1
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Zhang F, Ji Q, Chaturvedi J, Morales M, Mao Y, Meng X, Dong L, Deng J, Qian SB, Xiang Y. Human SAMD9 is a poxvirus-activatable anticodon nuclease inhibiting codon-specific protein synthesis. SCIENCE ADVANCES 2023; 9:eadh8502. [PMID: 37285440 PMCID: PMC10246899 DOI: 10.1126/sciadv.adh8502] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023]
Abstract
As a defense strategy against viruses or competitors, some microbes use anticodon nucleases (ACNases) to deplete essential tRNAs, effectively halting global protein synthesis. However, this mechanism has not been observed in multicellular eukaryotes. Here, we report that human SAMD9 is an ACNase that specifically cleaves phenylalanine tRNA (tRNAPhe), resulting in codon-specific ribosomal pausing and stress signaling. While SAMD9 ACNase activity is normally latent in cells, it can be activated by poxvirus infection or rendered constitutively active by SAMD9 mutations associated with various human disorders, revealing tRNAPhe depletion as an antiviral mechanism and a pathogenic condition in SAMD9 disorders. We identified the N-terminal effector domain of SAMD9 as the ACNase, with substrate specificity primarily determined by a eukaryotic tRNAPhe-specific 2'-O-methylation at the wobble position, making virtually all eukaryotic tRNAPhe susceptible to SAMD9 cleavage. Notably, the structure and substrate specificity of SAMD9 ACNase differ from known microbial ACNases, suggesting convergent evolution of a common immune defense strategy targeting tRNAs.
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Affiliation(s)
- Fushun Zhang
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Quanquan Ji
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Juhi Chaturvedi
- Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
| | - Marisol Morales
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Yuanhui Mao
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Xiangzhi Meng
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Leiming Dong
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Junpeng Deng
- Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
| | - Shu-Bing Qian
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Yan Xiang
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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2
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Mathew BA, Katta M, Ludhiadch A, Singh P, Munshi A. Role of tRNA-Derived Fragments in Neurological Disorders: a Review. Mol Neurobiol 2023; 60:655-671. [PMID: 36348262 DOI: 10.1007/s12035-022-03078-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 10/05/2022] [Indexed: 11/10/2022]
Abstract
tRFs are small tRNA derived fragments that are emerging as novel therapeutic targets and regulatory molecules in the pathophysiology of various neurological disorders. These are derived from precursor or mature tRNA, forming different subtypes that have been reported to be involved in neurological disorders like stroke, Alzheimer's, epilepsy, Parkinson's, MELAS, autism, and Huntington's disorder. tRFs were earlier believed to be random degradation debris of tRNAs. The significant variation in the expression level of tRFs in disease conditions indicates their salient role as key players in regulation of these disorders. Various animal studies are being carried out to decipher their exact role; however, more inputs are required to transform this research knowledge into clinical application. Future investigations also call for high-throughput technologies that could help to bring out the other hidden aspects of these entities. However, studies on tRFs require further research efforts to overcome the challenges posed in quantifying tRFs, their interactions with other molecules, and the exact mechanism of function. In this review, we are abridging the current understanding of tRFs, including their biogenesis, function, relevance in clinical therapies, and potential as diagnostic and prognostic biomarkers of these neurological disorders.
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Affiliation(s)
- Blessy Aksa Mathew
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, India, 151401
| | - Madhumitha Katta
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, India, 151401
| | - Abhilash Ludhiadch
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, India, 151401
| | - Paramdeep Singh
- Department of Radiology, All India Institute of Medical Sciences, Bathinda, Punjab, India, 151001
| | - Anjana Munshi
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, India, 151401.
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3
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Ogawa T, Takahashi K, Ishida W, Aono T, Hidaka M, Terada T, Masaki H. Substrate recognition mechanism of tRNA-targeting ribonuclease, colicin D, and an insight into tRNA cleavage-mediated translation impairment. RNA Biol 2020; 18:1193-1205. [PMID: 33211605 DOI: 10.1080/15476286.2020.1838782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Colicin D is a plasmid-encoded bacteriocin that specifically cleaves tRNAArg of sensitive Escherichia coli cells. E. coli has four isoaccepting tRNAArgs; the cleavage occurs at the 3' end of anticodon-loop, leading to translation impairment in the sensitive cells. tRNAs form a common L-shaped structure and have many conserved nucleotides that limit tRNA identity elements. How colicin D selects tRNAArgs from the tRNA pool of sensitive E. coli cells is therefore intriguing. Here, we reveal the recognition mechanism of colicin D via biochemical analyses as well as structural modelling. Colicin D recognizes tRNAArgICG, the most abundant species of E. coli tRNAArgs, at its anticodon-loop and D-arm, and selects it as the most preferred substrate by distinguishing its anticodon-loop sequence from that of others. It has been assumed that translation impairment is caused by a decrease in intact tRNA molecules due to cleavage. However, we found that intracellular levels of intact tRNAArgICG do not determine the viability of sensitive cells after such cleavage; rather, an accumulation of cleaved ones does. Cleaved tRNAArgICG dominant-negatively impairs translation in vitro. Moreover, we revealed that EF-Tu, which is required for the delivery of tRNAs, does not compete with colicin D for binding tRNAArgICG, which is consistent with our structural model. Finally, elevation of cleaved tRNAArgICG level decreases the viability of sensitive cells. These results suggest that cleaved tRNAArgICG transiently occupies ribosomal A-site in an EF-Tu-dependent manner, leading to translation impairment. The strategy should also be applicable to other tRNA-targeting RNases, as they, too, recognize anticodon-loops.Abbreviations: mnm5U: 5-methylaminomethyluridine; mcm5s2U: 5-methoxycarbonylmethyl-2-thiouridine.
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Affiliation(s)
- Tetsuhiro Ogawa
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Kazutoshi Takahashi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Wataru Ishida
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Toshihiro Aono
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan.,Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
| | - Makoto Hidaka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Tohru Terada
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Haruhiko Masaki
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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4
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Oberbauer V, Schaefer MR. tRNA-Derived Small RNAs: Biogenesis, Modification, Function and Potential Impact on Human Disease Development. Genes (Basel) 2018; 9:genes9120607. [PMID: 30563140 PMCID: PMC6315542 DOI: 10.3390/genes9120607] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 11/27/2018] [Accepted: 11/29/2018] [Indexed: 12/11/2022] Open
Abstract
Transfer RNAs (tRNAs) are abundant small non-coding RNAs that are crucially important for decoding genetic information. Besides fulfilling canonical roles as adaptor molecules during protein synthesis, tRNAs are also the source of a heterogeneous class of small RNAs, tRNA-derived small RNAs (tsRNAs). Occurrence and the relatively high abundance of tsRNAs has been noted in many high-throughput sequencing data sets, leading to largely correlative assumptions about their potential as biologically active entities. tRNAs are also the most modified RNAs in any cell type. Mutations in tRNA biogenesis factors including tRNA modification enzymes correlate with a variety of human disease syndromes. However, whether it is the lack of tRNAs or the activity of functionally relevant tsRNAs that are causative for human disease development remains to be elucidated. Here, we review the current knowledge in regard to tsRNAs biogenesis, including the impact of RNA modifications on tRNA stability and discuss the existing experimental evidence in support for the seemingly large functional spectrum being proposed for tsRNAs. We also argue that improved methodology allowing exact quantification and specific manipulation of tsRNAs will be necessary before developing these small RNAs into diagnostic biomarkers and when aiming to harness them for therapeutic purposes.
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Affiliation(s)
- Vera Oberbauer
- Division of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.
| | - Matthias R Schaefer
- Division of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.
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5
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Krutkina E, Klaiman D, Margalit T, Jerabeck-Willemsen M, Kaufmann G. Dual nucleotide specificity determinants of an infection aborting anticodon nuclease. Virology 2015; 487:260-72. [PMID: 26569352 DOI: 10.1016/j.virol.2015.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/25/2015] [Accepted: 10/13/2015] [Indexed: 10/22/2022]
Abstract
The anticodon nuclease (ACNase) PrrC is silenced by a DNA restriction-modification (RM) protein and activated by a phage T4-encoded restriction inhibitor. The activation is driven by GTP hydrolysis while dTTP, which accumulates during the infection, stabilizes the active form. We show here, first, that the ABC-ATPase N-domains of PrrC can accommodate the two nucleotides simultaneously. Second, mutating a sequence motif that distinguishes the N-domain of PrrC from typical ABC-ATPases implicates three residues in the specificity for dTTP. Third, failure to bind dTTP or its deprivation hastened the centrifugal sedimentation of PrrC, possibly due to exposed sticky PrrC surfaces. Fourth, dTTP inhibited the GTPase activity of PrrC, probably by preventing GDP from leaving. These observations, correlated with relevant traits of a related ACNase, further suggest that PrrC utilizes GTP at canonical ABC-ATPase sites and binds dTTP to distinct sites exposed upon disruption of the ACNase-silencing interaction with the RM partner.
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Affiliation(s)
- Ekaterina Krutkina
- Department of Biochemistry, Tel Aviv University, Ramat Aviv, 69978, Israel
| | - Daniel Klaiman
- Department of Biochemistry, Tel Aviv University, Ramat Aviv, 69978, Israel
| | - Tamar Margalit
- Department of Biochemistry, Tel Aviv University, Ramat Aviv, 69978, Israel
| | | | - Gabriel Kaufmann
- Department of Biochemistry, Tel Aviv University, Ramat Aviv, 69978, Israel.
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6
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Structure, mechanism, and specificity of a eukaryal tRNA restriction enzyme involved in self-nonself discrimination. Cell Rep 2014; 7:339-347. [PMID: 24726365 DOI: 10.1016/j.celrep.2014.03.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/26/2014] [Accepted: 03/11/2014] [Indexed: 11/22/2022] Open
Abstract
tRNA restriction by anticodon nucleases underlies cellular stress responses and self-nonself discrimination in a wide range of taxa. Anticodon breakage inhibits protein synthesis, which, in turn, results in growth arrest or cell death. The eukaryal ribotoxin PaT secreted by Pichia acaciae inhibits growth of Saccharomyces cerevisiae via cleavage of tRNA(Gln(UUG)). We find that recombinant PaT incises a synthetic tRNA(Gln(UUG)) stem-loop RNA by transesterification at a single site 3' of the wobble uridine, yielding 2',3'-cyclic phosphate and 5'-OH ends. Incision is suppressed by replacement of the wobble nucleobase with adenine or guanine. The crystal structure of PaT reveals a distinctive fold and active site, essential components of which are demonstrated by mutagenesis. Pichia acaciae evades self-toxicity via a distinctive intracellular immunity protein, ImmPaT, which binds PaT and blocks nuclease activity. Our results highlight the evolutionary diversity of tRNA restriction and immunity systems.
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7
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Klaiman D, Steinfels-Kohn E, Kaufmann G. A DNA break inducer activates the anticodon nuclease RloC and the adaptive immunity in Acinetobacter baylyi ADP1. Nucleic Acids Res 2013; 42:328-39. [PMID: 24062157 PMCID: PMC3874168 DOI: 10.1093/nar/gkt851] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Double-stranded DNA breaks (DSB) cause bacteria to augment expression of DNA repair and various stress response proteins. A puzzling exception educes the anticodon nuclease (ACNase) RloC, which resembles the DSB responder Rad50 and the antiviral, translation-disabling ACNase PrrC. While PrrC's ACNase is regulated by a DNA restriction-modification (R-M) protein and a phage anti-DNA restriction peptide, RloC has an internal ACNase switch comprising a putative DSB sensor and coupled ATPase. Further exploration of RloC's controls revealed, first, that its ACNase is stabilized by the activating DNA and hydrolysed nucleotide. Second, DSB inducers activated RloC's ACNase in heterologous contexts as well as in a natural host, even when R-M deficient. Third, the DSB-induced activation of the indigenous RloC led to partial and temporary disruption of tRNA(Glu) and tRNA(Gln). Lastly, accumulation of CRISPR-derived RNA that occurred in parallel raises the possibility that the adaptive immunity and RloC provide the genotoxicated host with complementary protection from impending infections.
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Affiliation(s)
- Daniel Klaiman
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
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8
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Klaiman D, Steinfels-Kohn E, Krutkina E, Davidov E, Kaufmann G. The wobble nucleotide-excising anticodon nuclease RloC is governed by the zinc-hook and DNA-dependent ATPase of its Rad50-like region. Nucleic Acids Res 2012; 40:8568-78. [PMID: 22730290 PMCID: PMC3458546 DOI: 10.1093/nar/gks593] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The conserved bacterial anticodon nuclease (ACNase) RloC and its phage-excluding homolog PrrC comprise respective ABC-adenosine triphosphatase (ATPase) and ACNase N- and C-domains but differ in three key attributes. First, prrC is always linked to an ACNase silencing, DNA restriction–modification (R–M) locus while rloC rarely features such linkage. Second, RloC excises its substrate’s wobble nucleotide, a lesion expected to impede damage reversal by phage transfer RNA (tRNA) repair enzymes that counteract the nick inflicted by PrrC. Third, a distinct coiled-coil/zinc-hook (CC/ZH) insert likens RloC’s N-region to the universal DNA damage checkpoint/repair protein Rad50. Previous work revealed that ZH mutations activate RloC’s ACNase. Data shown here suggest that RloC has an internal ACNase silencing/activating switch comprising its ZH and DNA-break-responsive ATPase. The existence of this control may explain the lateral transfer of rloC without an external silencer and supports the proposed role of RloC as an antiviral contingency acting when DNA restriction is alleviated under genotoxic stress. We also discuss RloC’s possible evolution from a PrrC-like ancestor.
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Affiliation(s)
- Daniel Klaiman
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel
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9
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Meineke B, Shuman S. Structure-function relations in the NTPase domain of the antiviral tRNA ribotoxin Escherichia coli PrrC. Virology 2012; 427:144-50. [PMID: 22386822 DOI: 10.1016/j.virol.2012.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 02/08/2012] [Accepted: 02/11/2012] [Indexed: 01/26/2023]
Abstract
Breakage of tRNA by Escherichia coli anticodon nuclease PrrC (EcoPrrC) underlies a host antiviral response to phage T4 infection. Expression of EcoPrrC is cytocidal in yeast, signifying that PrrC ribotoxicity crosses phylogenetic domain boundaries. EcoPrrC consists of an N-terminal NTPase module that resembles ABC transporters and a C-terminal nuclease module that is sui generis. PrrC homologs are prevalent in many other bacteria. Here we report that Haemophilus influenzae PrrC is toxic in E. coli and yeast. To illuminate structure-activity relations, we conducted a new round of mutational analysis of EcoPrrC guided by primary structure conservation among toxic PrrC homologs. We indentify 17 candidate active site residues in the NTPase module that are essential for toxicity in yeast when EcoPrrC is expressed at high gene dosage. Their functions could be educed by integrating mutational data with the atomic structure of the transition-state complex of a homologous ABC protein.
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Affiliation(s)
- Birthe Meineke
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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10
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Meineke B, Shuman S. Determinants of the cytotoxicity of PrrC anticodon nuclease and its amelioration by tRNA repair. RNA (NEW YORK, N.Y.) 2012; 18:145-54. [PMID: 22101242 PMCID: PMC3261736 DOI: 10.1261/rna.030171.111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 10/10/2011] [Indexed: 05/23/2023]
Abstract
Breakage of tRNA(Lys(UUU)) by the Escherichia coli anticodon nuclease PrrC (EcoPrrC) underlies a host antiviral response to phage T4 infection that is ultimately thwarted by a virus-encoded RNA repair system. PrrC homologs are prevalent in other bacteria, but their activities and substrates are not defined. We find that induced expression of EcoPrrC is toxic in Saccharomyces cerevisiae and E. coli, whereas the Neisseria meningitidis PrrC (NmePrrC) is not. PrrCs consist of an N-terminal NTPase module and a C-terminal nuclease module. Domain swaps identified the EcoPrrC nuclease domain as decisive for toxicity when linked to either the Eco or Nme NTPase. Indeed, a single arginine-to-tryptophan change in the NmePrrC nuclease domain (R316W) educed a gain-of-function and rendered NmePrrC toxic to yeast, with genetic evidence for tRNA(Lys(UUU)) being the relevant target. The reciprocal Trp-to-Arg change in EcoPrrC (W335R) abolished its toxicity. Further mutagenesis of the EcoPrrC nuclease domain highlighted an ensemble of 15 essential residues and distinguished between hypomorphic alleles and potential nuclease-nulls. We report that the RNA repair phase of the bacterial virus-host dynamic is also portable to yeast, where coexpression of the T4 enzymes Pnkp and Rnl1 ameliorated the toxicity of NmePrrC-R316W. Plant tRNA ligase AtRNL also countered NmePrrC-R316W toxicity, in a manner that depended on AtRNL's 5'-kinase and ligase functions.
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Affiliation(s)
- Birthe Meineke
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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11
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Nawrot B, Sochacka E, Düchler M. tRNA structural and functional changes induced by oxidative stress. Cell Mol Life Sci 2011; 68:4023-32. [PMID: 21833586 PMCID: PMC3221842 DOI: 10.1007/s00018-011-0773-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 07/04/2011] [Accepted: 07/07/2011] [Indexed: 11/29/2022]
Abstract
Oxidatively damaged biomolecules impair cellular functions and contribute to the pathology of a variety of diseases. RNA is also attacked by reactive oxygen species, and oxidized RNA is increasingly recognized as an important contributor to neurodegenerative complications in humans. Recently, evidence has accumulated supporting the notion that tRNA is involved in cellular responses to various stress conditions. This review focuses on the intriguing consequences of oxidative modification of tRNA at the structural and functional level.
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Affiliation(s)
- Barbara Nawrot
- Department of Bioorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 112, Sienkiewicza Street, 90-363 Lodz, Poland
| | - Elzbieta Sochacka
- Institute of Organic Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz, Poland
| | - Markus Düchler
- Department of Bioorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 112, Sienkiewicza Street, 90-363 Lodz, Poland
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12
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Uzan M, Miller ES. Post-transcriptional control by bacteriophage T4: mRNA decay and inhibition of translation initiation. Virol J 2010; 7:360. [PMID: 21129205 PMCID: PMC3014915 DOI: 10.1186/1743-422x-7-360] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 12/03/2010] [Indexed: 01/02/2023] Open
Abstract
Over 50 years of biological research with bacteriophage T4 includes notable discoveries in post-transcriptional control, including the genetic code, mRNA, and tRNA; the very foundations of molecular biology. In this review we compile the past 10 - 15 year literature on RNA-protein interactions with T4 and some of its related phages, with particular focus on advances in mRNA decay and processing, and on translational repression. Binding of T4 proteins RegB, RegA, gp32 and gp43 to their cognate target RNAs has been characterized. For several of these, further study is needed for an atomic-level perspective, where resolved structures of RNA-protein complexes are awaiting investigation. Other features of post-transcriptional control are also summarized. These include: RNA structure at translation initiation regions that either inhibit or promote translation initiation; programmed translational bypassing, where T4 orchestrates ribosome bypass of a 50 nucleotide mRNA sequence; phage exclusion systems that involve T4-mediated activation of a latent endoribonuclease (PrrC) and cofactor-assisted activation of EF-Tu proteolysis (Gol-Lit); and potentially important findings on ADP-ribosylation (by Alt and Mod enzymes) of ribosome-associated proteins that might broadly impact protein synthesis in the infected cell. Many of these problems can continue to be addressed with T4, whereas the growing database of T4-related phage genome sequences provides new resources and potentially new phage-host systems to extend the work into a broader biological, evolutionary context.
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Affiliation(s)
- Marc Uzan
- Department of Microbiology, North Carolina State University, Raleigh, NC 27695-7615, USA
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13
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Meineke B, Schwer B, Schaffrath R, Shuman S. Determinants of eukaryal cell killing by the bacterial ribotoxin PrrC. Nucleic Acids Res 2010; 39:687-700. [PMID: 20855293 PMCID: PMC3025547 DOI: 10.1093/nar/gkq831] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
tRNA damage inflicted by the Escherichia coli anticodon nuclease PrrC (EcoPrrC) underlies an antiviral response to phage T4 infection. PrrC homologs are present in many bacterial proteomes, though their biological activities are uncharted. PrrCs consist of two domains: an N-terminal NTPase module related to the ABC family and a distinctive C-terminal ribonuclease module. In this article, we report that the expression of EcoPrrC in budding yeast is fungicidal, signifying that PrrC is toxic in a eukaryon in the absence of other bacterial or viral proteins. Whereas Streptococcus PrrC is also toxic in yeast, Neisseria and Xanthomonas PrrCs are not. Via analysis of the effects of 118 mutations on EcoPrrC toxicity in yeast, we identified 22 essential residues in the NTPase domain and 11 in the nuclease domain. Overexpressing PrrCs with mutations in the NTPase active site ameliorated the toxicity of wild-type EcoPrrC. Our findings support a model in which EcoPrrC toxicity is contingent on head-to-tail dimerization of the NTPase domains to form two composite NTP phosphohydrolase sites. Comparisons of EcoPrrC activity in a variety of yeast genetic backgrounds, and the rescuing effects of tRNA overexpression, implicate tRNALys(UUU) as a target of EcoPrrC toxicity in yeast.
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Affiliation(s)
- Birthe Meineke
- Molecular Biology Program, Sloan-Kettering Institute, Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065 USA and Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Beate Schwer
- Molecular Biology Program, Sloan-Kettering Institute, Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065 USA and Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Raffael Schaffrath
- Molecular Biology Program, Sloan-Kettering Institute, Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065 USA and Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065 USA and Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
- *To whom correspondence should be addressed. Tel: +1 212 639 7145; Fax: +1 212 717 3623;
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14
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Keppetipola N, Jain R, Meineke B, Diver M, Shuman S. Structure-activity relationships in Kluyveromyces lactis gamma-toxin, a eukaryal tRNA anticodon nuclease. RNA (NEW YORK, N.Y.) 2009; 15:1036-44. [PMID: 19383764 PMCID: PMC2685522 DOI: 10.1261/rna.1637809] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Accepted: 03/27/2009] [Indexed: 05/23/2023]
Abstract
tRNA anticodon damage inflicted by secreted ribotoxins such as Kluyveromyces lactis gamma-toxin and bacterial colicins underlies a rudimentary innate immune system that distinguishes self from nonself species. The intracellular expression of gamma-toxin (a 232-amino acid polypeptide) arrests the growth of Saccharomyces cerevisiae by incising a single RNA phosphodiester 3' of the modified wobble base of tRNA(Glu). Fungal gamma-toxin bears no primary structure similarity to any known nuclease and has no plausible homologs in the protein database. To gain insight to gamma-toxin's mechanism, we tested the effects of alanine mutations at 62 basic, acidic, and polar amino acids on ribotoxin activity in vivo. We thereby identified 22 essential residues, including 10 lysines, seven arginines, three glutamates, one cysteine, and one histidine (His209, the only histidine present in gamma-toxin). Structure-activity relations were gleaned from the effects of 44 conservative substitutions. Recombinant tag-free gamma-toxin, a monomeric protein, incised an oligonucleotide corresponding to the anticodon stem-loop of tRNA(Glu) at a single phosphodiester 3' of the wobble uridine. The anticodon nuclease was metal independent. RNA cleavage was abolished by ribose 2'-H and 2'-F modifications of the wobble uridine. Mutating His209 to alanine, glutamine, or asparagine abolished nuclease activity. We propose that gamma-toxin catalyzes an RNase A-like transesterification reaction that relies on His209 and a second nonhistidine side chain as general acid-base catalysts.
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15
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Abstract
The conserved bacterial protein RloC, a distant homologue of the tRNALys anticodon nuclease (ACNase) PrrC, is shown here to act as a wobble nucleotide-excising and Zn++-responsive tRNase. The more familiar PrrC is silenced by a genetically linked type I DNA restriction-modification (R-M) enzyme, activated by a phage anti-DNA restriction factor and counteracted by phage tRNA repair enzymes. RloC shares PrrC's ABC ATPase motifs and catalytic ACNase triad but features a distinct zinc-hook/coiled-coil insert that renders its ATPase domain similar to Rad50 and related DNA repair proteins. Geobacillus kaustophilus RloC expressed in Escherichia coli exhibited ACNase activity that differed from PrrC's in substrate preference and ability to excise the wobble nucleotide. The latter specificity could impede reversal by phage tRNA repair enzymes and account perhaps for RloC's more frequent occurrence. Mutagenesis and functional assays confirmed RloC's catalytic triad assignment and implicated its zinc hook in regulating the ACNase function. Unlike PrrC, RloC is rarely linked to a type I R-M system but other genomic attributes suggest their possible interaction in trans. As DNA damage alleviates type I DNA restriction, we further propose that these related perturbations prompt RloC to disable translation and thus ward off phage escaping DNA restriction during the recovery from DNA damage.
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Affiliation(s)
- Elena Davidov
- Department of Biochemistry, Tel Aviv University, Ramat Aviv 69978, Israel
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16
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Abstract
Growth inhibition of Saccharomyces cerevisiae by the plasmid-encoded trimeric (alphabetagamma) zymocin toxin from dairy yeast, Kluyveromyces lactis, depends on a multistep response pathway in budding yeast. Following early processes that mediate cell-surface contact by the chitinase alpha-subunit of zymocin, later steps enable import of the gamma-toxin tRNase subunit and cleavage of target tRNAs that carry modified U34 (wobble uridine) bases. With the emergence of zymocin-like toxins, continued zymocin research is expected to yield new insights into the evolution of yeast pathosystems and their lethal modes of action.
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17
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Lu J, Esberg A, Huang B, Byström AS. Kluyveromyces lactis gamma-toxin, a ribonuclease that recognizes the anticodon stem loop of tRNA. Nucleic Acids Res 2007; 36:1072-80. [PMID: 18096622 PMCID: PMC2275089 DOI: 10.1093/nar/gkm1121] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Kluyveromyces lactis γ-toxin is a tRNA endonuclease that cleaves Saccharomyces cerevisiaetRNAmcm5s2UUCGlu3, tRNAmcm5s2UUULys and tRNAmcm5s2UUGGln between position 34 and position 35. All three substrate tRNAs carry a 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) residue at position 34 (wobble position) of which the mcm5 group is required for efficient cleavage. However, the different cleavage efficiencies of mcm5s2U34-containing tRNAs suggest that additional features of these tRNAs affect cleavage. In the present study, we show that a stable anticodon stem and the anticodon loop are the minimal requirements for cleavage by γ-toxin. A synthetic minihelix RNA corresponding to the anticodon stem loop (ASL) of the natural substrate tRNAmcm5s2UUCGlu3 is cleaved at the same position as the natural substrate. In ASLUUCGlu3, the nucleotides U34U35C36A37C38 are required for optimal γ-toxin cleavage, whereas a purine at position 32 or a G in position 33 dramatically reduces the cleavage of the ASL. Comparing modified and partially modified forms of E. coli and yeast tRNAUUCGlu reinforced the strong stimulatory effects of the mcm5 group, revealed a weak positive effect of the s2 group and a negative effect of the bacterial 5-methylaminomethyl (mnm5) group. The data underscore the high specificity of this yeast tRNA toxin.
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Affiliation(s)
- Jian Lu
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
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18
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Suhasini AN, Sirdeshmukh R. Onconase action on tRNA(Lys3), the primer for HIV-1 reverse transcription. Biochem Biophys Res Commun 2007; 363:304-9. [PMID: 17888404 DOI: 10.1016/j.bbrc.2007.08.157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2007] [Accepted: 08/23/2007] [Indexed: 11/20/2022]
Abstract
Onconase, a cytotoxic and antitumor RNase inhibits viral replication in chronically HIV-1-infected human cells under sub lethal concentrations. Cellular tRNA has been implicated as the target for onconase action. We have recently shown that onconase cleaves selectively at GG residues in the UGG context in the variable loop and D-arm of the tRNA substrates. We therefore examined onconase cleavage specificity in in vitro transcribed tRNA(Lys3), which is the primer for HIV-1 reverse transcription but does not have UGG anywhere in its sequence. Onconase was found to cleave tRNA(Lys3) predominantly at the GG residues in the GGG triplet present in the variable loop. Mutations at this site did not effect onconase cleavages. Interestingly thus, onconase seems to cleave predominantly in the variable loop of tRNA(Lys3) regardless of the sequence context implying possible contribution of even structural determinants for its selective cleavages.
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Affiliation(s)
- Avvaru N Suhasini
- Center for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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19
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Klaiman D, Amitsur M, Blanga-Kanfi S, Chai M, Davis DR, Kaufmann G. Parallel dimerization of a PrrC-anticodon nuclease region implicated in tRNALys recognition. Nucleic Acids Res 2007; 35:4704-14. [PMID: 17604307 PMCID: PMC1950546 DOI: 10.1093/nar/gkm494] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The optional Escherichia coli restriction tRNase PrrC represents a family of potential antiviral devices widespread among bacteria. PrrC comprises a functional C-domain of unknown structure and regulatory ABC/ATPase-like N-domain. The possible involvement of a C-domain sequence in tRNALys recognition was investigated using a matching end-protected 11-meric peptide. This mimic, termed here LARP (Lys-anticodon recognizing peptide) UV-cross-linked tRNALys anticodon stem-loop (ASL) analogs and inhibited their PrrC-catalyzed cleavage. Trimming LARP or introducing in it inactivating PrrC missense mutations impaired these activities. LARP appeared to mimic its matching protein sequence in ability to dimerize in parallel, as inferred from the following results. First, tethering Cys to the amino- or carboxy-end of LARP dramatically enhanced the ASL-cross-linking and PrrC-inhibiting activities under suitable redox conditions. Second, Cys-substitutions in a C-domain region containing the sequence corresponding to LARP elicited specific intersubunit cross-links. The parallel dimerization of PrrC's C-domains and expected head-to-tail dimerization of its N-domains further suggest that the NTPase and tRNALys-binding sites of PrrC arise during distinct assembly stages of its dimer of dimers form.
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Affiliation(s)
- Daniel Klaiman
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
| | - Michal Amitsur
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
| | - Shani Blanga-Kanfi
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
| | - Michal Chai
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
| | - Darrell R. Davis
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
| | - Gabriel Kaufmann
- Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel and Department of Medicinal Chemistry, University of Utah, Salt Lake City, 84112 UT, USA
- *To whom correspondence should be addressed.+1 972 3 642 6213+1 972 3 640 6834
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20
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Blanga-Kanfi S, Amitsur M, Azem A, Kaufmann G. PrrC-anticodon nuclease: functional organization of a prototypical bacterial restriction RNase. Nucleic Acids Res 2006; 34:3209-19. [PMID: 16790566 PMCID: PMC1484252 DOI: 10.1093/nar/gkl415] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The tRNALys anticodon nuclease PrrC is associated in latent form with the type Ic DNA restriction endonuclease EcoprrI and activated by a phage T4-encoded inhibitor of EcoprrI. The activation also requires the hydrolysis of GTP and presence of dTTP and is inhibited by ATP. The N-proximal NTPase domain of PrrC has been implicated in relaying the activating signal to a C-proximal anticodon nuclease site by interacting with the requisite nucleotide cofactors [Amitsur et al. (2003) Mol. Microbiol., 50, 129–143]. Means described here to bypass PrrC's self-limiting translation and thermal instability allowed purifying an active mutant form of the protein, demonstrating its oligomeric structure and confirming its anticipated interactions with the nucleotide cofactors of the activation reaction. Mutagenesis and chemical rescue data shown implicate the C-proximal Arg320, Glu324 and, possibly, His356 in anticodon nuclease catalysis. This triad exists in all the known PrrC homologs but only some of them feature residues needed for tRNALys recognition by the Escherichia coli prototype. The differential conservation and consistent genetic linkage of the PrrC proteins with EcoprrI homologs portray them as a family of restriction RNases of diverse substrate specificities that are mobilized when an associated DNA restriction nuclease is compromised.
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Affiliation(s)
| | | | | | - Gabriel Kaufmann
- To whom correspondence should be addressed. Tel: 972 3 642 6213; Fax: 972 3 640 6834;
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Lu J, Huang B, Esberg A, Johansson MJO, Byström AS. The Kluyveromyces lactis gamma-toxin targets tRNA anticodons. RNA (NEW YORK, N.Y.) 2005; 11:1648-54. [PMID: 16244131 PMCID: PMC1370851 DOI: 10.1261/rna.2172105] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Kluyveromyces lactis killer strains secrete a heterotrimeric toxin (zymocin), which causes an irreversible growth arrest of sensitive yeast cells. Despite many efforts, the target(s) of the cytotoxic gamma-subunit of zymocin has remained elusive. Here we show that three tRNA species tRNA(Glu)(mcm(5)s(2)UUC), tRNA(Lys)(mcm(5)s(2)UUU), and tRNA(Gln)(mcm(5)s(2)UUG) are the targets of gamma-toxin. The toxin inhibits growth by cleaving these tRNAs at the 3' side of the modified wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U). Transfer RNA lacking a part of or the entire mcm(5) group is inefficiently cleaved by gamma-toxin, explaining the gamma-toxin resistance of the modification-deficient trm9, elp1-elp6, and kti11-kti13 mutants. The K. lactis gamma-toxin is the first eukaryotic toxin shown to target tRNA.
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Affiliation(s)
- Jian Lu
- Department of Molecular Biology, Umeå University, Sweden
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Amitsur M, Benjamin S, Rosner R, Chapman-Shimshoni D, Meidler R, Blanga S, Kaufmann G. Bacteriophage T4-encoded Stp can be replaced as activator of anticodon nuclease by a normal host cell metabolite. Mol Microbiol 2003; 50:129-43. [PMID: 14507369 DOI: 10.1046/j.1365-2958.2003.03691.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The bacterial tRNALys-specific anticodon nuclease is known as a phage T4 exclusion system. In the uninfected host cell anticodon nuclease is kept latent due to the association of its core protein PrrC with the DNA restriction-modification endonuclease EcoprrI. Stp, the T4-encoded peptide inhibitor of EcoprrI activates the latent enzyme. Previous in vitro work indicated that the activation by Stp is sensitive to DNase and requires added nucleotides. Biochemical and mutational data reported here suggest that Stp activates the latent holoenzyme when its EcoprrI component is tethered to a cognate DNA substrate. Moreover, the activation is driven by GTP hydrolysis, possibly mediated by the NTPase domain of PrrC. The data also reveal that Stp can be replaced as the activator of latent anticodon nuclease by certain pyrimidine nucleotides, the most potent of which is dTTP. The activation by dTTP likewise requires an EcoprrI DNA substrate and GTP hydrolysis but involves a different form of the latent holoenzyme/DNA complex. Moreover, whereas Stp relays its activating effect through EcoprrI, dTTP targets PrrC. The activation of the latent enzyme by a normal cell constituent hints that anticodon nuclease plays additional roles, other than warding off phage T4 infection.
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Affiliation(s)
- Michal Amitsur
- Department of Biochemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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23
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Abstract
Colicins E5 and D cleave the anticodon loops of distinct tRNAs of Escherichia coli both in vivo and in vitro, which accounts for their bactericidal actions through depletion of tRNAs and prevention of protein synthesis. The targets of colicin E5 are five tRNA species for four amino acids, tyrosine, histidine, asparagine and aspartic acid, and those of colicin D are four isoaccepting tRNAs for arginine. These two colicins represent a new class, the "tRNase-type", of the nuclease-type colicins, which previously comprised the DNase-type and ribotoxin-type (or rRNase-type). On the other hand, a certain clinical E. coli strain produces a potentially suicidal "anticodon-nuclease", PrrC, in response to phage T4 infection, which specifically cleaves its own lysine tRNA. For these three tRNases, i.e. colicins E5 and D, and PrrC, the substrates and reaction products, as well as their physiological consequences, are very similar to each other, but so many molecular features are different that these three proteins are assumed to have acquired similar functions through evolutionary convergence from different origins.
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Affiliation(s)
- Haruhiko Masaki
- Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
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