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Shirokikh NE, Jensen KB, Thakor N. Editorial: RNA machines. Front Genet 2023; 14:1290420. [PMID: 37829284 PMCID: PMC10565666 DOI: 10.3389/fgene.2023.1290420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023] Open
Affiliation(s)
- Nikolay E. Shirokikh
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Kirk Blomquist Jensen
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Nehal Thakor
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
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2
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Seys FM, Humphreys CM, Tomi-Andrino C, Li Q, Millat T, Yang S, Minton NP. Base editing enables duplex point mutagenesis in Clostridium autoethanogenum at the price of numerous off-target mutations. Front Bioeng Biotechnol 2023; 11:1211197. [PMID: 37496853 PMCID: PMC10366002 DOI: 10.3389/fbioe.2023.1211197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 06/06/2023] [Indexed: 07/28/2023] Open
Abstract
Base editors are recent multiplex gene editing tools derived from the Cas9 nuclease of Streptomyces pyogenes. They can target and modify a single nucleotide in the genome without inducing double-strand breaks (DSB) of the DNA helix. As such, they hold great potential for the engineering of microbes that lack effective DSB repair pathways such as homologous recombination (HR) or non-homologous end-joining (NHEJ). However, few applications of base editors have been reported in prokaryotes to date, and their advantages and drawbacks have not been systematically reported. Here, we used the base editors Target-AID and Target-AID-NG to introduce nonsense mutations into four different coding sequences of the industrially relevant Gram-positive bacterium Clostridium autoethanogenum. While up to two loci could be edited simultaneously using a variety of multiplexing strategies, most colonies exhibited mixed genotypes and most available protospacers led to undesired mutations within the targeted editing window. Additionally, fifteen off-target mutations were detected by sequencing the genome of the resulting strain, among them seven single-nucleotide polymorphisms (SNP) in or near loci bearing some similarity with the targeted protospacers, one 15 nt duplication, and one 12 kb deletion which removed uracil DNA glycosylase (UDG), a key DNA repair enzyme thought to be an obstacle to base editing mutagenesis. A strategy to process prokaryotic single-guide RNA arrays by exploiting tRNA maturation mechanisms is also illustrated.
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Affiliation(s)
- François M. Seys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Christopher M. Humphreys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Claudio Tomi-Andrino
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
- Centre for Analytical Bioscience, Advanced Materials and Healthcare Technologies Division, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
- Nottingham BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Qi Li
- College of Life Sciences, Sichuan Normal University, Chengdu, China
| | - Thomas Millat
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Sheng Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Nigel P. Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
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3
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Yi X, Yang D, Xu X, Wang Y, Guo Y, Zhang M, Wang Y, He Y, Zhu J. Cold plasma pretreatment reinforces the lignocellulose-derived aldehyde inhibitors tolerance and bioethanol fermentability for Zymomonas mobilis. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:102. [PMID: 37322470 DOI: 10.1186/s13068-023-02354-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/29/2023] [Indexed: 06/17/2023]
Abstract
BACKGROUND Lignocellulose-derived aldehyde inhibitors seriously blocked the biorefinery of biofuels and biochemicals. To date, the economic production of lignocellulose-based products heavily relied on high productivities of fermenting strains. However, it was expensive and time-consuming for the achievable rational modification to strengthen stress tolerance robustness of aldehyde inhibitors. Here, it aimed to improve aldehyde inhibitors tolerance and cellulosic bioethanol fermentability for the chassis Zymomonas mobilis ZM4 pretreated using energy-efficient and eco-friendly cold plasma. RESULTS It was found that bioethanol fermentability was weaker in CSH (corn stover hydrolysates) than that in synthetic medium for Z. mobilis, and thus was attributed to the inhibition of the lignocellulose-derived aldehyde inhibitors in CSH. Convincingly, it further confirmed that the mixed aldehydes severely decreased bioethanol accumulation through additional aldehydes supplementary assays in synthetic medium. After assayed under different processing time (10-30 s), discharge power (80-160 W), and working pressure (120-180 Pa) using cold atmosphere plasma (CAP), it achieved the increased bioethanol fermentability for Z. mobilis after pretreated at the optimized parameters (20 s, 140 W and 165 Pa). It showed that cold plasma brought about three mutation sites including ZMO0694 (E220V), ZMO0843 (L471L) and ZMO0843 (P505H) via Genome resequencing-based SNPs (single nucleotide polymorphisms). A serial of differentially expressed genes (DEGs) were further identified as the potential contributors for stress tolerance via RNA-Seq sequencing, including ZMO0253 and ZMO_RS09265 (type I secretion outer membrane protein), ZMO1941 (Type IV secretory pathway protease TraF-like protein), ZMOr003 and ZMOr006 (16S ribosomal RNA), ZMO0375 and ZMO0374 (levansucrase) and ZMO1705 (thioredoxins). It enriched cellular process, followed by metabolic process and single-organism process for biological process. For KEGG analysis, the mutant was also referred to starch and sucrose metabolism, galactose metabolism and two-component system. Finally, but interestingly, it simultaneously achieved the enhanced stress tolerance capacity of aldehyde inhibitors and bioethanol fermentability in CSH for the mutant Z. mobilis. CONCLUSIONS Of several candidate genetic changes, the mutant Z. mobilis treated with cold plasma was conferred upon the facilitated aldehyde inhibitors tolerance and bioethanol production. This work would provide a strain biocatalyst for the efficient production of lignocellulosic biofuels and biochemicals.
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Affiliation(s)
- Xia Yi
- National-Local Joint Engineering Research Center for Biomass Refining and High-Quality Utilization, Changzhou University, Changzhou, 213164, China.
- Institute of Urban and Rural Mining, Changzhou University, Changzhou, 213164, China.
- Changzhou Key Laboratory of Biomass Green, Safe & High Value Utilization Technology, Changzhou University, Changzhou, 213164, Jiangsu, China.
| | - Dong Yang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Xiaoyan Xu
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Youjun Wang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Yan Guo
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Meng Zhang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Yilong Wang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Yucai He
- National-Local Joint Engineering Research Center for Biomass Refining and High-Quality Utilization, Changzhou University, Changzhou, 213164, China.
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China.
| | - Jie Zhu
- National-Local Joint Engineering Research Center for Biomass Refining and High-Quality Utilization, Changzhou University, Changzhou, 213164, China.
- Institute of Urban and Rural Mining, Changzhou University, Changzhou, 213164, China.
- Changzhou Key Laboratory of Biomass Green, Safe & High Value Utilization Technology, Changzhou University, Changzhou, 213164, Jiangsu, China.
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China.
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4
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Rusch DB, Huang J, Hemmerich C, Hahn MW. High-resolution phylogenetic and population genetic analysis of microbial communities with RoC-ITS. ISME COMMUNICATIONS 2022; 2:99. [PMID: 37938727 PMCID: PMC9723582 DOI: 10.1038/s43705-022-00183-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/19/2022] [Accepted: 09/23/2022] [Indexed: 11/09/2023]
Abstract
Microbial communities are inter-connected systems of incredible complexity and dynamism that play crucial roles in health, energy, and the environment. To better understand microbial communities and how they respond to change, it is important to know which microbes are present and their relative abundances at the greatest taxonomic resolution possible. Here, we describe a novel protocol (RoC-ITS) that uses the single-molecule Nanopore sequencing platform to assay the composition of microbial communities at the subspecies designation. Using rolling-circle amplification, this methodology produces long-read sequences from a circular construct containing the complete 16S ribosomal gene and the neighboring internally transcribed spacer (ITS). These long reads can be used to generate a high-fidelity circular consensus sequence. Generally, the ribosomal 16S gene provides phylogenetic information down to the species-level, while the much less conserved ITS region contains strain-level information. When linked together, this combination of markers allows for the identification of individual ribosomal units within a specific organism and the assessment of their relative stoichiometry, as well as the ability to monitor subtle shifts in microbial community composition with a single generic assay. We applied RoC-ITS to an artificial microbial community that was also sequenced using the Illumina platform, to assess its accuracy in quantifying the relative abundance and identity of each species.
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Affiliation(s)
- Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, 47405, USA.
| | - Jie Huang
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, 47405, USA
| | - Chris Hemmerich
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, 47405, USA
| | - Matthew W Hahn
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, 47405, USA
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Computer Science, Indiana University, Bloomington, IN, 47405, USA
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5
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Wu K, Cheng ZH, Williams E, Turner NT, Ran D, Li H, Zhou X, Guo H, Sung W, Liu DF, Lynch M, Long H. Unexpected Discovery of Hypermutator Phenotype Sounds the Alarm for Quality Control Strains. Genome Biol Evol 2021; 13:evab148. [PMID: 34180992 PMCID: PMC8350357 DOI: 10.1093/gbe/evab148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2021] [Indexed: 12/30/2022] Open
Abstract
Microbial strains with high genomic stability are particularly sought after for testing the quality of commercial microbiological products, such as biological media and antibiotics. Yet, using mutation-accumulation experiments and de novo assembled complete genomes based on Nanopore long-read sequencing, we find that the widely used quality-control strain Shewanella putrefaciens ATCC-8071, also a facultative pathogen, is a hypermutator, with a base-pair substitution mutation rate of 2.42 × 10-8 per nucleotide site per cell division, ∼146-fold greater than that of the wild-type strain CGMCC-1.6515. Using complementation experiments, we confirm that mutL dysfunction, which was a recent evolutionary event, is the cause for the high mutation rate of ATCC-8071. Further analyses also give insight into possible relationships between mutation and genome evolution in this important bacterium. This discovery of a well-known strain being a hypermutator necessitates screening the mutation rate of bacterial strains before any quality control or experiments.
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Affiliation(s)
- Kun Wu
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhou-Hua Cheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China
| | - Emily Williams
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Nathan T Turner
- Department of Bioinformatics and Genomics, University of North Carolina, Charlotte, North Carolina, USA
| | - Dapeng Ran
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
| | - Haichao Li
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
| | - Xia Zhou
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
| | - Huilin Guo
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
| | - Way Sung
- Department of Bioinformatics and Genomics, University of North Carolina, Charlotte, North Carolina, USA
| | - Dong-Feng Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China
| | - Michael Lynch
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Hongan Long
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Pilot National Laboratory for Marine Science and Technology, Qingdao, China
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6
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Chan J, Qinqin F, Jianwei L, Ying C, Machida S, Wei C, Yuan YA, Jobichen C. Structural and mechanistic insight into stem-loop RNA processing by yeast Pichia stipitis Dicer. Protein Sci 2021; 30:1210-1220. [PMID: 33884665 DOI: 10.1002/pro.4086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 11/11/2022]
Abstract
Dicer is a member of the ribonuclease III enzyme family and processes double-stranded RNA into small functional RNAs. The variation in the domain architecture of Dicer among different species whilst preserving its biological dicing function is intriguing. Here, we describe the structure and function of a novel catalytically active RNase III protein, a non-canonical Dicer (PsDCR1), found in budding yeast Pichia stipitis. The structure of the catalytically active region (the catalytic RNase III domain and double-stranded RNA-binding domain 1 [dsRBD1]) of DCR1 showed that RNaseIII domain is structurally similar to yeast RNase III (Rnt1p) but uniquely presents dsRBD1 in a diagonal orientation, forming a catalytic core made of homodimer and large RNA-binding surface. The second dsRNA binding domain at C-terminus, which is absent in Rnt1, enhances the RNA cleavage activity. Although the cleavage pattern of PsDCR1 anchors an apical loop similar to Rnt1, the cleavage activity depended on the sequence motif at the lower stem, not the apical loop, of hairpin RNA. Through RNA sequencing and RNA mutations, we showed that RNA cleavage by PsDCR1 is determined by the stem-loop structure of the RNA substrate, suggesting the possibility that stem-loop RNA-guided gene silencing pathway exists in budding yeast.
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Affiliation(s)
- JingRu Chan
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Fu Qinqin
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Li Jianwei
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Chen Ying
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Satoru Machida
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Chen Wei
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore
| | - Yuren Adam Yuan
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.,National University of Singapore (Suzhou) Research Institute, Suzhou, China
| | - Chacko Jobichen
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.,Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
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7
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Nagy-Staron A, Tomasek K, Caruso Carter C, Sonnleitner E, Kavčič B, Paixão T, Guet CC. Local genetic context shapes the function of a gene regulatory network. eLife 2021; 10:e65993. [PMID: 33683203 PMCID: PMC7968929 DOI: 10.7554/elife.65993] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/19/2021] [Indexed: 11/13/2022] Open
Abstract
Gene expression levels are influenced by multiple coexisting molecular mechanisms. Some of these interactions such as those of transcription factors and promoters have been studied extensively. However, predicting phenotypes of gene regulatory networks (GRNs) remains a major challenge. Here, we use a well-defined synthetic GRN to study in Escherichia coli how network phenotypes depend on local genetic context, i.e. the genetic neighborhood of a transcription factor and its relative position. We show that one GRN with fixed topology can display not only quantitatively but also qualitatively different phenotypes, depending solely on the local genetic context of its components. Transcriptional read-through is the main molecular mechanism that places one transcriptional unit (TU) within two separate regulons without the need for complex regulatory sequences. We propose that relative order of individual TUs, with its potential for combinatorial complexity, plays an important role in shaping phenotypes of GRNs.
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Affiliation(s)
- Anna Nagy-Staron
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Kathrin Tomasek
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | | | - Elisabeth Sonnleitner
- Department of MicrobiologyImmunobiology and Genetics, Max F. Perutz Laboratories, Center Of Molecular Biology, University of ViennaViennaAustria
| | - Bor Kavčič
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Tiago Paixão
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Calin C Guet
- Institute of Science and Technology AustriaKlosterneuburgAustria
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8
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Bennison DJ, Irving SE, Corrigan RM. The Impact of the Stringent Response on TRAFAC GTPases and Prokaryotic Ribosome Assembly. Cells 2019; 8:cells8111313. [PMID: 31653044 PMCID: PMC6912228 DOI: 10.3390/cells8111313] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/17/2019] [Accepted: 10/23/2019] [Indexed: 12/24/2022] Open
Abstract
Many facets of ribosome biogenesis and function, including ribosomal RNA (rRNA) transcription, 70S assembly and protein translation, are negatively impacted upon induction of a nutrient stress-sensing signalling pathway termed the stringent response. This stress response is mediated by the alarmones guanosine tetra- and penta-phosphate ((p)ppGpp), the accumulation of which leads to a massive cellular response that slows growth and aids survival. The 70S bacterial ribosome is an intricate structure, with assembly both complex and highly modular. Presiding over the assembly process is a group of P-loop GTPases within the TRAFAC (Translation Factor Association) superclass that are crucial for correct positioning of both early and late stage ribosomal proteins (r-proteins) onto the rRNA. Often described as 'molecular switches', members of this GTPase superfamily readily bind and hydrolyse GTP to GDP in a cyclic manner that alters the propensity of the GTPase to carry out a function. TRAFAC GTPases are considered to act as checkpoints to ribosome assembly, involved in binding to immature sections in the GTP-bound state, preventing further r-protein association until maturation is complete. Here we review our current understanding of the impact of the stringent response and (p)ppGpp production on ribosome maturation in prokaryotic cells, focusing on the inhibition of (p)ppGpp on GTPase-mediated subunit assembly, but also touching upon the inhibition of rRNA transcription and protein translation.
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Affiliation(s)
- Daniel J Bennison
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
| | - Sophie E Irving
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
| | - Rebecca M Corrigan
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
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9
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Abou Elela S, Ji X. Structure and function of Rnt1p: An alternative to RNAi for targeted RNA degradation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1521. [PMID: 30548404 DOI: 10.1002/wrna.1521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/30/2018] [Accepted: 11/15/2018] [Indexed: 12/27/2022]
Abstract
The double-stranded RNA-binding protein (dsRBP) family controls RNA editing, stability, and function in all eukaryotes. The central feature of this family is the recognition of a generic RNA duplex using highly conserved double-stranded RNA-binding domain (dsRBD) that recognizes the characteristic distance between the minor grooves created by the RNA helix. Variations on this theme that confer species and functional specificities have been reported but most dsRBPs retain their capacity to bind generic dsRNA. The ribonuclease III (RNase III) family members fall into four classes, represented by bacterial RNase III, yeast Rnt1p, human Drosha, and human Dicer, respectively. Like all dsRBPs and most members of the RNase III family, Rnt1p has a dsRBD, but unlike most of its kin, it poorly binds to generic RNA helices. Instead, Rnt1p, the only known RNase III expressed in Saccharomyces cerevisiae that lacks the RNAi (RNA interference) machinery, recognizes a specific class of stem-loop structures. To recognize the specific substrates, the dsRBD of Rnt1p is specialized, featuring a αβββααα topology and a sequence-specific RNA-binding motif at the C-terminus. Since the discovery of Rnt1p in 1996, significant progress has been made in studies of its genetics, function, structure, and mechanism of action, explaining the reasons and mechanisms for the increased specificity of this enzyme and its impact on the mechanism of RNA degradation. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Processing > Processing of Small RNAs RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Sherif Abou Elela
- Microbiology and Infectiology Department, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland
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10
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Espejo RT, Plaza N. Multiple Ribosomal RNA Operons in Bacteria; Their Concerted Evolution and Potential Consequences on the Rate of Evolution of Their 16S rRNA. Front Microbiol 2018; 9:1232. [PMID: 29937760 PMCID: PMC6002687 DOI: 10.3389/fmicb.2018.01232] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 05/22/2018] [Indexed: 12/12/2022] Open
Abstract
Bacterial species differ greatly in the number and location of the rRNA operons which may be present in the bacterial chromosomes and plasmids. Most bacterial species contain more than one ribosomal RNA operon copy in their genomes, with some species containing up to 15 such copies. We review the number and location of the rRNA operons and discuss evolution of 16S rRNA (rrs) genes -which are considered as ultimate chronometers for phylogenetic classification- in bacteria with multiple copies of these genes. In these bacterial species, the rrs genes must evolve in concert and sequence changes generated by mutation or horizontal gene transfer must be either erased or spread to every gene copy to avoid divergence, as it occurs when they are present in different species. Analysis of polymorphic sites in intra-genomic rrs copies identifies putative conversion events and demonstrates that sequence conversion is patchy and occurs in small conversion tracts. Sequence conversion probably arises by a non-reciprocal transfer between two or more copies where one copy contributes only a small contiguous segment of DNA, whereas the other copy contributes the rest of the genome in a fairly well understood molecular process. Because concerted evolution implies that a mutation in any of the rrs copies is either eliminated or transferred to every rrs gene in the genome, this process should slow their evolution rate relative to that of single copy genes. However, available data on the rrs genes in bacterial genomes do not show a clear relationship between their evolution rates and the number of their copies in the genome.
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Affiliation(s)
- Romilio T Espejo
- Institute of Nutrition and Food Technology, Universidad de Chile, Santiago, Chile
| | - Nicolás Plaza
- Institute of Nutrition and Food Technology, Universidad de Chile, Santiago, Chile.,Centro de Investigación Biomédica, Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
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11
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Abstract
Multiple models have been advanced for the evolution of cloverleaf tRNA. Here, the conserved archaeal tRNA core (75-nt) is posited to have evolved from ligation of three proto-tRNA minihelices (31-nt) and two-symmetrical 9-nt deletions within joined acceptor stems (93 – 18 = 75-nt). The primary evidence for this conclusion is that the 5-nt stem 7-nt anticodon loop and the 5-nt stem 7-nt T loop are structurally homologous and related by coding sequence. We posit that the D loop was generated from a third minihelix (31-nt) in which the stem and loop became rearranged after 9-nt acceptor stem deletions and cloverleaf folding. The most 3´-5-nt segment of the D loop and the 5-nt V loop are apparent remnants of the joined acceptor stems (14 – 9 = 5-nt). Before refolding in the tRNA cloverleaf, we posit that the 3′-5-nt segment of the D loop and the 5-nt V loop were paired, and, in the tRNA cloverleaf, frequent pairing of positions 29 (D loop) and 47 (V loop) remains (numbered on a 75-nt tRNA cloverleaf core). Amazingly, after >3.5 billion years of evolutionary pressure on the tRNA cloverleaf structure, a model can be constructed that convincingly describes the genesis of 75/75-nt conserved archaeal tRNA core positions. Judging from the tRNA structure, cloverleaf tRNA appears to represent at least a second-generation scheme (and possibly a third-generation scheme) that replaced a robust 31-nt minihelix protein-coding system, evidence for which is preserved in the cloverleaf structure. Understanding tRNA evolution provides insights into ribosome and rRNA evolution.
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Affiliation(s)
| | | | | | - Zachary F Burton
- c Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA
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12
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Tomecki R, Sikorski PJ, Zakrzewska-Placzek M. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases. FEBS Lett 2017; 591:1801-1850. [PMID: 28524231 DOI: 10.1002/1873-3468.12682] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/14/2017] [Accepted: 05/15/2017] [Indexed: 12/17/2022]
Abstract
Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans.
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Affiliation(s)
- Rafal Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.,Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Poland
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13
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Takada H, Shimada T, Dey D, Quyyum MZ, Nakano M, Ishiguro A, Yoshida H, Yamamoto K, Sen R, Ishihama A. Differential Regulation of rRNA and tRNA Transcription from the rRNA-tRNA Composite Operon in Escherichia coli. PLoS One 2016; 11:e0163057. [PMID: 28005933 PMCID: PMC5179076 DOI: 10.1371/journal.pone.0163057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 09/01/2016] [Indexed: 11/18/2022] Open
Abstract
Escherichia coli contains seven rRNA operons, each consisting of the genes for three rRNAs (16S, 23S and 5S rRNA in this order) and one or two tRNA genes in the spacer between 16S and 23S rRNA genes and one or two tRNA genes in the 3’ proximal region. All of these rRNA and tRNA genes are transcribed from two promoters, P1 and P2, into single large precursors that are afterward processed to individual rRNAs and tRNAs by a set of RNases. In the course of Genomic SELEX screening of promoters recognized by RNA polymerase (RNAP) holoenzyme containing RpoD sigma, a strong binding site was identified within 16S rRNA gene in each of all seven rRNA operons. The binding in vitro of RNAP RpoD holoenzyme to an internal promoter, referred to the promoter of riRNA (an internal RNA of the rRNA operon), within each 16S rRNA gene was confirmed by gel shift assay and AFM observation. Using this riRNA promoter within the rrnD operon as a representative, transcription in vitro was detected with use of the purified RpoD holoenzyme, confirming the presence of a constitutive promoter in this region. LacZ reporter assay indicated that this riRNA promoter is functional in vivo. The location of riRNA promoter in vivo as identified using a set of reporter plasmids agrees well with that identified in vitro. Based on transcription profile in vitro and Northern blot analysis in vivo, the majority of transcript initiated from this riRNA promoter was estimated to terminate near the beginning of 23S rRNA gene, indicating that riRNA leads to produce the spacer-coded tRNA. Under starved conditions, transcription of the rRNA operon is markedly repressed to reduce the intracellular level of ribosomes, but the levels of both riRNA and its processed tRNAGlu stayed unaffected, implying that riRNA plays a role in the continued steady-state synthesis of tRNAs from the spacers of rRNA operons. We then propose that the tRNA genes organized within the spacers of rRNA-tRNA composite operons are expressed independent of rRNA synthesis under specific conditions where further synthesis of ribosomes is not needed.
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Affiliation(s)
- Hiraku Takada
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
| | - Tomohiro Shimada
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
- Laboratory for Chemistry and Life Science, Tokyo Institute of Technology, Nagatsuda, Yokohama, Japan
| | - Debashish Dey
- Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | | | - Masahiro Nakano
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Akira Ishiguro
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
| | - Hideji Yoshida
- Department of Physics, Osaka Medical College, Takatsuki, Osaka, Japan
| | - Kaneyoshi Yamamoto
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Ranjan Sen
- Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Akira Ishihama
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
- * E-mail:
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14
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Gajera HP, Savaliya DD, Hirapara DG, Patel SV, Golakiya BA. Biocontrol Mechanism of Bacillus for Fusarium Wilt Management in Cumin (Cuminum cyminum L.). Fungal Biol 2016. [DOI: 10.1007/978-3-319-27312-9_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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15
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A 3′ External Transcribed Spacer in a tRNA Transcript Acts as a Sponge for Small RNAs to Prevent Transcriptional Noise. Mol Cell 2015; 58:393-405. [DOI: 10.1016/j.molcel.2015.03.013] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 02/13/2015] [Accepted: 03/09/2015] [Indexed: 10/23/2022]
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16
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Shepherd J, Ibba M. Bacterial transfer RNAs. FEMS Microbiol Rev 2015; 39:280-300. [PMID: 25796611 DOI: 10.1093/femsre/fuv004] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/21/2015] [Indexed: 11/14/2022] Open
Abstract
Transfer RNA is an essential adapter molecule that is found across all three domains of life. The primary role of transfer RNA resides in its critical involvement in the accurate translation of messenger RNA codons during protein synthesis and, therefore, ultimately in the determination of cellular gene expression. This review aims to bring together the results of intensive investigations into the synthesis, maturation, modification, aminoacylation, editing and recycling of bacterial transfer RNAs. Codon recognition at the ribosome as well as the ever-increasing number of alternative roles for transfer RNA outside of translation will be discussed in the specific context of bacterial cells.
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Affiliation(s)
- Jennifer Shepherd
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
| | - Michael Ibba
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
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17
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Janezic S, Indra A, Rattei T, Weinmaier T, Rupnik M. Recombination drives evolution of the Clostridium difficile 16S-23S rRNA intergenic spacer region. PLoS One 2014; 9:e106545. [PMID: 25222120 PMCID: PMC4164361 DOI: 10.1371/journal.pone.0106545] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/05/2014] [Indexed: 12/18/2022] Open
Abstract
PCR-ribotyping, a typing method based on size variation in 16S-23S rRNA intergenic spacer region (ISR), has been used widely for molecular epidemiological investigations of C. difficile infections. In the present study, we describe the sequence diversity of ISRs from 43 C. difficile strains, representing different PCR-ribotypes and suggest homologous recombination as a possible mechanism driving the evolution of 16S-23S rRNA ISRs. ISRs of 45 different lengths (ranging from 185 bp to 564 bp) were found among 458 ISRs. All ISRs could be described with one of the 22 different structural groups defined by the presence or absence of different sequence modules; tRNAAla genes and different combinations of spacers of different lengths (33 bp, 53 bp or 20 bp) and 9 bp direct repeats separating the spacers. The ISR structural group, in most cases, coincided with the sequence length. ISRs that were of the same lengths had also very similar nucleotide sequence, suggesting that ISRs were not suitable for discriminating between different strains based only on the ISR sequence. Despite large variations in the length, the alignment of ISR sequences, based on the primary sequence and secondary structure information, revealed many conserved regions which were mainly involved in maturation of pre-rRNA. Phylogenetic analysis of the ISR alignment yielded strong evidence for intra- and inter-homologous recombination which could be one of the mechanisms driving the evolution of C. difficile 16S-23S ISRs. The modular structure of the ISR, the high sequence similarities of ISRs of the same sizes and the presence of homologous recombination also suggest that different copies of C. difficile 16S-23S rRNA ISR are evolving in concert.
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Affiliation(s)
- Sandra Janezic
- National Laboratory for Health, Environment and Food, Maribor, Slovenia
| | - Alexander Indra
- Austrian Agency for Health and Food Safety (AGES), Vienna, Austria
| | - Thomas Rattei
- Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | | | - Maja Rupnik
- National Laboratory for Health, Environment and Food, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Ljubljana, Slovenia
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18
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Malagon F. RNase III is required for localization to the nucleoid of the 5' pre-rRNA leader and for optimal induction of rRNA synthesis in E. coli. RNA (NEW YORK, N.Y.) 2013; 19:1200-7. [PMID: 23893733 PMCID: PMC3753927 DOI: 10.1261/rna.038588.113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 06/14/2013] [Indexed: 05/24/2023]
Abstract
It has recently been demonstrated that ribosomes are preferentially localized outside the nucleoid in Escherichia coli, but little is known about the spatial regulation of pre-rRNA processing. In this work, I investigate the cellular distribution of leader pre-rRNAs using RNA-FISH. In contrast to mature rRNA, the 5' proximal leader region associates with the nucleoid, and this association occurs in an RNase III-dependent manner. Moreover, RNase III plays a role in the rapid induction of ribosomal operons during outgrowth and is essential in the absence of the transcriptional regulator Fis, suggesting a linkage of transcription and RNA processing for ribosomal operons in E. coli.
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Affiliation(s)
- Francisco Malagon
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, USA.
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19
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Sulthana S, Deutscher MP. Multiple exoribonucleases catalyze maturation of the 3' terminus of 16S ribosomal RNA (rRNA). J Biol Chem 2013; 288:12574-9. [PMID: 23532845 DOI: 10.1074/jbc.c113.459172] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Processing of ribosomal RNA (rRNA) precursors is an important component of RNA metabolism in all cells. However, in no system have we yet identified all the RNases involved in this process. Here, we show that four 3'→5'-exoribonucleases, RNases II, R, and PH, and polynucleotide phosphorylase (PNPase), participate in maturation of the 3' end of 16S rRNA. In their absence, 16S precursor molecules with 33 extra 3'-nt accumulate; however, the presence of any one of the four RNases is sufficient to allow processing to occur, although with different efficiencies. Additionally, we find that in the absence of 3' maturation, 5' processing proceeds much less efficiently. Moreover, mutant 30S particles, containing immature 16S rRNA, form 70S ribosomes very poorly. These findings, together with the earlier discovery that RNases E and G are the 5'-processing enzymes, completes the catalogue of RNases involved in maturation of Escherichia coli 16S rRNA.
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Affiliation(s)
- Shaheen Sulthana
- Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, Florida 33101, USA
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20
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Bernstein DA, Vyas VK, Fink GR. Genes come and go: the evolutionarily plastic path of budding yeast RNase III enzymes. RNA Biol 2012; 9:1123-8. [PMID: 23018782 PMCID: PMC3579876 DOI: 10.4161/rna.21360] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Our recent finding that the Candida albicans RNase III enzyme CaDcr1 is an unusual, multifunctional RNase III coupled with data on the RNase III enzymes from other fungal species prompted us to seek a model that explained the evolution of RNase III’s in modern budding yeast species. CaDcr1 has both dicer function (generates small RNA molecules from dsRNA precursors) and Rnt1 function, (catalyzes the maturation of 35S rRNA and U4 snRNA). Some budding yeast species have two distinct genes that encode these functions, a Dicer and RNT1, whereas others have only an RNT1 and no Dicer. As none of the budding yeast species has the canonical Dicer found in many other fungal lineages and most eukaryotes, the extant species must have evolved from an ancestor that lost the canonical Dicer, and evolved a novel Dicer from the essential RNT1 gene. No single, simple model could explain the evolution of RNase III enzymes from this ancestor because existing sequence data are consistent with two equally plausible models. The models share an architecture for RNase III evolution that involves gene duplication, loss, subfunctionalization, and neofunctionalization. This commentary explains our reasoning, and offers the prospect that further genomic data could further resolve the dilemma surrounding the budding yeast RNase III’s evolution.
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Affiliation(s)
- Douglas A Bernstein
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA, USA
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21
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Liguori AP, Warrington SD, Ginther JL, Pearson T, Bowers J, Glass MB, Mayo M, Wuthiekanun V, Engelthaler D, Peacock SJ, Currie BJ, Wagner DM, Keim P, Tuanyok A. Diversity of 16S-23S rDNA internal transcribed spacer (ITS) reveals phylogenetic relationships in Burkholderia pseudomallei and its near-neighbors. PLoS One 2011; 6:e29323. [PMID: 22195045 PMCID: PMC3237603 DOI: 10.1371/journal.pone.0029323] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/24/2011] [Indexed: 11/19/2022] Open
Abstract
Length polymorphisms within the 16S-23S ribosomal DNA internal transcribed spacer (ITS) have been described as stable genetic markers for studying bacterial phylogenetics. In this study, we used these genetic markers to investigate phylogenetic relationships in Burkholderia pseudomallei and its near-relative species. B. pseudomallei is known as one of the most genetically recombined bacterial species. In silico analysis of multiple B. pseudomallei genomes revealed approximately four homologous rRNA operons and ITS length polymorphisms therein. We characterized ITS distribution using PCR and analyzed via a high-throughput capillary electrophoresis in 1,191 B. pseudomallei strains. Three major ITS types were identified, two of which were commonly found in most B. pseudomallei strains from the endemic areas, whereas the third one was significantly correlated with worldwide sporadic strains. Interestingly, mixtures of the two common ITS types were observed within the same strains, and at a greater incidence in Thailand than Australia suggesting that genetic recombination causes the ITS variation within species, with greater recombination frequency in Thailand. In addition, the B. mallei ITS type was common to B. pseudomallei, providing further support that B. mallei is a clone of B. pseudomallei. Other B. pseudomallei near-neighbors possessed unique and monomorphic ITS types. Our data shed light on evolutionary patterns of B. pseudomallei and its near relative species.
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Affiliation(s)
- Andrew P. Liguori
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Stephanie D. Warrington
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Jennifer L. Ginther
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Talima Pearson
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Jolene Bowers
- Division of Pathogen Genomics, The Translational Genomics Research Institute North, Flagstaff, Arizona, United States of America
| | - Mindy B. Glass
- Bacterial Zoonoses Branch, Division of Foodborne, Bacterial and Mycotic Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America
| | - Mark Mayo
- Charles Darwin University, Menzies School of Health Research, Darwin, Northern Territory, Australia
| | | | - David Engelthaler
- Division of Pathogen Genomics, The Translational Genomics Research Institute North, Flagstaff, Arizona, United States of America
| | | | - Bart J. Currie
- Charles Darwin University, Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - David M. Wagner
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Paul Keim
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Apichai Tuanyok
- Department of Biological Sciences, Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, Arizona, United States of America
- * E-mail:
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22
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Daoud R, Forget L, Lang BF. Yeast mitochondrial RNase P, RNase Z and the RNA degradosome are part of a stable supercomplex. Nucleic Acids Res 2011; 40:1728-36. [PMID: 22034500 PMCID: PMC3287206 DOI: 10.1093/nar/gkr941] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Initial steps in the synthesis of functional tRNAs require 5'- and 3'-processing of precursor tRNAs (pre-tRNAs), which in yeast mitochondria are achieved by two endonucleases, RNase P and RNase Z. In this study, using a combination of detergent-free Blue Native Gel Electrophoresis, proteomics and in vitro testing of pre-tRNA maturation, we reveal the physical association of these plus other mitochondrial activities in a large, stable complex of 136 proteins. It contains a total of seven proteins involved in RNA processing including RNase P and RNase Z, five out of six subunits of the mitochondrial RNA degradosome, components of the fatty acid synthesis pathway, translation, metabolism and protein folding. At the RNA level, there are the small and large rRNA subunits and RNase P RNA. Surprisingly, this complex is absent in an oar1Δ deletion mutant of the type II fatty acid synthesis pathway, supporting a recently published functional link between pre-tRNA processing and the FAS II pathway--apparently by integration into a large complex as we demonstrate here. Finally, the question of mt-RNase P localization within mitochondria was investigated, by GFP-tracing of a known protein subunit (Rpm2p). We find that about equal fractions of RNase P are soluble versus membrane-attached.
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Affiliation(s)
- Rachid Daoud
- Robert-Cedergren Centre for Bioinformatics and Genomics, Department of Biochemistry, Université de Montréal, 2900 Edouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
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23
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René O, Alix JH. Late steps of ribosome assembly in E. coli are sensitive to a severe heat stress but are assisted by the HSP70 chaperone machine. Nucleic Acids Res 2010; 39:1855-67. [PMID: 21059683 PMCID: PMC3061059 DOI: 10.1093/nar/gkq1049] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The late stages of 30S and 50S ribosomal subunits biogenesis have been studied in a wild-type (wt) strain of Escherichia coli (MC4100) subjected to a severe heat stress (45–46°C). The 32S and 45S ribosomal particles (precursors to 50S subunits) and 21S ribosomal particles (precursors to 30S subunits) accumulate under these conditions. They are authentic precursors, not degraded or dead-end particles. The 21S particles are shown, by way of a modified 3′5′ RACE procedure, to contain 16S rRNA unprocessed, or processed at its 5′ end, and not at the 3′ end. This implies that maturation of 16S rRNA is ordered and starts at its 5′-terminus, and that the 3′-terminus is trimmed at a later step. This observation is not limited to heat stress conditions, but it also can be verified in bacteria growing at a normal temperature (30°C), supporting the idea that this is the general pathway. Assembly defects at very high temperature are partially compensated by plasmid-driven overexpression of the DnaK/DnaJ chaperones. The ribosome assembly pattern in wt bacteria under a severe heat stress is therefore reminiscent of that observed at lower temperatures in E. coli mutants lacking the chaperones DnaK or DnaJ.
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Affiliation(s)
- Olivier René
- CNRS UPR9073 (affiliated with University Paris 7-Denis Diderot), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris
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24
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Korelusová J, Kasˇtovský J, Komárek J. HETEROGENEITY OF THE CYANOBACTERIAL GENUS SYNECHOCYSTIS AND DESCRIPTION OF A NEW GENUS, GEMINOCYSTIS(1). JOURNAL OF PHYCOLOGY 2009; 45:928-937. [PMID: 27034224 DOI: 10.1111/j.1529-8817.2009.00701.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The study and revision of the unicellular cyanobacterial genus Synechocystis was based on the type species S. aquatilis Sauv. and strain PCC 6803, a reference strain for this species. Uniformity in rRNA gene sequence, morphology, and ultrastructure was observed in all available Synechocystis strains, with the exception of the strain PCC 6308, which has been considered by some to be a model strain for Synechocystis. This strain differs substantially from the typical Synechocystis cluster according to both molecular (<90% of similarity, differences in 16S-23S rRNA internal transcribed spacer [ITS] secondary structure) and phenotypic criteria (different ultrastructure of cells). This strain is herein classified into the new genus Geminocystis gen. nov., as a sister taxon to the genus Cyanobacterium. Geminocystis differs from Cyanobacterium by genetic position (<94.4% of similarity) and more importantly by its different type of cell division. Because strain PCC 6308 was designated as a reference strain of the Synechocystis cluster 1 in Bergey's Manual, the members of this genetic cluster have to be revised and reclassified into Geminocystis gen. nov. Only the members of the Synechocystis cluster 2 allied with PCC 6803 correspond both genetically and phenotypically to the type species of the genus Synechocystis (S. aquatilis).
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Affiliation(s)
- Jana Korelusová
- University of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech RepublicUniversity of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic Academy of Sciences of the Czech Republic, Institute of Botany, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic
| | - Jan Kasˇtovský
- University of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech RepublicUniversity of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic Academy of Sciences of the Czech Republic, Institute of Botany, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic
| | - Jiří Komárek
- University of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech RepublicUniversity of South Bohemia, Faculty of Sciences, Institute of Botany, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic Academy of Sciences of the Czech Republic, Institute of Botany, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic
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25
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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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26
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Hao YJ, Montiel R, Nascimento G, Toubarro D, Simoes N. Identification, characterization of functional candidate genes for host-parasite interactions in entomopathogenetic nematode Steinernema carpocapsae by suppressive subtractive hybridization. Parasitol Res 2008; 103:671-83. [PMID: 18543000 DOI: 10.1007/s00436-008-1030-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 05/05/2008] [Indexed: 11/25/2022]
Abstract
Identifying parasitism genes encoding proteins secreted from nematodes is the key to understanding the molecular basis of nematode parasitism to insects. In this paper, a cDNA with two introns and three exons encoding a cysteine protease inhibitor was identified by screening a cDNA subtractive library constructed from the nematode, Steinernema carpocapsae, induced by Galleria mellonella hemolymph. The full-length cDNA contains an open reading frame encoding a 139-amino acid protein, designated Sc-cys, with a 19-residue signal peptide. The mature protein was predicted to have a molecular weight of 12,531.59 Da, a pI of 9.44, one disulfide bond, and three conserved domains believed to be important for the inhibition of cysteine proteases. In Basic Local Alignment and Search Tool analyses, the putative protein precursor displayed 26-42% identities to a multitude of cystatins or cystatin-like proteins. Phylogenetic analysis suggested the novel cystatin is likely a new member of the family 2 cystatins. Reverse northern blot, semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and real-time RT-PCR analyses showed that the expression level of Sc-cys was upregulated substantially after induction by insect hemolymph. The specific analysis of genes encoding secretory proteins is providing a profile of putative parasitism genes expressed in S. carpocapsae throughout the parasitic cycle.
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Affiliation(s)
- You-Jin Hao
- CIRN, Departamento de Biologia, Universidade dos Acores, Ponta Delgada, Azores, Portugal.
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27
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Wilson DN, Nierhaus KH. The weird and wonderful world of bacterial ribosome regulation. Crit Rev Biochem Mol Biol 2007; 42:187-219. [PMID: 17562451 DOI: 10.1080/10409230701360843] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In every organism, translation of the genetic information into functional proteins is performed on the ribosome. In Escherichia coli up to 40% of the cell's total energy turnover is channelled toward the ribosome and protein synthesis. Thus, elaborate networks of translation regulation pathways have evolved to modulate gene expression in response to growth rate and external factors, ranging from nutrient deprivation, to chemical (pH, ionic strength) and physical (temperature) fluctuations. Since the fundamental players involved in regulation of the different phases of translation have already been extensively reviewed elsewhere, this review focuses on lesser known and characterized factors that regulate the ribosome, ranging from processing, modification and assembly factors, unusual initiation and elongation factors, to a variety of stress response proteins.
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Affiliation(s)
- Daniel N Wilson
- Gene Center and Department of Chemistry and Biochemistry, University of Munich, Munich, Germany.
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28
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Bubunenko M, Baker T, Court DL. Essentiality of ribosomal and transcription antitermination proteins analyzed by systematic gene replacement in Escherichia coli. J Bacteriol 2007; 189:2844-53. [PMID: 17277072 PMCID: PMC1855809 DOI: 10.1128/jb.01713-06] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 01/18/2007] [Indexed: 11/20/2022] Open
Abstract
We describe here details of the method we used to identify and distinguish essential from nonessential genes on the bacterial Escherichia coli chromosome. Three key features characterize our method: high-efficiency recombination, precise replacement of just the open reading frame of a chromosomal gene, and the presence of naturally occurring duplications within the bacterial genome. We targeted genes encoding functions critical for processes of transcription and translation. Proteins from three complexes were evaluated to determine if they were essential to the cell by deleting their individual genes. The transcription elongation Nus proteins and termination factor Rho, which are involved in rRNA antitermination, the ribosomal proteins of the small 30S ribosome subunit, and minor ribosome-associated proteins were analyzed. It was concluded that four of the five bacterial transcription antitermination proteins are essential, while all four of the minor ribosome-associated proteins examined (RMF, SRA, YfiA, and YhbH), unlike most ribosomal proteins, are dispensable. Interestingly, although most 30S ribosomal proteins were essential, the knockouts of six ribosomal protein genes, rpsF (S6), rpsI (S9), rpsM (S13), rpsO (S15), rpsQ (S17), and rpsT (S20), were viable.
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Affiliation(s)
- Mikhail Bubunenko
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
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MacRae IJ, Doudna JA. Ribonuclease revisited: structural insights into ribonuclease III family enzymes. Curr Opin Struct Biol 2006; 17:138-45. [PMID: 17194582 DOI: 10.1016/j.sbi.2006.12.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 11/09/2006] [Accepted: 12/13/2006] [Indexed: 11/20/2022]
Abstract
Ribonuclease III (RNase III) enzymes occur ubiquitously in biology and are responsible for processing RNA precursors into functional RNAs that participate in protein synthesis, RNA interference and a range of other cellular activities. Members of the RNase III enzyme family, including Escherichia coli RNase III, Rnt1, Dicer and Drosha, share the ability to recognize and cleave double-stranded RNA (dsRNA), typically at specific positions or sequences. Recent biochemical and structural data have shed new light on how RNase III enzymes catalyze dsRNA hydrolysis and how substrate specificity is achieved. A major theme emerging from these studies is that accessory domains present in different RNase III enzymes are the key determinants of substrate selectivity, which in turn dictates the specialized biological function of each type of RNase III protein.
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Affiliation(s)
- Ian J MacRae
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
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30
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Mani N, Dupuy B, Sonenshein AL. Isolation of RNA polymerase from Clostridium difficile and characterization of glutamate dehydrogenase and rRNA gene promoters in vitro and in vivo. J Bacteriol 2006; 188:96-102. [PMID: 16352825 PMCID: PMC1317598 DOI: 10.1128/jb.188.1.96-102.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile is the primary causative agent of antibiotic-associated diarrheal disease. To facilitate molecular genetic analysis of gene expression in this organism, methods were developed to study transcriptional regulation in vitro and in vivo. That is, C. difficile RNA polymerase was partially purified and shown to bind to and initiate transcription in vitro from bona fide C. difficile promoters for rRNA and glutamate dehydrogenase genes. In addition, primer extension analyses and a beta-glucuronidase reporter system were used to quantitate transcription from these promoters in vivo. With these tools in hand, it is now possible to characterize the behavior of any C. difficile gene in vivo and to study the regulation of its expression in detail.
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Affiliation(s)
- Nagraj Mani
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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31
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Schuster J, Betat H, Mörl M. Is yeast on its way to evolving tRNA editing? EMBO Rep 2005; 6:367-72. [PMID: 15791267 PMCID: PMC1299291 DOI: 10.1038/sj.embor.7400381] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 02/18/2005] [Accepted: 02/22/2005] [Indexed: 11/08/2022] Open
Abstract
In human mitochondria, genes for tRNA(Tyr) and tRNA(Cys) overlap by a single nucleotide. From polycistronic precursors, a 3'-truncated upstream tRNA(Tyr) is released, missing the overlapping position. A subsequent editing reaction restores this position. Similar mitochondrial tRNA gene overlaps exist in all metazoans, but not in organisms such as yeast or Escherichia coli. Therefore, we asked whether tRNA overlaps are processed in these organisms. Corresponding constructs were introduced and transcripts tested for processing and editing in E. coli and yeast. E. coli produces only one functional tRNA from these precursors, indicating that tRNA overlaps are incompatible with its processing pathway. In contrast, yeast processes overlapping tRNAs similar to human mitochondria, releasing a 3'-truncated upstream tRNA. This tRNA is restored in an editing-like event, although yeast does not carry a corresponding endogenous editing substrate. These findings support the hypothesis of the evolution of editing by recruitment of a pre-existing and promiscuous editing enzyme.
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Affiliation(s)
- Jens Schuster
- Max-Planck-Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Heike Betat
- Max-Planck-Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
- Institute for Biochemistry, University of Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Mario Mörl
- Max-Planck-Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
- Institute for Biochemistry, University of Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
- Tel: +49 341 3550 507; Fax: +49 341 3550 555; E-mail:
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32
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Ghazal G, Ge D, Gervais-Bird J, Gagnon J, Abou Elela S. Genome-wide prediction and analysis of yeast RNase III-dependent snoRNA processing signals. Mol Cell Biol 2005; 25:2981-94. [PMID: 15798187 PMCID: PMC1069626 DOI: 10.1128/mcb.25.8.2981-2994.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Saccharomyces cerevisiae, the maturation of both pre-rRNA and pre-small nucleolar RNAs (pre-snoRNAs) involves common factors, thereby providing a potential mechanism for the coregulation of snoRNA and rRNA synthesis. In this study, we examined the global impact of the double-stranded-RNA-specific RNase Rnt1p, which is required for pre-rRNA processing, on the maturation of all known snoRNAs. In silico searches for Rnt1p cleavage signals, and genome-wide analysis of the Rnt1p-dependent expression profile, identified seven new Rnt1p substrates. Interestingly, two of the newly identified Rnt1p-dependent snoRNAs, snR39 and snR59, are located in the introns of the ribosomal protein genes RPL7A and RPL7B. In vitro and in vivo experiments indicated that snR39 is normally processed from the lariat of RPL7A, suggesting that the expressions of RPL7A and snR39 are linked. In contrast, snR59 is produced by a direct cleavage of the RPL7B pre-mRNA, indicating that a single pre-mRNA transcript cannot be spliced to produce a mature RPL7B mRNA and processed by Rnt1p to produce a mature snR59 simultaneously. The results presented here reveal a new role of yeast RNase III in the processing of intron-encoded snoRNAs that permits independent regulation of the host mRNA and its associated snoRNA.
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Affiliation(s)
- Ghada Ghazal
- Université de Sherbrooke, Département de Microbiologie et d'Infectiologie, 3001 12e Ave nord, Sherbrooke, Québec J1H 5N4, Canada
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33
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Amblar M, Arraiano CM. A single mutation in Escherichia coli ribonuclease II inactivates the enzyme without affecting RNA binding. FEBS J 2004; 272:363-74. [PMID: 15654875 DOI: 10.1111/j.1742-4658.2004.04477.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Exoribonuclease II (RNase II), encoded by the rnb gene, is a ubiquitous enzyme that is responsible for 90% of the hydrolytic activity in Escherichia coli crude extracts. The E. coli strain SK4803, carrying the mutant allele rnb296, has been widely used in the study of the role of RNase II. We determined the DNA sequence of rnb296 and cloned this mutant gene in an expression vector. Only a point mutation in the coding sequence of the gene was detected, which results in the single substitution of aspartate 209 for asparagine. The mutant and the wild-type RNase II enzymes were purified, and their 3' to 5' exoribonucleolytic activity, as well as their RNA binding capability, were characterized. We also studied the metal dependency of the exoribonuclease activity of RNase II. The results obtained demonstrated that aspartate 209 is absolutely essential for RNA hydrolysis, but is not required for substrate binding. This is the first evidence of an acidic residue that is essential for the activity of RNase II-like enzymes. The possible involvement of this residue in metal binding at the active site of the enzyme is discussed. These results are particularly relevant at this time given that no structural or mutational analysis has been performed for any protein of the RNR family of exoribonucleases.
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Affiliation(s)
- Mónica Amblar
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
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34
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Day-Storms JJ, Niranjanakumari S, Fierke CA. Ionic interactions between PRNA and P protein in Bacillus subtilis RNase P characterized using a magnetocapture-based assay. RNA (NEW YORK, N.Y.) 2004; 10:1595-608. [PMID: 15337847 PMCID: PMC1370646 DOI: 10.1261/rna.7550104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Ribonuclease P (RNase P) is a ribonucleoprotein complex that catalyzes the cleavage of the 5' end of precursor tRNA. To characterize the interface between the Bacillus subtilis RNA (PRNA) and protein (P protein) components, the intraholoenzyme KD is determined as a function of ionic strength using a magnetocapture-based assay. Three distinct phases are evident. At low ionic strength, the affinity of PRNA for P protein is enhanced as the ionic strength increases mainly due to stabilization of the PRNA structure by cations. Lithium substitution in lieu of potassium enhances the affinity at low ionic strength, whereas the addition of ATP, known to stabilize the structure of P protein, does not affect the affinity. At high ionic strength, the observed affinity decreases as the ionic strength increases, consistent with disruption of ionic interactions. These data indicate that three to four ions are released on formation of holoenzyme, reflecting the number of ion pairs that occur between the P protein and PRNA. At moderate ionic strength, the two effects balance so that the apparent KD is not dependent on the ionic strength. The KD between the catalytic domain (C domain) and P protein has a similar triphasic dependence on ionic strength. Furthermore, the intraholoenzyme KD is identical to or tighter than that of full-length PRNA, demonstrating that the P protein binds solely to the C domain. Finally, pre-tRNAasp (but not tRNAasp) stabilizes the PRNA*P protein complex, as predicted by the direct interaction between the P protein and pre-tRNA leader.
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Affiliation(s)
- Jeremy J Day-Storms
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, MI 48109, USA
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35
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Calegari F, Marzesco AM, Kittler R, Buchholz F, Huttner WB. Tissue-specific RNA interference in post-implantation mouse embryos using directional electroporation and whole embryo culture. Differentiation 2004; 72:92-102. [PMID: 15066189 DOI: 10.1111/j.1432-0436.2004.07202002.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In mammals, embryonic development is more difficult to analyze than in non-mammalian species because this development occurs in utero. Interestingly, whole embryo culture allows the normal development of mouse post-implantation embryos for up to 2 days in vitro. One limitation of this technology has been the difficulty of performing loss-of-gene function studies in this system. RNA interference (RNAi), whereby double-stranded RNA molecules suppress the expression of complementary genes, has rapidly become a widely used tool for gene function analyses. We have combined the technologies of mouse whole embryo culture and RNAi to allow the molecular dissection of developmental processes. Here, we review the manipulation by topical injection followed by directional electroporation of endoribonuclease-prepared siRNA to demonstrate that this technology may be useful to knock down genes in a tissue- and region-specific manner in several organs of the developing mouse embryo.
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Affiliation(s)
- Federico Calegari
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307, Dresden, Germany
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36
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Abstract
Transfer-messenger RNA (tmRNA, or SsrA), found in all eubacteria, has both transfer and messenger RNA activity. Relieving ribosome stalling by a process called trans-translation, tmRNAala enters the ribosome and adds its aminoacylated alanine to the nascent polypeptide. The original mRNA is released and tmRNA becomes the template for translation of a 10-amino-acid tag that signals for proteolytic degradation. Although essential in a few bacterial species, tmRNA is nonessential in Escherichia coli and many other bacteria. Proteins known to be associated with tmRNA include SmpB, ribosomal protein S1, RNase R, and phosphoribosyl pyrophosphate. SmpB, having no other known function, is essential for tmRNA activity. trans-translation operates within ribosomes stalled both at the end of truncated mRNAs and at rare codons and some natural termination sites. Both the release of stalled ribosomes and the subsequent degradation of tagged proteins are important consequences of trans-translation.
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Affiliation(s)
- Jeffrey H Withey
- Unit for Lab Animal Medicine, University of Michigan Medical School, 104 ARF, Ann Arbor, Michigan 48109-0614, USA.
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37
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Xu D, Côté JC. Phylogenetic relationships between Bacillus species and related genera inferred from comparison of 3' end 16S rDNA and 5' end 16S-23S ITS nucleotide sequences. Int J Syst Evol Microbiol 2003; 53:695-704. [PMID: 12807189 DOI: 10.1099/ijs.0.02346-0] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nucleotide sequences of the 3' end of the 16S rDNA and the 16S-23S internal transcribed spacer (ITS) of 40 Bacillaceae species were determined. These included 21 Bacillus, 9 Paenibacillus, 6 Brevibacillus, 2 Geobacillus, 1 Marinibacillus and 1 Virgibacillus species. Comparative sequence analysis of a 220 bp region covering a highly conserved 150 bp sequence located at the 3' end of the 16S rRNA coding region and a conserved 70 bp sequence located at the 5' end of the 16S-23S ITS of the 40 species and six sequences available in GenBank were used to infer the phylogenetic relationships between all 46 taxa. When a maximal distance (D(max), where D refers to the number of nucleotide substitutions per site) of 0.31 was introduced as a threshold to determine groupings, 10 phylogenetically distinct clusters were revealed. Twenty-six Bacillus species were separated in seven groups (I, II, III, IV, V, VI and X), but Bacillus circulans remained ungrouped. All six Brevibacillus species under study were in Group VII. The nine Paenibacillus species fell into two distinct groups (VIII and IX). Species with D(max) values within 0.05 were considered to be very closely related. These were Bacillus psychrophilus and Bacillus psychrosaccharolyticus in Group II; 'Bacillus maroccanus' and Bacillus simplex in Group II; Bacillus amyloliquefaciens, Bacillus atrophaeus, Bacillus mojavensis and Bacillus subtilis in Group VI; Bacillus fusiformis and Bacillus sphaericus in Group VI; Brevibacillus brevis and Brevibacillus formosus in Group VII; Paenibacillus gordonae and Paenibacillus validus in Group VIII; and Bacillus anthracis, Bacillus cereus, Bacillus mycoides and Bacillus thuringiensis in Group X. The phylogenetic classification presented here is, in general, in agreement with current classifications based on phenotypic and molecular data. Our findings suggest, however, that in some cases, further divisions or, conversely, further groupings might be warranted. Should current classifications be re-examined in the light of our results, D(max) values of 0.31 and 0.05, as exemplified here, may prove useful threshold values for the grouping of Bacillaceae into taxa akin to genera and species, respectively. These D(max) thresholds may also reveal, in a different way, bacterial species for which further characterization might be warranted for proper classification and/or reassignment.
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Affiliation(s)
- Dong Xu
- Agriculture and Agri-Food Canada, Research Centre, 430 Gouin Blvd, St-Jean-sur-Richelieu, Quebec, Canada J3B 3E6
| | - Jean-Charles Côté
- Agriculture and Agri-Food Canada, Research Centre, 430 Gouin Blvd, St-Jean-sur-Richelieu, Quebec, Canada J3B 3E6
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38
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Wenner T, Roth V, Decaris B, Leblond P. Intragenomic and intraspecific polymorphism of the 16S-23S rDNA internally transcribed sequences of Streptomyces ambofaciens. MICROBIOLOGY (READING, ENGLAND) 2002; 148:633-642. [PMID: 11882697 DOI: 10.1099/00221287-148-3-633] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The nucleotide composition of the internally transcribed sequences (ITSs) of the six rDNA operons of two strains of Streptomyces ambofaciens were determined. Four variable and five conserved nucleotide blocks were distinguished. Five different modular organizations were revealed for each strain and no homologous loci showed the same succession of blocks. This suggests that recombination frequently occurs between the rDNA loci, leading to the exchange of nucleotide blocks. The modular structure was also observed within the ITSs of Streptomyces coelicolor M145, which is closely related to Streptomyces ambofaciens, and Streptomyces griseus 2247, showing the same number of constant blocks but with fewer variable regions. This confirms that a high degree of ITS variability is a common characteristic among Streptomyces spp. The functional significance of the combinations of variable and constant nucleotide blocks of the ITS was examined by in silico prediction of secondary structures from nucleotide sequences. The secondary structures were shown to be analogous whatever the combination of variable/constant blocks at the intragenomic, intraspecific and interspecific levels.
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MESH Headings
- Base Sequence
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal Spacer/chemistry
- DNA, Ribosomal Spacer/genetics
- Evolution, Molecular
- Molecular Sequence Data
- Phylogeny
- Polymorphism, Genetic
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 23S/genetics
- Recombination, Genetic
- Sequence Analysis, DNA
- Streptomyces/chemistry
- Streptomyces/genetics
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Affiliation(s)
- Thomas Wenner
- Laboratoire de Génétique et Microbiologie UMR INRA 1128-IFR110, Faculté des Sciences, Université Henri Poincaré - Nancy 1, BP 239, Boulevard des Aiguillettes, F-54506 Vandoeuvre-lès-Nancy, France1
| | - Virginie Roth
- Laboratoire de Génétique et Microbiologie UMR INRA 1128-IFR110, Faculté des Sciences, Université Henri Poincaré - Nancy 1, BP 239, Boulevard des Aiguillettes, F-54506 Vandoeuvre-lès-Nancy, France1
| | - Bernard Decaris
- Laboratoire de Génétique et Microbiologie UMR INRA 1128-IFR110, Faculté des Sciences, Université Henri Poincaré - Nancy 1, BP 239, Boulevard des Aiguillettes, F-54506 Vandoeuvre-lès-Nancy, France1
| | - Pierre Leblond
- Laboratoire de Génétique et Microbiologie UMR INRA 1128-IFR110, Faculté des Sciences, Université Henri Poincaré - Nancy 1, BP 239, Boulevard des Aiguillettes, F-54506 Vandoeuvre-lès-Nancy, France1
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39
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Rocap G, Distel DL, Waterbury JB, Chisholm SW. Resolution of Prochlorococcus and Synechococcus ecotypes by using 16S-23S ribosomal DNA internal transcribed spacer sequences. Appl Environ Microbiol 2002; 68:1180-91. [PMID: 11872466 PMCID: PMC123739 DOI: 10.1128/aem.68.3.1180-1191.2002] [Citation(s) in RCA: 390] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2001] [Accepted: 12/12/2001] [Indexed: 11/20/2022] Open
Abstract
Cultured isolates of the marine cyanobacteria Prochlorococcus and Synechococcus vary widely in their pigment compositions and growth responses to light and nutrients, yet show greater than 96% identity in their 16S ribosomal DNA (rDNA) sequences. In order to better define the genetic variation that accompanies their physiological diversity, sequences for the 16S-23S rDNA internal transcribed spacer (ITS) region were determined in 32 Prochlorococcus isolates and 25 Synechococcus isolates from around the globe. Each strain examined yielded one ITS sequence that contained two tRNA genes. Dramatic variations in the length and G+C content of the spacer were observed among the strains, particularly among Prochlorococcus strains. Secondary-structure models of the ITS were predicted in order to facilitate alignment of the sequences for phylogenetic analyses. The previously observed division of Prochlorococcus into two ecotypes (called high and low-B/A after their differences in chlorophyll content) were supported, as was the subdivision of the high-B/A ecotype into four genetically distinct clades. ITS-based phylogenies partitioned marine cluster A Synechococcus into six clades, three of which can be associated with a particular phenotype (motility, chromatic adaptation, and lack of phycourobilin). The pattern of sequence divergence within and between clades is suggestive of a mode of evolution driven by adaptive sweeps and implies that each clade represents an ecologically distinct population. Furthermore, many of the clades consist of strains isolated from disparate regions of the world's oceans, implying that they are geographically widely distributed. These results provide further evidence that natural populations of Prochlorococcus and Synechococcus consist of multiple coexisting ecotypes, genetically closely related but physiologically distinct, which may vary in relative abundance with changing environmental conditions.
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Affiliation(s)
- Gabrielle Rocap
- Joint Program in Biological Oceanography, Massachusetts Institute of Technology & Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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40
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Affiliation(s)
- M Wachi
- Department of Bioengineering, Tokyo Institute of Technology, Midori-ku, Yokohama, 226-8501, Japan
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41
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Abstract
To generate functional tRNA molecules, precursor RNAs must undergo several processing steps. While the enzyme that generates the mature tRNA 5'-end, RNase P, has been thoroughly investigated, the 3'-processing activity is, despite its importance, less understood. While nothing is known about tRNA 3'-processing in archaea, the phenomenon has been analysed in detail in bacteria and is known to be a multistep process involving several enzymes, including both exo- and endonucleases. tRNA 3'-end processing in the eukaryotic nucleus seems to be either exonucleolytic or endonucleolytic, depending on the organism analysed, whereas in organelles, 3'-end maturation occurs via a single endonucleolytic cut. An interesting feature of organellar tRNA 3'-processing is the occurrence of overlapping tRNA genes in metazoan mitochondria, which presents a unique challenge for the mitochondrial tRNA maturation enzymes, since it requires not only the removal but also the addition of nucleotides by an editing reaction.
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Affiliation(s)
- M Mörl
- Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany
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42
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Saito R, Ozawa Y, Kuzuno N, Tomita M. Computer analysis of potential stem structures of rRNA operons in various procaryote genomes. Gene 2000; 259:217-22. [PMID: 11163979 DOI: 10.1016/s0378-1119(00)00429-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The processing of 16S rRNA and 23S rRNA by RNase III in E.coli is known to involve stem structures formed by both ends of the rRNA. Indeed, complementary nucleotide sequences are usually found at both ends of 16S rRNA and 23S rRNA. However, whether or not this phenomenon exists in various other bacteria has not yet been adequately studied. We have conducted computer analyses of potential stem structures of rRNA operons in 12 bacterial and 3 archaeal genomes, and compared characteristics of the stem structures among these species. We systematically computed free energy values by exhaustively 'annealing' sequences around the 5' end and sequences around the 3' end of both 16S rRNA and 23S rRNA genes, in order to predict potential stem structures. The results suggest that rRNAs in most species form stem structures at both ends. Some species, such as A.aeolicus, seem to form unusually stable stem structures. On the other hand, some rRNAs, such as rRNAs of D.radiodurans, seem not to form solid stem structures. This suggests that rRNA processing in those species must employ a reliable targeting mechanism other than recognizing stem structures by RNase III.
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MESH Headings
- Bacteria/genetics
- Base Sequence
- Computational Biology
- Databases, Factual
- Genome, Bacterial
- Nucleic Acid Conformation
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- Sequence Alignment
- Species Specificity
- Thermodynamics
- rRNA Operon
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Affiliation(s)
- R Saito
- Laboratory for Genome Exploration Research Group, RIKEN Genomic Sciences Center and Genome Science Laboratory, RIKEN Tsukuba Institute Koyadai 3-1-1, Tsukuba Ibaraki 305-0074, Japan
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43
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Recognition of a conserved class of RNA tetraloops by Saccharomyces cerevisiae RNase III. Proc Natl Acad Sci U S A 2000. [PMID: 10716739 PMCID: PMC16206 DOI: 10.1073/pnas.070043997] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ribonucleases III are double-stranded RNA (dsRNA) endonucleases required for the processing of a large number of prokaryotic and eukaryotic transcripts. Although the specificity of bacterial RNase III cleavage relies on antideterminants in the dsRNA, the molecular basis of eukaryotic RNase III specificity is unknown. All substrates of yeast RNase III (Rnt1p) are capped by terminal tetraloops showing the consensus AGNN and located within 13-16 bp to Rnt1p cleavage sites. We show that these tetraloops are essential for Rnt1p cleavage and that the distance to the tetraloop is the primary determinant of cleavage site selection. The presence of AGNN tetraloops also enhances Rnt1p binding, as shown by surface plasmon resonance monitoring and modification interference studies. These results define a paradigm of RNA loops and show that yeast RNase III behaves as a helical RNA ruler that recognizes these tetraloops and cleaves the dsRNA at a fixed distance to this RNA structure. These results also indicate that proteins belonging to the same class of RNA endonucleases require different structural elements for RNA cleavage.
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44
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Chanfreau G, Buckle M, Jacquier A. Recognition of a conserved class of RNA tetraloops by Saccharomyces cerevisiae RNase III. Proc Natl Acad Sci U S A 2000; 97:3142-7. [PMID: 10716739 PMCID: PMC16206 DOI: 10.1073/pnas.97.7.3142] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ribonucleases III are double-stranded RNA (dsRNA) endonucleases required for the processing of a large number of prokaryotic and eukaryotic transcripts. Although the specificity of bacterial RNase III cleavage relies on antideterminants in the dsRNA, the molecular basis of eukaryotic RNase III specificity is unknown. All substrates of yeast RNase III (Rnt1p) are capped by terminal tetraloops showing the consensus AGNN and located within 13-16 bp to Rnt1p cleavage sites. We show that these tetraloops are essential for Rnt1p cleavage and that the distance to the tetraloop is the primary determinant of cleavage site selection. The presence of AGNN tetraloops also enhances Rnt1p binding, as shown by surface plasmon resonance monitoring and modification interference studies. These results define a paradigm of RNA loops and show that yeast RNase III behaves as a helical RNA ruler that recognizes these tetraloops and cleaves the dsRNA at a fixed distance to this RNA structure. These results also indicate that proteins belonging to the same class of RNA endonucleases require different structural elements for RNA cleavage.
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Affiliation(s)
- G Chanfreau
- Unité de Génétique des Interactions Macromoléculaires, URA1300 Centre National de la Recherche Scientifique, Département des Biotechnologies, Institut Pasteur, Paris, France.
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45
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Varmanen P, Savijoki K, Avall S, Palva A, Tynkkynen S. X-prolyl dipeptidyl aminopeptidase gene (pepX) is part of the glnRA operon in Lactobacillus rhamnosus. J Bacteriol 2000; 182:146-54. [PMID: 10613874 PMCID: PMC94251 DOI: 10.1128/jb.182.1.146-154.2000] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A peptidase gene expressing X-prolyl dipeptidyl aminopeptidase (PepX) activity was cloned from Lactobacillus rhamnosus 1/6 by using the chromogenic substrate L-glycyl-L-prolyl-beta-naphthylamide for screening of a genomic library in Escherichia coli. The nucleotide sequence of a 3.5-kb HindIII fragment expressing the peptidase activity revealed one complete open reading frame (ORF) of 2,391 nucleotides. The 797-amino-acid protein encoded by this ORF was shown to be 40, 39, and 36% identical with PepXs from Lactobacillus helveticus, Lactobacillus delbrueckii, and Lactococcus lactis, respectively. By Northern analysis with a pepX-specific probe, transcripts of 4.5 and 7.0 kb were detected, indicating that pepX is part of a polycistronic operon in L. rhamnosus. Cloning and sequencing of the upstream region of pepX revealed the presence of two ORFs of 360 and 1,338 bp that were shown to be able to encode proteins with high homology to GlnR and GlnA proteins, respectively. By multiple primer extension analyses, the only functional promoter in the pepX region was located 25 nucleotides upstream of glnR. Northern analysis with glnA- and pepX-specific probes indicated that transcription from glnR promoter results in a 2.0-kb dicistronic glnR-glnA transcript and also in a longer read-through polycistronic transcript of 7.0 kb that was detected with both probes in samples from cells in exponential growth phase. The glnA gene was disrupted by a single-crossover recombinant event using a nonreplicative plasmid carrying an internal part of glnA. In the disruption mutant, glnRA-specific transcription was derepressed 10-fold compared to the wild type, but the 7.0-kb transcript was no longer detectable with either the glnA- or pepX-specific probe, demonstrating that pepX is indeed part of glnRA operon in L. rhamnosus. Reverse transcription-PCR analysis further supported this operon structure. An extended stem-loop structure was identified immediately upstream of pepX in the glnA-pepX intergenic region, a sequence that showed homology to a 23S-5S intergenic spacer and to several other L. rhamnosus-related entries in data banks.
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Affiliation(s)
- P Varmanen
- R&D, Valio Ltd., FIN-00039 Valio, Helsinki, Finland.
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Kressler D, Linder P, de La Cruz J. Protein trans-acting factors involved in ribosome biogenesis in Saccharomyces cerevisiae. Mol Cell Biol 1999; 19:7897-912. [PMID: 10567516 PMCID: PMC84875 DOI: 10.1128/mcb.19.12.7897] [Citation(s) in RCA: 299] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- D Kressler
- Département de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, 1211 Genève 4, Switzerland
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Wachi M, Umitsuki G, Shimizu M, Takada A, Nagai K. Escherichia coli cafA gene encodes a novel RNase, designated as RNase G, involved in processing of the 5' end of 16S rRNA. Biochem Biophys Res Commun 1999; 259:483-8. [PMID: 10362534 DOI: 10.1006/bbrc.1999.0806] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We found that the Escherichia coli cafA::cat mutant accumulated a precursor of 16S rRNA. This precursor migrated to the same position with 16.3S precursor found in the BUMMER strain that is known to be deficient in the 5' end processing of 16S rRNA. Accumulation of 16. 3S rRNA in the BUMMER mutant was complemented by introduction of a plasmid carrying the cafA gene. The mutant type cafA gene cloned from the BUMMER strain had a 11-bp deletion in its coding region. A small amount of the mature 16S rRNA was still formed in the cafA::cat mutant. This residual activity was found to be due to RNase E encoded by the rne/ams gene by rifampicin-chase experiments of the cafA::cat ams1 double mutant. These results indicated that the cafA gene encodes a novel RNase responsible for processing of the 5' end of 16S rRNA.
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Affiliation(s)
- M Wachi
- Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan.
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Li Z, Pandit S, Deutscher MP. RNase G (CafA protein) and RNase E are both required for the 5' maturation of 16S ribosomal RNA. EMBO J 1999; 18:2878-85. [PMID: 10329633 PMCID: PMC1171368 DOI: 10.1093/emboj/18.10.2878] [Citation(s) in RCA: 235] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In Escherichia coli, rRNA operons are transcribed as 30S precursor molecules that must be extensively processed to generate mature 16S, 23S and 5S rRNA. While it is known that RNase III cleaves the primary transcript to separate the individual rRNAs, there is little information about the secondary processing reactions needed to form their mature 3' and 5' termini. We have now found that inactivation of the endoribonuclease RNase E slows down in vivo maturation of 16S RNA from the 17S RNase III cleavage product. Moreover, in the absence of CafA protein, a homolog of RNase E, formation of 16S RNA also slows down, but in this case a 16.3S intermediate accumulates. When both RNase E and CafA are inactivated, 5' maturation of 16S rRNA is completely blocked. In contrast, 3' maturation is essentially unaffected. The 5' unprocessed precursor that accumulates in the double mutant can be assembled into 30S and 70S ribosomes. Precursors also can be processed in vitro by RNase E and CafA. These data indicate that both RNase E and CafA protein are required for a two step, sequential maturation of the 5' end of 16S rRNA, and that CafA protein is a new ribonuclease. We propose that it be renamed RNase G.
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Affiliation(s)
- Z Li
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, FL 33101, USA
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Nomura N, Sako Y, Uchida A. Molecular characterization and postsplicing fate of three introns within the single rRNA operon of the hyperthermophilic archaeon Aeropyrum pernix K1. J Bacteriol 1998; 180:3635-43. [PMID: 9658008 PMCID: PMC107333 DOI: 10.1128/jb.180.14.3635-3643.1998] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The single rRNA operon (arnS-arnL) of the hyperthermophilic archaeon Aeropyrum pernix K1 was sequenced. The DNA sequence data and detailed RNA analyses disclosed an unusual feature: the presence of three introns at hitherto undescribed insertion positions within the rRNA genes. The 699-nucleotide (nt) intron Ialpha was located at position 908 (Escherichia coli numbering [H. F. Noller, Annu. Rev. Biochem. 53:119-162, 1984]) of the 16S rRNA, while the 202-nt intron Ibeta and 575-nt intron Igamma were located at positions 1085 and 1927 (E. coli numbering), respectively, of the 23S rRNA. They were located within highly conserved sites which have been implicated as crucial for rRNA function in E. coli. All three introns were remarkably AT rich (41.5 to 43.1 mol% G+C) compared with the mature rRNAs (67.7 and 69.2 mol% G+C for 16S and 23S rRNAs, respectively). No obvious primary sequence similarities were detected among them. After splicing from rRNA transcripts in vivo, a large quantity of intronic RNAs were stably retained in the linear monomeric form, whereas a trace of topoisomeric RNA molecules also appeared, as characterized by their behavior in two-dimensional gel electrophoresis. Secondary structural models of the Ialpha-, Ibeta-, and Igamma-containing rRNA precursors agree with the bulge-helix-bulge motif. Two of the introns, Ialpha and Igamma, contained open reading frames whose protein translation exhibited no overall similarity with proteins reported so far. However, both share a LAGLI-DADG motif characteristic of homing endonucleases.
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Affiliation(s)
- N Nomura
- Laboratory of Marine Microbiology, Division of Applied Bioscience, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502,
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Nour M. 16S-23S and 23S-5S intergenic spacer regions of lactobacilli: nucleotide sequence, secondary structure and comparative analysis. Res Microbiol 1998; 149:433-48. [PMID: 9766243 DOI: 10.1016/s0923-2508(98)80326-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Lactobacilli have been used as industrial starters for a long time, but in several cases their identification was, and still is, neither easy nor reliable. The aim of the present work was to examine whether the intergenic spacer regions could be of value in the identification of Lactobacillus species. For that purpose, the polymerase chain reaction (PCR) was used to amplify 16S-23S and 23S-5S spacer regions of Lactobacillus (L.) acidophilus, L. delbrueckii subsp. bulgaricus, L. casei, L. helveticus and L. curvatus. The PCR products were directly sequenced, and two forms of ribosomal RNA (rrn) operons were identified in each species studied: one with tandem tRNA(Ile)/tRNA(Ala) genes and the other one without tRNA genes. Our study revealed that the rrn operons of Lactobacillus species studied comprise the genes of 16S, 23S and 5S rRNA, in that order. Only the tRNA genes and the rRNA processing stems are highly conserved in spacer regions of lactobacilli. The divergence between the lactobacilli spacer region sequences arises from insertions and deletions of short sequences. These sequences could be interesting candidates for the development of species-specific probes. Theoretical RNA/RNA secondary structure models of the interaction between the two spacer region sequences were constructed. In conclusion, the two spacer region sequences may prove to be a useful alternative to 16S and 23S rDNA sequencing for designing species-specific probes and for establishing phylogenetic relationships between closely related species such as L. curvatus and L. casei or L. acidophilus and L. helveticus.
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MESH Headings
- Base Sequence
- Fermentation/genetics
- Lactobacillus/genetics
- Molecular Sequence Data
- Nucleic Acid Conformation
- Phylogeny
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 5S/genetics
- RNA, Transfer, Ala/genetics
- RNA, Transfer, Ile/genetics
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Affiliation(s)
- M Nour
- Département des Sciences Biologiques (Microbiologie), Faculté des Sciences de Monastir, Tunisia
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