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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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Hespanhol JT, Karman L, Sanchez-Limache DE, Bayer-Santos E. Intercepting biological messages: Antibacterial molecules targeting nucleic acids during interbacterial conflicts. Genet Mol Biol 2023; 46:e20220266. [PMID: 36880694 PMCID: PMC9990079 DOI: 10.1590/1678-4685-gmb-2022-0266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/25/2022] [Indexed: 03/08/2023] Open
Abstract
Bacteria live in polymicrobial communities and constantly compete for resources. These organisms have evolved an array of antibacterial weapons to inhibit the growth or kill competitors. The arsenal comprises antibiotics, bacteriocins, and contact-dependent effectors that are either secreted in the medium or directly translocated into target cells. During bacterial antagonistic encounters, several cellular components important for life become a weak spot prone to an attack. Nucleic acids and the machinery responsible for their synthesis are well conserved across the tree of life. These molecules are part of the information flow in the central dogma of molecular biology and mediate long- and short-term storage for genetic information. The aim of this review is to summarize the diversity of antibacterial molecules that target nucleic acids during antagonistic interbacterial encounters and discuss their potential to promote the emergence antibiotic resistance.
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Affiliation(s)
- Julia Takuno Hespanhol
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Lior Karman
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | | | - Ethel Bayer-Santos
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
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3
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Maviza TP, Zarechenskaia AS, Burmistrova NR, Tchoub AS, Dontsova OA, Sergiev PV, Osterman IA. RtcB2-PrfH Operon Protects E. coli ATCC25922 Strain from Colicin E3 Toxin. Int J Mol Sci 2022; 23:6453. [PMID: 35742896 PMCID: PMC9223846 DOI: 10.3390/ijms23126453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/28/2022] [Accepted: 06/07/2022] [Indexed: 02/01/2023] Open
Abstract
In the bid to survive and thrive in an environmental setting, bacterial species constantly interact and compete for resources and space in the microbial ecosystem. Thus, they have adapted to use various antibiotics and toxins to fight their rivals. Simultaneously, they have evolved an ability to withstand weapons that are directed against them. Several bacteria harbor colicinogenic plasmids which encode toxins that impair the translational apparatus. One of them, colicin E3 ribotoxin, mediates cleavage of the 16S rRNA in the decoding center of the ribosome. In order to thrive upon deployment of such ribotoxins, competing bacteria may have evolved counter-conflict mechanisms to prevent their demise. A recent study demonstrated the role of PrfH and the RtcB2 module in rescuing a damaged ribosome and the subsequent re-ligation of the cleaved 16S rRNA by colicin E3 in vitro. The rtcB2-prfH genes coexist as gene neighbors in an operon that is sporadically spread among different bacteria. In the current study, we report that the RtcB2-PrfH module confers resistance to colicin E3 toxicity in E. coli ATCC25922 cells in vivo. We demonstrated that the viability of E. coli ATCC25922 strain that is devoid of rtcB2 and prfH genes is impaired upon action of colicin E3, in contrast to the parental strain which has intact rtcB2 and prfH genes. Complementation of the rtcB2 and prfH gene knockout with a high copy number-plasmid (encoding either rtcB2 alone or both rtcB2-prfH operon) restored resistance to colicin E3. These results highlight a counter-conflict system that may have evolved to thwart colicin E3 activity.
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Affiliation(s)
- Tinashe P. Maviza
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 121205, Russia; (T.P.M.); (A.S.Z.); (O.A.D.); (P.V.S.)
| | - Anastasiia S. Zarechenskaia
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 121205, Russia; (T.P.M.); (A.S.Z.); (O.A.D.); (P.V.S.)
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
| | - Nadezhda R. Burmistrova
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
| | - Andrey S. Tchoub
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
| | - Olga A. Dontsova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 121205, Russia; (T.P.M.); (A.S.Z.); (O.A.D.); (P.V.S.)
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 119992, Russia
| | - Petr V. Sergiev
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 121205, Russia; (T.P.M.); (A.S.Z.); (O.A.D.); (P.V.S.)
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
| | - Ilya A. Osterman
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 121205, Russia; (T.P.M.); (A.S.Z.); (O.A.D.); (P.V.S.)
- Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; (N.R.B.); (A.S.T.)
- Genetics and Life Sciences Research Center, Sirius University of Science and Technology, 1 Olympic Ave., Sochi 354340, Russia
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Structure of Schlafen13 reveals a new class of tRNA/rRNA- targeting RNase engaged in translational control. Nat Commun 2018; 9:1165. [PMID: 29563550 PMCID: PMC5862951 DOI: 10.1038/s41467-018-03544-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/20/2018] [Indexed: 01/07/2023] Open
Abstract
Cleavage of transfer (t)RNA and ribosomal (r)RNA are critical and conserved steps of translational control for cells to overcome varied environmental stresses. However, enzymes that are responsible for this event have not been fully identified in high eukaryotes. Here, we report a mammalian tRNA/rRNA-targeting endoribonuclease: SLFN13, a member of the Schlafen family. Structural study reveals a unique pseudo-dimeric U-pillow-shaped architecture of the SLFN13 N'-domain that may clamp base-paired RNAs. SLFN13 is able to digest tRNAs and rRNAs in vitro, and the endonucleolytic cleavage dissevers 11 nucleotides from the 3'-terminus of tRNA at the acceptor stem. The cytoplasmically localised SLFN13 inhibits protein synthesis in 293T cells. Moreover, SLFN13 restricts HIV replication in a nucleolytic activity-dependent manner. According to these observations, we term SLFN13 RNase S13. Our study provides insights into the modulation of translational machinery in high eukaryotes, and sheds light on the functional mechanisms of the Schlafen family.
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Ogawa T. tRNA-targeting ribonucleases: molecular mechanisms and insights into their physiological roles. Biosci Biotechnol Biochem 2016; 80:1037-45. [PMID: 26967967 DOI: 10.1080/09168451.2016.1148579] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Most bacteria produce antibacterial proteins known as bacteriocins, which aid bacterial defence systems to provide a physiological advantage. To date, many kinds of bacteriocins have been characterized. Colicin has long been known as a plasmidborne bacteriocin that kills other Escherichia coli cells lacking the same plasmid. To defeat other cells, colicins exert specific activities such as ion-channel, DNase, and RNase activity. Colicin E5 and colicin D impair protein synthesis in sensitive E. coli cells; however, their physiological targets have not long been identified. This review describes our finding that colicins E5 and D are novel RNases targeting specific E. coli tRNAs and elucidates their enzymatic properties based on biochemical analyses and X-ray crystal structures. Moreover, tRNA cleavage mediates bacteriostasis, which depends on trans-translation. Based on these results and others, cell growth regulation depending on tRNA cleavage is also discussed.
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Affiliation(s)
- Tetsuhiro Ogawa
- a Department of Biotechnology , The University of Tokyo , Tokyo , Japan
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6
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Beck CM, Diner EJ, Kim JJ, Low DA, Hayes CS. The F pilus mediates a novel pathway of CDI toxin import. Mol Microbiol 2014; 93:276-90. [PMID: 24889811 DOI: 10.1111/mmi.12658] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2014] [Indexed: 11/29/2022]
Abstract
Contact-dependent growth inhibition (CDI) is a widespread form of inter-bacterial competition that requires direct cell-to-cell contact. CDI(+) inhibitor cells express CdiA effector proteins on their surface. CdiA binds to specific receptors on susceptible target bacteria and delivers a toxin derived from its C-terminal region (CdiA-CT). Here, we show that purified CdiA-CT(536) toxin from uropathogenic Escherichia coli 536 translocates into bacteria, thereby by-passing the requirement for cell-to-cell contact during toxin delivery. Genetic analyses demonstrate that the N-terminal domain of CdiA-CT(536) is necessary and sufficient for toxin import. The CdiA receptor plays no role in this import pathway; nor do the Tol and Ton systems, which are exploited to internalize colicin toxins. Instead, CdiA-CT(536) import requires conjugative F pili. We provide evidence that the N-terminal domain of CdiA-CT(536) interacts with F pilin, and that pilus retraction is critical for toxin import. This pathway is reminiscent of the strategy used by small RNA leviviruses to infect F(+) cells. We propose that CdiA-CT(536) mimics the pilin-binding maturation proteins of leviviruses, allowing the toxin to bind F pili and become internalized during pilus retraction.
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Affiliation(s)
- Christina M Beck
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, 93106-9625, USA
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7
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Inoue-Ito S, Yajima S, Fushinobu S, Nakamura S, Ogawa T, Hidaka M, Masaki H. Identification of the catalytic residues of sequence-specific and histidine-free ribonuclease colicin E5. J Biochem 2012; 152:365-72. [PMID: 22815490 DOI: 10.1093/jb/mvs077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Colicin E5 cleaves tRNAs for Tyr, His, Asn and Asp in their anticodons to abolish protein synthesis in Escherichia coli. We previously showed how its C-terminal RNase domain, E5-CRD, recognizes the anticodon bases but the catalytic mechanism remained to be elucidated. Although the reaction products with 5'-OH and 2',3'-cyclic phosphate ends suggested a similar mechanism to those of RNases A and T1, E5-CRD does not have the His residues necessary as a catalyst in usual RNases. To identify residues important for the catalytic reaction, mutants as to all residues within 5 Å from the central phosphorus of the scissile phosphodiester bond were prepared. Evaluation of the killing activities of the mutant colicins and the RNase activities of the mutant E5-CRDs suggested direct involvement of Arg33, Lys25, Gln29 and Lys60 in the reaction. Particularly, Arg33 plays a critical role and Ile94 provides a structural support of Arg33. Crystal structure of the complex of E5-CRD(R33Q)/dGpdUp showed structural and binding functional integrity of this mutant protein, suggesting involvement of Arg33 in the catalytic reaction. The structure of the free E5-CRD, we also determined, showed great flexibility of a flap region, which facilitates the access of Lys60 to the substrate in an induced-fit manner.
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Affiliation(s)
- Sakura Inoue-Ito
- Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Tokyo 113-8654, Japan
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8
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Nikolakakis K, Amber S, Wilbur JS, Diner EJ, Aoki SK, Poole SJ, Tuanyok A, Keim PS, Peacock S, Hayes CS, Low DA. The toxin/immunity network of Burkholderia pseudomallei contact-dependent growth inhibition (CDI) systems. Mol Microbiol 2012; 84:516-29. [PMID: 22435733 DOI: 10.1111/j.1365-2958.2012.08039.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Burkholderia pseudomallei is a category B pathogen and the causative agent of melioidosis--a serious infectious disease that is typically acquired directly from environmental reservoirs. Nearly all B. pseudomallei strains sequenced to date (> 85 isolates) contain gene clusters that are related to the contact-dependent growth inhibition (CDI) systems of γ-proteobacteria. CDI systems from Escherichia coli and Dickeya dadantii play significant roles in bacterial competition, suggesting these systems may also contribute to the competitive fitness of B. pseudomallei. Here, we identify 10 distinct CDI systems in B. pseudomallei based on polymorphisms within the cdiA-CT/cdiI coding regions, which are predicted to encode CdiA-CT/CdiI toxin/immunity protein pairs. Biochemical analysis of three B. pseudomallei CdiA-CTs revealed that each protein possesses a distinct tRNase activity capable of inhibiting cell growth. These toxin activities are blocked by cognate CdiI immunity proteins, which specifically bind the CdiA-CT and protect cells from growth inhibition. Using Burkholderia thailandensis E264 as a model, we show that a CDI system from B. pseudomallei 1026b mediates CDI and is capable of delivering CdiA-CT toxins derived from other B. pseudomallei strains. These results demonstrate that Burkholderia species contain functional CDI systems, which may confer a competitive advantage to these bacteria.
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Affiliation(s)
- Kiel Nikolakakis
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
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9
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Abstract
It is more than 80 years since Gratia first described 'a remarkable antagonism between two strains of Escherichia coli'. Shown subsequently to be due to the action of proteins (or peptides) produced by one bacterium to kill closely related species with which it might be cohabiting, such bacteriocins have since been shown to be commonplace in the internecine warfare between bacteria. Bacteriocins have been studied primarily from the twin perspectives of how they shape microbial communities and how they penetrate bacteria to kill them. Here, we review the modes of action of a family of bacteriocins that cleave nucleic acid substrates in E. coli, known collectively as nuclease colicins, and the specific immunity (inhibitor) proteins that colicin-producing organisms make in order to avoid committing suicide. In a process akin to targeting in mitochondria, nuclease colicins engage in a variety of cellular associations in order to translocate their cytotoxic domains through the cell envelope to the cytoplasm. As well as informing on the process itself, the study of nuclease colicin import has also illuminated functional aspects of the host proteins they parasitize. We also review recent studies where nuclease colicins and their immunity proteins have been used as model systems for addressing fundamental problems in protein folding and protein-protein interactions, areas of biophysics that are intimately linked to the role of colicins in bacterial competition and to the import process itself.
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10
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Crystal Structure of the Antitoxin–Toxin Protein Complex RelB–RelE from Methanococcus jannaschii. J Mol Biol 2009; 393:898-908. [DOI: 10.1016/j.jmb.2009.08.048] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 08/04/2009] [Accepted: 08/18/2009] [Indexed: 12/15/2022]
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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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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: 66] [Impact Index Per Article: 4.1] [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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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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14
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Keppetipola N, Shuman S. Characterization of the 2',3' cyclic phosphodiesterase activities of Clostridium thermocellum polynucleotide kinase-phosphatase and bacteriophage lambda phosphatase. Nucleic Acids Res 2007; 35:7721-32. [PMID: 17986465 PMCID: PMC2190708 DOI: 10.1093/nar/gkm868] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium thermocellum polynucleotide kinase-phosphatase (CthPnkp) catalyzes 5′ and 3′ end-healing reactions that prepare broken RNA termini for sealing by RNA ligase. The central phosphatase domain of CthPnkp belongs to the dinuclear metallophosphoesterase superfamily exemplified by bacteriophage λ phosphatase (λ-Pase). CthPnkp is a Ni2+/Mn2+-dependent phosphodiesterase-monoesterase, active on nucleotide and non-nucleotide substrates, that can be transformed toward narrower metal and substrate specificities via mutations of the active site. Here we characterize the Mn2+-dependent 2′,3′ cyclic nucleotide phosphodiesterase activity of CthPnkp, the reaction most relevant to RNA repair pathways. We find that CthPnkp prefers a 2′,3′ cyclic phosphate to a 3′,5′ cyclic phosphate. A single H189D mutation imposes strict specificity for a 2′,3′ cyclic phosphate, which is cleaved to form a single 2′-NMP product. Analysis of the cyclic phosphodiesterase activities of mutated CthPnkp enzymes illuminates the active site and the structural features that affect substrate affinity and kcat. We also characterize a previously unrecognized phosphodiesterase activity of λ-Pase, which catalyzes hydrolysis of bis-p-nitrophenyl phosphate. λ-Pase also has cyclic phosphodiesterase activity with nucleoside 2′,3′ cyclic phosphates, which it hydrolyzes to yield a mixture of 2′-NMP and 3′-NMP products. We discuss our results in light of available structural and functional data for other phosphodiesterase members of the binuclear metallophosphoesterase family and draw inferences about how differences in active site composition influence catalytic repertoire.
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15
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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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Cascales E, Buchanan SK, Duché D, Kleanthous C, Lloubès R, Postle K, Riley M, Slatin S, Cavard D. Colicin biology. Microbiol Mol Biol Rev 2007; 71:158-229. [PMID: 17347522 PMCID: PMC1847374 DOI: 10.1128/mmbr.00036-06] [Citation(s) in RCA: 784] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology are presented: their synthesis, which is under SOS regulation; their release into the extracellular medium, which involves the colicin lysis protein; and their uptake mechanisms and modes of action. Colicins are organized into three domains, each one involved in a different step of the process of killing sensitive bacteria. The structures of some colicins are known at the atomic level and are discussed. Colicins exert their lethal action by first binding to specific receptors, which are outer membrane proteins used for the entry of specific nutrients. They are then translocated through the outer membrane and transit through the periplasm by either the Tol or the TonB system. The components of each system are known, and their implication in the functioning of the system is described. Colicins then reach their lethal target and act either by forming a voltage-dependent channel into the inner membrane or by using their endonuclease activity on DNA, rRNA, or tRNA. The mechanisms of inhibition by specific and cognate immunity proteins are presented. Finally, the use of colicins as laboratory or biotechnological tools and their mode of evolution are discussed.
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Affiliation(s)
- Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires,Institut de Biologie Structurale et Microbiologie, Centre National de la Recherche Scientifique, UPR 9027, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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Yajima S, Inoue S, Ogawa T, Nonaka T, Ohsawa K, Masaki H. Structural basis for sequence-dependent recognition of colicin E5 tRNase by mimicking the mRNA-tRNA interaction. Nucleic Acids Res 2006; 34:6074-82. [PMID: 17099236 PMCID: PMC1669751 DOI: 10.1093/nar/gkl729] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Colicin E5—a tRNase toxin—specifically cleaves QUN (Q: queuosine) anticodons of the Escherichia coli tRNAs for Tyr, His, Asn and Asp. Here, we report the crystal structure of the C-terminal ribonuclease domain (CRD) of E5 complexed with a substrate analog, namely, dGpdUp, at a resolution of 1.9 Å. Thisstructure is the first to reveal the substrate recognition mechanism of sequence-specific ribonucleases. E5-CRD realized the strict recognition for both the guanine and uracil bases of dGpdUp forming Watson–Crick-type hydrogen bonds and ring stacking interactions, thus mimicking the codons of mRNAs to bind to tRNA anticodons. The docking model of E5-CRD with tRNA also suggests its substrate preference for tRNA over ssRNA. In addition, the structure of E5-CRD/dGpdUp along with the mutational analysis suggests that Arg33 may play an important role in the catalytic activity, and Lys25/Lys60 may also be involved without His in E5-CRD. Finally, the comparison of the structures of E5-CRD/dGpdUp and E5-CRD/ImmE5 (an inhibitor protein) complexes suggests that the binding mode of E5-CRD and ImmE5 mimics that of mRNA and tRNA; this may represent the evolutionary pathway of these proteins from the RNA–RNA interaction through the RNA–protein interaction of tRNA/E5-CRD.
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Affiliation(s)
- Shunsuke Yajima
- Department of Bioscience, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya-ku, Tokyo 156-8502, Japan.
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Ogawa T, Inoue S, Yajima S, Hidaka M, Masaki H. Sequence-specific recognition of colicin E5, a tRNA-targeting ribonuclease. Nucleic Acids Res 2006; 34:6065-73. [PMID: 16963495 PMCID: PMC1635277 DOI: 10.1093/nar/gkl629] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Colicin E5 is a novel Escherichia coli ribonuclease that specifically cleaves the anticodons of tRNA(Tyr), tRNA(His), tRNA(Asn) and tRNA(Asp). Since this activity is confined to its 115 amino acid long C-terminal domain (CRD), the recognition mechanism of E5-CRD is of great interest. The four tRNA substrates share the unique sequence UQU within their anticodon loops, and are cleaved between Q (modified base of G) and 3' U. Synthetic minihelix RNAs corresponding to the substrate tRNAs were completely susceptible to E5-CRD and were cleaved in the same manner as the authentic tRNAs. The specificity determinant for E5-CRD was YGUN at -1 to +3 of the 'anticodon'. The YGU is absolutely required and the extent of susceptibility of minihelices depends on N (third letter of the anticodon) in the order A > C > G > U accounting for the order of susceptibility tRNA(Tyr) > tRNA(Asp) > tRNA(His), tRNA(Asn). Contrastingly, we showed that GpUp is the minimal substrate strictly retaining specificity to E5-CRD. The effect of contiguous nucleotides is inconsistent between the loop and linear RNAs, suggesting that nucleotide extension on each side of GpUp introduces a structural constraint, which is reduced by a specific loop structure formation that includes a 5' pyrimidine and 3' A.
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Affiliation(s)
- Tetsuhiro Ogawa
- Department of Biotechnology, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Luna-Chávez C, Lin YL, Huang RH. Molecular Basis of Inhibition of the Ribonuclease Activity in Colicin E5 by Its Cognate Immunity Protein. J Mol Biol 2006; 358:571-9. [PMID: 16524591 DOI: 10.1016/j.jmb.2006.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 01/31/2006] [Accepted: 02/06/2006] [Indexed: 10/25/2022]
Abstract
Colicin E5 is a tRNA-specific ribonuclease that recognizes and cleaves four tRNAs in Escherichia coli that contain the hypermodified nucleoside queuosine (Q) at the wobble position. Cells that produce colicin E5 also synthesize the cognate immunity protein (Im5) that rapidly and tightly associates with colicin E5 to prevent it from cleaving its own tRNAs to avoid suicide. We report here the crystal structure of Im5 in a complex with the activity domain of colicin E5 (E5-CRD) at 1.15A resolution. The structure reveals an extruded domain from Im5 that docks into the recessed RNA binding cleft in E5-CRD, resulting in extensive interactions between the two proteins. The interactions are primarily hydrophilic, with an interface that contains complementary surface charges between the two proteins. Detailed interactions in three separate regions of the interface account for specific recognition of colicin E5 by Im5. Furthermore, single-site mutational studies of Im5 confirmed the important role of particular residues in recognition and binding of colicin E5. Structural comparison of the complex reported here with E5-CRD alone, as well as with a docking model of RNA-E5-CRD, indicates that Im5 achieves its inhibition by physically blocking the cleft in colicin E5 that engages the RNA substrate.
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Affiliation(s)
- César Luna-Chávez
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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