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Khisamutdinov EF, Sweeney BA, Leontis NB. Context-sensitivity of isosteric substitutions of non-Watson-Crick basepairs in recurrent RNA 3D motifs. Nucleic Acids Res 2021; 49:9574-9593. [PMID: 34403481 PMCID: PMC8450098 DOI: 10.1093/nar/gkab703] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 07/29/2021] [Indexed: 02/01/2023] Open
Abstract
Sequence variation in a widespread, recurrent, structured RNA 3D motif, the Sarcin/Ricin (S/R), was studied to address three related questions: First, how do the stabilities of structured RNA 3D motifs, composed of non-Watson–Crick (non-WC) basepairs, compare to WC-paired helices of similar length and sequence? Second, what are the effects on the stabilities of such motifs of isosteric and non-isosteric base substitutions in the non-WC pairs? And third, is there selection for particular base combinations in non-WC basepairs, depending on the temperature regime to which an organism adapts? A survey of large and small subunit rRNAs from organisms adapted to different temperatures revealed the presence of systematic sequence variations at many non-WC paired sites of S/R motifs. UV melting analysis and enzymatic digestion assays of oligonucleotides containing the motif suggest that more stable motifs tend to be more rigid. We further found that the base substitutions at non-Watson–Crick pairing sites can significantly affect the thermodynamic stabilities of S/R motifs and these effects are highly context specific indicating the importance of base-stacking and base-phosphate interactions on motif stability. This study highlights the significance of non-canonical base pairs and their contributions to modulating the stability and flexibility of RNA molecules.
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Affiliation(s)
- Emil F Khisamutdinov
- Department of Chemistry and Center for Photochemical Science, Bowling Green State University, Bowling Green, OH 43403, USA.,Department of Chemistry, Ball State University, Muncie, IN 47306, USA
| | - Blake A Sweeney
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.,European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Neocles B Leontis
- Department of Chemistry and Center for Photochemical Science, Bowling Green State University, Bowling Green, OH 43403, USA
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2
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ENDO Y. Development of a cell-free protein synthesis system for practical use. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:261-276. [PMID: 33980755 PMCID: PMC8141837 DOI: 10.2183/pjab.97.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
Conventional cell-free protein synthesis systems had been the major platform to study the mechanism behind translating genetic information into proteins, as proven in the central dogma of molecular biology. Albeit being powerful research tools, most of the in vitro methods at the time failed to produce enough protein for practical use. Tremendous efforts were being made to overcome the limitations of in vitro translation systems, though mostly with limited success. While great knowledge was accumulated on the translation mechanism and ribosome structure, researchers rationalized that it may be impossible to fully reconstitute such a complex molecular process in a test tube. This review will examine how we have solved the difficulties holding back progress. Our newly developed cell-free protein synthesis system is based on wheat embryos and has many excellent characteristics, in addition to its high translation activity and robustness. Combined with other novel elementary technologies, we have established cell-free protein synthesis systems for practical use in research and applied sciences.
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Affiliation(s)
- Yaeta ENDO
- Ehime Prefectural University of Health Sciences, Tobe-cho, Iyo-gun, Ehime, Japan
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3
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How Ricin Damages the Ribosome. Toxins (Basel) 2019; 11:toxins11050241. [PMID: 31035546 PMCID: PMC6562825 DOI: 10.3390/toxins11050241] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Ricin belongs to the group of ribosome-inactivating proteins (RIPs), i.e., toxins that have evolved to provide particular species with an advantage over other competitors in nature. Ricin possesses RNA N-glycosidase activity enabling the toxin to eliminate a single adenine base from the sarcin-ricin RNA loop (SRL), which is a highly conserved structure present on the large ribosomal subunit in all species from the three domains of life. The SRL belongs to the GTPase associated center (GAC), i.e., a ribosomal element involved in conferring unidirectional trajectory for the translational apparatus at the expense of GTP hydrolysis by translational GTPases (trGTPases). The SRL represents a critical element in the GAC, being the main triggering factor of GTP hydrolysis by trGTPases. Enzymatic removal of a single adenine base at the tip of SRL by ricin blocks GTP hydrolysis and, at the same time, impedes functioning of the translational machinery. Here, we discuss the consequences of SRL depurination by ricin for ribosomal performance, with emphasis on the mechanistic model overview of the SRL modus operandi.
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4
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Zhong C, Zhang S. Clustering RNA structural motifs in ribosomal RNAs using secondary structural alignment. Nucleic Acids Res 2011; 40:1307-17. [PMID: 21976732 PMCID: PMC3273805 DOI: 10.1093/nar/gkr804] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
RNA structural motifs are the building blocks of the complex RNA architecture. Identification of non-coding RNA structural motifs is a critical step towards understanding of their structures and functionalities. In this article, we present a clustering approach for de novo RNA structural motif identification. We applied our approach on a data set containing 5S, 16S and 23S rRNAs and rediscovered many known motifs including GNRA tetraloop, kink-turn, C-loop, sarcin–ricin, reverse kink-turn, hook-turn, E-loop and tandem-sheared motifs, with higher accuracy than the state-of-the-art clustering method. We also identified a number of potential novel instances of GNRA tetraloop, kink-turn, sarcin–ricin and tandem-sheared motifs. More importantly, several novel structural motif families have been revealed by our clustering analysis. We identified a highly asymmetric bulge loop motif that resembles the rope sling. We also found an internal loop motif that can significantly increase the twist of the helix. Finally, we discovered a subfamily of hexaloop motif, which has significantly different geometry comparing to the currently known hexaloop motif. Our discoveries presented in this article have largely increased current knowledge of RNA structural motifs.
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Affiliation(s)
- Cuncong Zhong
- Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, FL 32816, USA
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5
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Lee H, Diavatis T, Tennakoon S, Yu P, Gao X. Solution structure of DNA/RNA hybrid duplex with C8-propynyl 2'-deoxyadenosine modifications: Implication of RNase H and DNA/RNA duplex interaction. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1769:20-8. [PMID: 17196678 DOI: 10.1016/j.bbaexp.2006.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 10/10/2006] [Accepted: 11/06/2006] [Indexed: 05/13/2023]
Abstract
Solution structures of DNA/RNA hybrid duplexes, d(GCGCA*AA*ACGCG): r(cgcguuuugcg)d(C) (designated PP57), containing two C8-propynyl 2'-deoxyadenosines (A*) and unmodified hybrid (designated U4A4) are solved. The C8-propynyl groups on 2'-deoxyadenosine perturb the local structure of the hybrid duplex, but overall the structure is similar to that of canonical DNA/RNA hybrid duplex except that Hoogsteen hydrogen bondings between A* and U result in lower thermal stability. RNase H is known to cleave RNA only in DNA/RNA hybrid duplexes. Minor groove widths of hybrid duplexes, sugar puckerings of DNA are reported to be responsible for RNase H mediated cleavage, but structural requirements for RNase H mediated cleavage still remain elusive. Despite the presence of bulky propynyl groups of PP57 in the minor groove and greater flexibility, the PP57 is an RNase H substrate. To provide an insight on the interactions between RNase H and substrates we have modeled Bacillus halodurans RNase H-PP57 complex, our NMR structure and modeling study suggest that the residue Gly(15) and Asn(16) of the loop residues between first beta sheet and second beta sheet of RNase HI of Escherichia coli might participate in substrate binding.
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Affiliation(s)
- Hunjoong Lee
- Department of Chemistry, University of Houston, 136 Fleming Building, Houston, TX 77204-5003, USA.
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6
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García-Mayoral F, García-Ortega L, Alvarez-García E, Bruix M, Gavilanes JG, del Pozo AM. Modeling the highly specific ribotoxin recognition of ribosomes. FEBS Lett 2005; 579:6859-64. [PMID: 16337202 DOI: 10.1016/j.febslet.2005.11.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 10/27/2005] [Accepted: 11/01/2005] [Indexed: 11/16/2022]
Abstract
The three-dimensional structures of the alpha-sarcin ribotoxin and its delta(7-22) deletion mutant, both complexed with a 20-mer oligonucleotide mimicking the sarcin/ricin loop (SRL) of the ribosome, have been docked into the structure of the Halobacterium marismortui ribosome by fitting the nucleotide atomic coordinates into those of the ribosomal SRL. This study has revealed that two regions of the ribotoxin, residues 11-16 and 84-85, contact the ribosomal proteins L14 (residues 99-105) and L6 (residues 88-92), respectively. The first of these two ribotoxin regions appears to be crucial for its specific ribosome recognition.
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Affiliation(s)
- Flor García-Mayoral
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
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7
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García-Mayoral MF, García-Ortega L, Lillo MP, Santoro J, Martínez del Pozo A, Gavilanes JG, Rico M, Bruix M. NMR structure of the noncytotoxic alpha-sarcin mutant Delta(7-22): the importance of the native conformation of peripheral loops for activity. Protein Sci 2004; 13:1000-11. [PMID: 15044731 PMCID: PMC2280062 DOI: 10.1110/ps.03532204] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The deletion mutant Delta(7-22) of alpha-sarcin, unlike its wild-type protein counterpart, lacks the specific ability to degrade rRNA in intact ribosomes and exhibits an increased unspecific ribonuclease activity and decreased interaction with lipid vesicles. In trying to shed light on these differences, we report here on the three-dimensional structure of the Delta(7-22) alpha-sarcin mutant using NMR methods. We also evaluated its dynamic properties on the basis of theoretical models and measured its correlation time (6.2 nsec) by time-resolved fluorescence anisotropy. The global fold characteristic of ribotoxins is preserved in the mutant. The most significant differences with respect to the alpha-sarcin structure are concentrated in (1) loop 2, (2) loop 3, which adopts a new orientation, and (3) loop 5, which shows multiple conformations and an altered dynamics. The interactions between loop 5 and the N-terminal hairpin are lost in the mutant, producing increased solvent accessibility of the active-site residues. The degree of solvent exposure of the catalytic His 137 is similar to that shown by His 92 in RNase T1. Additionally, the calculated order parameters of residues belonging to loop 5 in the mutant correspond to an internal dynamic behavior more similar to RNase T1 than alpha-sarcin. On the other hand, changes in the relative orientation of loop 3 move the lysine-rich region 111-114, crucial for substrate recognition, away from the active site. All of the structural and dynamic data presented here reveal that the mutant is a hybrid of ribotoxins and noncytotoxic ribonucleases, consistent with its biological properties.
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Affiliation(s)
- Ma Flor García-Mayoral
- Departamento de Espectroscopía y Estructura Molecular, Instituto de Química Física Rocasolano, Serrano 119, CSIC, 28006 Madrid, Spain
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8
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Correll CC, Beneken J, Plantinga MJ, Lubbers M, Chan YL. The common and the distinctive features of the bulged-G motif based on a 1.04 A resolution RNA structure. Nucleic Acids Res 2003; 31:6806-18. [PMID: 14627814 PMCID: PMC290275 DOI: 10.1093/nar/gkg908] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2003] [Revised: 10/15/2003] [Accepted: 10/15/2003] [Indexed: 11/13/2022] Open
Abstract
Bulged-G motifs are ubiquitous internal RNA loops that provide specific recognition sites for proteins and RNAs. To establish the common and distinctive features of the motif we determined the structures of three variants and compared them with related structures. The variants are 27-nt mimics of the sarcin/ricin loop (SRL) from Escherichia coli 23S ribosomal RNA that is an essential part of the binding site for elongation factors (EFs). The wild-type SRL has now been determined at 1.04 A resolution, supplementing data obtained before at 1.11 A and allowing the first calculation of coordinate error for an RNA motif. The other two structures, having a viable (C2658U*G2663A) or a lethal mutation (C2658G*G2663C), were determined at 1.75 and 2.25 A resolution, respectively. Comparisons reveal that bulged-G motifs have a common hydration and geometry, with flexible junctions at flanking structural elements. Six conserved nucleotides preserve the fold of the motif; the remaining seven to nine vary in sequence and alter contacts in both grooves. Differences between accessible functional groups of the lethal mutation and those of the viable mutation and wild-type SRL may account for the impaired elongation factor binding to ribosomes with the C2658G*G2663C mutation and may underlie the lethal phenotype.
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MESH Headings
- Animals
- Base Sequence
- Crystallization
- Crystallography, X-Ray
- Escherichia coli/genetics
- Genes, Essential/genetics
- Genes, Lethal/genetics
- Models, Molecular
- Mutation/genetics
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- Rats
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Affiliation(s)
- Carl C Correll
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
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9
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Correll CC, Swinger K. Common and distinctive features of GNRA tetraloops based on a GUAA tetraloop structure at 1.4 A resolution. RNA (NEW YORK, N.Y.) 2003; 9:355-63. [PMID: 12592009 PMCID: PMC1370402 DOI: 10.1261/rna.2147803] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Accepted: 11/12/2002] [Indexed: 05/18/2023]
Abstract
GNRA tetraloops (N is A, C, G, or U; R is A or G) are basic building blocks of RNA structure that often interact with proteins or other RNA structural elements. Understanding sequence-dependent structural variation among different GNRA tetraloops is an important step toward elucidating the molecular basis of specific GNRA tetraloop recognition by proteins and RNAs. Details of the geometry and hydration of this motif have been based on high-resolution crystallographic structures of the GRRA subset of tetraloops; less is known about the GYRA subset (Y is C or U). We report here the structure of a GUAA tetraloop determined to 1.4 A resolution to better define these details and any distinctive features of GYRA tetraloops. The tetraloop is part of a 27-nt structure that mimics the universal sarcin/ricin loop from Escherichia coli 23S ribosomal RNA in which a GUAA tetraloop replaces the conserved GAGA tetraloop. The adenosines of the GUAA tetraloop form an intermolecular contact that is a commonplace RNA tertiary interaction called an A-minor motif. This is the first structure to reveal in great detail the geometry and hydration of a GUAA tetraloop and an A-minor motif. Comparison of tetraloop structures shows a common backbone geometry for each of the eight possible tetraloop sequences and suggests a common hydration. After backbone atom superposition, equivalent bases from different tetraloops unexpectedly depart from coplanarity by as much as 48 degrees. This variation displaces the functional groups of tetraloops implicated in protein and RNA binding, providing a recognition feature.
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MESH Headings
- Crystallography, X-Ray
- Models, Molecular
- Mutation
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
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Affiliation(s)
- Carl C Correll
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA.
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10
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Schrader O, Baumstark T, Riesner D. A mini-RNA containing the tetraloop, wobble-pair and loop E motifs of the central conserved region of potato spindle tuber viroid is processed into a minicircle. Nucleic Acids Res 2003; 31:988-98. [PMID: 12560495 PMCID: PMC149213 DOI: 10.1093/nar/gkg193] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A Mini-RNA from potato spindle tuber viroid (PSTVd) was constructed specifically for cleavage and ligation to circles in vitro. It contains the C-domain with the so-called central conserved region (CCR) of PSTVd with a 17 nt duplication in the upper strand and hairpin structures at the left and rights ends of the secondary structure. The CCR was previously shown to be essential for processing of in vitro transcripts. When folded under conditions which favor formation of a kinetically controlled conformation and incubated in a potato nuclear extract, the Mini-RNA is cleaved correctly at the 5'- and the 3'-end and ligated to a circle. Thus, the CCR obviously contains all structural and functional requirements for correct processing and therefore may be regarded as 'processing domain' of PSTVd. Using the Mini-RNA as a model substrate, the structural and functional relevance of its conserved non-canonical motifs GAAA tetraloop, loop E and G:U wobble base pair were studied by mutational analysis. It was found that (i) the conserved GAAA tetraloop is essential for processing by favoring the kinetically controlled conformation, (ii) a G:U wobble base pair at the 5'-cleavage site contributes to its correct recognition and (iii) an unpaired nucleotide in loop E, which is different from the corresponding nucleotide in the conserved loop E motif, is essential for ligation of the 5'- with the 3'-end. Hence all three structural motifs are functional elements for processing in a potato nuclear extract.
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Affiliation(s)
- O Schrader
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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11
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Uchiumi T, Honma S, Endo Y, Hachimori A. Ribosomal proteins at the stalk region modulate functional rRNA structures in the GTPase center. J Biol Chem 2002; 277:41401-9. [PMID: 12198134 DOI: 10.1074/jbc.m207424200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Replacement of the L10.L7/L12 protein complex and L11 in Escherichia coli ribosomes with the respective rat counterparts P0.P1/P2 and eukaryotic L12 causes conversion of ribosomal specificity for elongation factors from prokaryotic elongation factor (EF)-Tu/EF-G to eukaryotic EF (eEF)-1alpha/eEF-2. Here we have investigated the effects of protein replacement on the structure and function of two rRNA domains around positions 1070 and 2660 (sarcin/ricin loop) of 23 S rRNA. Protein replacement at the 1070 region in E. coli 50 S subunits was demonstrated by chemical probing analysis. Binding of rat proteins to the 1070 region caused increased accessibility of the 2660 and 1070 regions to ligands for eukaryotic ribosomes: the ribotoxin pepocin for the 2660 region (E. coli numbering), anti-28 S autoantibody for the 1070 region, and eEF-2 for both regions. Moreover, binding of the E. coli L10.L7/L12 complex and L11 to the 1070 region was shown to be responsible for E. coli ribosomal accessibility to another ribotoxin, gypsophilin. Ribosomal proteins at the 1070 region appear to modulate the structures and functions of the 2660 and 1070 RNA regions in slightly different modes in prokaryotes and eukaryotes.
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Affiliation(s)
- Toshio Uchiumi
- Institute of High Polymer Research, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
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12
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Affiliation(s)
- C U Hellen
- Department of Microbiology and Immunology, Morse Institute for Molecular Genetics, State University of New York Health Science Center at Brooklyn, Brooklyn, New York 11203, USA.
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13
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Fabris D. Steady-State Kinetics of Ricin A-Chain Reaction with the Sarcin−Ricin Loop and with HIV-1 Ψ-RNA Hairpins Evaluated by Direct Infusion Electrospray Ionization Mass Spectrometry. J Am Chem Soc 2000. [DOI: 10.1021/ja0019676] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniele Fabris
- Department of Chemistry and Biochemistry University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, Maryland 21250
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14
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Abstract
An RNA motif is a discrete sequence or combination of base juxtapositions found in naturally occurring RNAs in unexpectedly high abundance. Because all the motifs examined so far have three-dimensional structures independent of the context in which they are embedded, they are important components of the "kit" of structural elements from which RNAs are constructed. This review discusses the structures of the motifs that have been identified so far and speculates on the importance of their role in determining RNA conformation and their evolutionary origin.
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Affiliation(s)
- P B Moore
- Department of Chemistry and Molecular Biophysics, Yale University, New Haven, Connecticut 06520-8107, USA.
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15
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Kao R, Davies J. Single amino acid substitutions affecting the specificity of the fungal ribotoxin mitogillin. FEBS Lett 2000; 466:87-90. [PMID: 10648818 DOI: 10.1016/s0014-5793(99)01753-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mitogillin and related fungal ribotoxins are small basic ribonucleolytic proteins that inhibit protein synthesis by specifically hydrolyzing a single phosphodiester bond in the universally conserved alpha-sarcin/ricin loop (SRL) of large subunit ribosomal RNAs. It was previously shown that mitogillin is a natural derivative of a T1/U2-like ribonuclease with inserted domains that are involved in target selection and specificity. Site-directed mutagenesis was used to substitute single amino acids in the previously identified functional domains Ala1-Tyr24 (B1-L1-B2 domain) and Lys106-Lys113 (L4 region). Examination of the activities of the mutants in the digestion of polyinosinic acid (a ribonuclease substrate) and specific cleavage of the SRL shows that Asn7Ala and Lys111Gln substitutions lead to altered ribonuclease activity and diminished substrate specificity consistent with the proposed functions of these domains.
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Affiliation(s)
- R Kao
- Department of Microbiology and Immunology, The University of British Columbia, 6174 University Blvd., Vancouver, B.C., Canada.
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16
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Correll CC, Wool IG, Munishkin A. The two faces of the Escherichia coli 23 S rRNA sarcin/ricin domain: the structure at 1.11 A resolution. J Mol Biol 1999; 292:275-87. [PMID: 10493875 DOI: 10.1006/jmbi.1999.3072] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sarcin/ricin domain of 23 S - 28 S ribosomal RNA is essential for protein synthesis because it forms a critical part of the binding site for elongation factors. A crystal structure of an RNA of 27 nucleotides that mimics the domain in Escherichia coli 23 S rRNA was determined at 1.11 A resolution. The domain folds into a hairpin distorted by four non-canonical base-pairs and one base triple. The fold is stabilized by cross-strand and intra-stand stacking; no intramolecular stabilizing metal ions are observed. This is the first structure to reveal in great detail the geometry and the hydration of two common motifs that are conserved in this rRNA domain, a GAGA tetraloop and a G-bulged cross-strand A stack. Differences in the region connecting these motifs to the stem in the E. coli and in the rat sarcin/ricin domains may contribute to the species-specific binding of elongation factors. Correlation of nucleotide protection data with the structure indicates that the domain has two surfaces. One surface is accessible, lies primarily in the major groove, and is likely to bind the elongation factors. The second lies primarily in the minor groove, and is likely to be buried in the ribosome. This minor groove surface includes the Watson-Crick faces of the cytosine bases in the unusual A2654.C2666 and U2653.C2667 water-mediated base-pairs.
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Affiliation(s)
- C C Correll
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
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17
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Abstract
Significant progress is occurring at an accelerated rate in structural studies of ribosomes. A 3D cryoelectron microscopy map of the 70S ribosome from Escherichia coli is available at 15 A resolution and a combination of cryoelectron microscopy with X-ray crystallography has yielded a 9 A resolution map of the 50S subunit from Haloarcula marismortui, an archaebacterium. For eukaryotes, 3D cryomaps of the 80S ribosomes from yeast and from mammals have now been produced at resolutions in the range 20 to 30 A. The most ground-breaking results have been obtained from the 3D mapping of ligands in functional studies of prokaryotic ribosomes. These studies, which directly visualize the protein synthesis machine in action, have brought new excitement to a field that was relatively dormant during the past decade.
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Affiliation(s)
- R K Agrawal
- Wadsworth Center, Department of Biomedical Sciences, State University of New York at Albany, Empire State Plaza, Albany, NY 12201-0509, USA.
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