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Wang L, Li H, Lei Z, Jeong DH, Cho J. The CARBON CATABOLITE REPRESSION 4A-mediated RNA deadenylation pathway acts on the transposon RNAs that are not regulated by small RNAs. THE NEW PHYTOLOGIST 2024; 241:1636-1645. [PMID: 38009859 DOI: 10.1111/nph.19435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/13/2023] [Indexed: 11/29/2023]
Abstract
Transposable elements (TEs) are mobile genetic elements that can impair the host genome stability and integrity. It has been well documented that activated transposons in plants are suppressed by small interfering (si) RNAs. However, transposon repression by the cytoplasmic RNA surveillance system is unknown. Here, we show that mRNA deadenylation is critical for controlling transposons in Arabidopsis. Trimming of poly(A) tail is a rate-limiting step that precedes the RNA decay and is primarily mediated by the CARBON CATABOLITE REPRESSION 4 (CCR4)-NEGATIVE ON TATA-LESS (NOT) complex. We found that the loss of CCR4a leads to strong derepression and mobilization of TEs in Arabidopsis. Intriguingly, CCR4a regulates a largely distinct set of TEs from those controlled by RNA-dependent RNA Polymerase 6 (RDR6), a key enzyme that produces cytoplasmic siRNAs. This indicates that the cytoplasmic RNA quality control mechanism targets the TEs that are poorly recognized by the previously well-characterized RDR6-mediated pathway, and thereby augments the host genome stability. Our study suggests a hitherto unknown mechanism for transposon repression mediated by RNA deadenylation and unveils a complex nature of the host's strategy to maintain the genome integrity.
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Affiliation(s)
- Ling Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- University of Chinese Academy of Science, Beijing, 100049, China
| | - Hui Li
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- University of Chinese Academy of Science, Beijing, 100049, China
| | - Zhen Lei
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- University of Chinese Academy of Science, Beijing, 100049, China
| | - Dong-Hoon Jeong
- Department of Life Science, Hallym University, Chuncheon, 24252, Korea
- Multidisciplinary Genome Institute, Hallym University, Chuncheon, 24252, Korea
| | - Jungnam Cho
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
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2
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Krempl C, Lazzaretti D, Sprangers R. A structural biology view on the enzymes involved in eukaryotic mRNA turnover. Biol Chem 2023; 404:1101-1121. [PMID: 37709756 DOI: 10.1515/hsz-2023-0182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023]
Abstract
The cellular environment contains numerous ribonucleases that are dedicated to process mRNA transcripts that have been targeted for degradation. Here, we review the three dimensional structures of the ribonuclease complexes (Pan2-Pan3, Ccr4-Not, Xrn1, exosome) and the mRNA decapping enzymes (Dcp2, DcpS) that are involved in mRNA turnover. Structures of major parts of these proteins have been experimentally determined. These enzymes and factors do not act in isolation, but are embedded in interaction networks which regulate enzyme activity and ensure that the appropriate substrates are recruited. The structural details of the higher order complexes that form can, in part, be accurately deduced from known structural data of sub-complexes. Interestingly, many of the ribonuclease and decapping enzymes have been observed in structurally different conformations. Together with experimental data, this highlights that structural changes are often important for enzyme function. We conclude that the known structural data of mRNA decay factors provide important functional insights, but that static structural data needs to be complemented with information regarding protein motions to complete the picture of how transcripts are turned over. In addition, we highlight multiple aspects that influence mRNA turnover rates, but that have not been structurally characterized so far.
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Affiliation(s)
- Christina Krempl
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Daniela Lazzaretti
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Remco Sprangers
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, D-93053 Regensburg, Germany
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3
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Zhao Q, Pavanello L, Bartlam M, Winkler GS. Structure and function of molecular machines involved in deadenylation-dependent 5'-3' mRNA degradation. Front Genet 2023; 14:1233842. [PMID: 37876592 PMCID: PMC10590902 DOI: 10.3389/fgene.2023.1233842] [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: 06/02/2023] [Accepted: 09/25/2023] [Indexed: 10/26/2023] Open
Abstract
In eukaryotic cells, the synthesis, processing, and degradation of mRNA are important processes required for the accurate execution of gene expression programmes. Fully processed cytoplasmic mRNA is characterised by the presence of a 5'cap structure and 3'poly(A) tail. These elements promote translation and prevent non-specific degradation. Degradation via the deadenylation-dependent 5'-3' degradation pathway can be induced by trans-acting factors binding the mRNA, such as RNA-binding proteins recognising sequence elements and the miRNA-induced repression complex. These factors recruit the core mRNA degradation machinery that carries out the following steps: i) shortening of the poly(A) tail by the Ccr4-Not and Pan2-Pan3 poly (A)-specific nucleases (deadenylases); ii) removal of the 5'cap structure by the Dcp1-Dcp2 decapping complex that is recruited by the Lsm1-7-Pat1 complex; and iii) degradation of the mRNA body by the 5'-3' exoribonuclease Xrn1. In this review, the biochemical function of the nucleases and accessory proteins involved in deadenylation-dependent mRNA degradation will be reviewed with a particular focus on structural aspects of the proteins and enzymes involved.
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Affiliation(s)
- Qi Zhao
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Lorenzo Pavanello
- School of Pharmacy, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Mark Bartlam
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
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4
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Zhang G, Luo H, Li X, Hu Z, Wang Q. The Dynamic Poly(A) Tail Acts as a Signal Hub in mRNA Metabolism. Cells 2023; 12:cells12040572. [PMID: 36831239 PMCID: PMC9954528 DOI: 10.3390/cells12040572] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023] Open
Abstract
In eukaryotes, mRNA metabolism requires a sophisticated signaling system. Recent studies have suggested that polyadenylate tail may play a vital role in such a system. The poly(A) tail used to be regarded as a common modification at the 3' end of mRNA, but it is now known to be more than just that. It appears to act as a platform or hub that can be understood in two ways. On the one hand, polyadenylation and deadenylation machinery constantly regulates its dynamic activity; on the other hand, it exhibits the ability to recruit RNA-binding proteins and then interact with diverse factors to send various signals to regulate mRNA metabolism. In this paper, we outline the main complexes that regulate the dynamic activities of poly(A) tails, explain how these complexes participate polyadenylation/deadenylation process and summarize the diverse signals this hub emit. We are trying to make a point that the poly(A) tail can metaphorically act as a "flagman" who is supervised by polyadenylation and deadenylation and sends out signals to regulate the orderly functioning of mRNA metabolism.
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Affiliation(s)
- Guiying Zhang
- Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Haolin Luo
- Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China
| | - Xinyi Li
- Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China
| | - Zhangli Hu
- Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
- Correspondence: (Z.H.); (Q.W.)
| | - Quan Wang
- Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, China
- Correspondence: (Z.H.); (Q.W.)
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5
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Adamiec M, Dobrogojski J, Wojtyla Ł, Luciński R. Stress-related expression of the chloroplast EGY3 pseudoprotease and its possible impact on chloroplasts' proteome composition. FRONTIERS IN PLANT SCIENCE 2022; 13:965143. [PMID: 35937369 PMCID: PMC9355673 DOI: 10.3389/fpls.2022.965143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
The EGY3 is a pseudoprotease, located in the thylakoid membrane, that shares homology with the family of site-2-proteases (S2P). Although S2P proteases are present in the cells of all living organisms, the EGY3 was found only in plant cells. The sequence of the pseudoprotease is highly conserved in the plant kingdom; however, little is known about its physiological importance. Results obtained with real-time PCR indicated that the expression of the EGY3 gene is dramatically induced during the first few hours of exposure to high light and high-temperature stress. The observed increase in transcript abundance correlates with protein accumulation level, which indicates that EGY3 participates in response to both high-temperature and high light stresses. The lack of the pseudoprotease leads, in both stresses, to lower concentrations of hydrogen peroxide. However, the decrease of chloroplast copper/zinc superoxide dismutase 2 level was observed only during the high light stress. In both analyzed stressful conditions, proteins related to RubisCO folding, glycine metabolism, and photosystem I were identified as differently accumulating in egy3 mutant lines and WT plants; however, the functional status of PSII during analyzed stressful conditions remains very similar. Our results lead to a conclusion that EGY3 pseudoprotease participates in response to high light and high-temperature stress; however, its role is associated rather with photosystem I and light-independent reactions of photosynthesis.
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Affiliation(s)
- Małgorzata Adamiec
- Department of Plant Physiology, Faculty of Biology, Institute of Experimental Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Jędrzej Dobrogojski
- Department of Biochemistry and Biotechnology, Faculty of Agronomy, Horticulture and Bioengineering, University of Life Sciences, Poznań, Poland
| | - Łukasz Wojtyla
- Department of Plant Physiology, Faculty of Biology, Institute of Experimental Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Robert Luciński
- Department of Plant Physiology, Faculty of Biology, Institute of Experimental Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
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6
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Kyritsis A, Papanastasi E, Kokkori I, Maragozidis P, Chatzileontiadou DSM, Pallaki P, Labrou M, Zarogiannis SG, Chrousos GP, Vlachakis D, Gourgoulianis KI, Balatsos NAA. Integrated Deadenylase Genetic Association Network and Transcriptome Analysis in Thoracic Carcinomas. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103102. [PMID: 35630580 PMCID: PMC9145511 DOI: 10.3390/molecules27103102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/20/2022] [Accepted: 04/26/2022] [Indexed: 12/03/2022]
Abstract
The poly(A) tail at the 3′ end of mRNAs determines their stability, translational efficiency, and fate. The shortening of the poly(A) tail, and its efficient removal, triggers the degradation of mRNAs, thus, regulating gene expression. The process is catalyzed by a family of enzymes, known as deadenylases. As the dysregulation of gene expression is a hallmark of cancer, understanding the role of deadenylases has gained additional interest. Herein, the genetic association network shows that CNOT6 and CNOT7 are the most prevalent and most interconnected nodes in the equilibrated diagram. Subsequent silencing and transcriptomic analysis identifies transcripts possibly regulated by specific deadenylases. Furthermore, several gene ontologies are enriched by common deregulated genes. Given the potential concerted action and overlapping functions of deadenylases, we examined the effect of silencing a deadenylase on the remaining ones. Our results suggest that specific deadenylases target unique subsets of mRNAs, whilst at the same time, multiple deadenylases may affect the same mRNAs with overlapping functions.
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Affiliation(s)
- Athanasios Kyritsis
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, Biopolis, 411 10 Larissa, Greece;
| | - Eirini Papanastasi
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
| | - Ioanna Kokkori
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, Biopolis, 411 10 Larissa, Greece;
- Department of Pneumonology-Oncology, Theagenio Cancer Hospital, 540 07 Thessaloniki, Greece
| | - Panagiotis Maragozidis
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
| | - Demetra S. M. Chatzileontiadou
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
| | - Paschalina Pallaki
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
| | - Maria Labrou
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
| | - Sotirios G. Zarogiannis
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, Biopolis, 411 10 Larissa, Greece;
- Department of Physiology, Faculty of Medicine, University of Thessaly, Biopolis, 415 00 Larissa, Greece
- Correspondence: (S.G.Z.); (K.I.G.); (N.A.A.B.)
| | - George P. Chrousos
- University Research Institute of Maternal and Child Health and Precision Medicine, ‘Aghia Sophia’ Children’s Hospital, National and Kapodistrian University of Athens, 115 27 Athens, Greece; (G.P.C.); (D.V.)
- UNESCO Chair on Adolescent Health Care, ‘Aghia Sophia’ Children’s Hospital, National and Kapodistrian University of Athens, 115 27 Athens, Greece
- Center of Clinical, Experimental Surgery and Translational Research, Division of Endocrinology and Metabolism, Biomedical Research Foundation of the Academy of Athens, 115 27 Athens, Greece
| | - Dimitrios Vlachakis
- University Research Institute of Maternal and Child Health and Precision Medicine, ‘Aghia Sophia’ Children’s Hospital, National and Kapodistrian University of Athens, 115 27 Athens, Greece; (G.P.C.); (D.V.)
- UNESCO Chair on Adolescent Health Care, ‘Aghia Sophia’ Children’s Hospital, National and Kapodistrian University of Athens, 115 27 Athens, Greece
- Center of Clinical, Experimental Surgery and Translational Research, Division of Endocrinology and Metabolism, Biomedical Research Foundation of the Academy of Athens, 115 27 Athens, Greece
- Laboratory of Genetics, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 118 55 Athens, Greece
| | - Konstantinos I. Gourgoulianis
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, Biopolis, 411 10 Larissa, Greece;
- Correspondence: (S.G.Z.); (K.I.G.); (N.A.A.B.)
| | - Nikolaos A. A. Balatsos
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 415 00 Larissa, Greece; (A.K.); (E.P.); (P.M.); (D.S.M.C.); (P.P.); (M.L.)
- Correspondence: (S.G.Z.); (K.I.G.); (N.A.A.B.)
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7
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Roles of mRNA poly(A) tails in regulation of eukaryotic gene expression. Nat Rev Mol Cell Biol 2022; 23:93-106. [PMID: 34594027 PMCID: PMC7614307 DOI: 10.1038/s41580-021-00417-y] [Citation(s) in RCA: 187] [Impact Index Per Article: 93.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2021] [Indexed: 02/06/2023]
Abstract
In eukaryotes, poly(A) tails are present on almost every mRNA. Early experiments led to the hypothesis that poly(A) tails and the cytoplasmic polyadenylate-binding protein (PABPC) promote translation and prevent mRNA degradation, but the details remained unclear. More recent data suggest that the role of poly(A) tails is much more complex: poly(A)-binding protein can stimulate poly(A) tail removal (deadenylation) and the poly(A) tails of stable, highly translated mRNAs at steady state are much shorter than expected. Furthermore, the rate of translation elongation affects deadenylation. Consequently, the interplay between poly(A) tails, PABPC, translation and mRNA decay has a major role in gene regulation. In this Review, we discuss recent work that is revolutionizing our understanding of the roles of poly(A) tails in the cytoplasm. Specifically, we discuss the roles of poly(A) tails in translation and control of mRNA stability and how poly(A) tails are removed by exonucleases (deadenylases), including CCR4-NOT and PAN2-PAN3. We also discuss how deadenylation rate is determined, the integration of deadenylation with other cellular processes and the function of PABPC. We conclude with an outlook for the future of research in this field.
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8
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Chen Y, Khazina E, Izaurralde E, Weichenrieder O. Crystal structure and functional properties of the human CCR4-CAF1 deadenylase complex. Nucleic Acids Res 2021; 49:6489-6510. [PMID: 34038562 PMCID: PMC8216464 DOI: 10.1093/nar/gkab414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 04/28/2021] [Accepted: 05/05/2021] [Indexed: 01/07/2023] Open
Abstract
The CCR4 and CAF1 deadenylases physically interact to form the CCR4-CAF1 complex and function as the catalytic core of the larger CCR4-NOT complex. Together, they are responsible for the eventual removal of the 3′-poly(A) tail from essentially all cellular mRNAs and consequently play a central role in the posttranscriptional regulation of gene expression. The individual properties of CCR4 and CAF1, however, and their respective contributions in different organisms and cellular environments are incompletely understood. Here, we determined the crystal structure of a human CCR4-CAF1 complex and characterized its enzymatic and substrate recognition properties. The structure reveals specific molecular details affecting RNA binding and hydrolysis, and confirms the CCR4 nuclease domain to be tethered flexibly with a considerable distance between both enzyme active sites. CCR4 and CAF1 sense nucleotide identity on both sides of the 3′-terminal phosphate, efficiently differentiating between single and consecutive non-A residues. In comparison to CCR4, CAF1 emerges as a surprisingly tunable enzyme, highly sensitive to pH, magnesium and zinc ions, and possibly allowing distinct reaction geometries. Our results support a picture of CAF1 as a primordial deadenylase, which gets assisted by CCR4 for better efficiency and by the assembled NOT proteins for selective mRNA targeting and regulation.
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Affiliation(s)
- Ying Chen
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elena Khazina
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
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9
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Mace PD, Murphy JM. There's more to death than life: Noncatalytic functions in kinase and pseudokinase signaling. J Biol Chem 2021; 296:100705. [PMID: 33895136 PMCID: PMC8141879 DOI: 10.1016/j.jbc.2021.100705] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Protein kinases are present in all domains of life and play diverse roles in cellular signaling. Whereas the impact of substrate phosphorylation by protein kinases has long been appreciated, it is becoming increasingly clear that protein kinases also play other, noncatalytic, functions. Here, we review recent developments in understanding the noncatalytic functions of protein kinases. Many noncatalytic activities are best exemplified by protein kinases that are devoid of enzymatic activity altogether-known as pseudokinases. These dead proteins illustrate that, beyond conventional notions of kinase function, catalytic activity can be dispensable for biological function. Through key examples we illustrate diverse mechanisms of noncatalytic kinase activity: as allosteric modulators; protein-based switches; scaffolds for complex assembly; and as competitive inhibitors in signaling pathways. In common, these noncatalytic mechanisms exploit the nature of the protein kinase fold as a versatile protein-protein interaction module. Many examples are also intrinsically linked to the ability of the protein kinase to switch between multiple states, a function shared with catalytic protein kinases. Finally, we consider the contemporary landscape of small molecules to modulate noncatalytic functions of protein kinases, which, although challenging, has significant potential given the scope of noncatalytic protein kinase function in health and disease.
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Affiliation(s)
- Peter D Mace
- Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
| | - James M Murphy
- Inflammation Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
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10
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Tang TTL, Passmore LA. Recognition of Poly(A) RNA through Its Intrinsic Helical Structure. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:21-30. [PMID: 32295929 PMCID: PMC7116106 DOI: 10.1101/sqb.2019.84.039818] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The polyadenosine (poly(A)) tail, which is found on the 3’ end of almost all eukaryotic messenger RNAs (mRNAs), plays an important role in the posttranscriptional regulation of gene expression. Shortening of the poly(A) tail, a process known as deadenylation, is thought to be the first and rate-limiting step of mRNA turnover. Deadenylation is performed by the Pan2–Pan3 and Ccr4–Not complexes that contain highly conserved exonuclease enzymes Pan2, and Ccr4 and Caf1, respectively. These complexes have been extensively studied, but the mechanisms of how the deadenylase enzymes recognize the poly(A) tail were poorly understood until recently. Here, we summarize recent work from our laboratory demonstrating that the highly conserved Pan2 exonuclease recognizes the poly(A) tail, not through adenine-specific functional groups, but through the conformation of poly(A) RNA. Our biochemical, biophysical, and structural investigations suggest that poly(A) forms an intrinsic base-stacked, single-stranded helical conformation that is recognized by Pan2, and that disruption of this structure inhibits both Pan2 and Caf1. This intrinsic structure has been shown to be important in poly(A) recognition in other biological processes, further underlining the importance of the unique conformation of poly(A).
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Affiliation(s)
- Terence T L Tang
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Lori A Passmore
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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11
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Abstract
Pseudokinases are members of the protein kinase superfamily but signal primarily through noncatalytic mechanisms. Many pseudokinases contribute to the pathologies of human diseases, yet they remain largely unexplored as drug targets owing to challenges associated with modulation of their biological functions. Our understanding of the structure and physiological roles of pseudokinases has improved substantially over the past decade, revealing intriguing similarities between pseudokinases and their catalytically active counterparts. Pseudokinases often adopt conformations that are analogous to those seen in catalytically active kinases and, in some cases, can also bind metal cations and/or nucleotides. Several clinically approved kinase inhibitors have been shown to influence the noncatalytic functions of active kinases, providing hope that similar properties in pseudokinases could be pharmacologically regulated. In this Review, we discuss known roles of pseudokinases in disease, their unique structural features and the progress that has been made towards developing pseudokinase-directed therapeutics.
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12
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Shang J, Chen WM, Liu S, Wang ZH, Wei TN, Chen ZZ, Wu WB. CircPAN3 contributes to drug resistance in acute myeloid leukemia through regulation of autophagy. Leuk Res 2019; 85:106198. [DOI: 10.1016/j.leukres.2019.106198] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 07/07/2019] [Accepted: 08/01/2019] [Indexed: 12/24/2022]
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13
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Ribeiro AJM, Das S, Dawson N, Zaru R, Orchard S, Thornton JM, Orengo C, Zeqiraj E, Murphy JM, Eyers PA. Emerging concepts in pseudoenzyme classification, evolution, and signaling. Sci Signal 2019; 12:eaat9797. [PMID: 31409758 DOI: 10.1126/scisignal.aat9797] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 21st century is witnessing an explosive surge in our understanding of pseudoenzyme-driven regulatory mechanisms in biology. Pseudoenzymes are proteins that have sequence homology with enzyme families but that are proven or predicted to lack enzyme activity due to mutations in otherwise conserved catalytic amino acids. The best-studied pseudoenzymes are pseudokinases, although examples from other families are emerging at a rapid rate as experimental approaches catch up with an avalanche of freely available informatics data. Kingdom-wide analysis in prokaryotes, archaea and eukaryotes reveals that between 5 and 10% of proteins that make up enzyme families are pseudoenzymes, with notable expansions and contractions seemingly associated with specific signaling niches. Pseudoenzymes can allosterically activate canonical enzymes, act as scaffolds to control assembly of signaling complexes and their localization, serve as molecular switches, or regulate signaling networks through substrate or enzyme sequestration. Molecular analysis of pseudoenzymes is rapidly advancing knowledge of how they perform noncatalytic functions and is enabling the discovery of unexpected, and previously unappreciated, functions of their intensively studied enzyme counterparts. Notably, upon further examination, some pseudoenzymes have previously unknown enzymatic activities that could not have been predicted a priori. Pseudoenzymes can be targeted and manipulated by small molecules and therefore represent new therapeutic targets (or anti-targets, where intervention should be avoided) in various diseases. In this review, which brings together broad bioinformatics and cell signaling approaches in the field, we highlight a selection of findings relevant to a contemporary understanding of pseudoenzyme-based biology.
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Affiliation(s)
- António J M Ribeiro
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Sayoni Das
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Natalie Dawson
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Rossana Zaru
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Sandra Orchard
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Janet M Thornton
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Christine Orengo
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Elton Zeqiraj
- Astbury Centre for Structural Molecular Biology, Molecular and Cellular Biology, Faculty of Biological Sciences, Astbury Building, Room 8.109, University of Leeds, Leeds LS2 9JT, UK
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
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14
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Abshire ET, Chasseur J, Bohn JA, Del Rizzo PA, Freddolino PL, Goldstrohm AC, Trievel RC. The structure of human Nocturnin reveals a conserved ribonuclease domain that represses target transcript translation and abundance in cells. Nucleic Acids Res 2019; 46:6257-6270. [PMID: 29860338 PMCID: PMC6158716 DOI: 10.1093/nar/gky412] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/09/2018] [Indexed: 12/22/2022] Open
Abstract
The circadian protein Nocturnin (NOCT) belongs to the exonuclease, endonuclease and phosphatase superfamily and is most similar to the CCR4-class of deadenylases that degrade the poly-adenosine tails of mRNAs. NOCT-deficient mice are resistant to high-fat diet induced weight gain, and exhibit dysregulation of bone formation. However, the mechanisms by which NOCT regulates these processes remain to be determined. Here, we describe a pair of high-resolution crystal structures of the human NOCT catalytic domain. The active site of NOCT is highly conserved with other exoribonucleases, and when directed to a transcript in cells, NOCT can reduce translation and abundance of that mRNA in a manner dependent on key active site residues. In contrast to the related deadenylase CNOT6L, purified recombinant NOCT lacks in vitro ribonuclease activity, suggesting that unidentified factors are necessary for enzymatic activity. We also find the ability of NOCT to repress reporter mRNAs in cells depends upon the 3' end of the mRNA, as reporters terminating with a 3' MALAT1 structure cannot be repressed by NOCT. Together, these data demonstrate that NOCT is an exoribonuclease that can degrade mRNAs to inhibit protein expression, suggesting a molecular mechanism for its regulatory role in lipid metabolism and bone development.
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Affiliation(s)
- Elizabeth T Abshire
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jennifer Chasseur
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jennifer A Bohn
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul A Del Rizzo
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Aaron C Goldstrohm
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Raymond C Trievel
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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15
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Calvanese L, Squeglia F, Romano M, D'Auria G, Falcigno L, Berisio R. Structural and dynamic studies provide insights into specificity and allosteric regulation of ribonuclease as, a key enzyme in mycobacterial virulence. J Biomol Struct Dyn 2019; 38:2455-2467. [PMID: 31299874 DOI: 10.1080/07391102.2019.1643786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ribonuclease AS (RNase AS) is a crucial enzyme for virulence of Mycobacterium tuberculosis. We previously observed that RNase AS structurally resembles RNase T from Escherichia coli, an important enzyme for tRNA maturation and turnover. Here, we combine X-ray crystallography and molecular dynamics (MD) to investigate the specificity and dynamic properties of substrate binding. Both X-ray and MD data provide structural determinants that corroborate the strict substrate specificity of RNase AS to cleave only adenosine residues, due to the structural features of adenine base. Beside suggesting tRNA as most likely substrate of RNase AS, MD and modeling studies identify key enzyme-ligand interactions, both involving the catalytic site and the double helix region of tRNA, which is locked by interactions with a set of arginine residues. The MD data also evidence a ligand-induced conformational change of the enzyme which is transferred from one chain to the adjacent one. These data will explain the dimeric nature of both RNase AS and RNase T, with two catalytic grooves composed of both chains. Also, they account for the dichotomy of tRNA, which contains both the substrate poly(A) chain and an inhibiting double strand RNA. Indeed, they provide a possible mechanism of allosteric regulation, which unlocks one catalytic groove when the second groove is inhibited by the double strand region of tRNA. Finally, a full comprehension of the molecular details of tRNA maturation processes is essential to develop novel strategies to modulate RNA processing, for therapeutic purposes. AbbreviationsMDmolecular dynamicsPDBProtein Data BankRMSDroot mean square deviationRMSFroot mean square fluctuationRNAribonucleotidic acidRNase ASRibonuclease ASCommunicated by Ramasamy H. Sarma.
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Affiliation(s)
- Luisa Calvanese
- CIRPeB, University of Naples Federico II, Naples, Italy.,Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Flavia Squeglia
- Institute of Bio-Structures and Bio-Imaging - CNR-IBB, Naples, Italy
| | - Maria Romano
- Department of Life Sciences, Imperial College London, London, UK
| | - Gabriella D'Auria
- CIRPeB, University of Naples Federico II, Naples, Italy.,Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Lucia Falcigno
- CIRPeB, University of Naples Federico II, Naples, Italy.,Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Rita Berisio
- Institute of Bio-Structures and Bio-Imaging - CNR-IBB, Naples, Italy
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16
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Abstract
In trypanosomes, RNA polymerase II transcription is polycistronic and individual mRNAs are excised by trans-splicing and polyadenylation. The lack of individual gene transcription control is compensated by control of mRNA processing, translation and degradation. Although the basic mechanisms of mRNA decay and translation are evolutionarily conserved, there are also unique aspects, such as the existence of six cap-binding translation initiation factor homologues, a novel decapping enzyme and an mRNA stabilizing complex that is recruited by RNA-binding proteins. High-throughput analyses have identified nearly a hundred regulatory mRNA-binding proteins, making trypanosomes valuable as a model system to investigate post-transcriptional regulation.
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Affiliation(s)
- Christine Clayton
- University of Heidelberg Center for Molecular Biology (ZMBH), Im Neuenheimer Feld 282, D69120 Heidelberg, Germany
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17
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Tang TTL, Stowell JAW, Hill CH, Passmore LA. The intrinsic structure of poly(A) RNA determines the specificity of Pan2 and Caf1 deadenylases. Nat Struct Mol Biol 2019; 26:433-442. [PMID: 31110294 PMCID: PMC6555765 DOI: 10.1038/s41594-019-0227-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/11/2019] [Indexed: 11/09/2022]
Abstract
The 3' poly(A) tail of messenger RNA is fundamental to regulating eukaryotic gene expression. Shortening of the poly(A) tail, termed deadenylation, reduces transcript stability and inhibits translation. Nonetheless, the mechanism for poly(A) recognition by the conserved deadenylase complexes Pan2-Pan3 and Ccr4-Not is poorly understood. Here we provide a model for poly(A) RNA recognition by two DEDD-family deadenylase enzymes, Pan2 and the Ccr4-Not nuclease Caf1. Crystal structures of Saccharomyces cerevisiae Pan2 in complex with RNA show that, surprisingly, Pan2 does not form canonical base-specific contacts. Instead, it recognizes the intrinsic stacked, helical conformation of poly(A) RNA. Using a fully reconstituted biochemical system, we show that disruption of this structure-for example, by incorporation of guanosine into poly(A)-inhibits deadenylation by both Pan2 and Caf1. Together, these data establish a paradigm for specific recognition of the conformation of poly(A) RNA by proteins that regulate gene expression.
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Affiliation(s)
| | | | - Chris H Hill
- MRC Laboratory of Molecular Biology, Cambridge, UK
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18
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Schäfer IB, Yamashita M, Schuller JM, Schüssler S, Reichelt P, Strauss M, Conti E. Molecular Basis for poly(A) RNP Architecture and Recognition by the Pan2-Pan3 Deadenylase. Cell 2019; 177:1619-1631.e21. [PMID: 31104843 PMCID: PMC6547884 DOI: 10.1016/j.cell.2019.04.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/08/2019] [Accepted: 04/05/2019] [Indexed: 01/17/2023]
Abstract
The stability of eukaryotic mRNAs is dependent on a ribonucleoprotein (RNP) complex of poly(A)-binding proteins (PABPC1/Pab1) organized on the poly(A) tail. This poly(A) RNP not only protects mRNAs from premature degradation but also stimulates the Pan2-Pan3 deadenylase complex to catalyze the first step of poly(A) tail shortening. We reconstituted this process in vitro using recombinant proteins and show that Pan2-Pan3 associates with and degrades poly(A) RNPs containing two or more Pab1 molecules. The cryo-EM structure of Pan2-Pan3 in complex with a poly(A) RNP composed of 90 adenosines and three Pab1 protomers shows how the oligomerization interfaces of Pab1 are recognized by conserved features of the deadenylase and thread the poly(A) RNA substrate into the nuclease active site. The structure reveals the basis for the periodic repeating architecture at the 3′ end of cytoplasmic mRNAs. This illustrates mechanistically how RNA-bound Pab1 oligomers act as rulers for poly(A) tail length over the mRNAs’ lifetime. Oligomerization of PABP on the poly(A) tail creates a series of consecutive arches Pan2-Pan3 deadenylase recognizes the oligomerized state of poly(A)-bound PABP The dimerization interface of juxtaposed PABPs creates the Pan2-Pan3 docking site The poly(A) RNP arches are flexible and moldable by the interacting proteins
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Affiliation(s)
- Ingmar B Schäfer
- Department of Structural Cell Biology, MPI of Biochemistry, Munich, Germany.
| | - Masami Yamashita
- Department of Structural Cell Biology, MPI of Biochemistry, Munich, Germany
| | | | - Steffen Schüssler
- Department of Structural Cell Biology, MPI of Biochemistry, Munich, Germany
| | - Peter Reichelt
- Department of Structural Cell Biology, MPI of Biochemistry, Munich, Germany
| | - Mike Strauss
- cryoEM Facility, MPI of Biochemistry, Munich, Germany
| | - Elena Conti
- Department of Structural Cell Biology, MPI of Biochemistry, Munich, Germany.
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19
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Mugridge JS, Coller J, Gross JD. Structural and molecular mechanisms for the control of eukaryotic 5'-3' mRNA decay. Nat Struct Mol Biol 2018; 25:1077-1085. [PMID: 30518847 DOI: 10.1038/s41594-018-0164-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 10/31/2018] [Indexed: 12/15/2022]
Abstract
5'-3' RNA decay pathways are critical for quality control and regulation of gene expression. Structural and biochemical studies have provided insights into the key nucleases that carry out deadenylation, decapping, and exonucleolysis during 5'-3' decay, but detailed understanding of how these activities are coordinated is only beginning to emerge. Here we review recent mechanistic insights into the control of 5'-3' RNA decay, including coupling between translation and decay, coordination between the complexes and activities that process 5' and 3' RNA termini, conformational control of enzymatic activity, liquid phase separation, and RNA modifications.
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Affiliation(s)
- Jeffrey S Mugridge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Jeff Coller
- The Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, USA
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA.
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20
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Meir Z, Osherov N. Vitamin Biosynthesis as an Antifungal Target. J Fungi (Basel) 2018; 4:E72. [PMID: 29914189 PMCID: PMC6023522 DOI: 10.3390/jof4020072] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 12/18/2022] Open
Abstract
The large increase in the population of immunosuppressed patients, coupled with the limited efficacy of existing antifungals and rising resistance toward them, have dramatically highlighted the need to develop novel drugs for the treatment of invasive fungal infections. An attractive possibility is the identification of possible drug targets within essential fungal metabolic pathways not shared with humans. Here, we review the vitamin biosynthetic pathways (vitamins A⁻E, K) as candidates for the development of antifungals. We present a set of ranking criteria that identify the vitamin B2 (riboflavin), B5 (pantothenic acid), and B9 (folate) biosynthesis pathways as being particularly rich in new antifungal targets. We propose that recent scientific advances in the fields of drug design and fungal genomics have developed sufficiently to merit a renewed look at these pathways as promising sources for the development of novel classes of antifungals.
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Affiliation(s)
- Zohar Meir
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
| | - Nir Osherov
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
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21
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Heck AM, Wilusz J. The Interplay between the RNA Decay and Translation Machinery in Eukaryotes. Cold Spring Harb Perspect Biol 2018; 10:a032839. [PMID: 29311343 PMCID: PMC5932591 DOI: 10.1101/cshperspect.a032839] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
RNA decay plays a major role in regulating gene expression and is tightly networked with other aspects of gene expression to effectively coordinate post-transcriptional regulation. The goal of this work is to provide an overview of the major factors and pathways of general messenger RNA (mRNA) decay in eukaryotic cells, and then discuss the effective interplay of this cytoplasmic process with the protein synthesis machinery. Given the transcript-specific and fluid nature of mRNA stability in response to changing cellular conditions, understanding the fundamental networking between RNA decay and translation will provide a foundation for a complete mechanistic understanding of this important aspect of cell biology.
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Affiliation(s)
- Adam M Heck
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80525
- Program in Cell & Molecular Biology, Colorado State University, Fort Collins, Colorado 80525
| | - Jeffrey Wilusz
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80525
- Program in Cell & Molecular Biology, Colorado State University, Fort Collins, Colorado 80525
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22
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USP52 acts as a deubiquitinase and promotes histone chaperone ASF1A stabilization. Nat Commun 2018; 9:1285. [PMID: 29599486 PMCID: PMC5876348 DOI: 10.1038/s41467-018-03588-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/22/2018] [Indexed: 12/31/2022] Open
Abstract
Histone chaperone ASF1A has been reported to be dysregulated in multiple tumors; however, the underlying molecular mechanism that how the abundance and function of ASF1A are regulated remains unclear. Here we report that ASF1A is physically associated with USP52, which is previously identified as a pseudo-deubiquitinase. Interestingly, we demonstrate that USP52 is a bona fide ubiquitin-specific protease, and USP52 promotes ASF1A deubiquitination and stabilization. USP52-promoted ASF1A stabilization facilitates chromatin assembly and favors cell cycle progression. Additionally, we find that USP52 is overexpressed in breast carcinomas, and its level of expression correlates with that of ASF1A. Moreover, we reveal that impairment of USP52-promoted ASF1A stabilization results in growth arrest of breast cancer cells and sensitizes these cells to DNA damage. Our experiments identify USP52 as a truly protein deubiquitinase, uncover a molecular mechanism of USP52 in chromatin assembly, and reveal a potential role of USP52 in breast carcinogenesis. Histone chaperone ASF1A is often dysregulated in cancers, however the regulation of its abundance is unclear. Here, the authors show that USP52 promotes ASF1A stability through deubiquitination while impairment of this stability reduces breast tumorigenesis and confers sensitivity to DNA damage.
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23
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Sheu-Gruttadauria J, MacRae IJ. Phase Transitions in the Assembly and Function of Human miRISC. Cell 2018; 173:946-957.e16. [PMID: 29576456 DOI: 10.1016/j.cell.2018.02.051] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 12/08/2017] [Accepted: 02/21/2018] [Indexed: 12/16/2022]
Abstract
miRISC is a multi-protein assembly that uses microRNAs (miRNAs) to identify mRNAs targeted for repression. Dozens of miRISC-associated proteins have been identified, and interactions between many factors have been examined in detail. However, the physical nature of the complex remains unknown. Here, we show that two core protein components of human miRISC, Argonaute2 (Ago2) and TNRC6B, condense into phase-separated droplets in vitro and in live cells. Phase separation is promoted by multivalent interactions between the glycine/tryptophan (GW)-rich domain of TNRC6B and three evenly spaced tryptophan-binding pockets in the Ago2 PIWI domain. miRISC droplets formed in vitro recruit deadenylation factors and sequester target RNAs from the bulk solution. The condensation of miRISC is accompanied by accelerated deadenylation of target RNAs bound to Ago2. The combined results may explain how miRISC silences mRNAs of varying size and structure and provide experimental evidence that protein-mediated phase separation can facilitate an RNA processing reaction.
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Affiliation(s)
- Jessica Sheu-Gruttadauria
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ian J MacRae
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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24
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Panagopoulos I, Gorunova L, Andersen HK, Bergrem A, Dahm A, Andersen K, Micci F, Heim S. PAN3- PSMA2 fusion resulting from a novel t(7;13)(p14;q12) chromosome translocation in a myelodysplastic syndrome that evolved into acute myeloid leukemia. Exp Hematol Oncol 2018; 7:7. [PMID: 29560286 PMCID: PMC5859504 DOI: 10.1186/s40164-018-0099-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 03/14/2018] [Indexed: 11/30/2022] Open
Abstract
Background Acquired primary chromosomal changes in cancer are sometimes found as sole karyotypic abnormalities. They are specifically associated with particular types of neoplasia, essential in establishing the neoplasm, and they often lead to the generation of chimeric genes of pathogenetic, diagnostic, and prognostic importance. Thus, the report of new primary cancer-specific chromosomal aberrations is not only of scientific but also potentially of clinical interest, as is the detection of their gene-level consequences. Case presentation RNA-sequencing was performed on a bone marrow sample from a patient with myelodysplastic syndrome (MDS). The karyotype was 46,XX,t(7;13)(p14;q12)[2]/46,XX[23]. The MDS later evolved into acute myeloid leukemia (AML) at which point the bone marrow cells also contained additional, secondary aberrations. The 7;13-translocation resulted in fusion of the gene PAN3 from 13q12 with PSMA2 from 7p14 to generate an out-of-frame PAN3–PSMA2 fusion transcript whose presence was verified by RT-PCR together with Sanger sequencing. Interphase fluorescence in situ hybridization analysis confirmed the existence of the chimeric gene. Conclusions The novel t(7;13)(p14;q12)/PAN3–PSMA2 in the neoplastic bone marrow cells could affect two key protein complex: (a) the PAN2/PAN3 complex (PAN3 rearrangement) which is responsible for deadenylation, the process of removing the poly(A) tail from RNA, and (b) the proteasome (PSMA2 rearrangement) which is responsible for degradation of intracellular proteins. The patient showed a favorable response to decitabine after treatment with 5-azacitidine and conventional intensive chemotherapy had failed. Whether this might represent a consistent feature of MDS/AML with this particular gene fusion, remains unknown.
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Affiliation(s)
- Ioannis Panagopoulos
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway
| | - Ludmila Gorunova
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway
| | - Hege Kilen Andersen
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway
| | - Astrid Bergrem
- 2Department of Haematology, Akershus University Hospital, Nordbyhagen, Norway
| | - Anders Dahm
- 2Department of Haematology, Akershus University Hospital, Nordbyhagen, Norway.,3Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Kristin Andersen
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway
| | - Francesca Micci
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway
| | - Sverre Heim
- 1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, PO Box 49534 Nydalen, 0424 Oslo, Norway.,3Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
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25
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Pseudo-DUBs as allosteric activators and molecular scaffolds of protein complexes. Biochem Soc Trans 2018; 46:453-466. [PMID: 29472364 DOI: 10.1042/bst20160268] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/10/2018] [Accepted: 01/13/2018] [Indexed: 12/17/2022]
Abstract
The ubiquitin (Ub) proteasome system and Ub signalling networks are crucial to cell biology and disease development. Deubiquitylases (DUBs) control cell signalling by removing mono-Ub and polyubiquitin chains from substrates. DUBs take part in almost all processes that regulate cellular life and are frequently dysregulated in disease. We have catalogued 99 currently known DUBs in the human genome and sequence conservation analyses of catalytic residues suggest that 11 lack enzyme activity and are classed as pseudo-DUBs. These pseudoenzymes play important biological roles by allosterically activating catalytically competent DUBs as well as other active enzymes. Additionally, pseudoenzymes act as assembly scaffolds of macromolecular complexes. We discuss how pseudo-DUBs have lost their catalytic activity, their diverse mechanisms of action and their potential as therapeutic targets. Many known pseudo-DUBs play crucial roles in cell biology and it is likely that unstudied and overlooked pseudo-DUB genes will have equally important functions.
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26
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Patel O, Griffin MDW, Panjikar S, Dai W, Ma X, Chan H, Zheng C, Kropp A, Murphy JM, Daly RJ, Lucet IS. Structure of SgK223 pseudokinase reveals novel mechanisms of homotypic and heterotypic association. Nat Commun 2017; 8:1157. [PMID: 29079850 PMCID: PMC5660093 DOI: 10.1038/s41467-017-01279-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 09/01/2017] [Indexed: 12/26/2022] Open
Abstract
The mammalian pseudokinase SgK223, and its structurally related homologue SgK269, are oncogenic scaffolds that nucleate the assembly of specific signalling complexes and regulate tyrosine kinase signalling. Both SgK223 and SgK269 form homo- and hetero-oligomers, a mechanism that underpins a diversity of signalling outputs. However, mechanistic insights into SgK223 and SgK269 homo- and heterotypic association are lacking. Here we present the crystal structure of SgK223 pseudokinase domain and its adjacent N- and C-terminal helices. The structure reveals how the N- and C-regulatory helices engage in a novel fold to mediate the assembly of a high-affinity dimer. In addition, we identified regulatory interfaces on the pseudokinase domain required for the self-assembly of large open-ended oligomers. This study highlights the diversity in how the kinase fold mediates non-catalytic functions and provides mechanistic insights into how the assembly of these two oncogenic scaffolds is achieved in order to regulate signalling output. Pseudokinases lack kinase activity, yet they impact cellular physiology through the regulation of bona fide signaling kinases. Here the authors describe the structure of the SgK223 pseudokinase and its adjacent domains, and identify regulatory interfaces required for self-assembly and downstream signaling.
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Affiliation(s)
- Onisha Patel
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - Michael D W Griffin
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Santosh Panjikar
- Australian Synchrotron, Clayton, VIC, 3168, Australia.,Department of Biochemistry and Molecular Biology, Level 1, Building 77, Monash University, Clayton, VIC, 3800, Australia
| | - Weiwen Dai
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Xiuquan Ma
- Department of Biochemistry and Molecular Biology, Level 1, Building 77, Monash University, Clayton, VIC, 3800, Australia.,Cancer Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Howard Chan
- Department of Biochemistry and Molecular Biology, Level 1, Building 77, Monash University, Clayton, VIC, 3800, Australia.,Cancer Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Celine Zheng
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Ashleigh Kropp
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - James M Murphy
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Roger J Daly
- Department of Biochemistry and Molecular Biology, Level 1, Building 77, Monash University, Clayton, VIC, 3800, Australia.,Cancer Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Isabelle S Lucet
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
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27
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Chen CYA, Zhang Y, Xiang Y, Han L, Chang JT, Shyu AB. Antagonistic actions of two human Pan3 isoforms on global mRNA turnover. RNA (NEW YORK, N.Y.) 2017; 23:1404-1418. [PMID: 28559491 PMCID: PMC5558910 DOI: 10.1261/rna.061556.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/25/2017] [Indexed: 05/03/2023]
Abstract
Deadenylation is a fundamental process that regulates eukaryotic gene expression. Mammalian deadenylation exhibits biphasic kinetics, with the Pan2-Pan3 and Ccr4-Caf1 deadenylase complexes mediating the first and second phase, respectively; however, the significance of the biphasic nature of deadenylation in mRNA turnover remains unclear. In this study, we discovered that two distinct isoforms of human Pan3 display opposing properties necessary for coordinating the two phases of deadenylation. The shorter isoform (Pan3S) interacts more strongly with PABP than the longer isoform (Pan3L) does. Pan2 deadenylase activity is enhanced by Pan3S but suppressed by Pan3L. Knocking down individual Pan3 isoforms has opposing effects on the global poly(A) tail length profile, P-body formation, and different mRNA decay pathways. Transcriptome-wide analysis of Pan3 knockdown effects on mRNA turnover shows that depleting either Pan3 isoform causes profound and extensive changes in mRNA stability globally. These results reveal a new fundamental step governing mammalian mRNA metabolism. We propose that the first phase of deadenylation, coordinated through the interplay among the two Pan3 isoforms, Pan2, and PABP, represents a cytoplasmic mRNA maturation step important for proper mRNA turnover.
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Affiliation(s)
- Chyi-Ying A Chen
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Yueqiang Zhang
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Yu Xiang
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Leng Han
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Jeffrey T Chang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
- School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Ann-Bin Shyu
- Department of Biochemistry and Molecular Biology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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28
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The secret life of kinases: insights into non-catalytic signalling functions from pseudokinases. Biochem Soc Trans 2017; 45:665-681. [PMID: 28620028 DOI: 10.1042/bst20160331] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 12/31/2022]
Abstract
Over the past decade, our understanding of the mechanisms by which pseudokinases, which comprise ∼10% of the human and mouse kinomes, mediate signal transduction has advanced rapidly with increasing structural, biochemical, cellular and genetic studies. Pseudokinases are the catalytically defective counterparts of conventional, active protein kinases and have been attributed functions as protein interaction domains acting variously as allosteric modulators of conventional protein kinases and other enzymes, as regulators of protein trafficking or localisation, as hubs to nucleate assembly of signalling complexes, and as transmembrane effectors of such functions. Here, by categorising mammalian pseudokinases based on their known functions, we illustrate the mechanistic diversity among these proteins, which can be viewed as a window into understanding the non-catalytic functions that can be exerted by conventional protein kinases.
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Murphy JM, Mace PD, Eyers PA. Live and let die: insights into pseudoenzyme mechanisms from structure. Curr Opin Struct Biol 2017; 47:95-104. [PMID: 28787627 DOI: 10.1016/j.sbi.2017.07.004] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/30/2017] [Accepted: 07/20/2017] [Indexed: 12/22/2022]
Abstract
Pseudoenzymes were first described more than 50 years ago, when it was recognised that a subset of proteins that are structurally homologous to active enzymes lack amino acids necessary for catalytic activity. Recently, interest in pseudoenzymes has surged as it has become apparent that they constitute ∼10% of proteomes and perform essential metabolic and signalling functions that can be experimentally distinguished from catalytic outputs of enzymes. Here, we highlight recent structural studies of pseudoenzymes, which have revealed the molecular basis for roles as allosteric regulators of conventional enzymes, as molecular switches and integrators, as hubs for assembling protein complexes, and as competitors of substrate availability and holoenzyme assembly. As structural studies continue to illuminate pseudoenzyme molecular mechanisms, we anticipate that our knowledge of the breadth of their biological functions will expand in parallel.
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Affiliation(s)
- James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia.
| | - Peter D Mace
- Biochemistry Department, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK.
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30
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Structural Foundations of RNA Silencing by Argonaute. J Mol Biol 2017; 429:2619-2639. [PMID: 28757069 DOI: 10.1016/j.jmb.2017.07.018] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 12/19/2022]
Abstract
Nearly every cell in the human body contains a set of programmable gene-silencing proteins named Argonaute. Argonaute proteins mediate gene regulation by small RNAs and thereby contribute to cellular homeostasis during diverse physiological process, such as stem cell maintenance, fertilization, and heart development. Over the last decade, remarkable progress has been made toward understanding Argonaute proteins, small RNAs, and their roles in eukaryotic biology. Here, we review current understanding of Argonaute proteins from a structural prospective and discuss unanswered questions surrounding this fascinating class of enzymes.
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Abstract
Poly(A) tails are found at the 3' end of almost every eukaryotic mRNA and are important for the stability of mRNAs and their translation into proteins. Thus, removal of the poly(A) tail, a process called deadenylation, is critical for regulation of gene expression. Most deadenylation enzymes are components of large multi-protein complexes. Here, we describe an in vitro deadenylation assay developed to study the exonucleolytic activities of the multi-protein Ccr4-Not and Pan2-Pan3 complexes. We discuss how this assay can be used with short synthetic RNAs, as well as longer RNA substrates generated using in vitro transcription. Importantly, quantitation of the reactions allows detailed analyses of deadenylation in the presence and absence of accessory factors, leading to new insights into targeted mRNA decay.
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32
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Łabno A, Tomecki R, Dziembowski A. Cytoplasmic RNA decay pathways - Enzymes and mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:3125-3147. [PMID: 27713097 DOI: 10.1016/j.bbamcr.2016.09.023] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 12/14/2022]
Abstract
RNA decay plays a crucial role in post-transcriptional regulation of gene expression. Work conducted over the last decades has defined the major mRNA decay pathways, as well as enzymes and their cofactors responsible for these processes. In contrast, our knowledge of the mechanisms of degradation of non-protein coding RNA species is more fragmentary. This review is focused on the cytoplasmic pathways of mRNA and ncRNA degradation in eukaryotes. The major 3' to 5' and 5' to 3' mRNA decay pathways are described with emphasis on the mechanisms of their activation by the deprotection of RNA ends. More recently discovered 3'-end modifications such as uridylation, and their relevance to cytoplasmic mRNA decay in various model organisms, are also discussed. Finally, we provide up-to-date findings concerning various pathways of non-coding RNA decay in the cytoplasm.
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Affiliation(s)
- Anna Łabno
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Rafał Tomecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland.
| | - Andrzej Dziembowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland.
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33
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Shin JJ, Aftab Q, Austin P, McQueen JA, Poon T, Li SC, Young BP, Roskelley CD, Loewen CJR. Systematic identification of genes involved in metabolic acid stress resistance in yeast and their potential as cancer targets. Dis Model Mech 2016; 9:1039-49. [PMID: 27519690 PMCID: PMC5047693 DOI: 10.1242/dmm.023374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 07/18/2016] [Indexed: 12/12/2022] Open
Abstract
A hallmark of all primary and metastatic tumours is their high rate of glucose uptake and glycolysis. A consequence of the glycolytic phenotype is the accumulation of metabolic acid; hence, tumour cells experience considerable intracellular acid stress. To compensate, tumour cells upregulate acid pumps, which expel the metabolic acid into the surrounding tumour environment, resulting in alkalization of intracellular pH and acidification of the tumour microenvironment. Nevertheless, we have only a limited understanding of the consequences of altered intracellular pH on cell physiology, or of the genes and pathways that respond to metabolic acid stress. We have used yeast as a genetic model for metabolic acid stress with the rationale that the metabolic changes that occur in cancer that lead to intracellular acid stress are likely fundamental. Using a quantitative systems biology approach we identified 129 genes required for optimal growth under conditions of metabolic acid stress. We identified six highly conserved protein complexes with functions related to oxidative phosphorylation (mitochondrial respiratory chain complex III and IV), mitochondrial tRNA biosynthesis [glutamyl-tRNA(Gln) amidotransferase complex], histone methylation (Set1C-COMPASS), lysosome biogenesis (AP-3 adapter complex), and mRNA processing and P-body formation (PAN complex). We tested roles for two of these, AP-3 adapter complex and PAN deadenylase complex, in resistance to acid stress using a myeloid leukaemia-derived human cell line that we determined to be acid stress resistant. Loss of either complex inhibited growth of Hap1 cells at neutral pH and caused sensitivity to acid stress, indicating that AP-3 and PAN complexes are promising new targets in the treatment of cancer. Additionally, our data suggests that tumours may be genetically sensitized to acid stress and hence susceptible to acid stress-directed therapies, as many tumours accumulate mutations in mitochondrial respiratory chain complexes required for their proliferation.
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Affiliation(s)
- John J Shin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Qurratulain Aftab
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Pamela Austin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Jennifer A McQueen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Tak Poon
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Shu Chen Li
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Barry P Young
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Calvin D Roskelley
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Christopher J R Loewen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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34
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Terwilliger TC, Bunkóczi G, Hung LW, Zwart PH, Smith JL, Akey DL, Adams PD. Can I solve my structure by SAD phasing? Anomalous signal in SAD phasing. Acta Crystallogr D Struct Biol 2016; 72:346-58. [PMID: 26960122 PMCID: PMC4784666 DOI: 10.1107/s2059798315019269] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 10/12/2015] [Indexed: 12/19/2022] Open
Abstract
A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. A simple theoretical framework for describing measurements of anomalous differences and the resulting useful anomalous correlation and anomalous signal in a SAD experiment is presented. Here, the useful anomalous correlation is defined as the correlation of anomalous differences with ideal anomalous differences from the anomalous substructure. The useful anomalous correlation reflects the accuracy of the data and the absence of minor sites. The useful anomalous correlation also reflects the information available for estimating crystallographic phases once the substructure has been determined. In contrast, the anomalous signal (the peak height in a model-phased anomalous difference Fourier at the coordinates of atoms in the anomalous substructure) reflects the information available about each site in the substructure and is related to the ability to find the substructure. A theoretical analysis shows that the expected value of the anomalous signal is the product of the useful anomalous correlation, the square root of the ratio of the number of unique reflections in the data set to the number of sites in the substructure, and a function that decreases with increasing values of the atomic displacement factor for the atoms in the substructure. This means that the ability to find the substructure in a SAD experiment is increased by high data quality and by a high ratio of reflections to sites in the substructure, and is decreased by high atomic displacement factors for the substructure.
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Affiliation(s)
- Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Mail Stop M888, Los Alamos, NM 87545, USA
| | - Gábor Bunkóczi
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge CB2 0XY, England
| | - Li-Wei Hung
- Physics Division, Los Alamos National Laboratory, Mail Stop D454, Los Alamos, NM 87545, USA
| | - Peter H. Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Janet L. Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - David L. Akey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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35
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Terwilliger TC, Bunkóczi G, Hung LW, Zwart PH, Smith JL, Akey DL, Adams PD. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal. Acta Crystallogr D Struct Biol 2016; 72:359-74. [PMID: 26960123 PMCID: PMC4784667 DOI: 10.1107/s2059798315019403] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 10/13/2015] [Indexed: 01/15/2023] Open
Abstract
A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment are described. A simple theoretical framework [Terwilliger et al. (2016), Acta Cryst. D72, 346-358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. The phenix.plan_sad_experiment tool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimate the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. The phenix.scale_and_merge tool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and the phenix.anomalous_signal tool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing.
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Affiliation(s)
- Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Mail Stop M888, Los Alamos, NM 87545, USA
| | - Gábor Bunkóczi
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge CB2 0XY, England
| | - Li-Wei Hung
- Physics Division, Los Alamos National Laboratory, Mail Stop D454, Los Alamos, NM 87545, USA
| | - Peter H. Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Janet L. Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - David L. Akey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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36
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Stupfler B, Birck C, Séraphin B, Mauxion F. BTG2 bridges PABPC1 RNA-binding domains and CAF1 deadenylase to control cell proliferation. Nat Commun 2016; 7:10811. [PMID: 26912148 PMCID: PMC4773420 DOI: 10.1038/ncomms10811] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 01/24/2016] [Indexed: 12/12/2022] Open
Abstract
While BTG2 plays an important role in cellular differentiation and cancer, its precise molecular function remains unclear. BTG2 interacts with CAF1 deadenylase through its APRO domain, a defining feature of BTG/Tob factors. Our previous experiments revealed that expression of BTG2 promoted mRNA poly(A) tail shortening through an undefined mechanism. Here we report that the APRO domain of BTG2 interacts directly with the first RRM domain of the poly(A)-binding protein PABPC1. Moreover, PABPC1 RRM and BTG2 APRO domains are sufficient to stimulate CAF1 deadenylase activity in vitro in the absence of other CCR4–NOT complex subunits. Our results unravel thus the mechanism by which BTG2 stimulates mRNA deadenylation, demonstrating its direct role in poly(A) tail length control. Importantly, we also show that the interaction of BTG2 with the first RRM domain of PABPC1 is required for BTG2 to control cell proliferation. BTG2 promotes mRNA poly(A) tail shortening and regulates cellular differentiation. Here, Stupfler et al. show that the BTG2 APRO domain interacts with PABPC1 RRM1, allowing the former to recruit and stimulate the poly(A) tail shortening activity of CAF1 deadenylase and to control cell proliferation.
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Affiliation(s)
- Benjamin Stupfler
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.,Centre National de la Recherche Scientifique UMR7104, 67404 Illkirch, France.,Institut National de la Santé et de la Recherche Médicale U964, 67404 Illkirch, France.,Université de Strasbourg, 67404 Illkirch, France
| | - Catherine Birck
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.,Centre National de la Recherche Scientifique UMR7104, 67404 Illkirch, France.,Institut National de la Santé et de la Recherche Médicale U964, 67404 Illkirch, France.,Université de Strasbourg, 67404 Illkirch, France
| | - Bertrand Séraphin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.,Centre National de la Recherche Scientifique UMR7104, 67404 Illkirch, France.,Institut National de la Santé et de la Recherche Médicale U964, 67404 Illkirch, France.,Université de Strasbourg, 67404 Illkirch, France
| | - Fabienne Mauxion
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.,Centre National de la Recherche Scientifique UMR7104, 67404 Illkirch, France.,Institut National de la Santé et de la Recherche Médicale U964, 67404 Illkirch, France.,Université de Strasbourg, 67404 Illkirch, France
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37
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Hammarén HM, Virtanen AT, Silvennoinen O. Nucleotide-binding mechanisms in pseudokinases. Biosci Rep 2015; 36:e00282. [PMID: 26589967 PMCID: PMC4718504 DOI: 10.1042/bsr20150226] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/11/2015] [Accepted: 11/20/2015] [Indexed: 01/01/2023] Open
Abstract
Pseudokinases are classified by the lack of one or several of the highly conserved motifs involved in nucleotide (nt) binding or catalytic activity of protein kinases (PKs). Pseudokinases represent ∼10% of the human kinome and they are found in all evolutionary classes of kinases. It has become evident that pseudokinases, which were initially considered somewhat peculiar dead kinases, are important components in several signalling cascades. Furthermore, several pseudokinases have been linked to human diseases, particularly cancer, which is raising interest for therapeutic approaches towards these proteins. The ATP-binding pocket is a well-established drug target and elucidation of the mechanism and properties of nt binding in pseudokinases is of significant interest and importance. Recent studies have demonstrated that members of the pseudokinase family are very diverse in structure as well as in their ability and mechanism to bind nts or perform phosphoryl transfer reactions. This diversity also precludes prediction of pseudokinase function, or the importance of nt binding for said function, based on primary sequence alone. Currently available data indicate that ∼40% of pseudokinases are able to bind nts, whereas only few are able to catalyse occasional phosphoryl transfer. Pseudokinases employ diverse mechanisms to bind nts, which usually occurs at low, but physiological, affinity. ATP binding serves often a structural role but in most cases the functional roles are not precisely known. In the present review, we discuss the various mechanisms that pseudokinases employ for nt binding and how this often low-affinity binding can be accurately analysed.
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Affiliation(s)
- Henrik M Hammarén
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland
| | - Anniina T Virtanen
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland
| | - Olli Silvennoinen
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland Clinical Hematology, Department of Internal Medicine, Tampere University Hospital, Medisiinarinkatu 3, FI-33520 Tampere, Finland
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38
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Iwakawa HO, Tomari Y. The Functions of MicroRNAs: mRNA Decay and Translational Repression. Trends Cell Biol 2015; 25:651-665. [PMID: 26437588 DOI: 10.1016/j.tcb.2015.07.011] [Citation(s) in RCA: 520] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 12/14/2022]
Abstract
MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs, which regulate complementary mRNAs by inducing translational repression and mRNA decay. Although this dual repression system seems to operate in both animals and plants, genetic and biochemical studies suggest that the mechanism underlying the miRNA-mediated silencing is different in the two kingdoms. Here, we review the recent progress in our understanding of how miRNAs mediate translational repression and mRNA decay, and discuss the contributions of the two silencing modes to the overall silencing effect in both kingdoms.
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Affiliation(s)
- Hiro-Oki Iwakawa
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yukihide Tomari
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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39
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Jonas S, Izaurralde E. Towards a molecular understanding of microRNA-mediated gene silencing. Nat Rev Genet 2015; 16:421-33. [PMID: 26077373 DOI: 10.1038/nrg3965] [Citation(s) in RCA: 1314] [Impact Index Per Article: 146.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
MicroRNAs (miRNAs) are a conserved class of small non-coding RNAs that assemble with Argonaute proteins into miRNA-induced silencing complexes (miRISCs) to direct post-transcriptional silencing of complementary mRNA targets. Silencing is accomplished through a combination of translational repression and mRNA destabilization, with the latter contributing to most of the steady-state repression in animal cell cultures. Degradation of the mRNA target is initiated by deadenylation, which is followed by decapping and 5'-to-3' exonucleolytic decay. Recent work has enhanced our understanding of the mechanisms of silencing, making it possible to describe in molecular terms a continuum of direct interactions from miRNA target recognition to mRNA deadenylation, decapping and 5'-to-3' degradation. Furthermore, an intricate interplay between translational repression and mRNA degradation is emerging.
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Affiliation(s)
- Stefanie Jonas
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany
| | - Elisa Izaurralde
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany
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40
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Croll TI. The rate of cis-trans conformation errors is increasing in low-resolution crystal structures. ACTA ACUST UNITED AC 2015; 71:706-9. [PMID: 25760617 DOI: 10.1107/s1399004715000826] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/15/2015] [Indexed: 11/10/2022]
Abstract
Cis-peptide bonds (with the exception of X-Pro) are exceedingly rare in native protein structures, yet a check for these is not currently included in the standard workflow for some common crystallography packages nor in the automated quality checks that are applied during submission to the Protein Data Bank. This appears to be leading to a growing rate of inclusion of spurious cis-peptide bonds in low-resolution structures both in absolute terms and as a fraction of solved residues. Most concerningly, it is possible for structures to contain very large numbers (>1%) of spurious cis-peptide bonds while still achieving excellent quality reports from MolProbity, leading to concerns that ignoring such errors is allowing software to overfit maps without producing telltale errors in, for example, the Ramachandran plot.
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Affiliation(s)
- Tristan Ian Croll
- Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, QLD 4059, Australia
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41
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Martin S, Coller J. PAN-orama: three convergent views of a eukaryotic deadenylase. Nat Struct Mol Biol 2014; 21:577-8. [PMID: 24992224 DOI: 10.1038/nsmb.2850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Sophie Martin
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland. Ohio, USA
| | - Jeff Coller
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland. Ohio, USA
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42
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Affiliation(s)
- Milton T Stubbs
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle, Halle, Germany
| | - Elmar Wahle
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle, Halle, Germany
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