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Senft MD, Maier R, Hiremath A, Zhang F, Schreiber F. Effective interactions and phase behavior of protein solutions in the presence of hexamine cobalt(III) chloride. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:119. [PMID: 38051398 PMCID: PMC10698144 DOI: 10.1140/epje/s10189-023-00376-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 11/09/2023] [Indexed: 12/07/2023]
Abstract
It is well established that deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) exhibit a reentrant condensation (RC) phase behavior in the presence of the trivalent hexamine cobalt(III) cations (Hac) which can be important for their packing and folding. A similar behavior can be observed for negatively charged globular proteins in the presence of trivalent metal cations, such as Y3+ or La3+. This phase behavior is mainly driven by charge inversion upon an increasing salt concentration for a fixed protein concentration (cp). However, as Hac exhibits structural differences compared to other multivalent metal cations, with six ammonia ligands (NH3) covalently bonded to the central cobalt atom, it is not clear that Hac can induce a similar phase behavior for proteins. In this work, we systematically investigate whether negatively charged globular proteins β-lactoglobulin (BLG), bovine serum albumin (BSA), human serum albumin (HSA) and ovalbumin (OVA) feature Hac-induced RC. Effective protein-protein interactions were investigated by small-angle X-ray scattering. The reduced second virial coefficient (B2/B2HS) was obtained as a function of salt concentration. The virial coefficient analysis performed confirms the reentrant interaction (RI) behavior for BLG without actually inducing RC, given the insufficient strengths of the interactions for the latter to occur. In contrast, the strength of attraction for BSA, HSA and OVA are too weak to show RC. Model free analysis of the inverse intensity [Formula: see text] also supports this finding. Looking at different q-range by employing static (SLS) and dynamic light scattering experiments, the presence of RI behavior can be confirmed. The results are further discussed in view of metal cation binding sites in nucleic acids (DNA and RNA), where Hac induced RC phase behavior.
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Affiliation(s)
- Maximilian D Senft
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany.
| | - Ralph Maier
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
| | - Anusha Hiremath
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
| | - Fajun Zhang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany.
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
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2
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Zhuo B, Ou X, Li J. Structure and Mechanical Stabilities of the Three-Way Junction Motifs in Prohead RNA. J Phys Chem B 2021; 125:12125-12134. [PMID: 34719230 DOI: 10.1021/acs.jpcb.1c04681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The core structure of phi29 prohead RNA (pRNA) is composed of three major helices organized into three-way junction pRNA (3WJ-pRNA) and has stout structural rigidity along the coaxial helices. Prohead RNAs of the other Bacillus subtilis bacteriophages such as GA1 and SF5 share similar secondary structure and function with phi29; whether these pRNAs have similar mechanical rigidity remains to be elucidated. In this study, we constructed the tertiary structures of GA1 and SF5 3WJ-pRNAs by comparative modeling. Both GA1 and SF5 3WJ-pRNAs adopt a similar structure, in which three helices are organized as the three-way junction and two of the three helices are stacked coaxially. Moreover, detailed structural features of GA1 and SF5 3WJ-pRNAs are also similar to those of phi29 3WJ-pRNA: all of the bases of the coaxial helices are paired, and all of the adenines in the junction region are paired, which eliminates the interference of A-minor tertiary interactions. Hence, the coaxial helices tightly join to each other, and the major groove between them is very narrow. Two Mg2+ ions can thus fit into this major groove and form double Mg clamps. A steered molecular dynamics simulation was used to study the mechanical properties of these 3WJ-pRNAs. Both GA1 and SF5 3WJ-pRNAs show strong resistance to applied force in the direction of their coaxial helices. Such mechanical stability can be attributed to the Mg clamps.
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Affiliation(s)
- Boyang Zhuo
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Xinwen Ou
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Jingyuan Li
- Department of Physics, Zhejiang University, Hangzhou 310027, China
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3
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Assembly factors chaperone ribosomal RNA folding by isolating helical junctions that are prone to misfolding. Proc Natl Acad Sci U S A 2021; 118:2101164118. [PMID: 34135123 DOI: 10.1073/pnas.2101164118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
While RNAs are known to misfold, the underlying molecular causes have been mainly studied in fragments of biologically relevant larger RNAs. As these small RNAs are dominated by secondary structures, misfolding of these secondary structures remains the most-explored cause for global RNA misfolding. Conversely, how RNA chaperones function in a biological context to promote native folding beyond duplex annealing remains unknown. Here, in a combination of dimethylsulfate mutational profiling with sequencing (DMS-MaPseq), structural analyses, biochemical experiments, and yeast genetics, we show that three-helix junctions are prone to misfolding during assembly of the small ribosomal subunit in vivo. We identify ubiquitous roles for ribosome assembly factors in chaperoning their folding by preventing the formation of premature tertiary interactions, which otherwise kinetically trap misfolded junctions, thereby blocking further progress in the assembly cascade. While these protein chaperones act indirectly by binding the interaction partners of junctions, our analyses also suggest direct roles for small nucleolar RNAs (snoRNAs) in binding and chaperoning helical junctions during transcription. While these assembly factors do not utilize energy to ameliorate misfolding, our data demonstrate how their dissociation renders reversible folding steps irreversible, thereby driving native folding and assembly and setting up a timer that dictates the propensity of misfolded intermediates to escape quality control. Finally, the data demonstrate that RNA chaperones act locally on individual tertiary interactions, in contrast to protein chaperones, which globally unfold misfolded proteins.
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4
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Zhang Q, Ma C, Duan Y, Heinrich B, Rosato U, Diggs LP, Ma L, Roy S, Fu Q, Brown ZJ, Wabitsch S, Thovarai V, Fu J, Feng D, Ruf B, Cui LL, Subramanyam V, Frank KM, Wang S, Kleiner DE, Ritz T, Rupp C, Gao B, Longerich T, Kroemer A, Wang XW, Ruchirawat M, Korangy F, Schnabl B, Trinchieri G, Greten TF. Gut Microbiome Directs Hepatocytes to Recruit MDSCs and Promote Cholangiocarcinoma. Cancer Discov 2020; 11:1248-1267. [PMID: 33323397 DOI: 10.1158/2159-8290.cd-20-0304] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 10/14/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023]
Abstract
Gut dysbiosis is commonly observed in patients with cirrhosis and chronic gastrointestinal disorders; however, its effect on antitumor immunity in the liver is largely unknown. Here we studied how the gut microbiome affects antitumor immunity in cholangiocarcinoma. Primary sclerosing cholangitis (PSC) or colitis, two known risk factors for cholangiocarcinoma which promote tumor development in mice, caused an accumulation of CXCR2+ polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC). A decrease in gut barrier function observed in mice with PSC and colitis allowed gut-derived bacteria and lipopolysaccharide to appear in the liver and induced CXCL1 expression in hepatocytes through a TLR4-dependent mechanism and an accumulation of CXCR2+ PMN-MDSCs. In contrast, neomycin treatment blocked CXCL1 expression and PMN-MDSC accumulation and inhibited tumor growth even in the absence of liver disease or colitis. Our study demonstrates that the gut microbiome controls hepatocytes to form an immunosuppressive environment by increasing PMN-MDSCs to promote liver cancer. SIGNIFICANCE: MDSCs have been shown to be induced by tumors and suppress antitumor immunity. Here we show that the gut microbiome can control accumulation of MDSCs in the liver in the context of a benign liver disease or colitis.See related commentary by Chagani and Kwong, p. 1014.This article is highlighted in the In This Issue feature, p. 995.
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Affiliation(s)
- Qianfei Zhang
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Chi Ma
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Yi Duan
- Department of Medicine, University of California, San Diego, La Jolla, California.,Department of Medicine, VA San Diego Healthcare System, San Diego, California
| | - Bernd Heinrich
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Umberto Rosato
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Laurence P Diggs
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Lichun Ma
- Laboratory of Human Carcinogenesis, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Soumen Roy
- Cancer and Inflammation Program, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Qiong Fu
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Zachary J Brown
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Simon Wabitsch
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Vishal Thovarai
- Cancer and Inflammation Program, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Jianyang Fu
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Dechun Feng
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, Maryland
| | - Benjamin Ruf
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Linda L Cui
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Varun Subramanyam
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Karen M Frank
- Microbiology Service, Department of Laboratory Medicine, Clinical Center, NIH, Bethesda, Maryland
| | - Sophie Wang
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | | | - Thomas Ritz
- Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.,Institute of Pathology, University Hospital RWTH Aachen, Aachen, Germany
| | - Christian Rupp
- Department of Gastroenterology, University Hospital of Heidelberg, Heidelberg, Germany
| | - Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, Maryland
| | - Thomas Longerich
- Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany
| | - Alexander Kroemer
- MedStar Georgetown Transplant Institute, MedStar Georgetown University Hospital and the Center for Translational Transplant Medicine, Georgetown University Medical Center, Washington, District of Columbia
| | - Xin Wei Wang
- Laboratory of Human Carcinogenesis, Center for Cancer Research, NCI, NIH, Bethesda, Maryland.,NCI-CCR Liver Cancer Program, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Mathuros Ruchirawat
- Laboratory of Chemical Carcinogenesis, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, Office of the Higher Education Commission, Ministry of Education, Bangkok, Thailand
| | - Firouzeh Korangy
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Bernd Schnabl
- Department of Medicine, University of California, San Diego, La Jolla, California.,Department of Medicine, VA San Diego Healthcare System, San Diego, California
| | - Giorgio Trinchieri
- Cancer and Inflammation Program, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Tim F Greten
- Gastrointestinal Malignancy Section, Thoracic and GI Malignancies Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland. .,NCI-CCR Liver Cancer Program, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
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5
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Dong X, Qu G, Piazza CL, Belfort M. Group II intron as cold sensor for self-preservation and bacterial conjugation. Nucleic Acids Res 2020; 48:6198-6209. [PMID: 32379323 PMCID: PMC7293003 DOI: 10.1093/nar/gkaa313] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 04/01/2020] [Accepted: 04/20/2020] [Indexed: 01/18/2023] Open
Abstract
Group II introns are self-splicing ribozymes and mobile genetic elements. Splicing is required for both expression of the interrupted host gene and intron retromobility. For the pRS01 plasmid-encoded Lactococcus lactis group II intron, Ll.LtrB, splicing enables expression of the intron's host relaxase protein. Relaxase, in turn, initiates horizontal transfer of the conjugative pRS01 plasmid and stimulates retrotransposition of the intron. Little is known about how splicing of bacterial group II introns is influenced by environmental conditions. Here, we show that low temperatures can inhibit Ll.LtrB intron splicing. Whereas autocatalysis is abolished in the cold, splicing is partially restored by the intron-encoded protein (IEP). Structure profiling reveals cold-induced disruptions of key tertiary interactions, suggesting that a kinetic trap prevents the intron RNA from assuming its native state. Interestingly, while reduced levels of transcription and splicing lead to a paucity of excised intron in the cold, levels of relaxase mRNA are maintained, partially due to diminished intron-mediated mRNA targeting, allowing intron spread by conjugal transfer. Taken together, this study demonstrates not only the intrinsic cold sensitivity of group II intron splicing and the role of the IEP for cold-stress adaptation, but also maintenance of horizontal plasmid and intron transfer under cold-shock.
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Affiliation(s)
- Xiaolong Dong
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY 12222, USA
| | - Guosheng Qu
- College of Life Sciences, Hebei University, Baoding, Hebei 071002, China
| | - Carol Lyn Piazza
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY 12222, USA
| | - Marlene Belfort
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY 12222, USA
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6
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Zhang K, Frank AT. Conditional Prediction of Ribonucleic Acid Secondary Structure Using Chemical Shifts. J Phys Chem B 2019; 124:470-478. [DOI: 10.1021/acs.jpcb.9b09814] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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7
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Nikolaev Y, Ripin N, Soste M, Picotti P, Iber D, Allain FHT. Systems NMR: single-sample quantification of RNA, proteins and metabolites for biomolecular network analysis. Nat Methods 2019; 16:743-749. [PMID: 31363225 PMCID: PMC6837886 DOI: 10.1038/s41592-019-0495-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 06/17/2019] [Indexed: 12/14/2022]
Abstract
Cellular behavior is controlled by the interplay of diverse biomolecules. Most
experimental methods, however, can monitor only a single molecule class or
reaction type at a time. We developed an in vitro Nuclear Magnetic Resonance
spectroscopy (NMR) approach, which permitted dynamic quantification of an entire
“heterotypic” network – simultaneously monitoring three
distinct molecule classes (metabolites, proteins, RNA) and all elementary
reaction types (bimolecular interactions, catalysis, unimolecular changes).
Focusing on an 8-reaction co-transcriptional RNA folding network, in a single
sample we recorded over 35 time-points with over 170 observables each, and
accurately determined 5 core reaction constants in multiplex. This
reconstruction revealed unexpected cross-talk between the different reactions.
We further observed dynamic phase-separation in a system of five distinct RNA
binding domains in the course of the RNA transcription reaction. Our Systems NMR
approach provides a deeper understanding of biological network dynamics by
combining the dynamic resolution of biochemical assays and the multiplexing
ability of “omics”.
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Affiliation(s)
- Yaroslav Nikolaev
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland.
| | - Nina Ripin
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland
| | - Martin Soste
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Paola Picotti
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Dagmar Iber
- Department of Biosystems Science and Engineering, ETH Zurich, Zurich, Switzerland
| | - Frédéric H-T Allain
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zurich, Zurich, Switzerland.
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8
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Stasiewicz J, Mukherjee S, Nithin C, Bujnicki JM. QRNAS: software tool for refinement of nucleic acid structures. BMC STRUCTURAL BIOLOGY 2019; 19:5. [PMID: 30898165 PMCID: PMC6429776 DOI: 10.1186/s12900-019-0103-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 03/05/2019] [Indexed: 01/03/2023]
Abstract
BACKGROUND Computational models of RNA 3D structure often present various inaccuracies caused by simplifications used in structure prediction methods, such as template-based modeling or coarse-grained simulations. To obtain a high-quality model, the preliminary RNA structural model needs to be refined, taking into account atomic interactions. The goal of the refinement is not only to improve the local quality of the model but to bring it globally closer to the true structure. RESULTS We present QRNAS, a software tool for fine-grained refinement of nucleic acid structures, which is an extension of the AMBER simulation method with additional restraints. QRNAS is capable of handling RNA, DNA, chimeras, and hybrids thereof, and enables modeling of nucleic acids containing modified residues. CONCLUSIONS We demonstrate the ability of QRNAS to improve the quality of models generated with different methods. QRNAS was able to improve MolProbity scores of NMR structures, as well as of computational models generated in the course of the RNA-Puzzles experiment. The overall geometry improvement may be associated with increased model accuracy, especially on the level of correctly modeled base-pairs, but the systematic improvement of root mean square deviation to the reference structure should not be expected. The method has been integrated into a computational modeling workflow, enabling improved RNA 3D structure prediction.
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Affiliation(s)
- Juliusz Stasiewicz
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Sunandan Mukherjee
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Chandran Nithin
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Janusz M. Bujnicki
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
- Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznań, Poland
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9
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Covalent and non-covalent binding of platinated vitamin B12-derivatives to a B12 responsive riboswitch. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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10
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Specific phosphorothioate substitution within domain 6 of a group II intron ribozyme leads to changes in local structure and metal ion binding. J Biol Inorg Chem 2017; 23:167-177. [DOI: 10.1007/s00775-017-1519-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 11/14/2017] [Indexed: 10/18/2022]
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11
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Zhao C, Pyle AM. Structural Insights into the Mechanism of Group II Intron Splicing. Trends Biochem Sci 2017; 42:470-482. [PMID: 28438387 PMCID: PMC5492998 DOI: 10.1016/j.tibs.2017.03.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/28/2017] [Accepted: 03/30/2017] [Indexed: 12/19/2022]
Abstract
While the major architectural features and active-site components of group II introns have been known for almost a decade, information on the individual stages of splicing has been lacking. Recent advances in crystallography and cryo-electron microscopy (cryo-EM) have provided major new insights into the structure of intact lariat introns. Conformational changes that mediate the steps of splicing and retrotransposition are being elucidated, revealing the dynamic, highly coordinated motions that are required for group II intron activity. Finally, these ribozymes can now be viewed in their larger, more natural context as components of holoenzymes that include encoded maturase proteins. These studies expand our understanding of group II intron structural diversity and evolution, while setting the stage for rigorous mechanistic analysis of RNA splicing machines.
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Affiliation(s)
- Chen Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA; Department of Chemistry, Yale University, New Haven, CT 06520, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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12
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Guha TK, Hausner G. Insertion of Group II Intron-Based Ribozyme Switches into Homing Endonuclease Genes. Methods Mol Biol 2017; 1498:135-152. [PMID: 27709573 DOI: 10.1007/978-1-4939-6472-7_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Fungal mitochondrial genomes act as "reservoirs" for homing endonucleases. These enzymes with their DNA site-specific cleavage activities are attractive tools for genome editing, targeted mutagenesis and gene therapy applications. Herein, we present strategies where homing endonuclease open reading frames (HEases ORFs) are interrupted with group II intron sequences. The ultimate goal is to achieve in vivo expression of HEases that can be regulated by manipulating the splicing efficiency of the HEase ORF-embedded group II introns. That addition of exogenous magnesium chloride (MgCl2) appears to stimulate splicing of nonnative group II introns in Escherichia coli and the addition of cobalt chloride (CoCl2) to the growth medium antagonizes the expression of HEase activity (i.e., splicing). Group II introns are potentially autocatalytic self-splicing elements and thus can be used as molecular switches that allow for temporal regulated HEase expression. This should be useful in precision genome engineering, mutagenesis, and minimizing off-target activities.
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Affiliation(s)
- Tuhin Kumar Guha
- Department of Microbiology, 401 University of Manitoba, Buller Building 213, Winnipeg, MB, Canada, R3T 2N2
| | - Georg Hausner
- Department of Microbiology, 401 University of Manitoba, Buller Building 213, Winnipeg, MB, Canada, R3T 2N2.
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13
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Bartova S, Alberti E, Sigel RK, Donghi D. Metal ion binding to an RNA internal loop. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.02.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Bermejo GA, Clore GM, Schwieters CD. Improving NMR Structures of RNA. Structure 2016; 24:806-815. [PMID: 27066747 DOI: 10.1016/j.str.2016.03.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/26/2016] [Accepted: 03/04/2016] [Indexed: 01/27/2023]
Abstract
Here, we show that modern solution nuclear magnetic resonance (NMR) structures of RNA exhibit more steric clashes and conformational ambiguities than their crystallographic X-ray counterparts. To tackle these issues, we developed RNA-ff1, a new force field for structure calculation with Xplor-NIH. Using seven published NMR datasets, RNA-ff1 improves covalent geometry and MolProbity validation criteria for clashes and backbone conformation in most cases, relative to both the previous Xplor-NIH force field and the original structures associated with the experimental data. In addition, with smaller base-pair step rises in helical stems, RNA-ff1 structures enjoy more favorable base stacking. Finally, structural accuracy improves in the majority of cases, as supported by complete residual dipolar coupling cross-validation. Thus, the reported advances show great promise in bridging the quality gap that separates NMR and X-ray structures of RNA.
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Affiliation(s)
- Guillermo A Bermejo
- Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892-5624, USA
| | - G Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Charles D Schwieters
- Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892-5624, USA.
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15
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Guha TK, Hausner G. Using Group II Introns for Attenuating the In Vitro and In Vivo Expression of a Homing Endonuclease. PLoS One 2016; 11:e0150097. [PMID: 26909494 PMCID: PMC4801052 DOI: 10.1371/journal.pone.0150097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/09/2016] [Indexed: 01/09/2023] Open
Abstract
In Chaetomium thermophilum (DSM 1495) within the mitochondrial DNA (mtDNA) small ribosomal subunit (rns) gene a group IIA1 intron interrupts an open reading frame (ORF) encoded within a group I intron (mS1247). This arrangement offers the opportunity to examine if the nested group II intron could be utilized as a regulatory element for the expression of the homing endonuclease (HEase). Constructs were generated where the codon-optimized ORF was interrupted with either the native group IIA1 intron or a group IIB type intron. This study showed that the expression of the HEase (in vivo) in Escherichia coli can be regulated by manipulating the splicing efficiency of the HEase ORF-embedded group II introns. Exogenous magnesium chloride (MgCl2) stimulated the expression of a functional HEase but the addition of cobalt chloride (CoCl2) to growth media antagonized the expression of HEase activity. Ultimately the ability to attenuate HEase activity might be useful in precision genome engineering, minimizing off target activities, or where pathways have to be altered during a specific growth phase.
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Affiliation(s)
- Tuhin Kumar Guha
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Georg Hausner
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
- * E-mail:
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16
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Bartova S, Pechlaner M, Donghi D, Sigel RKO. Studying metal ion binding properties of a three-way junction RNA by heteronuclear NMR. J Biol Inorg Chem 2016; 21:319-28. [PMID: 26880094 DOI: 10.1007/s00775-016-1341-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/25/2016] [Indexed: 10/22/2022]
Abstract
Self-splicing group II introns are highly structured RNA molecules, containing a characteristic secondary and catalytically active tertiary structure, which is formed only in the presence of Mg(II). Mg(II) initiates the first folding step governed by the κζ element within domain 1 (D1κζ). We recently solved the NMR structure of D1κζ derived from the mitochondrial group II intron ribozyme Sc.ai5γ and demonstrated that Mg(II) is essential for its stabilization. Here, we performed a detailed multinuclear NMR study of metal ion interactions with D1κζ, using Cd(II) and cobalt(III)hexammine to probe inner- and outer-sphere coordination of Mg(II) and thus to better characterize its binding sites. Accordingly, we mapped (1)H, (15)N, (13)C, and (31)P spectral changes upon addition of different amounts of the metal ions. Our NMR data reveal a Cd(II)-assisted macrochelate formation at the 5'-end triphosphate, a preferential Cd(II) binding to guanines in a helical context, an electrostatic interaction in the ζ tetraloop receptor and various metal ion interactions in the GAAA tetraloop and κ element. These results together with our recently published data on Mg(II) interaction provide a much better understanding of Mg(II) binding to D1κζ, and reveal how intricate and complex metal ion interactions can be.
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Affiliation(s)
- Simona Bartova
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Department of Analytical Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague, Czech Republic
| | - Maria Pechlaner
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190, Vienna, Austria
| | - Daniela Donghi
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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17
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Chen JL, Bellaousov S, Tubbs JD, Kennedy SD, Lopez MJ, Mathews DH, Turner DH. Nuclear Magnetic Resonance-Assisted Prediction of Secondary Structure for RNA: Incorporation of Direction-Dependent Chemical Shift Constraints. Biochemistry 2015; 54:6769-82. [PMID: 26451676 PMCID: PMC4666457 DOI: 10.1021/acs.biochem.5b00833] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Knowledge
of RNA
structure is necessary to determine structure–function relationships
and to facilitate design of potential therapeutics.
RNA secondary structure prediction can be improved by applying constraints
from nuclear magnetic resonance (NMR) experiments to a dynamic programming
algorithm. Imino proton walks from NOESY spectra reveal double-stranded
regions. Chemical shifts of protons in GH1, UH3, and UH5 of GU pairs,
UH3, UH5, and AH2 of AU pairs, and GH1 of GC pairs were analyzed to
identify constraints for the 5′ to 3′ directionality
of base pairs in helices. The 5′ to 3′ directionality
constraints were incorporated into an NMR-assisted prediction of secondary
structure (NAPSS-CS) program. When it was tested on 18 structures,
including nine pseudoknots, the sensitivity and positive predictive
value were improved relative to those of three unrestrained programs.
The prediction accuracy for the pseudoknots improved the most. The
program also facilitates assignment of chemical shifts to individual
nucleotides, a necessary step for determining three-dimensional structure.
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Affiliation(s)
- Jonathan L Chen
- Department of Chemistry, University of Rochester , Rochester, New York 14627, United States
| | - Stanislav Bellaousov
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
| | - Jason D Tubbs
- Department of Chemistry, University of Rochester , Rochester, New York 14627, United States
| | - Scott D Kennedy
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
| | - Michael J Lopez
- Department of Chemistry, University of Rochester , Rochester, New York 14627, United States
| | - David H Mathews
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States.,Center for RNA Biology, University of Rochester , Rochester, New York 14642, United States
| | - Douglas H Turner
- Department of Chemistry, University of Rochester , Rochester, New York 14627, United States.,Center for RNA Biology, University of Rochester , Rochester, New York 14642, United States
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18
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Skilandat M, Sigel RKO. The role of Mg(II) in DNA cleavage site recognition in group II intron ribozymes: solution structure and metal ion binding sites of the RNA-DNA complex. J Biol Chem 2015; 289:20650-63. [PMID: 24895129 DOI: 10.1074/jbc.m113.542381] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Group II intron ribozymes catalyze the cleavage of (and their reinsertion into) DNA and RNA targets using a Mg2(+)-dependent reaction. The target is cleaved 3' to the last nucleotide of intron binding site 1 (IBS1), one of three regions that form base pairs with the intron's exon binding sites (EBS1 to -3).We solved the NMR solution structure of the d3' hairpin of the Sc.ai5γ intron containing EBS1 in its 11-nucleotide loop in complex with the dIBS1 DNA 7-mer and compare it with the analogous RNA-RNA contact. The EBS1-dIBS1 helix is slightly flexible and non-symmetric. NMR data reveal two major groove binding sites for divalent metal ions at the EBS1-dIBS1 helix, and surface plasmon resonance experiments show that low concentrations of Mg2(+) considerably enhance the affinity of dIBS1 for EBS1. Our results indicate that identification of both RNA and DNA IBS1 targets, presentation of the scissile bond, and stabilization of the structure by metal ions are governed by the overall structure of EBS1-dIBS1 and the surrounding loop nucleotides but are irrespective of different EBS1-(d)IBS1 geometries and interstrand affinities.
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19
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Bonneau E, Legault P. Nuclear magnetic resonance structure of the III-IV-V three-way junction from the Varkud satellite ribozyme and identification of magnesium-binding sites using paramagnetic relaxation enhancement. Biochemistry 2014; 53:6264-75. [PMID: 25238589 DOI: 10.1021/bi500826n] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The VS ribozyme is a catalytic RNA found within some natural isolates of Neurospora that is being used as a model system to improve our understanding of RNA structure, catalysis, and engineering. The catalytic domain contains five helical domains (SLII-SLVI) that are organized by two three-way junctions. The III-IV-V junction is required for high-affinity binding of the substrate domain (SLI) through formation of a kissing loop interaction with SLV. Here, we determine the high-resolution nuclear magnetic resonance (NMR) structure of a 47-nucleotide RNA containing the III-IV-V junction (J345). The J345 RNA adopts a Y-shaped fold typical of the family C three-way junctions, with coaxial stacking between stems III and IV and an acute angle between stems III and V. The NMR structure reveals that the core of the III-IV-V junction contains four stacked base triples, a U-turn motif, a cross-strand stacking interaction, an A-minor interaction, and a ribose zipper. In addition, the NMR structure shows that the cCUUGg tetraloop used to stabilize stem IV adopts a novel RNA tetraloop fold, different from the known gCUUGc tetraloop structure. Using Mn(2+)-induced paramagnetic relaxation enhancement, we identify six Mg(2+)-binding sites within J345, including one associated with the cCUUGg tetraloop and two with the junction core. The NMR structure of J345 likely represents the conformation of the III-IV-V junction in the context of the active VS ribozyme and suggests that this junction functions as a dynamic hinge that contributes to substrate recognition and catalysis. Moreover, this study highlights a new role for family C three-way junctions in long-range tertiary interactions.
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Affiliation(s)
- Eric Bonneau
- Département de Biochimie et Médecine Moléculaire, Université de Montréal , C.P. 6128, Succursale Centre-Ville, Montréal, QC, Canada H3C 3J7
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20
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Jiang T, Kennedy SD, Moss WN, Kierzek E, Turner DH. Secondary structure of a conserved domain in an intron of influenza A M1 mRNA. Biochemistry 2014; 53:5236-48. [PMID: 25026548 PMCID: PMC4139153 DOI: 10.1021/bi500611j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Influenza A virus utilizes RNA throughout infection. Little is known, however, about the roles of RNA structures. A previous bioinformatics survey predicted multiple regions of influenza A virus that are likely to generate evolutionarily conserved and stable RNA structures. One predicted conserved structure is in the pre-mRNA coding for essential proteins, M1 and M2. This structure starts 79 nucleotides downstream of the M2 mRNA 5' splice site. Here, a combination of biochemical structural mapping, mutagenesis, and NMR confirms the predicted three-way multibranch structure of this RNA. Imino proton NMR spectra reveal no change in secondary structure when 80 mM KCl is supplemented with 4 mM MgCl2. Optical melting curves in 1 M NaCl and in 100 mM KCl with 10 mM MgCl2 are very similar, with melting temperatures ∼14 °C higher than that for 100 mM KCl alone. These results provide a firm basis for designing experiments and potential therapeutics to test for function in cell culture.
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Affiliation(s)
- Tian Jiang
- Department of Chemistry and Center for RNA Biology, University of Rochester , Rochester, New York 14627, United States
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21
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Marcia M, Pyle AM. Principles of ion recognition in RNA: insights from the group II intron structures. RNA (NEW YORK, N.Y.) 2014; 20:516-27. [PMID: 24570483 PMCID: PMC3964913 DOI: 10.1261/rna.043414.113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/29/2014] [Indexed: 05/20/2023]
Abstract
Metal ions promote both RNA folding and catalysis, thus being essential in stabilizing the structure and determining the function of large RNA molecules, including group II introns. The latter are self-splicing metalloribozymes, containing a heteronuclear four-metal-ion center within the active site. In addition to these catalytic ions, group II introns bind many other structural ions, including delocalized ions that bind the RNA diffusively and well-ordered ions that bind the RNA tightly with high occupancy. The latter ions, which can be studied by biophysical methods, have not yet been analyzed systematically. Here, we compare crystal structures of the group IIC intron from Oceanobacillus iheyensis and classify numerous site-bound ions, which are primarily localized in the intron core and near long-range tertiary contacts. Certain ion-binding sites resemble motifs observed in known RNA structures, while others are idiosyncratic to the group II intron. Particularly interesting are (1) ions proximal to the active site, which may participate in splicing together with the catalytic four-metal-ion center, (2) organic ions that bind regions predicted to interact with intron-encoded proteins, and (3) unusual monovalent ions bound to GU wobble pairs, GA mismatches, the S-turn, the tetraloop-receptor, and the T-loop. Our analysis extends the general principles by which ions participate in RNA structural organization and it will aid in the determination and interpretation of future RNA structures.
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Affiliation(s)
- Marco Marcia
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06511, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06511, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA
- Corresponding authorE-mail
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22
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Sripakdeevong P, Cevec M, Chang AT, Erat MC, Ziegeler M, Zhao Q, Fox GE, Gao X, Kennedy SD, Kierzek R, Nikonowicz EP, Schwalbe H, Sigel RKO, Turner DH, Das R. Structure determination of noncanonical RNA motifs guided by ¹H NMR chemical shifts. Nat Methods 2014; 11:413-6. [PMID: 24584194 PMCID: PMC3985481 DOI: 10.1038/nmeth.2876] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 01/06/2014] [Indexed: 12/31/2022]
Abstract
Structured noncoding RNAs underlie fundamental cellular processes, but determining their three-dimensional structures remains challenging. We demonstrate that integrating ¹H NMR chemical shift data with Rosetta de novo modeling can be used to consistently determine high-resolution RNA structures. On a benchmark set of 23 noncanonical RNA motifs, including 11 'blind' targets, chemical-shift Rosetta for RNA (CS-Rosetta-RNA) recovered experimental structures with high accuracy (0.6-2.0 Å all-heavy-atom r.m.s. deviation) in 18 cases.
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Affiliation(s)
| | - Mirko Cevec
- Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
| | - Andrew T Chang
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, USA
| | - Michèle C Erat
- 1] Department of Biochemistry, University of Oxford, Oxford, UK. [2] Institute of Inorganic Chemistry, University of Zurich, Zurich, Switzerland
| | - Melanie Ziegeler
- Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
| | - Qin Zhao
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - George E Fox
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Xiaolian Gao
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Scott D Kennedy
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Ryszard Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Edward P Nikonowicz
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, USA
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
| | - Roland K O Sigel
- Institute of Inorganic Chemistry, University of Zurich, Zurich, Switzerland
| | - Douglas H Turner
- Department of Chemistry, University of Rochester, Rochester, New York, USA
| | - Rhiju Das
- 1] Biophysics Program, Stanford University, Stanford, California, USA. [2] Department of Biochemistry, Stanford University, Stanford, California, USA. [3] Department of Physics, Stanford University, Stanford, California, USA
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23
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Solution structure and metal ion binding sites of the human CPEB3 ribozyme's P4 domain. J Biol Inorg Chem 2014; 19:903-12. [PMID: 24652468 DOI: 10.1007/s00775-014-1125-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 03/05/2014] [Indexed: 01/18/2023]
Abstract
Three ribozymes are known to occur in humans, the CPEB3 ribozyme, the CoTC ribozyme, and the hammerhead ribozyme. Here, we present the NMR solution structure of a well-conserved motif within the CPEB3 ribozyme, the P4 domain. In addition, we discuss the binding sites and impact of Mg(2+) and [Co(NH3)6](3+), a spectroscopic probe for [Mg(H2O)6](2+), on the structure. The well-defined P4 region is a hairpin closed with a UGGU tetraloop that shows a distinct electrostatic surface potential and a characteristic, strongly curved backbone trajectory. The P4 hairpin contains two specific Mg(2+) binding sites: one outer-sphere binding site close to the proposed CPEB3 ribozyme active site with potential relevance for maintaining a compact fold of the ribozyme core, and one inner-sphere binding site, probably stabilizing the tetraloop structure. The structure of the tetraloop resembles an RNase III recognition structure, as previously described for an AGUU tetraloop. The detailed knowledge of the P4 domain and its metal ion binding preferences thus brings us closer to understanding the importance of Mg(2+) binding for the CPEB3 ribozyme's fold and function in the cell.
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24
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Comparison of the π-stacking properties of purine versus pyrimidine residues. Some generalizations regarding selectivity. J Biol Inorg Chem 2014; 19:691-703. [PMID: 24464134 DOI: 10.1007/s00775-013-1082-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 12/18/2013] [Indexed: 10/25/2022]
Abstract
Aromatic-ring stacking is pronounced among the noncovalent interactions occurring in biosystems and therefore some pertinent features regarding nucleobase residues are summarized. Self-stacking decreases in the series adenine > guanine > hypoxanthine > cytosine ~ uracil. This contrasts with the stability of binary (phen)(N) adducts formed by 1,10-phenanthroline (phen) and a nucleobase residue (N), which is largely independent of the type of purine residue involved, including (N1)H-deprotonated guanine. Furthermore, the association constant for (phen)(A)(0/4-) is rather independent of the type and charge of the adenine derivative (A) considered, be it adenosine or one of its nucleotides, including adenosine 5'-triphosphate (ATP(4-)). The same holds for the corresponding adducts of 2,2'-bipyridine (bpy), although owing to the smaller size of the aromatic-ring system of bpy, the (bpy)(A)(0/4-) adducts are less stable; the same applies correspondingly to the adducts formed with pyrimidines. In accord herewith, [M(bpy)](adenosine)(2+) adducts (M(2+) is Co(2+), Ni(2+), or Cu(2+)) show the same stability as the (bpy)(A)(0/4-) ones. The formation of an ionic bridge between -NH3 (+) and -PO3 (2-), as provided by tryptophan [H(Trp)(±)] and adenosine 5'-monophosphate (AMP(2-)), facilitates recognition and stabilizes the indole-purine stack in [H(Trp)](AMP)(2-). Such indole-purine stacks also occur in nature. Similarly, the formation of a metal ion bridge as occurs, e.g., between Cu(2+) coordinated to phen and the phosphonate group of 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA(2-)) dramatically favors the intramolecular stack in Cu(phen)(PMEA). The consequences of such interactions for biosystems are discussed, especially emphasizing that the energies involved in such isomeric equilibria are small, allowing Nature to shift such equilibria easily.
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25
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Somarowthu S, Legiewicz M, Keating KS, Pyle AM. Visualizing the ai5γ group IIB intron. Nucleic Acids Res 2013; 42:1947-58. [PMID: 24203709 PMCID: PMC3919574 DOI: 10.1093/nar/gkt1051] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has become apparent that much of cellular metabolism is controlled by large well-folded noncoding RNA molecules. In addition to crystallographic approaches, computational methods are needed for visualizing the 3D structure of large RNAs. Here, we modeled the molecular structure of the ai5γ group IIB intron from yeast using the crystal structure of a bacterial group IIC homolog. This was accomplished by adapting strategies for homology and de novo modeling, and creating a new computational tool for RNA refinement. The resulting model was validated experimentally using a combination of structure-guided mutagenesis and RNA structure probing. The model provides major insights into the mechanism and regulation of splicing, such as the position of the branch-site before and after the second step of splicing, and the location of subdomains that control target specificity, underscoring the feasibility of modeling large functional RNA molecules.
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Affiliation(s)
- Srinivas Somarowthu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA, Department of Chemistry, Yale University, New Haven, CT 06511, USA and Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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26
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Rowinska-Zyrek M, Skilandat M, Sigel RKO. Hexaamminecobalt(III) - Probing Metal Ion Binding Sites in Nucleic Acids by NMR Spectroscopy. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300123] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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27
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Complex formation of cadmium with sugar residues, nucleobases, phosphates, nucleotides, and nucleic acids. Met Ions Life Sci 2013; 11:191-274. [PMID: 23430775 DOI: 10.1007/978-94-007-5179-8_8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cadmium(II), commonly classified as a relatively soft metal ion, prefers indeed aromatic-nitrogen sites (e.g., N7 of purines) over oxygen sites (like sugar-hydroxyl groups). However, matters are not that simple, though it is true that the affinity of Cd(2+) towards ribose-hydroxyl groups is very small; yet, a correct orientation brought about by a suitable primary binding site and a reduced solvent polarity, as it is expected to occur in a folded nucleic acid, may facilitate metal ion-hydroxyl group binding very effectively. Cd(2+) prefers the guanine(N7) over the adenine(N7), mainly because of the steric hindrance of the (C6)NH(2) group in the adenine residue. This Cd(2+)-(N7) interaction in a guanine moiety leads to a significant acidification of the (N1)H meaning that the deprotonation reaction occurs now in the physiological pH range. N3 of the cytosine residue, together with the neighboring (C2)O, is also a remarkable Cd(2+) binding site, though replacement of (C2)O by (C2)S enhances the affinity towards Cd(2+) dramatically, giving in addition rise to the deprotonation of the (C4)NH(2) group. The phosphodiester bridge is only a weak binding site but the affinity increases further from the mono- to the di- and the triphosphate. The same also holds for the corresponding nucleotides. Complex stability of the pyrimidine-nucleotides is solely determined by the coordination tendency of the phosphate group(s), whereas in the case of purine-nucleotides macrochelate formation takes place by the interaction of the phosphate-coordinated Cd(2+) with N7. The extents of the formation degrees of these chelates are summarized and the effect of a non-bridging sulfur atom in a thiophosphate group (versus a normal phosphate group) is considered. Mixed ligand complexes containing a nucleotide and a further mono- or bidentate ligand are covered and it is concluded that in these species N7 is released from the coordination sphere of Cd(2+). In the case that the other ligand contains an aromatic residue (e.g., 2,2'-bipyridine or the indole ring of tryptophanate) intramolecular stack formation takes place. With buffers like Tris or Bistris mixed ligand complexes are formed. Cd(2+) coordination to dinucleotides and to dinucleoside monophosphates provides some insights regarding the interaction between Cd(2+) and nucleic acids. Cd(2+) binding to oligonucleotides follows the principles of coordination to its units. The available crystal studies reveal that N7 of purines is the prominent binding site followed by phosphate oxygens and other heteroatoms in nucleic acids. Due to its high thiophilicity, Cd(2+) is regularly used in so-called thiorescue experiments, which lead to the identification of a direct involvement of divalent metal ions in ribozyme catalysis.
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