1
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Ahammed KS, van Hoof A. Fungi of the order Mucorales express a "sealing-only" tRNA ligase. RNA (NEW YORK, N.Y.) 2024; 30:354-366. [PMID: 38307611 PMCID: PMC10946435 DOI: 10.1261/rna.079957.124] [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: 11/16/2023] [Accepted: 01/20/2024] [Indexed: 02/04/2024]
Abstract
Some eukaryotic pre-tRNAs contain an intron that is removed by a dedicated set of enzymes. Intron-containing pre-tRNAs are cleaved by tRNA splicing endonuclease, followed by ligation of the two exons and release of the intron. Fungi use a "heal and seal" pathway that requires three distinct catalytic domains of the tRNA ligase enzyme, Trl1. In contrast, humans use a "direct ligation" pathway carried out by RTCB, an enzyme completely unrelated to Trl1. Because of these mechanistic differences, Trl1 has been proposed as a promising drug target for fungal infections. To validate Trl1 as a broad-spectrum drug target, we show that fungi from three different phyla contain Trl1 orthologs with all three domains. This includes the major invasive human fungal pathogens, and these proteins can each functionally replace yeast Trl1. In contrast, species from the order Mucorales, including the pathogens Rhizopus arrhizus and Mucor circinelloides, have an atypical Trl1 that contains the sealing domain but lacks both healing domains. Although these species contain fewer tRNA introns than other pathogenic fungi, they still require splicing to decode three of the 61 sense codons. These sealing-only Trl1 orthologs can functionally complement defects in the corresponding domain of yeast Trl1 and use a conserved catalytic lysine residue. We conclude that Mucorales use a sealing-only enzyme together with unidentified nonorthologous healing enzymes for their heal and seal pathway. This implies that drugs that target the sealing activity are more likely to be broader-spectrum antifungals than drugs that target the healing domains.
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Affiliation(s)
- Khondakar Sayef Ahammed
- Department of Microbiology and Molecular Genetics, UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston, Texas 77030, USA
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2
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Ghosh S, Dantuluri S, Jacewicz A, Sanchez AM, Abdullahu L, Damha MJ, Schwer B, Shuman S. Characterization of tRNA splicing enzymes RNA ligase and tRNA 2'-phosphotransferase from the pathogenic fungi Mucorales. RNA (NEW YORK, N.Y.) 2024; 30:367-380. [PMID: 38238085 PMCID: PMC10946426 DOI: 10.1261/rna.079911.123] [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: 12/04/2023] [Accepted: 01/09/2024] [Indexed: 03/20/2024]
Abstract
Fungal Trl1 is an essential trifunctional tRNA splicing enzyme that heals and seals tRNA exons with 2',3'-cyclic-PO4 and 5'-OH ends. Trl1 is composed of C-terminal cyclic phosphodiesterase and central polynucleotide kinase end-healing domains that generate the 3'-OH,2'-PO4 and 5'-PO4 termini required for sealing by an N-terminal ATP-dependent ligase domain. Trl1 enzymes are present in many human fungal pathogens and are promising targets for antifungal drug discovery because their domain structures and biochemical mechanisms are unique compared to the mammalian RtcB-type tRNA splicing enzyme. Here we report that Mucorales species (deemed high-priority human pathogens by WHO) elaborate a noncanonical tRNA splicing apparatus in which a monofunctional RNA ligase enzyme is encoded separately from any end-healing enzymes. We show that Mucor circinelloides RNA ligase (MciRNL) is active in tRNA splicing in vivo in budding yeast in lieu of the Trl1 ligase domain. Biochemical and kinetic characterization of recombinant MciRNL underscores its requirement for a 2'-PO4 terminus in the end-joining reaction, whereby the 2'-PO4 enhances the rates of RNA 5'-adenylylation (step 2) and phosphodiester synthesis (step 3) by ∼125-fold and ∼6200-fold, respectively. In the canonical fungal tRNA splicing pathway, the splice junction 2'-PO4 installed by RNA ligase is removed by a dedicated NAD+-dependent RNA 2'-phosphotransferase Tpt1. Here we identify and affirm by genetic complementation in yeast the biological activity of Tpt1 orthologs from three Mucorales species. Recombinant M. circinelloides Tpt1 has vigorous NAD+-dependent RNA 2'-phosphotransferase activity in vitro.
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Affiliation(s)
- Shreya Ghosh
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Swathi Dantuluri
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Agata Jacewicz
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Ana M Sanchez
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York 10065, USA
| | - Leonora Abdullahu
- Department of Chemistry, McGill University, Montreal, Quebec H3A0B8, Canada
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Quebec H3A0B8, Canada
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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3
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Shuman S. RNA Repair: Hiding in Plain Sight. Annu Rev Genet 2023; 57:461-489. [PMID: 37722686 DOI: 10.1146/annurev-genet-071719-021856] [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] [Indexed: 09/20/2023]
Abstract
Enzymes that phosphorylate, dephosphorylate, and ligate RNA 5' and 3' ends were discovered more than half a century ago and were eventually shown to repair purposeful site-specific endonucleolytic breaks in the RNA phosphodiester backbone. The pace of discovery and characterization of new candidate RNA repair activities in taxa from all phylogenetic domains greatly exceeds our understanding of the biological pathways in which they act. The key questions anent RNA break repair in vivo are (a) identifying the triggers, agents, and targets of RNA cleavage and (b) determining whether RNA repair results in restoration of the original RNA, modification of the RNA (by loss or gain at the ends), or rearrangements of the broken RNA segments (i.e., RNA recombination). This review provides a perspective on the discovery, mechanisms, and physiology of purposeful RNA break repair, highlighting exemplary repair pathways (e.g., tRNA restriction-repair and tRNA splicing) for which genetics has figured prominently in their elucidation.
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Affiliation(s)
- Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA;
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4
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Ahammed KS, van Hoof A. Fungi of the order Mucorales express a "sealing-only" tRNA ligase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.16.567474. [PMID: 38014270 PMCID: PMC10680797 DOI: 10.1101/2023.11.16.567474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Some eukaryotic pre-tRNAs contain an intron that is removed by a dedicated set of enzymes. Intron-containing pre-tRNAs are cleaved by tRNA splicing endonuclease (TSEN), followed by ligation of the two exons and release of the intron. Fungi use a "heal and seal" pathway that requires three distinct catalytic domains of the tRNA ligase enzyme, Trl1. In contrast, humans use a "direct ligation" pathway carried out by RTCB, an enzyme completely unrelated to Trl1. Because of these mechanistic differences, Trl1 has been proposed as a promising drug target for fungal infections. To validate Trl1 as a broad-spectrum drug target, we show that fungi from three different phyla contain Trl1 orthologs with all three domains. This includes the major invasive human fungal pathogens, and these proteins each can functionally replace yeast Trl1. In contrast, species from the order Mucorales, including the pathogens Rhizopus arrhizus and Mucor circinelloides, contain an atypical Trl1 that contains the sealing domain, but lack both healing domains. Although these species contain fewer tRNA introns than other pathogenic fungi, they still require splicing to decode three of the 61 sense codons. These sealing-only Trl1 orthologs can functionally complement defects in the corresponding domain of yeast Trl1 and use a conserved catalytic lysine residue. We conclude that Mucorales use a sealing-only enzyme together with unidentified non-orthologous healing enzymes for their heal and seal pathway. This implies that drugs that target the sealing activity are more likely to be broader-spectrum antifungals than drugs that target the healing domains.
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Affiliation(s)
- Khondakar Sayef Ahammed
- Department of Microbiology and Molecular Genetics. UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences. University of Texas Health Science Center at Houston
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics. UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences. University of Texas Health Science Center at Houston
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5
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Saito M, Inose R, Sato A, Tomita M, Suzuki H, Kanai A. Systematic Analysis of Diverse Polynucleotide Kinase Clp1 Family Proteins in Eukaryotes: Three Unique Clp1 Proteins of Trypanosoma brucei. J Mol Evol 2023; 91:669-686. [PMID: 37606665 PMCID: PMC10598085 DOI: 10.1007/s00239-023-10128-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 08/01/2023] [Indexed: 08/23/2023]
Abstract
The Clp1 family proteins, consisting of the Clp1 and Nol9/Grc3 groups, have polynucleotide kinase (PNK) activity at the 5' end of RNA strands and are important enzymes in the processing of some precursor RNAs. However, it remains unclear how this enzyme family diversified in the eukaryotes. We performed a large-scale molecular evolutionary analysis of the full-length genomes of 358 eukaryotic species to classify the diverse Clp1 family proteins. The average number of Clp1 family proteins in eukaryotes was 2.3 ± 1.0, and most representative species had both Clp1 and Nol9/Grc3 proteins, suggesting that the Clp1 and Nol9/Grc3 groups were already formed in the eukaryotic ancestor by gene duplication. We also detected an average of 4.1 ± 0.4 Clp1 family proteins in members of the protist phylum Euglenozoa. For example, in Trypanosoma brucei, there are three genes of the Clp1 group and one gene of the Nol9/Grc3 group. In the Clp1 group proteins encoded by these three genes, the C-terminal domains have been replaced by unique characteristics domains, so we designated these proteins Tb-Clp1-t1, Tb-Clp1-t2, and Tb-Clp1-t3. Experimental validation showed that only Tb-Clp1-t2 has PNK activity against RNA strands. As in this example, N-terminal and C-terminal domain replacement also contributed to the diversification of the Clp1 family proteins in other eukaryotic species. Our analysis also revealed that the Clp1 family proteins in humans and plants diversified through isoforms created by alternative splicing.
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Affiliation(s)
- Motofumi Saito
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-0882, Japan
| | - Rerina Inose
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
| | - Asako Sato
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
| | - Masaru Tomita
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-0882, Japan
- Faculty of Environment and Information Studies, Keio University, Fujisawa, 252-0882, Japan
| | - Haruo Suzuki
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan
- Faculty of Environment and Information Studies, Keio University, Fujisawa, 252-0882, Japan
| | - Akio Kanai
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0017, Japan.
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-0882, Japan.
- Faculty of Environment and Information Studies, Keio University, Fujisawa, 252-0882, Japan.
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6
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Gerber JL, Köhler S, Peschek J. Eukaryotic tRNA splicing - one goal, two strategies, many players. Biol Chem 2022; 403:765-778. [PMID: 35621519 DOI: 10.1515/hsz-2021-0402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 05/10/2022] [Indexed: 12/28/2022]
Abstract
Transfer RNAs (tRNAs) are transcribed as precursor molecules that undergo several maturation steps before becoming functional for protein synthesis. One such processing mechanism is the enzyme-catalysed splicing of intron-containing pre-tRNAs. Eukaryotic tRNA splicing is an essential process since intron-containing tRNAs cannot fulfil their canonical function at the ribosome. Splicing of pre-tRNAs occurs in two steps: The introns are first excised by a tRNA-splicing endonuclease and the exons are subsequently sealed by an RNA ligase. An intriguing complexity has emerged from newly identified tRNA splicing factors and their interplay with other RNA processing pathways during the past few years. This review summarises our current understanding of eukaryotic tRNA splicing and the underlying enzyme machinery. We highlight recent structural advances and how they have shaped our mechanistic understanding of tRNA splicing in eukaryotic cells. A special focus lies on biochemically distinct strategies for exon-exon ligation in fungi versus metazoans.
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Affiliation(s)
- Janina L Gerber
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany
| | - Sandra Köhler
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany
| | - Jirka Peschek
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany
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7
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Syed Abuthakir MH, Sharmila V, Jeyam M. Screening Balanites aegyptiaca for inhibitors against putative drug targets in Microsporum gypseum - Subtractive proteome, docking and simulation approach. INFECTION GENETICS AND EVOLUTION 2021; 90:104755. [PMID: 33549764 DOI: 10.1016/j.meegid.2021.104755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/31/2020] [Accepted: 01/31/2021] [Indexed: 02/07/2023]
Abstract
Microsporum gypseum is a keratinophilic fungi grouped under dermatophytes infecting skin, hair and nail portions in human and animals causing tinea corporis, tinea facei and tinea capitis. As both human and fungi are eukaryotes, the available drugs for treating dermatophytes produce some side effects due to drug interaction with human also. Apart from this, the gut microbiota has a very big role in the health of human which should not be affected by the drugs. Hence this study focused on finding a target which is unique and essential to M. gypseum and non-homologous to human and gut microbiota, non-homologous to human domain architecture, highly interacting with other proteins, sub-cellular localization of proteins and non-druggability analysis of the targets using subtractive proteomics approach which resulted with 3 novel drug targets from M. gypseum which were modeled using I-TASSER, refined by ModRefiner and validated by PROCHECK. Further these targets were docked with compounds identified through LC-MS of fractioned methanol extract of B. aegyptiaca fruit pulp using Glide module and the stability of the docked complex was analyzed by molecular dynamics simulation using Desmond module of Schrodinger. Cyanidin-3-O-rhamnoside had better interaction with all the targets and Taurocholic acid had better result with ECCP which suggests the multi-targeting potency of these two compounds against M. gypseum which has to be confirmed by in vitro and in vivo studies.
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Affiliation(s)
| | - Velusamy Sharmila
- Biochematics Lab, Department of Bioinformatics, Bharathiar University, Coimbatore., India
| | - Muthusamy Jeyam
- Biochematics Lab, Department of Bioinformatics, Bharathiar University, Coimbatore., India.
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8
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Unciuleac MC, Goldgur Y, Shuman S. Caveat mutator: alanine substitutions for conserved amino acids in RNA ligase elicit unexpected rearrangements of the active site for lysine adenylylation. Nucleic Acids Res 2020; 48:5603-5615. [PMID: 32315072 PMCID: PMC7261155 DOI: 10.1093/nar/gkaa238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/28/2020] [Accepted: 04/01/2020] [Indexed: 11/25/2022] Open
Abstract
Naegleria gruberi RNA ligase (NgrRnl) exemplifies the Rnl5 family of adenosine triphosphate (ATP)-dependent polynucleotide ligases that seal 3′-OH RNA strands in the context of 3′-OH/5′-PO4 nicked duplexes. Like all classic ligases, NgrRnl forms a covalent lysyl–AMP intermediate. A two-metal mechanism of lysine adenylylation was established via a crystal structure of the NgrRnl•ATP•(Mn2+)2 Michaelis complex. Here we conducted an alanine scan of active site constituents that engage the ATP phosphates and the metal cofactors. We then determined crystal structures of ligase-defective NgrRnl-Ala mutants in complexes with ATP/Mn2+. The unexpected findings were that mutations K170A, E227A, K326A and R149A (none of which impacted overall enzyme structure) triggered adverse secondary changes in the active site entailing dislocations of the ATP phosphates, altered contacts to ATP, and variations in the numbers and positions of the metal ions that perverted the active sites into off-pathway states incompatible with lysine adenylylation. Each alanine mutation elicited a distinctive off-pathway distortion of the ligase active site. Our results illuminate a surprising plasticity of the ligase active site in its interactions with ATP and metals. More broadly, they underscore a valuable caveat when interpreting mutational data in the course of enzyme structure-function studies.
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Affiliation(s)
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
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9
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Banerjee A, Goldgur Y, Schwer B, Shuman S. Atomic structures of the RNA end-healing 5'-OH kinase and 2',3'-cyclic phosphodiesterase domains of fungal tRNA ligase: conformational switches in the kinase upon binding of the GTP phosphate donor. Nucleic Acids Res 2020; 47:11826-11838. [PMID: 31722405 PMCID: PMC7145591 DOI: 10.1093/nar/gkz1049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/16/2019] [Accepted: 11/07/2019] [Indexed: 01/17/2023] Open
Abstract
Fungal tRNA ligase (Trl1) rectifies RNA breaks with 2′,3′-cyclic-PO4 and 5′-OH termini. Trl1 consists of three catalytic modules: an N-terminal ligase (LIG) domain; a central polynucleotide kinase (KIN) domain; and a C-terminal cyclic phosphodiesterase (CPD) domain. Trl1 enzymes found in all human fungal pathogens are untapped targets for antifungal drug discovery. Here we report a 1.9 Å crystal structure of Trl1 KIN-CPD from the pathogenic fungus Candida albicans, which adopts an extended conformation in which separate KIN and CPD domains are connected by an unstructured linker. CPD belongs to the 2H phosphotransferase superfamily by dint of its conserved central concave β sheet and interactions of its dual HxT motif histidines and threonines with phosphate in the active site. Additional active site motifs conserved among the fungal CPD clade of 2H enzymes are identified. We present structures of the Candida Trl1 KIN domain at 1.5 to 2.0 Å resolution—as apoenzyme and in complexes with GTP•Mg2+, IDP•PO4, and dGDP•PO4—that highlight conformational switches in the G-loop (which recognizes the guanine base) and lid-loop (poised over the nucleotide phosphates) that accompany nucleotide binding.
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Affiliation(s)
- Ankan Banerjee
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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10
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Yin Y, Frank D, Zhou W, Kaur N, French JB, Carpino N. An unexpected 2-histidine phosphoesterase activity of suppressor of T-cell receptor signaling protein 1 contributes to the suppression of cell signaling. J Biol Chem 2020; 295:8514-8523. [PMID: 32371395 DOI: 10.1074/jbc.ra120.013482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/30/2020] [Indexed: 11/06/2022] Open
Abstract
The suppressor of T-cell receptor (TCR) signaling (Sts) proteins Sts-1 and Sts-2 suppress receptor-mediated signaling pathways in various immune cells, including the TCR pathway in T cells and the Dectin-1 signaling pathway in phagocytes. As multidomain enzymes, they contain an N-terminal ubiquitin-association domain, a central Src homology 3 domain, and a C-terminal histidine phosphatase domain. Recently, a 2-histidine (2H) phosphoesterase motif was identified within the N-terminal portion of Sts. The 2H phosphoesterase motif defines an evolutionarily ancient protein domain present in several enzymes that hydrolyze cyclic phosphate bonds on different substrates, including cyclic nucleotides. It is characterized by two invariant histidine residues that play a critical role in catalytic activity. Consistent with its assignment as a phosphoesterase, we demonstrate here that the Sts-1 2H phosphoesterase domain displays catalytic, saturable phosphodiesterase activity toward the dinucleotide 2',3'-cyclic NADP. The enzyme exhibited a high degree of substrate specificity and selectively generated the 3'-nucleotide as the sole product. Sts-1 also had phosphodiesterase catalytic activity toward a 5-mer RNA oligonucleotide containing a 2',3'-cyclic phosphate group at its 3' terminus. To investigate the functional significance of Sts-1 2H phosphoesterase activity, we generated His-to-Ala variants and examined their ability to negatively regulate cellular signaling pathways. Substitution of either conserved histidine compromised the ability of Sts-1 to suppress signaling pathways downstream of both the TCR and the Dectin-1 receptor. Our results identify a heretofore unknown cellular enzyme activity associated with Sts-1 and indicate that this catalytic activity is linked to specific cell-signaling outcomes.
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Affiliation(s)
- Yue Yin
- Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - David Frank
- Department of Microbiology and Immunology, Stony Brook University Medical Center, Stony Brook, New York, USA
| | - Weijie Zhou
- Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - Neena Kaur
- Department of Microbiology and Immunology, Stony Brook University Medical Center, Stony Brook, New York, USA
| | - Jarrod B French
- Department of Chemistry, Stony Brook University, Stony Brook, New York, USA .,Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA
| | - Nick Carpino
- Department of Microbiology and Immunology, Stony Brook University Medical Center, Stony Brook, New York, USA
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11
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Saito M, Sato A, Nagata S, Tamaki S, Tomita M, Suzuki H, Kanai A. Large-Scale Molecular Evolutionary Analysis Uncovers a Variety of Polynucleotide Kinase Clp1 Family Proteins in the Three Domains of Life. Genome Biol Evol 2020; 11:2713-2726. [PMID: 31513263 PMCID: PMC6777427 DOI: 10.1093/gbe/evz195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 01/13/2023] Open
Abstract
Clp1, a polyribonucleotide 5′-hydroxyl kinase in eukaryotes, is involved in pretRNA splicing and mRNA 3′-end formation. Enzymes similar in amino acid sequence to Clp1, Nol9, and Grc3, are present in some eukaryotes and are involved in prerRNA processing. However, our knowledge of how these Clp1 family proteins evolved and diversified is limited. We conducted a large-scale molecular evolutionary analysis of the Clp1 family proteins in all living organisms for which protein sequences are available in public databases. The phylogenetic distribution and frequencies of the Clp1 family proteins were investigated in complete genomes of Bacteria, Archaea and Eukarya. In total, 3,557 Clp1 family proteins were detected in the three domains of life, Bacteria, Archaea, and Eukarya. Many were from Archaea and Eukarya, but a few were found in restricted, phylogenetically diverse bacterial species. The domain structures of the Clp1 family proteins also differed among the three domains of life. Although the proteins were, on average, 555 amino acids long (range, 196–2,728), 122 large proteins with >1,000 amino acids were detected in eukaryotes. These novel proteins contain the conserved Clp1 polynucleotide kinase domain and various other functional domains. Of these proteins, >80% were from Fungi or Protostomia. The polyribonucleotide kinase activity of Thermus scotoductus Clp1 (Ts-Clp1) was characterized experimentally. Ts-Clp1 preferentially phosphorylates single-stranded RNA oligonucleotides (Km value for ATP, 2.5 µM), or single-stranded DNA at higher enzyme concentrations. We propose a comprehensive assessment of the diversification of the Clp1 family proteins and the molecular evolution of their functional domains.
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Affiliation(s)
- Motofumi Saito
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Asako Sato
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
| | - Shohei Nagata
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Satoshi Tamaki
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
| | - Masaru Tomita
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan.,Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
| | - Haruo Suzuki
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan.,Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
| | - Akio Kanai
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan.,Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
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12
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Banerjee A, Ghosh S, Goldgur Y, Shuman S. Structure and two-metal mechanism of fungal tRNA ligase. Nucleic Acids Res 2019; 47:1428-1439. [PMID: 30590734 PMCID: PMC6379707 DOI: 10.1093/nar/gky1275] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/10/2018] [Accepted: 12/11/2018] [Indexed: 02/06/2023] Open
Abstract
Fungal tRNA ligase (Trl1) is an essential enzyme that repairs RNA breaks with 2′,3′-cyclic-PO4 and 5′-OH ends inflicted during tRNA splicing and non-canonical mRNA splicing in the fungal unfolded protein response. Trl1 is composed of C-terminal cyclic phosphodiesterase (CPD) and central GTP-dependent polynucleotide kinase (KIN) domains that heal the broken ends to generate the 3′-OH,2′-PO4 and 5′-PO4 termini required for sealing by an N-terminal ATP-dependent ligase domain (LIG). Here we report crystal structures of the Trl1-LIG domain from Chaetomium thermophilum at two discrete steps along the reaction pathway: the covalent LIG-(lysyl-Nζ)–AMP•Mn2+ intermediate and a LIG•ATP•(Mn2+)2 Michaelis complex. The structures highlight a two-metal mechanism whereby a penta-hydrated metal complex stabilizes the transition state of the ATP α phosphate and a second metal bridges the β and γ phosphates to help orient the pyrophosphate leaving group. A LIG-bound sulfate anion is a plausible mimetic of the essential RNA terminal 2′-PO4. Trl1-LIG has a distinctive C-terminal domain that instates fungal Trl1 as the founder of an Rnl6 clade of ATP-dependent RNA ligase. We discuss how the Trl1-LIG structure rationalizes the large body of in vivo structure–function data for Saccharomyces cerevisiae Trl1.
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Affiliation(s)
- Ankan Banerjee
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Shreya Ghosh
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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Peschek J, Walter P. tRNA ligase structure reveals kinetic competition between non-conventional mRNA splicing and mRNA decay. eLife 2019; 8:44199. [PMID: 31237564 PMCID: PMC6592678 DOI: 10.7554/elife.44199] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 06/11/2019] [Indexed: 01/11/2023] Open
Abstract
Yeast tRNA ligase (Trl1) is an essential trifunctional enzyme that catalyzes exon-exon ligation during tRNA biogenesis and the non-conventional splicing of HAC1 mRNA during the unfolded protein response (UPR). The UPR regulates the protein folding capacity of the endoplasmic reticulum (ER). ER stress activates Ire1, an ER-resident kinase/RNase, which excises an intron from HAC1 mRNA followed by exon-exon ligation by Trl1. The spliced product encodes for a potent transcription factor that drives the UPR. Here we report the crystal structure of Trl1 RNA ligase domain from Chaetomium thermophilum at 1.9 Å resolution. Structure-based mutational analyses uncovered kinetic competition between RNA ligation and degradation during HAC1 mRNA splicing. Incompletely processed HAC1 mRNA is degraded by Xrn1 and the Ski/exosome complex. We establish cleaved HAC1 mRNA as endogenous substrate for ribosome-associated quality control. We conclude that mRNA decay and surveillance mechanisms collaborate in achieving fidelity of non-conventional mRNA splicing during the UPR.
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Affiliation(s)
- Jirka Peschek
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Peter Walter
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
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14
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Hopper AK, Nostramo RT. tRNA Processing and Subcellular Trafficking Proteins Multitask in Pathways for Other RNAs. Front Genet 2019; 10:96. [PMID: 30842788 PMCID: PMC6391926 DOI: 10.3389/fgene.2019.00096] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/29/2019] [Indexed: 01/28/2023] Open
Abstract
This article focuses upon gene products that are involved in tRNA biology, with particular emphasis upon post-transcriptional RNA processing and nuclear-cytoplasmic subcellular trafficking. Rather than analyzing these proteins solely from a tRNA perspective, we explore the many overlapping functions of the processing enzymes and proteins involved in subcellular traffic. Remarkably, there are numerous examples of conserved gene products and RNP complexes involved in tRNA biology that multitask in a similar fashion in the production and/or subcellular trafficking of other RNAs, including small structured RNAs such as snRNA, snoRNA, 5S RNA, telomerase RNA, and SRP RNA as well as larger unstructured RNAs such as mRNAs and RNA-protein complexes such as ribosomes. Here, we provide examples of steps in tRNA biology that are shared with other RNAs including those catalyzed by enzymes functioning in 5' end-processing, pseudoU nucleoside modification, and intron splicing as well as steps regulated by proteins functioning in subcellular trafficking. Such multitasking highlights the clever mechanisms cells employ for maximizing their genomes.
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Affiliation(s)
- Anita K Hopper
- Department of Molecular Genetics, Center for RNA Biology, Ohio State University, Columbus, OH, United States
| | - Regina T Nostramo
- Department of Molecular Genetics, Center for RNA Biology, Ohio State University, Columbus, OH, United States
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15
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Remus BS, Goldgur Y, Shuman S. Structural basis for the GTP specificity of the RNA kinase domain of fungal tRNA ligase. Nucleic Acids Res 2018; 45:12945-12953. [PMID: 29165709 PMCID: PMC5728400 DOI: 10.1093/nar/gkx1159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 11/04/2017] [Indexed: 01/10/2023] Open
Abstract
Fungal tRNA ligase (Trl1) is an essential enzyme that repairs RNA breaks with 2′,3′-cyclic-PO4 and 5′-OH ends inflicted during tRNA splicing and non-canonical mRNA splicing in the fungal unfolded protein response. Trl1 is composed of C-terminal cyclic phosphodiesterase and central polynucleotide kinase domains that heal the broken ends to generate the 3′-OH,2′-PO4 and 5′-PO4 termini required for sealing by an N-terminal ligase domain. Trl1 enzymes are found in all human fungal pathogens and are promising targets for antifungal drug discovery because their domain compositions and biochemical mechanisms are unique compared to the mammalian RtcB-type tRNA splicing enzyme. A distinctive feature of Trl1 is its preferential use of GTP as phosphate donor for the RNA kinase reaction. Here we report the 2.2 Å crystal structure of the kinase domain of Trl1 from the fungal pathogen Candida albicans with GDP and Mg2+ in the active site. The P-loop phosphotransferase fold of the kinase is embellished by a unique ‘G-loop’ element that accounts for guanine nucleotide specificity. Mutations of amino acids that contact the guanine nucleobase efface kinase activity in vitro and Trl1 function in vivo. Our findings fortify the case for the Trl1 kinase as an antifungal target.
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Affiliation(s)
- Barbara S Remus
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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16
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Muruganandam G, Raasakka A, Myllykoski M, Kursula I, Kursula P. Structural similarities and functional differences clarify evolutionary relationships between tRNA healing enzymes and the myelin enzyme CNPase. BMC BIOCHEMISTRY 2017; 18:7. [PMID: 28511668 PMCID: PMC5434554 DOI: 10.1186/s12858-017-0084-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 05/10/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Eukaryotic tRNA splicing is an essential process in the transformation of a primary tRNA transcript into a mature functional tRNA molecule. 5'-phosphate ligation involves two steps: a healing reaction catalyzed by polynucleotide kinase (PNK) in association with cyclic phosphodiesterase (CPDase), and a sealing reaction catalyzed by an RNA ligase. The enzymes that catalyze tRNA healing in yeast and higher eukaryotes are homologous to the members of the 2H phosphoesterase superfamily, in particular to the vertebrate myelin enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase). RESULTS We employed different biophysical and biochemical methods to elucidate the overall structural and functional features of the tRNA healing enzymes yeast Trl1 PNK/CPDase and lancelet PNK/CPDase and compared them with vertebrate CNPase. The yeast and the lancelet enzymes have cyclic phosphodiesterase and polynucleotide kinase activity, while vertebrate CNPase lacks PNK activity. In addition, we also show that the healing enzymes are structurally similar to the vertebrate CNPase by applying synchrotron radiation circular dichroism spectroscopy and small-angle X-ray scattering. CONCLUSIONS We provide a structural analysis of the tRNA healing enzyme PNK and CPDase domains together. Our results support evolution of vertebrate CNPase from tRNA healing enzymes with a loss of function at its N-terminal PNK-like domain.
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Affiliation(s)
- Gopinath Muruganandam
- Centre for Structural Systems Biology - Helmholtz Centre for Infection Research, German Electron Synchrotron (DESY), Hamburg, Germany
| | - Arne Raasakka
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Matti Myllykoski
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Inari Kursula
- Centre for Structural Systems Biology - Helmholtz Centre for Infection Research, German Electron Synchrotron (DESY), Hamburg, Germany
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Petri Kursula
- Centre for Structural Systems Biology - Helmholtz Centre for Infection Research, German Electron Synchrotron (DESY), Hamburg, Germany
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
- Department of Biomedicine, University of Bergen, Bergen, Norway
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17
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Kumar S, Arumugam N, Permaul K, Singh S. Chapter 5 Thermostable Enzymes and Their Industrial Applications. Microb Biotechnol 2016. [DOI: 10.1201/9781315367880-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
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18
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Remus BS, Schwer B, Shuman S. Characterization of the tRNA ligases of pathogenic fungi Aspergillus fumigatus and Coccidioides immitis. RNA (NEW YORK, N.Y.) 2016; 22:1500-9. [PMID: 27492257 PMCID: PMC5029449 DOI: 10.1261/rna.057455.116] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/30/2016] [Indexed: 05/06/2023]
Abstract
Yeast tRNA ligase (Trl1) is an essential trifunctional enzyme that repairs RNA breaks with 2',3'-cyclic-PO4 and 5'-OH ends. Trl1 is composed of C-terminal cyclic phosphodiesterase and central polynucleotide kinase domains that heal the broken ends to generate the 3'-OH, 2'-PO4, and 5'-PO4 termini required for sealing by an N-terminal ligase domain. Trl1 enzymes are found in all human fungal pathogens and they are promising targets for antifungal drug discovery because: (i) their domain structures and biochemical mechanisms are unique compared to the mammalian RtcB-type tRNA splicing enzyme; and (ii) there are no obvious homologs of the Trl1 ligase domain in mammalian proteomes. Here we characterize the tRNA ligases of two human fungal pathogens: Coccidioides immitis and Aspergillus fumigatus The biological activity of CimTrl1 and AfuTrl1 was verified by showing that their expression complements a Saccharomyces cerevisiae trl1Δ mutant. Purified recombinant AfuTrl1 and CimTrl1 proteins were catalytically active in joining 2',3'-cyclic-PO4 and 5'-OH ends in vitro, either as full-length proteins or as a mixture of separately produced healing and sealing domains. The biochemical properties of CimTrl1 and AfuTrl1 are similar to those of budding yeast Trl1, particularly with respect to their preferential use of GTP as the phosphate donor for the polynucleotide kinase reaction. Our findings provide genetic and biochemical tools to screen for inhibitors of tRNA ligases from pathogenic fungi.
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Affiliation(s)
- Barbara S Remus
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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19
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Lopes RRS, Silveira GDO, Eitler R, Vidal RS, Kessler A, Hinger S, Paris Z, Alfonzo JD, Polycarpo C. The essential function of the Trypanosoma brucei Trl1 homolog in procyclic cells is maturation of the intron-containing tRNATyr. RNA (NEW YORK, N.Y.) 2016; 22:1190-9. [PMID: 27284166 PMCID: PMC4931112 DOI: 10.1261/rna.056242.116] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/20/2016] [Indexed: 05/27/2023]
Abstract
Trypanosoma brucei, the etiologic agent of sleeping sickness, encodes a single intron-containing tRNA, tRNA(Tyr), and splicing is essential for its viability. In Archaea and Eukarya, tRNA splicing requires a series of enzymatic steps that begin with intron cleavage by a tRNA-splicing endonuclease and culminates with joining the resulting tRNA exons by a splicing tRNA ligase. Here we explored the function of TbTrl1, the T. brucei homolog of the yeast Trl1 tRNA ligase. We used a combination of RNA interference and molecular biology approaches to show that down-regulation of TbTrl1 expression leads to accumulation of intron-containing tRNA(Tyr) and a concomitant growth arrest at the G1 phase. These defects were efficiently rescued by expression of an "intronless" version of tRNA(Tyr) in the same RNAi cell line. Taken together, these experiments highlight the crucial importance of the TbTrl1 for tRNA(Tyr) maturation and viability, while revealing tRNA splicing as its only essential function.
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Affiliation(s)
- Raphael R S Lopes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Caixa Postal 68041, Brazil Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Caixa Postal 68041, Brazil
| | - Gilbert de O Silveira
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Caixa Postal 68041, Brazil Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Caixa Postal 68041, Brazil
| | - Roberta Eitler
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Caixa Postal 68041, Brazil
| | - Raphael S Vidal
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Caixa Postal 68041, Brazil
| | - Alan Kessler
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Scott Hinger
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Zdeněk Paris
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, 37005 České Budějovice (Budweis), Czech Republic
| | - Juan D Alfonzo
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Carla Polycarpo
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Caixa Postal 68041, Brazil Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Caixa Postal 68041, Brazil
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20
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From Structure-Function Analyses to Protein Engineering for Practical Applications of DNA Ligase. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2015; 2015:267570. [PMID: 26508902 PMCID: PMC4609770 DOI: 10.1155/2015/267570] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/18/2015] [Indexed: 01/03/2023]
Abstract
DNA ligases are indispensable in all living cells and ubiquitous in all organs. DNA ligases are broadly utilized in molecular biology research fields, such as genetic engineering and DNA sequencing technologies. Here we review the utilization of DNA ligases in a variety of in vitro gene manipulations, developed over the past several decades. During this period, fewer protein engineering attempts for DNA ligases have been made, as compared to those for DNA polymerases. We summarize the recent progress in the elucidation of the DNA ligation mechanisms obtained from the tertiary structures solved thus far, in each step of the ligation reaction scheme. We also present some examples of engineered DNA ligases, developed from the viewpoint of their three-dimensional structures.
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21
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Archaeal Nucleic Acid Ligases and Their Potential in Biotechnology. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2015; 2015:170571. [PMID: 26494982 PMCID: PMC4606414 DOI: 10.1155/2015/170571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/18/2015] [Indexed: 12/23/2022]
Abstract
With their ability to catalyse the formation of phosphodiester linkages, DNA ligases and RNA ligases are essential tools for many protocols in molecular biology and biotechnology. Currently, the nucleic acid ligases from bacteriophage T4 are used extensively in these protocols. In this review, we argue that the nucleic acid ligases from Archaea represent a largely untapped pool of enzymes with diverse and potentially favourable properties for new and emerging biotechnological applications. We summarise the current state of knowledge on archaeal DNA and RNA ligases, which makes apparent the relative scarcity of information on in vitro activities that are of most relevance to biotechnologists (such as the ability to join blunt- or cohesive-ended, double-stranded DNA fragments). We highlight the existing biotechnological applications of archaeal DNA ligases and RNA ligases. Finally, we draw attention to recent experiments in which protein engineering was used to modify the activities of the DNA ligase from Pyrococcus furiosus and the RNA ligase from Methanothermobacter thermautotrophicus, thus demonstrating the potential for further work in this area.
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22
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Myllykoski M, Seidel L, Muruganandam G, Raasakka A, Torda AE, Kursula P. Structural and functional evolution of 2',3'-cyclic nucleotide 3'-phosphodiesterase. Brain Res 2015; 1641:64-78. [PMID: 26367445 DOI: 10.1016/j.brainres.2015.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/02/2015] [Accepted: 09/03/2015] [Indexed: 02/06/2023]
Abstract
2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is an abundant membrane-associated enzyme within the vertebrate myelin sheath. While the physiological function of CNPase still remains to be characterized in detail, it is known - in addition to its in vitro enzymatic activity - to interact with other proteins, small molecules, and membrane surfaces. From an evolutionary point of view, it can be deduced that CNPase is not restricted to myelin-forming cells or vertebrate tissues. Its evolution has involved gene fusion, addition of other small segments with distinct functions, such as membrane attachment, and possibly loss of function at the polynucleotide kinase-like domain. Currently, it is unclear whether the enzymatic function of the conserved phosphodiesterase domain in vertebrate myelin has a physiological role, or if CNPase could actually function - like many other classical myelin proteins - in a more structural role. This article is part of a Special Issue entitled SI: Myelin Evolution.
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Affiliation(s)
- Matti Myllykoski
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Leonie Seidel
- Centre for Bioinformatics, University of Hamburg, Bundesstraße 43, 20146 Hamburg, Germany
| | | | - Arne Raasakka
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Aapistie 7, 90220 Oulu, Finland; Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
| | - Andrew E Torda
- Centre for Bioinformatics, University of Hamburg, Bundesstraße 43, 20146 Hamburg, Germany
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Aapistie 7, 90220 Oulu, Finland; German Electron Synchrotron, Notkestraße 85, 22607 Hamburg, Germany; Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway.
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23
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Unciuleac MC, Shuman S. Characterization of a novel eukaryal nick-sealing RNA ligase from Naegleria gruberi. RNA (NEW YORK, N.Y.) 2015; 21:824-832. [PMID: 25740837 PMCID: PMC4408790 DOI: 10.1261/rna.049197.114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/07/2015] [Indexed: 06/04/2023]
Abstract
The proteome of the amoebo-flagellate protozoan Naegleria gruberi is rich in candidate RNA repair enzymes, including 15 putative RNA ligases, one of which, NgrRnl, is a eukaryal homolog of Deinococcus radiodurans RNA ligase, DraRnl. Here we report that purified recombinant NgrRnl seals nicked 3'-OH/5'-PO4 duplexes in which the 3'-OH strand is RNA. It does so via the "classic" ligase pathway, entailing reaction with ATP to form a covalent NgrRnl-AMP intermediate, transfer of AMP to the nick 5'-PO4, and attack of the RNA 3'-OH on the adenylylated nick to form a 3'-5' phosphodiester. Unlike members of the four known families of ATP-dependent RNA ligases, NgrRnl lacks a carboxy-terminal appendage to its nucleotidyltransferase domain. Instead, it contains a defining amino-terminal domain that we show is important for 3'-OH/5'-PO4 nick-sealing and ligase adenylylation, but dispensable for phosphodiester synthesis at a preadenylylated nick. We propose that NgrRnl, DraRnl, and their homologs from diverse bacteria, viruses, and unicellular eukarya comprise a new "Rnl5 family" of nick-sealing ligases with a signature domain organization.
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Affiliation(s)
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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24
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Lopes RRS, Kessler AC, Polycarpo C, Alfonzo JD. Cutting, dicing, healing and sealing: the molecular surgery of tRNA. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 6:337-49. [PMID: 25755220 DOI: 10.1002/wrna.1279] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/13/2015] [Accepted: 01/15/2015] [Indexed: 11/09/2022]
Abstract
All organisms encode transfer RNAs (tRNAs) that are synthesized as precursor molecules bearing extra sequences at their 5' and 3' ends; some tRNAs also contain introns, which are removed by splicing. Despite commonality in what the ultimate goal is (i.e., producing a mature tRNA), mechanistically, tRNA splicing differs between Bacteria and Archaea or Eukarya. The number and position of tRNA introns varies between organisms and even between different tRNAs within the same organism, suggesting a degree of plasticity in both the evolution and persistence of modern tRNA splicing systems. Here we will review recent findings that not only highlight nuances in splicing pathways but also provide potential reasons for the maintenance of introns in tRNA. Recently, connections between defects in the components of the tRNA splicing machinery and medically relevant phenotypes in humans have been reported. These differences will be discussed in terms of the importance of splicing for tRNA function and in a broader context on how tRNA splicing defects can often have unpredictable consequences.
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Affiliation(s)
- Raphael R S Lopes
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto de Bioquímica Médica Leopoldo de Meis, Programa de Biotecnologia e Biologia Molecular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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25
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RTCB-1 mediates neuroprotection via XBP-1 mRNA splicing in the unfolded protein response pathway. J Neurosci 2015; 34:16076-85. [PMID: 25429148 DOI: 10.1523/jneurosci.1945-14.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, is characterized by the degeneration of dopamine (DA) neurons and age-dependent formation of protein inclusions that contain the α-synuclein (α-syn) protein. RNA interference (RNAi) screening using Caenorhabditis elegans identified RTCB-1, an uncharacterized gene product, as one of several significant modifiers of α-syn protein misfolding. RTCB-1 is the worm ortholog of the human HSPC117 protein, a component of RNA trafficking granules in mammalian neurons. Here we show that RTCB-1 protects C. elegans DA neurons from age-dependent degeneration induced by human α-syn. Moreover, neuronal-specific RNAi depletion of rtcb-1 enhanced α-syn-induced degeneration. Similar results were obtained when worms were exposed to the DA neurotoxin 6-hydroxydopamine. HSPC117 has been characterized recently as an essential subunit of the human tRNA splicing ligase complex. tRNA ligases have alternative functions in RNA repair and nonconventional mRNA splicing events. For example, in yeast, unconventional splicing of HAC1, a transcription factor that controls the unfolded protein response (UPR), is mediated by a tRNA ligase. In C. elegans, we demonstrate that RTCB-1 is necessary for xbp-1 (worm homolog of HAC1) mRNA splicing. Moreover, using a RNA ligase-dead mutant, we determine that the ligase activity of worm RTCB-1 is required for its neuroprotective role, which, in turn, is mediated through XBP-1 in the UPR pathway. Collectively, these studies highlight the mechanistic intersection of RNA processing and proteostasis in mediating neuroprotection.
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26
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Yoshihisa T. Handling tRNA introns, archaeal way and eukaryotic way. Front Genet 2014; 5:213. [PMID: 25071838 PMCID: PMC4090602 DOI: 10.3389/fgene.2014.00213] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 06/20/2014] [Indexed: 11/25/2022] Open
Abstract
Introns are found in various tRNA genes in all the three kingdoms of life. Especially, archaeal and eukaryotic genomes are good sources of tRNA introns that are removed by proteinaceous splicing machinery. Most intron-containing tRNA genes both in archaea and eukaryotes possess an intron at a so-called canonical position, one nucleotide 3′ to their anticodon, while recent bioinformatics have revealed unusual types of tRNA introns and their derivatives especially in archaeal genomes. Gain and loss of tRNA introns during various stages of evolution are obvious both in archaea and eukaryotes from analyses of comparative genomics. The splicing of tRNA molecules has been studied extensively from biochemical and cell biological points of view, and such analyses of eukaryotic systems provided interesting findings in the past years. Here, I summarize recent progresses in the analyses of tRNA introns and the splicing process, and try to clarify new and old questions to be solved in the next stages.
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Affiliation(s)
- Tohru Yoshihisa
- Graduate School of Life Science, University of Hyogo Ako-gun, Hyogo, Japan
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27
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Remus BS, Shuman S. Distinctive kinetics and substrate specificities of plant and fungal tRNA ligases. RNA (NEW YORK, N.Y.) 2014; 20:462-73. [PMID: 24554441 PMCID: PMC3964908 DOI: 10.1261/rna.043752.113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 01/07/2014] [Indexed: 05/23/2023]
Abstract
Plant and fungal tRNA ligases are trifunctional enzymes that repair RNA breaks with 2',3'-cyclic-PO4 and 5'-OH ends. They are composed of cyclic phosphodiesterase (CPDase) and polynucleotide kinase domains that heal the broken ends to generate the 3'-OH, 2'-PO4, and 5'-PO4 required for sealing by a ligase domain. Here, we use short HORNA>p substrates to determine, in a one-pot assay format under single-turnover conditions, the order and rates of the CPDase, kinase and ligase steps. The observed reaction sequence for the plant tRNA ligase AtRNL, independent of RNA length, is that the CPDase engages first, converting HORNA>p to HORNA2'p, which is then phosphorylated to pRNA2'p by the kinase. Whereas the rates of the AtRNL CPDase and kinase reactions are insensitive to RNA length, the rate of the ligase reaction is slowed by a factor of 16 in the transition from 10-mer RNA to 8-mer and further by eightfold in the transition from 8-mer RNA to 6-mer. We report that a single ribonucleoside-2',3'-cyclic-PO4 moiety enables AtRNL to efficiently splice an otherwise all-DNA strand. Our characterization of a fungal tRNA ligase (KlaTrl1) highlights important functional distinctions vis à vis the plant homolog. We find that (1) the KlaTrl1 kinase is 300-fold faster than the AtRNL kinase; and (2) the KlaTrl1 kinase is highly specific for GTP or dGTP as the phosphate donor. Our findings recommend tRNA ligase as a tool to map ribonucleotides embedded in DNA and as a target for antifungal drug discovery.
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Tanabe M, Ishino S, Ishino Y, Nishida H. Mutations of Asp540 and the domain-connecting residues synergistically enhance Pyrococcus furiosus DNA ligase activity. FEBS Lett 2013; 588:230-5. [PMID: 24211832 DOI: 10.1016/j.febslet.2013.10.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/30/2013] [Accepted: 10/30/2013] [Indexed: 01/25/2023]
Abstract
The structure of Pyrococcus furiosus DNA ligase (PfuLig), which architecturally resembles human DNA ligase I (hLigI), revealed that the C-terminal helix stabilizes the closed conformation through several ionic interactions between two domains (adenylylation domain (AdD) and C-terminal OB-fold domain (OBD)). This helix is oriented differently in DNA-bound hLigI, suggesting that the disruption of its interactions with AdD facilitates DNA binding. Previously, we demonstrated that the replacement of Asp540 with arginine improves the ligation activity. Here we report that the combination of the Asp540-replacement and the elimination of ionic residues in the helix, forming interactions with AdD, effectively enhanced the activity.
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Affiliation(s)
- Maiko Tanabe
- Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581, Japan
| | - Hirokazu Nishida
- Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan.
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Czech A, Wende S, Mörl M, Pan T, Ignatova Z. Reversible and rapid transfer-RNA deactivation as a mechanism of translational repression in stress. PLoS Genet 2013; 9:e1003767. [PMID: 24009533 PMCID: PMC3757041 DOI: 10.1371/journal.pgen.1003767] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/17/2013] [Indexed: 12/24/2022] Open
Abstract
Stress-induced changes of gene expression are crucial for survival of eukaryotic cells. Regulation at the level of translation provides the necessary plasticity for immediate changes of cellular activities and protein levels. In this study, we demonstrate that exposure to oxidative stress results in a quick repression of translation by deactivation of the aminoacyl-ends of all transfer-RNA (tRNA). An oxidative-stress activated nuclease, angiogenin, cleaves first within the conserved single-stranded 3'-CCA termini of all tRNAs, thereby blocking their use in translation. This CCA deactivation is reversible and quickly repairable by the CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase]. Through this mechanism the eukaryotic cell dynamically represses and reactivates translation at low metabolic costs.
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Affiliation(s)
- Andreas Czech
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Sandra Wende
- Institute for Biochemistry, University of Leipzig, Leipzig, Germany
| | - Mario Mörl
- Institute for Biochemistry, University of Leipzig, Leipzig, Germany
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States of America
| | - Zoya Ignatova
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
- * E-mail:
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30
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Myllykoski M, Raasakka A, Lehtimäki M, Han H, Kursula I, Kursula P. Crystallographic analysis of the reaction cycle of 2',3'-cyclic nucleotide 3'-phosphodiesterase, a unique member of the 2H phosphoesterase family. J Mol Biol 2013; 425:4307-22. [PMID: 23831225 PMCID: PMC7094350 DOI: 10.1016/j.jmb.2013.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 11/26/2022]
Abstract
2H phosphoesterases catalyze reactions on nucleotide substrates and contain two conserved histidine residues in the active site. Very limited information is currently available on the details of the active site and substrate/product binding during the catalytic cycle of these enzymes. We performed a comprehensive X-ray crystallographic study of mouse 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase), a membrane-associated enzyme present at high levels in the tetrapod myelin sheath. We determined crystal structures of the CNPase phosphodiesterase domain complexed with substrate, product, and phosphorothioate analogues. The data provide detailed information on the CNPase reaction mechanism, including substrate binding mode and coordination of the nucleophilic water molecule. Linked to the reaction, an open/close motion of the β5–α7 loop is observed. The role of the N terminus of helix α7—unique for CNPase in the 2H family—during the reaction indicates that 2H phosphoesterases differ in their respective reaction mechanisms despite the conserved catalytic residues. Furthermore, based on small-angle X-ray scattering, we present a model for the full-length enzyme, indicating that the two domains of CNPase form an elongated molecule. Finally, based on our structural data and a comprehensive bioinformatics study, we discuss the conservation of CNPase in various organisms. A detailed structural analysis of the CNPase catalytic cycle was carried out. Complexes with substrates, products, and analogues highlight roles for a nearby helix and loop in the reaction mechanism. The full-length CNPase adopts an elongated conformation in solution. CNPase is a unique member of the 2H family, and the results will help understand its physiological significance.
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Affiliation(s)
- Matti Myllykoski
- Department of Biochemistry, University of Oulu, FIN-90014 Oulu, Finland; Biocenter Oulu, University of Oulu, FIN-90014 Oulu, Finland
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31
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Tanabe M, Ishino S, Yohda M, Morikawa K, Ishino Y, Nishida H. Structure-based mutational study of an archaeal DNA ligase towards improvement of ligation activity. Chembiochem 2012; 13:2575-82. [PMID: 23132734 DOI: 10.1002/cbic.201200336] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Indexed: 12/18/2022]
Abstract
DNA ligases catalyze the joining of strand breaks in duplex DNA. The DNA ligase of Pyrococcus furiosus (PfuLig), which architecturally resembles the human DNA ligase I (hLigI), comprises an N-terminal DNA-binding domain, a middle adenylylation domain, and a C-terminal oligonucleotide-binding (OB)-fold domain. Here we addressed the C-terminal helix in the OB-fold domain of PfuLig by mutational analysis. The crystal structure of PfuLig revealed that this helix stabilizes a closed conformation of the enzyme by forming several ionic interactions with the adenylylation domain. The C-terminal helix is oriented differently in hLigI when DNA is bound; this suggested that disruption of its interaction with the adenylylation domain might facilitate the binding of DNA substrates. We indeed identified one of its residues, Asp540, as being critical for ligation efficiency. The D540R mutation improved the overall ligation activity relative to the wild-type enzyme, and at lower temperatures; this is relevant to applications such as ligation amplification reactions. Physical and biochemical analyses indicated that the improved ligation activity of the D540R variant arises from effects on the ligase adenylylation step and on substrate DNA binding in particular.
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Affiliation(s)
- Maiko Tanabe
- Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Tokyo, Japan
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32
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Nohales MÁ, Molina-Serrano D, Flores R, Daròs JA. Involvement of the chloroplastic isoform of tRNA ligase in the replication of viroids belonging to the family Avsunviroidae. J Virol 2012; 86:8269-76. [PMID: 22623792 PMCID: PMC3421689 DOI: 10.1128/jvi.00629-12] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/15/2012] [Indexed: 11/20/2022] Open
Abstract
Avocado sunblotch viroid, peach latent mosaic viroid, chrysanthemum chlorotic mottle viroid, and eggplant latent viroid (ELVd), the four recognized members of the family Avsunviroidae, replicate through the symmetric pathway of an RNA-to-RNA rolling-circle mechanism in chloroplasts of infected cells. Viroid oligomeric transcripts of both polarities contain embedded hammerhead ribozymes that, during replication, mediate their self-cleavage to monomeric-length RNAs with 5'-hydroxyl and 2',3'-phosphodiester termini that are subsequently circularized. We report that a recombinant version of the chloroplastic isoform of the tRNA ligase from eggplant (Solanum melongena L.) efficiently catalyzes in vitro circularization of the plus [(+)] and minus [(-)] monomeric linear replication intermediates from the four Avsunviroidae. We also show that while this RNA ligase specifically recognizes the genuine monomeric linear (+) ELVd replication intermediate, it does not do so with five other monomeric linear (+) ELVd RNAs with their ends mapping at different sites along the molecule, despite containing the same 5'-hydroxyl and 2',3'-phosphodiester terminal groups. Moreover, experiments involving transient expression of a dimeric (+) ELVd transcript in Nicotiana benthamiana Domin plants preinoculated with a tobacco rattle virus-derived vector to induce silencing of the plant endogenous tRNA ligase show a significant reduction of ELVd circularization. In contrast, circularization of a viroid replicating in the nucleus occurring through a different pathway is unaffected. Together, these results support the conclusion that the chloroplastic isoform of the plant tRNA ligase is the host enzyme mediating circularization of both (+) and (-) monomeric linear intermediates during replication of the viroids belonging to the family Avsunviroidae.
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Affiliation(s)
- María-Ángeles Nohales
- Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), Valencia, Spain
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33
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Molina-Serrano D, Marqués J, Nohales MÁ, Flores R, Daròs JA. A chloroplastic RNA ligase activity analogous to the bacterial and archaeal 2´-5' RNA ligase. RNA Biol 2012; 9:326-33. [PMID: 22336712 DOI: 10.4161/rna.19218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Bacteria and archaea contain a 2'-5' RNA ligase that seals in vitro 2',3'-cyclic phosphodiester and 5'-hydroxyl RNA termini, generating a 2',5'-phosphodiester bond. In our search for an RNA ligase able to circularize the monomeric linear replication intermediates of viroids belonging to the family Avsunviroidae, which replicate in the chloroplast, we have identified in spinach (Spinacea oleracea L.) chloroplasts a new RNA ligase activity whose properties resemble those of the bacterial and archaeal 2'-5' RNA ligase. The spinach chloroplastic RNA ligase recognizes the 5'-hydroxyl and 2',3'-cyclic phosphodiester termini of Avocado sunblotch viroid and Eggplant latent viroid RNAs produced by hammerhead-mediated self-cleavage, yielding circular products linked through an atypical, most likely 2',5'-phosphodiester, bond. The enzyme neither requires divalent cations as cofactors, nor NTPs as substrate. The reaction apparently reaches equilibrium at a low ratio between the final circular product and the linear initial substrate. Even if its involvement in viroid replication seems unlikely, the identification of a 2'-5' RNA ligase activity in higher plant chloroplasts, with properties very similar to an analogous enzyme widely distributed in bacterial and archaeal proteomes, is intriguing and suggests an important biological role so far unknown.
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Affiliation(s)
- Diego Molina-Serrano
- Instituto de Biología Molecular y Celular de Plantas-Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Avenida de los Naranjos, Valencia, Spain
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34
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Tanaka N, Meineke B, Shuman S. RtcB, a novel RNA ligase, can catalyze tRNA splicing and HAC1 mRNA splicing in vivo. J Biol Chem 2011; 286:30253-30257. [PMID: 21757685 DOI: 10.1074/jbc.c111.274597] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
RtcB enzymes are novel RNA ligases that join 2',3'-cyclic phosphate and 5'-OH ends. The phylogenetic distribution of RtcB points to its candidacy as a tRNA splicing/repair enzyme. Here we show that Escherichia coli RtcB is competent and sufficient for tRNA splicing in vivo by virtue of its ability to complement growth of yeast cells that lack the endogenous "healing/sealing-type" tRNA ligase Trl1. RtcB also protects yeast trl1Δ cells against a fungal ribotoxin that incises the anticodon loop of cellular tRNAs. Moreover, RtcB can replace Trl1 as the catalyst of HAC1 mRNA splicing during the unfolded protein response. Thus, RtcB is a bona fide RNA repair enzyme with broad physiological actions. Biochemical analysis of RtcB highlights the uniqueness of its active site and catalytic mechanism. Our findings draw attention to tRNA ligase as a promising drug target.
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Affiliation(s)
- Naoko Tanaka
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065
| | - Birthe Meineke
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065.
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35
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Abstract
Nucleases cleave the phosphodiester bonds of nucleic acids and may be endo or exo, DNase or RNase, topoisomerases, recombinases, ribozymes, or RNA splicing enzymes. In this review, I survey nuclease activities with known structures and catalytic machinery and classify them by reaction mechanism and metal-ion dependence and by their biological function ranging from DNA replication, recombination, repair, RNA maturation, processing, interference, to defense, nutrient regeneration or cell death. Several general principles emerge from this analysis. There is little correlation between catalytic mechanism and biological function. A single catalytic mechanism can be adapted in a variety of reactions and biological pathways. Conversely, a single biological process can often be accomplished by multiple tertiary and quaternary folds and by more than one catalytic mechanism. Two-metal-ion-dependent nucleases comprise the largest number of different tertiary folds and mediate the most diverse set of biological functions. Metal-ion-dependent cleavage is exclusively associated with exonucleases producing mononucleotides and endonucleases that cleave double- or single-stranded substrates in helical and base-stacked conformations. All metal-ion-independent RNases generate 2',3'-cyclic phosphate products, and all metal-ion-independent DNases form phospho-protein intermediates. I also find several previously unnoted relationships between different nucleases and shared catalytic configurations.
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36
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Branchiostoma floridae has separate healing and sealing enzymes for 5'-phosphate RNA ligation. Proc Natl Acad Sci U S A 2010; 107:16834-9. [PMID: 20837552 DOI: 10.1073/pnas.1011703107] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Animal cells have two tRNA splicing pathways: (i) a 5'-P ligation mechanism, where the 5'-phosphate of the 3' tRNA half becomes the junction phosphate of the new phosphodiester linkage, and (ii) a 3'-P ligation process, in which the 3'-phosphate of the 5' tRNA half turns into the junction phosphate. Although both activities are known to exist in animals, in almost three decades of investigation, neither of the two RNA ligases has been identified. Here we describe a gene from the chordate Branchiostoma floridae that encodes an RNA ligase (Bf RNL) with a strict requirement for RNA substrates with a 2'-phosphate terminus for the ligation of RNAs with 5'-phosphate and 3'-hydroxyl ends. Unlike the yeast and plant tRNA ligases involved in tRNA splicing, Bf RNL lacks healing activities and requires the action of a polynucleotide kinase (PNK) and a cyclic phosphodiesterase (CDPase) in trans. The activities of these two enzymes were identified in a single B. floridae protein (Bf PNK/CPDase). The combined activities of Bf RNL and Bf PNK/CPDase are sufficient for the joining of tRNA splicing intermediates in vitro, and for the functional complementation of a tRNA ligase-deficient Saccharomyces cerevisiae strain in vivo. Hence, these two proteins constitute the 5'-P RNA ligation pathway in an animal organism.
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37
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Kanai A, Sato A, Fukuda Y, Okada K, Matsuda T, Sakamoto T, Muto Y, Yokoyama S, Kawai G, Tomita M. Characterization of a heat-stable enzyme possessing GTP-dependent RNA ligase activity from a hyperthermophilic archaeon, Pyrococcus furiosus. RNA (NEW YORK, N.Y.) 2009; 15:420-431. [PMID: 19155324 PMCID: PMC2657004 DOI: 10.1261/rna.1122109] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 11/24/2008] [Indexed: 05/27/2023]
Abstract
Using an expression protein library of a hyperthermophilic archaeon, Pyrococcus furiosus, we identified a gene (PF0027) that encodes a protein with heat-stable cyclic nucleotide phosphodiesterase (CPDase) activity. The PF0027 gene encoded a 21-kDa protein and an amino acid sequence that showed approximately 27% identity to that of the 2'-5' tRNA ligase protein, ligT (20 kDa), from Escherichia coli. We found that the purified PF0027 protein possessed GTP-dependent RNA ligase activity and that synthetic tRNA halves bearing 2',3'-cyclic phosphate and 5'-OH termini were substrates for the ligation reaction in vitro. GTP hydrolysis was not required for the reaction, and GTPgammaS enhanced the tRNA ligation activity of PF0027 protein, suggesting that the ligation step is regulated by a novel mechanism. In comparison to the strong CPDase activity of the PF0027 protein, the RNA ligase activity itself was quite weak, and the ligation product was unstable during in vitro reaction. Finally, we used NMR to determine the solution structure of the PF0027 protein and discuss the implications of our results in understanding the role of the PF0027 protein.
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Affiliation(s)
- Akio Kanai
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0017, Japan.
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38
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Ramirez A, Shuman S, Schwer B. Human RNA 5'-kinase (hClp1) can function as a tRNA splicing enzyme in vivo. RNA (NEW YORK, N.Y.) 2008; 14:1737-45. [PMID: 18648070 PMCID: PMC2525948 DOI: 10.1261/rna.1142908] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 05/16/2008] [Indexed: 05/22/2023]
Abstract
Yeast and human Clp1 proteins are homologous components of the mRNA 3'-cleavage-polyadenylation machinery. Recent studies highlighting an association of human Clp1 (hClp1) with tRNA splicing endonuclease and an intrinsic RNA-specific 5'-OH polynucleotide kinase activity of hClp1 have prompted speculation that Clp1 might play a catalytic role in tRNA splicing in animal cells. Here, we show that expression of hClp1 in budding yeast can complement conditional and lethal mutations in the essential 5'-OH RNA kinase module of yeast or plant tRNA ligases. The tRNA splicing activity of hClp1 in yeast is abolished by mutations in the kinase active site. In contrast, overexpression of yeast Clp1 (yClp1) cannot rescue kinase-defective tRNA ligase mutants, and, unlike hClp1, the purified recombinant yClp1 protein has no detectable RNA kinase activity in vitro. Mutations of the yClp1 ATP-binding site do not affect yeast viability. These findings, and the fact that hClp1 cannot complement growth of a yeast clp1Delta strain, indicate that yeast and human Clp1 proteins are not functional orthologs, despite their structural similarity. Although hClp1 can perform the 5'-end-healing step of a yeast-type tRNA splicing pathway in vivo, it is uncertain whether its kinase activity is necessary for tRNA splicing in human cells, given that other mammalian counterparts of yeast-type tRNA repair enzymes are nonessential in vivo.
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Affiliation(s)
- Alejandro Ramirez
- Graduate Program in Molecular Biology, Weill Cornell Medical College, New York, New York 10065, USA
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39
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Nandakumar J, Schwer B, Schaffrath R, Shuman S. RNA repair: an antidote to cytotoxic eukaryal RNA damage. Mol Cell 2008; 31:278-86. [PMID: 18657509 DOI: 10.1016/j.molcel.2008.05.019] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Revised: 04/10/2008] [Accepted: 05/02/2008] [Indexed: 02/05/2023]
Abstract
RNA healing and sealing enzymes drive informational and stress response pathways entailing repair of programmed 2',3' cyclic PO(4)/5'-OH breaks. Fungal, plant, and phage tRNA ligases use different strategies to discriminate the purposefully broken ends of the anticodon loop. Whereas phage ligase recognizes the tRNA fold, yeast and plant ligases do not and are instead hardwired to seal only the tRNA 3'-OH, 2'-PO(4) ends formed by healing of a cyclic phosphate. tRNA anticodon damage inflicted by secreted ribotoxins such as fungal gamma-toxin underlies a rudimentary innate immune system. Yeast cells are susceptible to gamma-toxin because the sealing domain of yeast tRNA ligase is unable to rectify a break at the modified wobble base of tRNA(Glu(UUC)). Plant andphage tRNA repair enzymes protect yeast from gamma-toxin because they are able to reverse the damage. Our studies underscore how a ribotoxin exploits an Achilles' heel in the target cell's tRNA repair system.
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40
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Schwer B, Aronova A, Ramirez A, Braun P, Shuman S. Mammalian 2',3' cyclic nucleotide phosphodiesterase (CNP) can function as a tRNA splicing enzyme in vivo. RNA (NEW YORK, N.Y.) 2008; 14:204-10. [PMID: 18094118 PMCID: PMC2212240 DOI: 10.1261/rna.858108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 11/06/2007] [Indexed: 05/24/2023]
Abstract
Yeast and plant tRNA splicing entails discrete healing and sealing steps catalyzed by a tRNA ligase that converts the 2',3' cyclic phosphate and 5'-OH termini of the broken tRNA exons to 3'-OH/2'-PO4 and 5'-PO4 ends, respectively, then joins the ends to yield a 2'-PO4, 3'-5' phosphodiester splice junction. The junction 2'-PO4 is removed by a tRNA phosphotransferase, Tpt1. Animal cells have two potential tRNA repair pathways: a yeast-like system plus a distinctive mechanism, also present in archaea, in which the 2',3' cyclic phosphate and 5'-OH termini are ligated directly. Here we report that a mammalian 2',3' cyclic nucleotide phosphodiesterase (CNP) can perform the essential 3' end-healing steps of tRNA splicing in yeast and thereby complement growth of strains bearing lethal or temperature-sensitive mutations in the tRNA ligase 3' end-healing domain. Although this is the first evidence of an RNA processing function in vivo for the mammalian CNP protein, it seems unlikely that the yeast-like pathway is responsible for animal tRNA splicing, insofar as neither CNP nor Tpt1 is essential in mice.
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41
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Wang LK, Nandakumar J, Schwer B, Shuman S. The C-terminal domain of T4 RNA ligase 1 confers specificity for tRNA repair. RNA (NEW YORK, N.Y.) 2007; 13:1235-44. [PMID: 17585047 PMCID: PMC1924901 DOI: 10.1261/rna.591807] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
T4 RNA ligase 1 (Rnl1) is a tRNA repair enzyme that thwarts a tRNA-damaging host response to virus infection. The 374-aa Rnl1 protein consists of an N-terminal nucleotidyltransferase domain fused to a unique C-terminal domain composed of 10 alpha helices. We exploited an in vitro tRNA splicing system to demonstrate that Rnl1 has an inherent specificity for sealing tRNA with a break in the anticodon loop. The tRNA specificity is imparted by the C domain, any deletion of which caused the broken tRNA to be sealed as poorly as the linear intron in vitro and also abolished Rnl1 tRNA splicing activity in vivo. Deletion analysis demarcated Rnl1-(1-254) as a minimal catalytic domain of Rnl1, capable of all chemical steps of the nonspecific RNA ligation reaction. Alanine scanning of the N domain identified Ser103, Leu104, Lys117, and Ser118 as important for pRNA ligation in vitro and tRNA repair in vivo.
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Affiliation(s)
- Li Kai Wang
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA
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42
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Keppetipola N, Nandakumar J, Shuman S. Reprogramming the tRNA-splicing activity of a bacterial RNA repair enzyme. Nucleic Acids Res 2007; 35:3624-30. [PMID: 17488852 PMCID: PMC1920235 DOI: 10.1093/nar/gkm110] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Programmed RNA breakage is an emerging theme underlying cellular responses to stress, virus infection and defense against foreign species. In many cases, site-specific cleavage of the target RNA generates 2′,3′ cyclic phosphate and 5′-OH ends. For the damage to be repaired, both broken ends must be healed before they can be sealed by a ligase. Healing entails hydrolysis of the 2′,3′ cyclic phosphate to form a 3′-OH and phosphorylation of the 5′-OH to form a 5′-PO4. Here, we demonstrate that a polynucleotide kinase-phosphatase enzyme from Clostridium thermocellum (CthPnkp) can catalyze both of the end-healing steps of tRNA splicing in vitro. The route of tRNA repair by CthPnkp can be reprogrammed by a mutation in the 3′ end-healing domain (H189D) that yields a 2′-PO4 product instead of a 2′-OH. Whereas tRNA ends healed by wild-type CthPnkp are readily sealed by T4 RNA ligase 1, the H189D enzyme generates ends that are spliced by yeast tRNA ligase. Our findings suggest that RNA repair enzymes can evolve their specificities to suit a particular pathway.
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Affiliation(s)
| | | | - Stewart Shuman
- *To whom correspondence should be addressed. +1-212 639-7145; +1-212 717-3623
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43
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Nandakumar J, Shuman S, Lima CD. RNA ligase structures reveal the basis for RNA specificity and conformational changes that drive ligation forward. Cell 2006; 127:71-84. [PMID: 17018278 DOI: 10.1016/j.cell.2006.08.038] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 07/20/2006] [Accepted: 08/04/2006] [Indexed: 11/24/2022]
Abstract
T4 RNA ligase 2 (Rnl2) and kinetoplastid RNA editing ligases exemplify a family of RNA repair enzymes that seal 3'OH/5'PO(4) nicks in duplex RNAs via ligase adenylylation (step 1), AMP transfer to the nick 5'PO(4) (step 2), and attack by the nick 3'OH on the 5'-adenylylated strand to form a phosphodiester (step 3). Crystal structures are reported for Rnl2 at discrete steps along this pathway: the covalent Rnl2-AMP intermediate; Rnl2 bound to an adenylylated nicked duplex, captured immediately following step 2; and Rnl2 at an adenylylated nick in a state poised for step 3. These structures illuminate the stereochemistry of nucleotidyl transfer and reveal how remodeling of active-site contacts and conformational changes propel the ligation reaction forward. Mutational analysis and comparison of nick-bound structures of Rnl2 and human DNA ligase I highlight common and divergent themes of substrate recognition that can explain their specialization for RNA versus DNA repair.
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44
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Wang LK, Schwer B, Shuman S. Structure-guided mutational analysis of T4 RNA ligase 1. RNA (NEW YORK, N.Y.) 2006; 12:2126-34. [PMID: 17068206 PMCID: PMC1664725 DOI: 10.1261/rna.271706] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
T4 RNA ligase 1 (Rnl1) is a tRNA repair enzyme that circumvents an RNA-damaging host antiviral response. Whereas the three-step reaction scheme of Rnl1 is well established, the structural basis for catalysis has only recently been appreciated as mutational and crystallographic approaches have converged. Here we performed a structure-guided alanine scan of nine conserved residues, including side chains that either contact the ATP substrate via adenine (Leu179, Val230), the 2'-OH (Glu159), or the gamma phosphate (Tyr37) or coordinate divalent metal ions at the ATP alpha phosphate (Glu159, Tyr246) or beta phosphate (Asp272, Asp273). We thereby identified Glu159 and Tyr246 as essential for RNA sealing activity in vitro and for tRNA repair in vivo. Structure-activity relationships at Glu159 and Tyr246 were clarified by conservative substitutions. Eliminating the phosphate-binding Tyr37, and the magnesium-binding Asp272 and Asp273 side chains had little impact on sealing activity in vitro or in vivo, signifying that not all atomic interactions in the active site are critical for function. Analysis of mutational effects on individual steps of the ligation pathway underscored how different functional groups come into play during the ligase-adenylylation reaction versus the subsequent steps of RNA-adenylylation and phosphodiester formation. Moreover, the requirements for sealing exogenous preformed RNA-adenylate are more stringent than are those for sealing the RNA-adenylate intermediate formed in situ during ligation of a 5'-PO4 RNA.
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Affiliation(s)
- Li Kai Wang
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10021, USA
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Gao YG, Yao M, Okada A, Tanaka I. The structure of Pyrococcus horikoshii 2'-5' RNA ligase at 1.94 A resolution reveals a possible open form with a wider active-site cleft. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:1196-200. [PMID: 17142895 PMCID: PMC2225383 DOI: 10.1107/s1744309106046616] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Accepted: 11/06/2006] [Indexed: 01/23/2023]
Abstract
Bacterial and archaeal 2'-5' RNA ligases, members of the 2H phosphoesterase superfamily, catalyze the linkage of the 5' and 3' exons via a 2'-5'-phosphodiester bond during tRNA-precursor splicing. The crystal structure of the 2'-5' RNA ligase PH0099 from Pyrococcus horikoshii OT3 was solved at 1.94 A resolution (PDB code 1vgj). The molecule has a bilobal alpha+beta arrangement with two antiparallel beta-sheets constituting a V-shaped active-site cleft, as found in other members of the 2H phosphoesterase superfamily. The present structure was significantly different from that determined previously at 2.4 A resolution (PDB code 1vdx) in the active-site cleft; the entrance to the cleft is wider and the active site is easily accessible to the substrate (RNA precursor) in our structure. Structural comparison with the 2'-5' RNA ligase from Thermus thermophilus HB8 also revealed differences in the RNA precursor-binding region. The structural differences in the active-site residues (tetrapeptide motifs H-X-T/S-X) between the members of the 2H phosphoesterase superfamily are discussed.
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Affiliation(s)
- Yong-Gui Gao
- Faculty of Advanced Life Sciences, Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Min Yao
- Faculty of Advanced Life Sciences, Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
- RIKEN Harima Institute/Spring-8, Hyogo, Japan
- Correspondence e-mail:
| | - Ayuko Okada
- Faculty of Advanced Life Sciences, Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Isao Tanaka
- Faculty of Advanced Life Sciences, Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
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Wang LK, Schwer B, Englert M, Beier H, Shuman S. Structure-function analysis of the kinase-CPD domain of yeast tRNA ligase (Trl1) and requirements for complementation of tRNA splicing by a plant Trl1 homolog. Nucleic Acids Res 2006; 34:517-27. [PMID: 16428247 PMCID: PMC1345694 DOI: 10.1093/nar/gkj441] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Trl1 is an essential 827 amino acid enzyme that executes the end-healing and end-sealing steps of tRNA splicing in Saccharomyces cerevisiae. Trl1 consists of two domains—an N-terminal ligase component and a C-terminal 5′-kinase/2′,3′-cyclic phosphodiesterase (CPD) component—that can function in tRNA splicing in vivo when expressed as separate polypeptides. To understand the structural requirements for the kinase-CPD domain, we performed an alanine scan of 30 amino acids that are conserved in Trl1 homologs from other fungi. We thereby identified four residues (Arg463, His515, Thr675 and Glu741) as essential for activity in vivo. Structure–function relationships at these positions, and at four essential or conditionally essential residues defined previously (Asp425, Arg511, His673 and His777), were clarified by introducing conservative substitutions. Biochemical analysis showed that lethal mutations of Asp425, Arg463, Arg511 and His515 in the kinase module abolished polynucleotide kinase activity in vitro. We report that a recently cloned 1104 amino acid Arabidopsis RNA ligase functions in lieu of yeast Trl1 in vivo and identify essential side chains in the ligase, kinase and CPD modules of the plant enzyme. The plant ligase, like yeast Trl1 but unlike T4 RNA ligase 1, requires a 2′-PO4 end for tRNA splicing in vivo.
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Affiliation(s)
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Medical College of Cornell UniversityNew York, NY 10021, USA
| | - Markus Englert
- Institut für Biochemie, Universität WürzburgBiozentrum, D-97074, Würzburg, Germany
| | - Hildburg Beier
- Institut für Biochemie, Universität WürzburgBiozentrum, D-97074, Würzburg, Germany
| | - Stewart Shuman
- To whom correspondence should be addressed. Tel: 212-639-7145; Fax: 212-717-3623;
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