmD-like methyltransferase from Mycobacterium tuberculosis and the role of its N-terminal domain in target recognition. J Biol Chem 2011; 286:19652-61. [PMID: 21474448 PMCID: PMC3103344 DOI: 10.1074/jbc.m110.200428] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 03/24/2011] [Indexed: 11/06/2022] Open
Abstract
Nine of ten methylated nucleotides of Escherichia coli 16 S rRNA are conserved in Mycobacterium tuberculosis. All the 10 different methyltransferases are known in E. coli, whereas only TlyA and GidB have been identified in mycobacteria. Here we have identified Rv2966c of M. tuberculosis as an ortholog of RsmD protein of E. coli. We have shown that rv2966c can complement rsmD-deleted E. coli cells. Recombinant Rv2966c can use 30 S ribosomes purified from rsmD-deleted E. coli as substrate and methylate G966 of 16 S rRNA in vitro. Structure determination of the protein shows the protein to be a two-domain structure with a short hairpin domain at the N terminus and a C-terminal domain with the S-adenosylmethionine-MT-fold. We show that the N-terminal hairpin is a minimalist functional domain that helps Rv2966c in target recognition. Deletion of the N-terminal domain prevents binding to nucleic acid substrates, and the truncated protein fails to carry out the m(2)G966 methylation on 16 S rRNA. The N-terminal domain also binds DNA efficiently, a property that may be utilized under specific conditions of cellular growth.
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MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Histones/chemistry
- Histones/genetics
- Histones/metabolism
- Methylation
- Mycobacterium tuberculosis/enzymology
- Mycobacterium tuberculosis/genetics
- Protein Structure, Tertiary
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/metabolism
- Structure-Activity Relationship
- tRNA Methyltransferases/chemistry
- tRNA Methyltransferases/genetics
- tRNA Methyltransferases/metabolism
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Affiliation(s)
- Atul Kumar
- From the Institute of Genomics and Integrative Biology (Council of Scientific and Industrial Research), Mall Road, Delhi University Campus, Delhi 110007 and
| | - Kashyap Saigal
- the Institute of Molecular Medicine, 254, Okhla Industrial Estate, Phase III, New Delhi 110020 India
| | - Ketan Malhotra
- the Institute of Molecular Medicine, 254, Okhla Industrial Estate, Phase III, New Delhi 110020 India
| | - Krishna Murari Sinha
- the Institute of Molecular Medicine, 254, Okhla Industrial Estate, Phase III, New Delhi 110020 India
| | - Bhupesh Taneja
- From the Institute of Genomics and Integrative Biology (Council of Scientific and Industrial Research), Mall Road, Delhi University Campus, Delhi 110007 and
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34
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Sergiev PV, Osterman IA, Prokhorova IV, Nesterchuk MV, Sergeeva OV, Golovina AI, Demina IA, Galiamina MA, Serebriakova MV, Dontsova OA. [Systems biology approach to the functional role of enzymatic modification of bacterial ribosome]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2011; 37:81-90. [PMID: 21460884 DOI: 10.1134/s1068162011010146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this work we describe methodology for studying the role of bacterial ribosome modification in the regulation of gene expression. Ribosomal components modification influences translation efficiencies of certain mRNAs. Proteome analysis allows us to identify cellular protein composition change caused by ribosome modification gene knockout. Particular stage of gene expression responsible for certain protein concentration change could be found using reporter constructs. After identification of mRNA species, whose translation is influenced by ribosome modification we can determine exact mRNA region responsible for the observed changes. The developed methodology can be applied for studying other translational control mechanisms.
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MESH Headings
- Bacterial Proteins/biosynthesis
- Bacterial Proteins/genetics
- Electrophoresis, Gel, Two-Dimensional
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Bacterial
- Genes, Reporter
- Immunoblotting
- Lac Operon
- Luciferases/genetics
- Methyltransferases/genetics
- Methyltransferases/metabolism
- Proteome/analysis
- RNA Processing, Post-Transcriptional
- RNA, Bacterial/metabolism
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Ribosomal/metabolism
- Ribosomes/metabolism
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- beta-Galactosidase/biosynthesis
- beta-Galactosidase/genetics
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35
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Pseudouridylation of 23S rRNA helix 69 promotes peptide release by release factor RF2 but not by release factor RF1. Biochimie 2011; 93:834-44. [PMID: 21281690 DOI: 10.1016/j.biochi.2010.12.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 12/30/2010] [Indexed: 11/22/2022]
Abstract
Pseudouridine [Ψ] is a frequent base modification in the ribosomal RNA [rRNA] and may be involved in the modulation of the conformational flexibility of rRNA helix-loop structures during protein synthesis. Helix 69 of 23S rRNA contains pseudouridines at the positions 1911, 1915 and 1917 which are formed by the helix 69-specific synthase RluD. The growth defect caused by the lack of RluD can be rescued by mutations in class I release factor RF2, indicating a role for helix 69 pseudouridines in translation termination. We investigated the role of helix 69 pseudouridines in peptide release by release factors RF1 and RF2 in an in vitro system consisting of purified components of the Escherichia coli translation apparatus. Lack of all three pseudouridines in helix 69 compromised the activity of RF2 about 3-fold but did not significantly affect the activity of RF1. Reintroduction of pseudouridines into helix 69 by RluD-treatment restored the activity of RF2 in peptide release. A Ψ-to-C substitution at the 1917 position caused an increase in the dissociation rate of RF1 and RF2 from the postrelease ribosome. Our results indicate that the presence of all three pseudouridines in helix 69 stimulates peptide release by RF2 but has little effect on the activity of RF1. The interactions around the pseudouridine at the 1917 position appear to be most critical for a proper interaction of helix 69 with release factors.
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36
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O'Connor M, Gregory ST. Inactivation of the RluD pseudouridine synthase has minimal effects on growth and ribosome function in wild-type Escherichia coli and Salmonella enterica. J Bacteriol 2011; 193:154-62. [PMID: 21037010 PMCID: PMC3019933 DOI: 10.1128/jb.00970-10] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 10/18/2010] [Indexed: 11/20/2022] Open
Abstract
The Escherichia coli rluD gene encodes a pseudouridine synthase responsible for the pseudouridine (Ψ) modifications at positions 1911, 1915, and 1917 in helix 69 of 23S rRNA. It has been reported that deletion of rluD in K-12 strains of E. coli is associated with extremely slow growth, increased readthrough of stop codons, and defects in 50S ribosomal subunit assembly and 30S-50S subunit association. Suppressor mutations in the prfB and prfC genes encoding release factor 2 (RF2) and RF3 that restore the wild type-growth rate and also correct the ribosomal defects have now been isolated. These suppressors link helix 69 Ψ residues with the termination phase of protein synthesis. However, further genetic analysis reported here also reveals that the slow growth and other defects associated with inactivation of rluD in E. coli K-12 strains are due to a defective RF2 protein, with a threonine at position 246, which is present in all K-12 strains. This is in contrast to the more typical alanine found at this position in most bacterial RF2s, including those of other E. coli strains. Inactivation of rluD in E. coli strains containing the prfB allele from E. coli B or in Salmonella enterica, both carrying an RF2 with Ala246, has negligible effects on growth, termination, or ribosome function. The results indicate that, in contrast to those in wild bacteria, termination functions in E. coli K-12 strains carrying a partially defective RF2 protein are especially susceptible to perturbation of ribosome-RF interactions, such as that caused by loss of h69 Ψ modifications.
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Affiliation(s)
- Michael O'Connor
- School of Biological Sciences, University of Missouri-Kansas City, 5007 Rockhill Rd, Kansas City, Missouri 64110, USA.
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37
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Schaub RE, Hayes CS. Deletion of the RluD pseudouridine synthase promotes SsrA peptide tagging of ribosomal protein S7. Mol Microbiol 2010; 79:331-41. [PMID: 21219455 DOI: 10.1111/j.1365-2958.2010.07467.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RluD catalyses formation of three pseudouridine residues within helix 69 of the 50S ribosome subunit. Helix 69 makes important contacts with the decoding centre on the 30S subunit and deletion of rluD was recently shown to interfere with translation termination in Escherichia coli. Here, we show that deletion of rluD increases tmRNA activity on ribosomes undergoing release factor 2 (RF2)-mediated termination at UGA stop codons. Strikingly, tmRNA-mediated SsrA peptide tagging of two proteins, ribosomal protein S7 and LacI, was dramatically increased in ΔrluD cells. S7 tagging was due to a unique C-terminal peptide extension found in E. coli K-12 strains. Introduction of the rpsG gene (encoding S7) from an E. coli B strain abrogated S7 tagging in the ΔrluD background, and partially complemented the mutant's slow-growth phenotype. Additionally, exchange of the K-12 prfB gene (encoding RF2) with the B strain allele greatly reduced tagging in ΔrluD cells. In contrast to E. coli K-12 cells, deletion of rluD in an E. coli B strain resulted in no growth phenotype. These findings indicate that the originally observed rluD phenotypes result from synthetic interactions with rpsG and prfB alleles found within E. coli K-12 strains.
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Affiliation(s)
- Ryan E Schaub
- Department of Molecular, Cellular and Developmental Biology Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA
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38
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Ero R, Leppik M, Liiv A, Remme J. Specificity and kinetics of 23S rRNA modification enzymes RlmH and RluD. RNA (NEW YORK, N.Y.) 2010; 16:2075-84. [PMID: 20817755 PMCID: PMC2957048 DOI: 10.1261/rna.2234310] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 07/30/2010] [Indexed: 05/29/2023]
Abstract
Along the ribosome assembly pathway, various ribosomal RNA processing and modification reactions take place. Stem-loop 69 in the large subunit of Escherichia coli ribosomes plays a substantial role in ribosome functioning. It contains three highly conserved pseudouridines synthesized by pseudouridine synthase RluD. One of the pseudouridines is further methylated by RlmH. In this paper we show that RlmH has unique substrate specificity among rRNA modification enzymes. It preferentially methylates pseudouridine and less efficiently uridine. Furthermore, RlmH is the only known modification enzyme that is specific to 70S ribosomes. Kinetic parameters determined for RlmH are the following: The apparent K(M) for substrate 70S ribosomes is 0.51 ± 0.06 μM, and for cofactor S-adenosyl-L-methionine 27 ± 3 μM; the k(cat) values are 4.95 ± 1.10 min⁻¹ and 6.4 ± 1.3 min⁻¹, respectively. Knowledge of the substrate specificity and the kinetic parameters of RlmH made it possible to determine the kinetic parameters for RluD as well. The K(M) value for substrate 50S subunits is 0.98 ± 0.18 μM and the k(cat) value is 1.97 ± 0.46 min⁻¹. RluD is the first rRNA pseudouridine synthase to be kinetically characterized. The determined rates of RluD- and RlmH-directed modifications of 23S rRNA are compatible with the rate of 50S assembly in vivo. The fact that RlmH requires 30S subunits demonstrates the dependence of 50S subunit maturation on the simultaneous presence of 30S subunits.
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Affiliation(s)
- Rya Ero
- Department of Molecular Biology, Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia
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39
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Scheunemann AE, Graham WD, Vendeix FAP, Agris PF. Binding of aminoglycoside antibiotics to helix 69 of 23S rRNA. Nucleic Acids Res 2010; 38:3094-105. [PMID: 20110260 PMCID: PMC2875026 DOI: 10.1093/nar/gkp1253] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Aminoglycosides antibiotics negate dissociation and recycling of the bacterial ribosome’s subunits by binding to Helix 69 (H69) of 23S rRNA. The differential binding of various aminoglycosides to the chemically synthesized terminal domains of the Escherichia coli and human H69 has been characterized using spectroscopy, calorimetry and NMR. The unmodified E. coli H69 hairpin exhibited a significantly higher affinity for neomycin B and tobramycin than for paromomycin (Kds = 0.3 ± 0.1, 0.2 ± 0.2 and 5.4 ± 1.1 µM, respectively). The binding of streptomycin was too weak to assess. In contrast to the E. coli H69, the human 28S rRNA H69 had a considerable decrease in affinity for the antibiotics, an important validation of the bacterial target. The three conserved pseudouridine modifications (Ψ1911, Ψ1915, Ψ1917) occurring in the loop of the E. coli H69 affected the dissociation constant, but not the stoichiometry for the binding of paromomycin (Kd = 2.6 ± 0.1 µM). G1906 and G1921, observed by NMR spectrometry, figured predominantly in the aminoglycoside binding to H69. The higher affinity of the E. coli H69 for neomycin B and tobramycin, as compared to paromomycin and streptomycin, indicates differences in the efficacy of the aminoglycosides.
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Affiliation(s)
- Ann E Scheunemann
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695-7622, USA
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40
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Identification and characterization of growth suppressors of Escherichia coli strains lacking phosphorolytic ribonucleases. J Bacteriol 2009; 191:5622-7. [PMID: 19617368 DOI: 10.1128/jb.01716-08] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RNases are involved in critical aspects of RNA metabolism in all organisms. Two classes of RNases that digest RNA from an end (exo-RNases) are known: RNases that use water as a nucleophile to catalyze RNA degradation (hydrolytic RNases) and RNases that use inorganic phosphate (phosphorolytic RNases). It has been shown previously that the absence of the two known Escherichia coli phosphorolytic RNases, polynucleotide phosphorylase and RNase PH, leads to marked growth and ribosome assembly defects. To investigate the basis for these defects, a screen for growth suppressors was performed. The majority of suppressor mutations were found to lie within nsrR, which encodes a nitric oxide (NO)-sensitive transcriptional repressor. Further analysis showed that the suppressors function not by inactivating nsrR but by causing overexpression of a downstream gene that encodes a hydrolytic RNase, RNase R. Additional studies revealed that overexpression of another hydrolytic RNase, RNase II, similarly suppressed the growth defects. These results suggest that the requirement for phosphorolytic RNases for robust cellular growth and efficient ribosome assembly can be bypassed by increased expression of hydrolytic RNases.
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41
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Seshadri A, Dubey B, Weber MHW, Varshney U. Impact of rRNA methylations on ribosome recycling and fidelity of initiation inEscherichia coli. Mol Microbiol 2009; 72:795-808. [DOI: 10.1111/j.1365-2958.2009.06685.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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42
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Al Refaii A, Alix JH. Ribosome biogenesis is temperature-dependent and delayed inEscherichia colilacking the chaperones DnaK or DnaJ. Mol Microbiol 2009; 71:748-62. [DOI: 10.1111/j.1365-2958.2008.06561.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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43
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Characterization of chromosomal regions conserved in Yersinia pseudotuberculosis and lost by Yersinia pestis. Infect Immun 2008; 76:4592-9. [PMID: 18678673 DOI: 10.1128/iai.00568-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transformation of the enteropathogenic bacterium Yersinia pseudotuberculosis into the plague bacillus, Yersinia pestis, has been accompanied by extensive genetic loss. This study focused on chromosomal regions conserved in Y. pseudotuberculosis and lost during its transformation into Y. pestis. An extensive PCR screening of 78 strains of the two species identified five regions (R1 to R5) and four open reading frames (ORFs; orf1 to orf4) that were conserved in Y. pseudotuberculosis and absent from Y. pestis. Their conservation in Y. pseudotuberculosis suggests a positive selective pressure and a role during the life cycle of this species. Attempts to delete two ORFs (orf3 and orf4) from the chromosome of strain IP32953 were unsuccessful, indicating that they are essential for its viability. The seven remaining loci were individually deleted from the IP32953 chromosome, and the ability of each mutant to grow in vitro and to kill mice upon intragastric infection was evaluated. Four loci (orf1, R2, R4, and R5) were not required for optimal growth or virulence of Y. pseudotuberculosis. In contrast, orf2, encoding a putative pseudouridylate synthase involved in RNA stability, was necessary for the optimal growth of IP32953 at 37 degrees C in a chemically defined medium (M63S). Deletion of R1, a region predicted to encode the methionine salvage pathway, altered the mutant pathogenicity, suggesting that the availability of free methionine is severely restricted in vivo. R3, a region composed mostly of genes of unknown functions, was necessary for both optimal growth of Y. pseudotuberculosis at 37 degrees C in M63S and for virulence. Therefore, despite their loss in Y. pestis, five of the nine Y. pseudotuberculosis-specific chromosomal loci studied play a role in the survival, growth, or virulence of this species.
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44
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Yu F, Liu X, Alsheikh M, Park S, Rodermel S. Mutations in SUPPRESSOR OF VARIEGATION1, a factor required for normal chloroplast translation, suppress var2-mediated leaf variegation in Arabidopsis. THE PLANT CELL 2008; 20:1786-804. [PMID: 18599582 PMCID: PMC2518225 DOI: 10.1105/tpc.107.054965] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 05/13/2008] [Accepted: 05/28/2008] [Indexed: 05/18/2023]
Abstract
The Arabidopsis thaliana yellow variegated2 (var2) mutant is variegated due to lack of a chloroplast FtsH-like metalloprotease (FtsH2/VAR2). We have generated suppressors of var2 variegation to gain insight into factors and pathways that interact with VAR2 during chloroplast biogenesis. Here, we describe two such suppressors. Suppression of variegation in the first line, TAG-FN, was caused by disruption of the nuclear gene (SUPPRESSOR OF VARIEGATION1 [SVR1]) for a chloroplast-localized homolog of pseudouridine (Psi) synthase, which isomerizes uridine to Psi in noncoding RNAs. svr1 single mutants were epistatic to var2, and they displayed a phenotypic syndrome that included defects in chloroplast rRNA processing, reduced chloroplast translation, reduced chloroplast protein accumulation, and elevated chloroplast mRNA levels. In the second line (TAG-IE), suppression of variegation was caused by a lesion in SVR2, the gene for the ClpR1 subunit of the chloroplast ClpP/R protease. Like svr1, svr2 was epistatic to var2, and clpR1 mutants had a phenotype that resembled svr1. We propose that an impairment of chloroplast translation in TAG-FN and TAG-IE decreased the demand for VAR2 activity during chloroplast biogenesis and that this resulted in the suppression of var2 variegation. Consistent with this hypothesis, var2 variegation was repressed by chemical inhibitors of chloroplast translation. In planta mutagenesis revealed that SVR1 not only played a role in uridine isomerization but that its physical presence was necessary for proper chloroplast rRNA processing. Our data indicate that defects in chloroplast rRNA processing are a common, but not universal, molecular phenotype associated with suppression of var2 variegation.
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Affiliation(s)
- Fei Yu
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011, USA
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45
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Peil L, Virumäe K, Remme J. Ribosome assembly in Escherichia coli strains lacking the RNA helicase DeaD/CsdA or DbpA. FEBS J 2008; 275:3772-82. [PMID: 18565105 DOI: 10.1111/j.1742-4658.2008.06523.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ribosome subunit assembly in bacteria is a fast and efficient process. Among the nonribosomal proteins involved in ribosome biogenesis are RNA helicases. We describe ribosome biogenesis in Escherichia coli strains lacking RNA helicase DeaD (CsdA) or DbpA. Ribosome large subunit assembly intermediate particles (40S) accumulate at 25 degrees C and at 37 degrees C in the absence of DeaD but not without DbpA. 23S rRNA is incompletely processed in the 40S and 50S particles of the DeaD(-) strain. Pulse labeling showed that the 40S particles are converted nearly completely into functional ribosomes. The rate of large ribosomal subunit assembly was reduced about four times in DeaD-deficient cells. Functional activity tests of the ribosomal particles demonstrated that the final step of 50S assembly, the activation step, was affected when DeaD was not present. The results are compatible with the model that predicts multiple DeaD-catalyzed structural transitions of the ribosome large subunit assembly.
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Affiliation(s)
- Lauri Peil
- Institute of Molecular and Cell Biology, University of Tartu, Estonia
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46
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Toh SM, Mankin AS. An indigenous posttranscriptional modification in the ribosomal peptidyl transferase center confers resistance to an array of protein synthesis inhibitors. J Mol Biol 2008; 380:593-7. [PMID: 18554609 DOI: 10.1016/j.jmb.2008.05.027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 05/13/2008] [Indexed: 10/22/2022]
Abstract
A number of nucleotide residues in ribosomal RNA (rRNA) undergo specific posttranscriptional modifications. The roles of most modifications are unclear, but their clustering in functionally important regions of rRNA suggests that they might either directly affect the activity of the ribosome or modulate its interactions with ligands. Of the 25 modified nucleotides in Escherichia coli 23S rRNA, 14 are located in the peptidyl transferase center, the main antibiotic target in the large ribosomal subunit. Since nucleotide modifications have been closely associated with both antibiotic sensitivity and antibiotic resistance, loss of some of these posttranscriptional modifications may affect the susceptibility of bacteria to antibiotics. We investigated the antibiotic sensitivity of E. coli cells in which the genes of 8 rRNA-modifying enzymes targeting the peptidyl transferase center were individually inactivated. The lack of pseudouridine at position 2504 of 23S rRNA was found to significantly increase the susceptibility of bacteria to peptidyl transferase inhibitors. Therefore, this indigenous posttranscriptional modification may have evolved as an intrinsic resistance mechanism protecting bacteria against natural antibiotics.
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Affiliation(s)
- Seok-Ming Toh
- Center for Pharmaceutical Biotechnology m/c 870, University of Illinois, 900 South Ashland Avenue, Chicago, IL 60607, USA
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47
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Roy-Chaudhuri B, Kirthi N, Kelley T, Culver GM. Suppression of a cold-sensitive mutation in ribosomal protein S5 reveals a role for RimJ in ribosome biogenesis. Mol Microbiol 2008; 68:1547-59. [PMID: 18466225 PMCID: PMC2440530 DOI: 10.1111/j.1365-2958.2008.06252.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A specific mutation of Escherichia coli ribosomal protein S5, in which glycine is changed to aspartate at position 28 [S5(G28D)], results in cold sensitivity and defects in ribosome biogenesis and translational fidelity. In an attempt to understand the roles of S5 in these essential cellular functions, we selected extragenic suppressors and identified rimJ as a high-copy suppressor of the cold-sensitive phenotype associated with the S5(G28D) mutation. Our studies indicate that RimJ overexpression suppresses the growth defects, anomalous ribosome profiles and mRNA misreading exhibited by the S5(G28D) mutant strain. Although previously characterized as the N-acetyltransferase of S5, our data indicate that RimJ, when devoid of acetyltransferase activity, can suppress S5(G28D) defects thus indicating that the suppression activity of RimJ is not dependent on its acetyltransferase activity. Additionally, RimJ appears to associate with pre-30S subunits indicating that it acts on the ribonucleoprotein particle. These findings suggest that RimJ has evolved dual functionality; it functions in r-protein acetylation and as a ribosome assembly factor in E. coli.
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48
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Wang F, Wang J, Jian H, Zhang B, Li S, Wang F, Zeng X, Gao L, Bartlett DH, Yu J, Hu S, Xiao X. Environmental adaptation: genomic analysis of the piezotolerant and psychrotolerant deep-sea iron reducing bacterium Shewanella piezotolerans WP3. PLoS One 2008; 3:e1937. [PMID: 18398463 PMCID: PMC2276687 DOI: 10.1371/journal.pone.0001937] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 02/28/2008] [Indexed: 01/01/2023] Open
Abstract
Shewanella species are widespread in various environments. Here, the genome sequence of Shewanella piezotolerans WP3, a piezotolerant and psychrotolerant iron reducing bacterium from deep-sea sediment was determined with related functional analysis to study its environmental adaptation mechanisms. The genome of WP3 consists of 5,396,476 base pairs (bp) with 4,944 open reading frames (ORFs). It possesses numerous genes or gene clusters which help it to cope with extreme living conditions such as genes for two sets of flagellum systems, structural RNA modification, eicosapentaenoic acid (EPA) biosynthesis and osmolyte transport and synthesis. And WP3 contains 55 open reading frames encoding putative c-type cytochromes which are substantial to its wide environmental adaptation ability. The mtr-omc gene cluster involved in the insoluble metal reduction in the Shewanella genus was identified and compared. The two sets of flagellum systems were found to be differentially regulated under low temperature and high pressure; the lateral flagellum system was found essential for its motility and living at low temperature.
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Affiliation(s)
- Fengping Wang
- Key Laboratory of Marine Biogenetic Resources, State Oceanic Administration, Xiamen, People's Republic of China
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China
| | - Jianbin Wang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Huahua Jian
- Key Laboratory of Marine Biogenetic Resources, State Oceanic Administration, Xiamen, People's Republic of China
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China
| | - Bing Zhang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Shengkang Li
- Key Laboratory of Marine Biogenetic Resources, State Oceanic Administration, Xiamen, People's Republic of China
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China
| | - Feng Wang
- Key Laboratory of Marine Biogenetic Resources, State Oceanic Administration, Xiamen, People's Republic of China
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China
| | - Xiaowei Zeng
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Lei Gao
- The T-Life Research Center, Fudan University, Shanghai, People's Republic of China
| | - Douglas Hoyt Bartlett
- Center for Marine Biotechnology and Biomedicine, Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, United States of America
| | - Jun Yu
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Songnian Hu
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, People's Republic of China
- * E-mail: (SH); (XX)
| | - Xiang Xiao
- Key Laboratory of Marine Biogenetic Resources, State Oceanic Administration, Xiamen, People's Republic of China
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China
- * E-mail: (SH); (XX)
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49
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Pai RD, Zhang W, Schuwirth BS, Hirokawa G, Kaji H, Kaji A, Cate JHD. Structural Insights into ribosome recycling factor interactions with the 70S ribosome. J Mol Biol 2008; 376:1334-47. [PMID: 18234219 PMCID: PMC2712656 DOI: 10.1016/j.jmb.2007.12.048] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Revised: 12/11/2007] [Accepted: 12/19/2007] [Indexed: 11/25/2022]
Abstract
At the end of translation in bacteria, ribosome recycling factor (RRF) is used together with elongation factor G to recycle the 30S and 50S ribosomal subunits for the next round of translation. In x-ray crystal structures of RRF with the Escherichia coli 70S ribosome, RRF binds to the large ribosomal subunit in the cleft that contains the peptidyl transferase center. Upon binding of either E. coli or Thermus thermophilus RRF to the E. coli ribosome, the tip of ribosomal RNA helix 69 in the large subunit moves away from the small subunit toward RRF by 8 A, thereby disrupting a key contact between the small and large ribosomal subunits termed bridge B2a. In the ribosome crystals, the ability of RRF to destabilize bridge B2a is influenced by crystal packing forces. Movement of helix 69 involves an ordered-to-disordered transition upon binding of RRF to the ribosome. The disruption of bridge B2a upon RRF binding to the ribosome seen in the present structures reveals one of the key roles that RRF plays in ribosome recycling, the dissociation of 70S ribosomes into subunits. The structures also reveal contacts between domain II of RRF and protein S12 in the 30S subunit that may also play a role in ribosome recycling.
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Affiliation(s)
- Raj D Pai
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Jain C. The E. coli RhlE RNA helicase regulates the function of related RNA helicases during ribosome assembly. RNA (NEW YORK, N.Y.) 2008; 14:381-9. [PMID: 18083833 PMCID: PMC2212244 DOI: 10.1261/rna.800308] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Escherichia coli contains five members of the DEAD-box RNA helicase family, a ubiquitous class of proteins characterized by their ability to unwind RNA duplexes. Although four of these proteins have been implicated in RNA turnover or ribosome biogenesis, no cellular function for the RhlE DEAD-box protein has been described as yet. During an analysis of the cold-sensitive growth defect of a strain lacking the DeaD/CsdA RNA helicase, rhlE plasmids were identified from a chromosomal library as multicopy suppressors of the growth defect. Remarkably, when tested for allele specificity, RhlE overproduction was found to exacerbate the cold-sensitive growth defect of a strain that lacks the SrmB RNA helicase. Moreover, the absence of RhlE exacerbated or alleviated the cold-sensitive defect of deaD or srmB strains, respectively. Primer extension and ribosome analysis indicated that RhlE regulates the accumulation of immature ribosomal RNA or ribosome precursors when deaD or srmB strains are grown at low temperatures. By using an epitope-tagged version of RhlE, the majority of RhlE in cell extracts was found to cosediment with ribosome-containing fractions. Since both DeaD and SrmB have been recently shown to function in ribosome assembly, these findings suggests that rhlE genetically interacts with srmB and deaD to modulate their function during ribosome maturation. On the basis of the available evidence, I propose that RhlE is a novel ribosome assembly factor, which plays a role in the interconversion of ribosomal RNA-folding intermediates that are further processed by DeaD or SrmB during ribosome maturation.
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Affiliation(s)
- Chaitanya Jain
- Department of Biochemistry and Molecular Biology, University of Miami, Miller School of Medicine, Miami, Florida 33136, USA.
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