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Abaeva IS, Pestova TV, Hellen CUT. Genetic mechanisms underlying the structural elaboration and dissemination of viral internal ribosomal entry sites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.590008. [PMID: 38883778 PMCID: PMC11178006 DOI: 10.1101/2024.04.17.590008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Viral internal ribosomal entry sites (IRESs) form several classes that use distinct mechanisms to mediate end-independent initiation of translation. The origin of viral IRESs is a longstanding question. The simplest IRESs comprise tandem pseudoknots and occur in the intergenic region (IGR) of Dicistroviridae genomes (order Picornavirales ). Larger IGR IRESs contain additional elements that determine specific properties such as binding to the head of the ribosoma l 40S subunit. Metagenomic analyses reported here identified novel groups of structurally distinct IGR-like IRESs. The smallest of these (∼120nt long) comprise three pseudoknots and bind directly to the ribosomal P site. Others are up to 260nt long: insertions occurred at specific loci, possibly reflecting non-templated nucleotide insertion during replication. Various groups can be arranged in order, differing by the cumulative addition of single structural elements, suggesting an accretion mechanism for the structural elaboration of IRESs. Identification of chimeric IRESs implicates recombinational exchange of domains as a second mechanism for the diversification of IRES structure. Recombination likely also accounts for the presence of IGR-like IRESs at the 5'-end of some dicistrovirus-like genomes (e.g. Hangzhou dicistrovirus 3) and in the RNA genomes of Tombusviridae (order Tolivirales ), Marnaviridae (order Picornavirale s), and the 'Ripiresk' picorna-like clade (order Picornavirale s).
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2
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Hyun JS, Pun R, Park SJ, Lee BJ. Effect of Divalent Metal Ions on the Ribonuclease Activity of the Toxin Molecule HP0894 from Helicobacter pylori. Life (Basel) 2024; 14:225. [PMID: 38398734 PMCID: PMC10890551 DOI: 10.3390/life14020225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
Bacteria and archaea respond and adapt to environmental stress conditions by modulating the toxin-antitoxin (TA) system for survival. Within the bacterium Helicobacter pylori, the protein HP0894 is a key player in the HP0894-HP0895 TA system, in which HP0894 serves as a toxin and HP0895 as an antitoxin. HP0894 has intrinsic ribonuclease (RNase) activity that regulates gene expression and translation, significantly influencing bacterial physiology and survival. This activity is influenced by the presence of metal ions such as Mg2+. In this study, we explore the metal-dependent RNase activity of HP0894. Surprisingly, all tested metal ions lead to a reduction in RNase activity, with zinc ions (Zn2+) causing the most significant decrease. The secondary structure of HP0894 remained largely unaffected by Zn2+ binding, whereas structural rigidity was notably increased, as revealed using CD analysis. NMR characterized the Zn2+ binding, implicating numerous His, Asp, and Glu residues in HP0894. In summary, these results suggest that metal ions play a regulatory role in the RNase activity of HP0894, contributing to maintaining the toxin molecule in an inactive state under normal conditions.
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Affiliation(s)
- Ja-Shil Hyun
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Rabin Pun
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Sung Jean Park
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Bong-Jin Lee
- College of Pharmacy, Ajou University, 206 World Cup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
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3
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Nielsen MR, Brodersen DE. Structural Variations and Rearrangements in Bacterial Type II Toxin-Antitoxin Systems. Subcell Biochem 2024; 104:245-267. [PMID: 38963490 DOI: 10.1007/978-3-031-58843-3_11] [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: 07/05/2024]
Abstract
Bacteria encode a wide range of survival and immunity systems, including CRISPR-Cas, restriction-modification systems, and toxin-antitoxin systems involved in defence against bacteriophages, as well as survival during challenging growth conditions or exposure to antibiotics. Toxin-antitoxin (TA) systems are small two- or three-gene cassettes consisting of a metabolic regulator (the "toxin") and its associated antidote (the "antitoxin"), which also often functions as a transcriptional regulator. TA systems are widespread in the genomes of pathogens but are also present in commensal bacterial species and on plasmids. For mobile elements such as plasmids, TA systems play a role in maintenance, and increasing evidence now points to roles of chromosomal toxin-antitoxin systems in anti-phage defence. Moreover, the widespread occurrence of toxin-antitoxin systems in the genomes of pathogens has been suggested to relate to survival during host infection as well as in persistence during antibiotic treatment. Upon repeated exposure to antibiotics, TA systems have been shown to acquire point mutations as well as more dramatic rearrangements such as in-frame deletions with potential relevance for bacterial survival and pathogenesis. In this review, we present an overview of the known functional and structural consequences of mutations and rearrangements arising in bacterial toxin-antitoxin systems and discuss their relevance for survival and persistence of pathogenic species.
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Affiliation(s)
| | - Ditlev E Brodersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark.
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4
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Mogila I, Tamulaitiene G, Keda K, Timinskas A, Ruksenaite A, Sasnauskas G, Venclovas Č, Siksnys V, Tamulaitis G. Ribosomal stalk-captured CARF-RelE ribonuclease inhibits translation following CRISPR signaling. Science 2023; 382:1036-1041. [PMID: 38033086 DOI: 10.1126/science.adj2107] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/31/2023] [Indexed: 12/02/2023]
Abstract
Prokaryotic type III CRISPR-Cas antiviral systems employ cyclic oligoadenylate (cAn) signaling to activate a diverse range of auxiliary proteins that reinforce the CRISPR-Cas defense. Here we characterize a class of cAn-dependent effector proteins named CRISPR-Cas-associated messenger RNA (mRNA) interferase 1 (Cami1) consisting of a CRISPR-associated Rossmann fold sensor domain fused to winged helix-turn-helix and a RelE-family mRNA interferase domain. Upon activation by cyclic tetra-adenylate (cA4), Cami1 cleaves mRNA exposed at the ribosomal A-site thereby depleting mRNA and leading to cell growth arrest. The structures of apo-Cami1 and the ribosome-bound Cami1-cA4 complex delineate the conformational changes that lead to Cami1 activation and the mechanism of Cami1 binding to a bacterial ribosome, revealing unexpected parallels with eukaryotic ribosome-inactivating proteins.
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Affiliation(s)
- Irmantas Mogila
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Giedre Tamulaitiene
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Konstanty Keda
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Albertas Timinskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Audrone Ruksenaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Giedrius Sasnauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Česlovas Venclovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Virginijus Siksnys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Gintautas Tamulaitis
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
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5
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Abaeva IS, Young C, Warsaba R, Khan N, Tran L, Jan E, Pestova T, Hellen CT. The structure and mechanism of action of a distinct class of dicistrovirus intergenic region IRESs. Nucleic Acids Res 2023; 51:9294-9313. [PMID: 37427788 PMCID: PMC10516663 DOI: 10.1093/nar/gkad569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/06/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023] Open
Abstract
Internal ribosomal entry sites (IRESs) engage with the eukaryotic translation apparatus to promote end-independent initiation. We identified a conserved class of ∼150 nt long intergenic region (IGR) IRESs in dicistrovirus genomes derived from members of the phyla Arthropoda, Bryozoa, Cnidaria, Echinodermata, Entoprocta, Mollusca and Porifera. These IRESs, exemplified by Wenling picorna-like virus 2, resemble the canonical cricket paralysis virus (CrPV) IGR IRES in comprising two nested pseudoknots (PKII/PKIII) and a 3'-terminal pseudoknot (PKI) that mimics a tRNA anticodon stem-loop base-paired to mRNA. However, they are ∼50 nt shorter than CrPV-like IRESs, and PKIII is an H-type pseudoknot that lacks the SLIV and SLV stem-loops that are primarily responsible for the affinity of CrPV-like IRESs for the 40S ribosomal subunit and that restrict initial binding of PKI to its aminoacyl (A) site. Wenling-class IRESs bound strongly to 80S ribosomes but only weakly to 40S subunits. Whereas CrPV-like IRESs must be translocated from the A site to the peptidyl (P) site by elongation factor 2 for elongation to commence, Wenling-class IRESs bound directly to the P site of 80S ribosomes, and decoding begins without a prior translocation step. A chimeric CrPV clone containing a Wenling-class IRES was infectious, confirming that the IRES functioned in cells.
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Affiliation(s)
- Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Christina Young
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Reid Warsaba
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nadiyah Khan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Lan Vy Tran
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
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Chen Z, Yao J, Zhang P, Wang P, Ni S, Liu T, Zhao Y, Tang K, Sun Y, Qian Q, Wang X. Minimized antibiotic-free plasmid vector for gene therapy utilizing a new toxin-antitoxin system. Metab Eng 2023; 79:86-96. [PMID: 37451534 DOI: 10.1016/j.ymben.2023.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/28/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Approaches to improve plasmid-mediated transgene expression are needed for gene therapy and genetic immunization applications. The backbone sequences needed for the production of plasmids in bacterial hosts and the use of antibiotic resistance genes as selection markers represent biological safety risks. Here, we report the development of an antibiotic-free expression plasmid vector with a minimized backbone utilizing a new toxin-antitoxin (TA) system. The Rs_0636/Rs_0637 TA pair was derived from the coral-associated bacterium Roseivirga sp. The toxin gene is integrated into the chromosome of Escherichia coli host cells, and a recombinant mammalian expression plasmid is constructed by replacing the antibiotic resistance gene with the antitoxin gene Rs_0637 (here named Tiniplasmid). The Tiniplasmid system affords high selection efficiency (∼80%) for target gene insertion into the plasmid and has high plasmid stability in E. coli (at least 9 days) in antibiotic-free conditions. Furthermore, with the aim of reducing the size of the backbone sequence, we found that the antitoxin gene can be reduced to 153 bp without a significant reduction in selection efficiency. To develop its applications in gene therapy and DNA vaccines, the biosafety and efficiency of the Tiniplasmid-based eukaryotic gene delivery and expression were further evaluated in CHO-K1 cells. The results showed that Rs_0636/Rs_0637 has no cell toxicity and that the Tiniplasmid vector has a higher gene expression efficiency than the commercial vectors pCpGfree and pSTD in the eukaryotic cells. Altogether, the results demonstrate the potential of the Rs_0636/Rs_0637-based antibiotic-free plasmid vector for the development and production of safe and efficacious DNA vaccines.
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Affiliation(s)
- Zhe Chen
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianyun Yao
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China.
| | - Pingjing Zhang
- Maxirna (Shanghai) Pharmaceutical Co., Ltd., China; Shanghai Cell Therapy Group Co., Ltd, China
| | - Pengxia Wang
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China
| | - Songwei Ni
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tao Liu
- Maxirna (Shanghai) Pharmaceutical Co., Ltd., China; Shanghai Cell Therapy Group Co., Ltd, China
| | - Yi Zhao
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kaihao Tang
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China
| | - Yan Sun
- Shanghai University Mengchao Cancer Hospital, China
| | - Qijun Qian
- Maxirna (Shanghai) Pharmaceutical Co., Ltd., China; Shanghai Cell Therapy Group Co., Ltd, China; Shanghai University Mengchao Cancer Hospital, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bioresources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou, 511458, China.
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7
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Miścicka A, Lu K, Abaeva IS, Pestova TV, Hellen CUT. Initiation of translation on nedicistrovirus and related intergenic region IRESs by their factor-independent binding to the P site of 80S ribosomes. RNA (NEW YORK, N.Y.) 2023; 29:1051-1068. [PMID: 37041031 PMCID: PMC10275262 DOI: 10.1261/rna.079599.123] [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: 01/17/2023] [Accepted: 03/27/2023] [Indexed: 06/18/2023]
Abstract
Initiation of translation on many viral mRNAs occurs by noncanonical mechanisms that involve 5' end-independent binding of ribosomes to an internal ribosome entry site (IRES). The ∼190-nt-long intergenic region (IGR) IRES of dicistroviruses such as cricket paralysis virus (CrPV) initiates translation without Met-tRNAi Met or initiation factors. Advances in metagenomics have revealed numerous dicistrovirus-like genomes with shorter, structurally distinct IGRs, such as nedicistrovirus (NediV) and Antarctic picorna-like virus 1 (APLV1). Like canonical IGR IRESs, the ∼165-nt-long NediV-like IGRs comprise three domains, but they lack key canonical motifs, including L1.1a/L1.1b loops (which bind to the L1 stalk of the ribosomal 60S subunit) and the apex of stem-loop V (SLV) (which binds to the head of the 40S subunit). Domain 2 consists of a compact, highly conserved pseudoknot (PKIII) that contains a UACUA loop motif and a protruding CrPV-like stem--loop SLIV. In vitro reconstitution experiments showed that NediV-like IRESs initiate translation from a non-AUG codon and form elongation-competent 80S ribosomal complexes in the absence of initiation factors and Met-tRNAi Met Unlike canonical IGR IRESs, NediV-like IRESs bind directly to the peptidyl (P) site of ribosomes leaving the aminoacyl (A) site accessible for decoding. The related structures of NediV-like IRESs and their common mechanism of action indicate that they exemplify a distinct class of IGR IRES.
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Affiliation(s)
- Anna Miścicka
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Kristen Lu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
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8
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Pulido S, Rückert H, Falsone SF, Göbl C, Meyer NH, Zangger K. The membrane-binding bacterial toxin long direct repeat D inhibits protein translation. Biophys Chem 2023; 298:107040. [PMID: 37229877 DOI: 10.1016/j.bpc.2023.107040] [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: 02/28/2023] [Revised: 05/08/2023] [Accepted: 05/08/2023] [Indexed: 05/27/2023]
Abstract
Bacterial plasmids and chromosomes widely contain toxin-antitoxin (TA) loci, which are implicated in stress response, growth regulation and even tolerance to antibiotics and environmental stress. Type I TA systems consist of a stable toxin-expressing mRNA, which is counteracted by an unstable RNA antitoxin. The Long Direct Repeat (LDR-) D locus, a type I TA system of Escherichia Coli (E. coli) K12, encodes a 35 amino acid toxic peptide, LdrD. Despite being characterized as a bacterial toxin, causing rapid killing and nucleoid condensation, little was known about its function and its mechanism of toxicity. Here, we show that LdrD specifically interacts with ribosomes which potentially blocks translation. Indeed, in vitro translation of LdrD-coding mRNA greatly reduces translation efficiency. The structure of LdrD in a hydrophobic environment, similar to the one found in the interior of ribosomes was determined by NMR spectroscopy in 100% trifluoroethanol solution. A single compact α-helix was found which would fit nicely into the ribosomal exit tunnel. Therefore, we conclude that rather than destroying bacterial membranes, LdrD exerts its toxic activity by inhibiting protein synthesis through binding to the ribosomes.
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Affiliation(s)
- Sergio Pulido
- Institute of Chemistry, University of Graz, Graz, Austria; LifeFactors ZF S.A.S., Zona France Rionegro, Rionegro, Colombia
| | - Hanna Rückert
- Institute of Chemistry, University of Graz, Graz, Austria
| | - S Fabio Falsone
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Christoph Göbl
- Dept. of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - N Helge Meyer
- Institute of Chemistry, University of Graz, Graz, Austria; Division of General and Visceral Surgery, Department of Human Medicine, University of Oldenburg, Germany.
| | - Klaus Zangger
- Institute of Chemistry, University of Graz, Graz, Austria.
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9
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Giuliodori AM, Belardinelli R, Duval M, Garofalo R, Schenckbecher E, Hauryliuk V, Ennifar E, Marzi S. Escherichia coli CspA stimulates translation in the cold of its own mRNA by promoting ribosome progression. Front Microbiol 2023; 14:1118329. [PMID: 36846801 PMCID: PMC9947658 DOI: 10.3389/fmicb.2023.1118329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 01/06/2023] [Indexed: 02/11/2023] Open
Abstract
Escherichia coli CspA is an RNA binding protein that accumulates during cold-shock and stimulates translation of several mRNAs-including its own. Translation in the cold of cspA mRNA involves a cis-acting thermosensor element, which enhances ribosome binding, and the trans-acting action of CspA. Using reconstituted translation systems and probing experiments we show that, at low temperature, CspA specifically promotes the translation of the cspA mRNA folded in the conformation less accessible to the ribosome, which is formed at 37°C but is retained upon cold shock. CspA interacts with its mRNA without inducing large structural rearrangements, but allowing the progression of the ribosomes during the transition from translation initiation to translation elongation. A similar structure-dependent mechanism may be responsible for the CspA-dependent translation stimulation observed with other probed mRNAs, for which the transition to the elongation phase is progressively facilitated during cold acclimation with the accumulation of CspA.
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Affiliation(s)
- Anna Maria Giuliodori
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy,*Correspondence: Anna Maria Giuliodori, ✉
| | - Riccardo Belardinelli
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Melodie Duval
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Raffaella Garofalo
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Emma Schenckbecher
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Vasili Hauryliuk
- Department of Experimental Medical Science, Lund University, Lund, Sweden,Institute of Technology, University of Tartu, Tartu, Estonia
| | - Eric Ennifar
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Stefano Marzi
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France,Stefano Marzi, ✉
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10
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Ding J, Schuergers N, Baehre H, Wilde A. Enzymatic properties of CARF-domain proteins in Synechocystis sp. PCC 6803. Front Microbiol 2022; 13:1046388. [DOI: 10.3389/fmicb.2022.1046388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
Prokaryotic CRISPR-Cas (clustered regularly interspaced short palindromic repeats and CRISPR-associated genes) systems provide immunity against invading genetic elements such as bacteriophages and plasmids. In type III CRISPR systems, the recognition of target RNA leads to the synthesis of cyclic oligoadenylate (cOA) second messengers that activate ancillary effector proteins via their CRISPR-associated Rossmann fold (CARF) domains. Commonly, these are ribonucleases (RNases) that unspecifically degrade both invader and host RNA. To mitigate adverse effects on cell growth, ring nucleases can degrade extant cOAs to switch off ancillary nucleases. Here we show that the model organism Synechocystis sp. PCC 6803 harbors functional CARF-domain effector and ring nuclease proteins. We purified and characterized the two ancillary CARF-domain proteins from the III-D type CRISPR system of this cyanobacterium. The Csx1 homolog, SyCsx1, is a cyclic tetraadenylate(cA4)-dependent RNase with a strict specificity for cytosine nucleotides. The second CARF-domain protein with similarity to Csm6 effectors, SyCsm6, did not show RNase activity in vitro but was able to break down cOAs and attenuate SyCsx1 RNase activity. Our data suggest that the CRISPR systems in Synechocystis confer a multilayered cA4-mediated defense mechanism.
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11
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Yu V, Ronzone E, Lord D, Peti W, Page R. MqsR is a noncanonical microbial RNase toxin that is inhibited by antitoxin MqsA via steric blockage of substrate binding. J Biol Chem 2022; 298:102535. [PMID: 36162504 PMCID: PMC9636575 DOI: 10.1016/j.jbc.2022.102535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/15/2022] [Accepted: 09/19/2022] [Indexed: 12/01/2022] Open
Abstract
The MqsRA toxin-antitoxin system is a component of the Escherichia coli stress response. Free MqsR, a ribonuclease, cleaves mRNAs containing a 5′-GC-3′ sequence causing a global shutdown of translation and the cell to enter a state of dormancy. Despite a general understanding of MqsR function, the molecular mechanism(s) by which MqsR binds and cleaves RNA and how one or more of these activities is inhibited by its cognate antitoxin MqsA is still poorly understood. Here, we used NMR spectroscopy coupled with mRNA cleavage assays to identify the molecular mechanism of MqsR substrate recognition and the MqsR residues that are essential for its catalytic activity. We show that MqsR preferentially binds substrates that contain purines in the −2 and −1 position relative to the MqsR consensus cleavage sequence and that two residues of MqsR, Tyr81, and Lys56 are strictly required for mRNA cleavage. We also show that MqsA inhibits MqsR activity by sterically blocking mRNA substrates from binding while leaving the active site fully accessible to mononucleotides. Together, these data identify the residues of MqsR that mediate RNA cleavage and reveal a novel mechanism that regulates MqsR substrate specificity.
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Affiliation(s)
- Victor Yu
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Erik Ronzone
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Dana Lord
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Wolfgang Peti
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Rebecca Page
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA.
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12
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Yusof TY, Ong EBB, Teh AH. RelEB3 toxin-antitoxin system of Salmonella Typhimurium with a ribosome-independent toxin and a mutated non-neutralising antitoxin. Int J Biol Macromol 2022; 219:1080-1086. [PMID: 36029963 DOI: 10.1016/j.ijbiomac.2022.08.144] [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: 05/11/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/28/2022]
Abstract
The RelEB3 toxin-antitoxin (TA) system of Salmonella enterica subsp. enterica serovar Typhimurium consists of a RelE3 toxin which suppresses bacterial growth, but its RelB3 antitoxin does not neutralise the toxin. The relEB3 operon is widespread in Proteobacteria and is related to higBA2 from Vibrio cholerae. In contrast to the ribosome-dependent HigB2 toxin, however, the RelE3 toxin degraded free RNA independently of the ribosome. A basic loop possibly involved in HigB2's binding to the ribosome is shortened in RelE3, which instead contains a uniquely conserved R51 important for RelE3's toxicity. The RelB3 antitoxin, meanwhile, specifically recognised the CACCTGGTG palindromic motif in the promoter site. RelB3 contains P14 which is conserved as Ala in most homologues, and mutating P14 to Ala enabled the antitoxin to bind to RelE3 and restored bacterial growth. The P14 RelB3 variant, which most likely arose by a point mutation in a recent ancestor of S. Typhimurium and closely related serovars, could have possibly provided the bacteria with a faster response to stress, and might have spread to other serovars through homologous recombination.
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Affiliation(s)
- Tengku Yasmin Yusof
- Centre for Chemical Biology, Universiti Sains Malaysia, Penang, Malaysia; University Hospital Development Centre, Universiti Sultan Zainal Abidin, Terengganu, Malaysia
| | - Eugene Boon Beng Ong
- Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang, Malaysia
| | - Aik-Hong Teh
- Centre for Chemical Biology, Universiti Sains Malaysia, Penang, Malaysia.
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13
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Song X, Lin Z, Yuan W. Toxin-antitoxin systems in pathogenic Vibrio species: a mini review from a structure perspective. 3 Biotech 2022; 12:125. [PMID: 35542053 DOI: 10.1007/s13205-022-03178-3] [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: 01/27/2022] [Accepted: 03/31/2022] [Indexed: 11/01/2022] Open
Abstract
Toxin-antitoxin (TA) genetic modules have been found to widely exist in bacterial chromosomes and mobile genetic elements. They are composed of stable toxins and less stable antitoxins that can counteract the toxicity of toxins. The interactions between toxins and antitoxins could play critical roles in the virulence and persistence of pathogenic bacteria. There are at least eight types of TA systems which have been identified in a variety of bacteria. Vibrio, a genus of Gram-negative bacteria, is widespread in aquatic environments and can cause various human diseases, such as epidemic cholera. In this review, we mainly explore the structures and functions of TA modules found in common Vibrio pathogens, mainly V. cholerae, for better understanding of TA action mechanisms in pathogenic bacteria.
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14
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Mansour M, Giudice E, Xu X, Akarsu H, Bordes P, Guillet V, Bigot DJ, Slama N, D'urso G, Chat S, Redder P, Falquet L, Mourey L, Gillet R, Genevaux P. Substrate recognition and cryo-EM structure of the ribosome-bound TAC toxin of Mycobacterium tuberculosis. Nat Commun 2022; 13:2641. [PMID: 35552387 PMCID: PMC9098466 DOI: 10.1038/s41467-022-30373-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/27/2022] [Indexed: 11/16/2022] Open
Abstract
Toxins of toxin-antitoxin systems use diverse mechanisms to control bacterial growth. Here, we focus on the deleterious toxin of the atypical tripartite toxin-antitoxin-chaperone (TAC) system of Mycobacterium tuberculosis, whose inhibition requires the concerted action of the antitoxin and its dedicated SecB-like chaperone. We show that the TAC toxin is a bona fide ribonuclease and identify exact cleavage sites in mRNA targets on a transcriptome-wide scale in vivo. mRNA cleavage by the toxin occurs after the second nucleotide of the ribosomal A-site codon during translation, with a strong preference for CCA codons in vivo. Finally, we report the cryo-EM structure of the ribosome-bound TAC toxin in the presence of native M. tuberculosis cspA mRNA, revealing the specific mechanism by which the TAC toxin interacts with the ribosome and the tRNA in the P-site to cleave its mRNA target. Toxin-antitoxin systems are widespread in bacteria. Here the authors present structures of M. tuberculosis HigBTAC alone and bound to the ribosome in the presence of native cspA mRNA, shedding light on its mechanism of translation inhibition.
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Affiliation(s)
- Moise Mansour
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Emmanuel Giudice
- Institut de Génétique et Développement de Rennes (IGDR), UMR6290, Université de Rennes, CNRS, Rennes, France
| | - Xibing Xu
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Hatice Akarsu
- Department of Biology, University of Fribourg & Swiss Institute of Bioinformatics, Fribourg, Switzerland.,Institute of Veterinary Bacteriology, University of Bern, Bern, Switzerland
| | - Patricia Bordes
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Valérie Guillet
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Donna-Joe Bigot
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France.,Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Nawel Slama
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Gaetano D'urso
- Institut de Génétique et Développement de Rennes (IGDR), UMR6290, Université de Rennes, CNRS, Rennes, France
| | - Sophie Chat
- Institut de Génétique et Développement de Rennes (IGDR), UMR6290, Université de Rennes, CNRS, Rennes, France
| | - Peter Redder
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laurent Falquet
- Department of Biology, University of Fribourg & Swiss Institute of Bioinformatics, Fribourg, Switzerland
| | - Lionel Mourey
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Reynald Gillet
- Institut de Génétique et Développement de Rennes (IGDR), UMR6290, Université de Rennes, CNRS, Rennes, France.
| | - Pierre Genevaux
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France.
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15
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Dawson CC, Cummings JE, Starkey JM, Slayden RA. Discovery of a novel type IIb RelBE toxin-antitoxin system in Mycobacterium tuberculosis defined by co-regulation with an antisense RNA. Mol Microbiol 2022; 117:1419-1433. [PMID: 35526138 PMCID: PMC9325379 DOI: 10.1111/mmi.14917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 04/30/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022]
Abstract
Toxin‐antitoxin loci regulate adaptive responses to stresses associated with the host environment and drug exposure. Phylogenomic studies have shown that Mycobacterium tuberculosis encodes a naturally expanded type II toxin‐antitoxin system, including ParDE/RelBE superfamily members. Type II toxins are presumably regulated exclusively through protein–protein interactions with type II antitoxins. However, experimental observations in M. tuberculosis indicated that additional control mechanisms regulate RelBE2 type II loci under host‐associated stress conditions. Herein, we describe for the first time a novel antisense RNA, termed asRelE2, that co‐regulates RelE2 production via targeted processing by the Mtb RNase III, Rnc. We find that convergent expression of this coding‐antisense hybrid TA locus, relBE2‐asrelE2, is controlled in a cAMP‐dependent manner by the essential cAMP receptor protein transcription factor, Crp, in response to the host‐associated stresses of low pH and nutrient limitation. Ex vivo survival studies with relE2 and asrelE2 knockout strains showed that RelE2 contributes to Mtb survival in activated macrophages and low pH to nutrient limitation. To our knowledge, this is the first report of a novel tripartite type IIb TA loci and antisense post‐transcriptional regulation of a type II TA loci.
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Affiliation(s)
- Clinton C Dawson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins.,Endolytix Technology, Inc. Beverly, 01915
| | - Jason E Cummings
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins
| | - Julie M Starkey
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins
| | - Richard A Slayden
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins
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16
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Choi E, Huh A, Oh C, Oh JI, Kang HY, Hwang J. Functional characterization of HigBA toxin-antitoxin system in an Arctic bacterium, Bosea sp. PAMC 26642. J Microbiol 2022; 60:192-206. [PMID: 35102526 DOI: 10.1007/s12275-022-1619-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 01/02/2023]
Abstract
Toxin-antitoxin (TA) systems are growth-controlling genetic elements consisting of an intracellular toxin protein and its cognate antitoxin. TA systems have been spread among microbial genomes through horizontal gene transfer and are now prevalent in most bacterial and archaeal genomes. Under normal growth conditions, antitoxins tightly counteract the activity of the toxins. Upon stresses, antitoxins are inactivated, releasing activated toxins, which induce growth arrest or cell death. In this study, among nine functional TA modules in Bosea sp. PAMC 26642 living in Arctic lichen, we investigated the functionality of BoHigBA2. BohigBA2 is located close to a genomic island and adjacent to flagellar gene clusters. The expression of BohigB2 induced the inhibition of E. coli growth at 37°C, which was more manifest at 18°C, and this growth defect was reversed when BohigA2 was co-expressed, suggesting that this BoHigBA2 module might be an active TA module in Bosea sp. PAMC 26642. Live/dead staining and viable count analyses revealed that the BoHigB2 toxin had a bactericidal effect, causing cell death. Furthermore, we demonstrated that BoHigB2 possessed mRNA-specific ribonuclease activity on various mRNAs and cleaved only mRNAs being translated, which might impede overall translation and consequently lead to cell death. Our study provides the insight to understand the cold adaptation of Bosea sp. PAMC 26642 living in the Arctic.
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Affiliation(s)
- Eunsil Choi
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Ahhyun Huh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Changmin Oh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Jeong-Il Oh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Ho Young Kang
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Jihwan Hwang
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea. .,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea.
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17
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Li H, Tan Y, Zhang D. Genomic discovery and structural dissection of a novel type of polymorphic toxin system in gram-positive bacteria. Comput Struct Biotechnol J 2022; 20:4517-4531. [PMID: 36051883 PMCID: PMC9424270 DOI: 10.1016/j.csbj.2022.08.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/15/2022] [Accepted: 08/15/2022] [Indexed: 11/26/2022] Open
Abstract
Bacteria have developed several molecular conflict systems to facilitate kin recognition and non-kin competition to gain advantages in the acquisition of growth niches and of limited resources. One such example is a large class of so-called polymorphic toxin systems (PTSs), which comprise a variety of the toxin proteins secreted via T2SS, T5SS, T6SS, T7SS and many others. These systems are highly divergent in terms of sequence/structure, domain architecture, toxin-immunity association, and organization of the toxin loci, which makes it difficult to identify and characterize novel systems using traditional experimental and bioinformatic strategies. In recent years, we have been developing and utilizing unique genome-mining strategies and pipelines, based on the organizational principles of both domain architectures and genomic loci of PTSs, for an effective and comprehensive discovery of novel PTSs, dissection of their components, and prediction of their structures and functions. In this study, we present our systematic discovery of a new type of PTS (S8-PTS) in several gram-positive bacteria. We show that the S8-PTS contains three components: a peptidase of the S8 family (subtilases), a polymorphic toxin, and an immunity protein. We delineated the typical organization of these polymorphic toxins, in which a N-terminal signal peptide is followed by a potential receptor binding domain, BetaH, and one of 16 toxin domains. We classified each toxin domain by the distinct superfamily to which it belongs, identifying nine BECR ribonucleases, one Restriction Endonuclease, one HNH nuclease, two novel toxin domains homologous to the VOC enzymes, one toxin domain with the Frataxin-like fold, and several other unique toxin families such as Ntox33 and HicA. Accordingly, we identified 20 immunity families and classified them into different classes of folds. Further, we show that the S8-PTS-associated peptidases are analogous to many other processing peptidases found in T5SS, T7SS, T9SS, and many proprotein-processing peptidases, indicating that they function to release the toxin domains during secretion. The S8-PTSs are mostly found in animal and plant-associated bacteria, including many pathogens. We propose S8-PTSs will facilitate the competition of these bacteria with other microbes or contribute to the pathogen-host interactions.
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Affiliation(s)
- Huan Li
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
| | - Yongjun Tan
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
| | - Dapeng Zhang
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
- Program of Bioinformatics and Computational Biology, College of Arts & Sciences, Saint Louis University, MO 63103, USA
- Corresponding author at: Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA.
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18
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Insights into the Neutralization and DNA Binding of Toxin-Antitoxin System ParE SO-CopA SO by Structure-Function Studies. Microorganisms 2021; 9:microorganisms9122506. [PMID: 34946107 PMCID: PMC8706911 DOI: 10.3390/microorganisms9122506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/25/2021] [Accepted: 11/27/2021] [Indexed: 12/03/2022] Open
Abstract
ParESO-CopASO is a new type II toxin–antitoxin (TA) system in prophage CP4So that plays an essential role in circular CP4So maintenance after the excision in Shewanella oneidensis. The toxin ParESO severely inhibits cell growth, while CopASO functions as an antitoxin to neutralize ParESO toxicity through direct interactions. However, the molecular mechanism of the neutralization and autoregulation of the TA operon transcription remains elusive. In this study, we determined the crystal structure of a ParESO-CopASO complex that adopted an open V-shaped heterotetramer with the organization of ParESO-(CopASO)2-ParESO. The structure showed that upon ParESO binding, the intrinsically disordered C-terminal domain of CopASO was induced to fold into a partially ordered conformation that bound into a positively charged and hydrophobic groove of ParESO. Thermodynamics analysis showed the DNA-binding affinity of CopASO was remarkably higher than that of the purified TA complex, accompanied by the enthalpy change reversion from an exothermic reaction to an endothermic reaction. These results suggested ParESO acts as a de-repressor of the TA operon transcription at the toxin:antitoxin level of 1:1. Site-directed mutagenesis of ParESO identified His91 as the essential residue for its toxicity by cell toxicity assays. Our structure-function studies therefore elucidated the transcriptional regulation mechanism of the ParESO-CopASO pair, and may help to understand the regulation of CP4So maintenance in S. oneidensis.
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19
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Singh G, Yadav M, Ghosh C, Rathore JS. Bacterial toxin-antitoxin modules: classification, functions, and association with persistence. CURRENT RESEARCH IN MICROBIAL SCIENCES 2021; 2:100047. [PMID: 34841338 PMCID: PMC8610362 DOI: 10.1016/j.crmicr.2021.100047] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/04/2021] [Accepted: 07/05/2021] [Indexed: 11/24/2022] Open
Abstract
Ubiquitously present bacterial Toxin-Antitoxin (TA) modules consist of stable toxin associated with labile antitoxin. Classification of TAs modules based on inhibition of toxin through antitoxin in 8 different classes. Variety of specific toxin targets and the abundance of TA modules in various deadly pathogens. Specific role of TAs modules in conservation of the resistant genes, emergence of persistence & biofilm formation. Proposed antibacterial strategies involving TA modules for elimination of multi-drug resistance.
Toxin-antitoxin (TA) modules are ubiquitous gene loci among bacteria and are comprised of a toxin part and its cognate antitoxin part. Under normal physiological conditions, antitoxin counteracts the toxicity of the toxin whereas, during stress conditions, TA modules play a crucial role in bacterial physiology through involvement in the post-segregational killing, abortive infection, biofilms, and persister cell formation. Most of the toxins are proteinaceous that affect translation or DNA replication, although some other intracellular molecular targets have also been described. While antitoxins may be a protein or RNA, that generally neutralizes its cognate toxin by direct interaction or with the help of other signaling elements and thus helps in the TA module regulation. In this review, we have discussed the current state of the multifaceted TA (type I–VIII) modules by highlighting their classification and specific targets. We have also discussed the presence of TA modules in the various pathogens and their role in antibiotic persistence development as well as biofilm formation, by influencing the different cellular processes. In the end, assembling knowledge about ubiquitous TA systems from pathogenic bacteria facilitated us to propose multiple novel antibacterial strategies involving artificial activation of TA modules.
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Affiliation(s)
- Garima Singh
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
| | - Mohit Yadav
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
| | - Chaitali Ghosh
- Department of Zoology Gargi College, University of Delhi, New Delhi, India
| | - Jitendra Singh Rathore
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
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20
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Xue L, Khan MH, Yue J, Zhu Z, Niu L. The two paralogous copies of the YoeB-YefM toxin-antitoxin module in Staphylococcus aureus differ in DNA binding and recognition patterns. J Biol Chem 2021; 298:101457. [PMID: 34861238 PMCID: PMC8717551 DOI: 10.1016/j.jbc.2021.101457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 12/13/2022] Open
Abstract
Toxin-antitoxin (TA) systems are ubiquitous regulatory modules for bacterial growth and cell survival following stress. YefM-YoeB, the most prevalent type II TA system, is present in a variety of bacterial species. In Staphylococcus aureus, the YefM-YoeB system exists as two independent paralogous copies. Our previous research resolved crystal structures of the two oligomeric states (heterotetramer and heterohexamer-DNA ternary complex) of the first paralog as well as the molecular mechanism of transcriptional autoregulation of this module. However, structural details reflecting molecular diversity in both paralogs have been relatively unexplored. To understand the molecular mechanism of how Sa2YoeB and Sa2YefM regulate their own transcription and how each paralog functions independently, we solved a series of crystal structures of the Sa2YoeB-Sa2YefM. Our structural and biochemical data demonstrated that both paralogous copies adopt similar mechanisms of transcriptional autoregulation. In addition, structural analysis suggested that molecular diversity between the two paralogs might be reflected in the interaction profile of YefM and YoeB and the recognition pattern of promoter DNA by YefM. Interaction analysis revealed unique conformational and activating force effected by the interface between Sa2YoeB and Sa2YefM. In addition, the recognition pattern analysis demonstrated that residues Thr7 and Tyr14 of Sa2YefM specifically recognizes the flanking sequences (G and C) of the promoter DNA. Together, these results provide the structural insights into the molecular diversity and independent function of the paralogous copies of the YoeB-YefM TA system.
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Affiliation(s)
- Lu Xue
- Hefei National Laboratory for Physical Sciences at the Microscale, Division of Molecular and Cellular Biophysics, University of Science and Technology of China, Hefei, Anhui, China; Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Muhammad Hidayatullah Khan
- Hefei National Laboratory for Physical Sciences at the Microscale, Division of Molecular and Cellular Biophysics, University of Science and Technology of China, Hefei, Anhui, China; Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Jian Yue
- Hefei National Laboratory for Physical Sciences at the Microscale, Division of Molecular and Cellular Biophysics, University of Science and Technology of China, Hefei, Anhui, China; Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Zhongliang Zhu
- Hefei National Laboratory for Physical Sciences at the Microscale, Division of Molecular and Cellular Biophysics, University of Science and Technology of China, Hefei, Anhui, China; Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
| | - Liwen Niu
- Hefei National Laboratory for Physical Sciences at the Microscale, Division of Molecular and Cellular Biophysics, University of Science and Technology of China, Hefei, Anhui, China; Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
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21
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Srinivas P, Steiner RE, Pavelich IJ, Guerrero-Ferreira R, Juneja P, Ibba M, Dunham CM. Oxidation alters the architecture of the phenylalanyl-tRNA synthetase editing domain to confer hyperaccuracy. Nucleic Acids Res 2021; 49:11800-11809. [PMID: 34581811 PMCID: PMC8599791 DOI: 10.1093/nar/gkab856] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/07/2021] [Accepted: 09/16/2021] [Indexed: 11/12/2022] Open
Abstract
High fidelity during protein synthesis is accomplished by aminoacyl-tRNA synthetases (aaRSs). These enzymes ligate an amino acid to a cognate tRNA and have proofreading and editing capabilities that ensure high fidelity. Phenylalanyl-tRNA synthetase (PheRS) preferentially ligates a phenylalanine to a tRNAPhe over the chemically similar tyrosine, which differs from phenylalanine by a single hydroxyl group. In bacteria that undergo exposure to oxidative stress such as Salmonella enterica serovar Typhimurium, tyrosine isomer levels increase due to phenylalanine oxidation. Several residues are oxidized in PheRS and contribute to hyperactive editing, including against mischarged Tyr-tRNAPhe, despite these oxidized residues not being directly implicated in PheRS activity. Here, we solve a 3.6 Å cryo-electron microscopy structure of oxidized S. Typhimurium PheRS. We find that oxidation results in widespread structural rearrangements in the β-subunit editing domain and enlargement of its editing domain. Oxidization also enlarges the phenylalanyl-adenylate binding pocket but to a lesser extent. Together, these changes likely explain why oxidation leads to hyperaccurate editing and decreased misincorporation of tyrosine. Taken together, these results help increase our understanding of the survival of S. Typhimurium during human infection.
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Affiliation(s)
- Pooja Srinivas
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Molecular and Systems Pharmacology Graduate Program, Emory University, Atlanta, GA 30322, USA.,Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
| | - Rebecca E Steiner
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Ian J Pavelich
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA.,Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Ricardo Guerrero-Ferreira
- Robert P. Apkarian Integrated Electron Microscopy Core, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Puneet Juneja
- Robert P. Apkarian Integrated Electron Microscopy Core, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Michael Ibba
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Christine M Dunham
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
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22
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Global Analysis of the Specificities and Targets of Endoribonucleases from Escherichia coli Toxin-Antitoxin Systems. mBio 2021; 12:e0201221. [PMID: 34544284 PMCID: PMC8546651 DOI: 10.1128/mbio.02012-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Toxin-antitoxin systems are widely distributed genetic modules typically featuring toxins that can inhibit bacterial growth and antitoxins that can reverse inhibition. Although Escherichia coli encodes 11 toxins with known or putative endoribonuclease activity, the targets of most of these toxins remain poorly characterized. Using a new RNA sequencing (RNA-seq) pipeline that enables the mapping and quantification of RNA cleavage with single-nucleotide resolution, we characterized the targets and specificities of 9 endoribonuclease toxins from E. coli. We found that these toxins use low-information cleavage motifs to cut a significant proportion of mRNAs in E. coli, but not tRNAs or the rRNAs from mature ribosomes. However, all the toxins, including those that are ribosome dependent and cleave only translated RNA, inhibit ribosome biogenesis. This inhibition likely results from the cleavage of ribosomal protein transcripts, which disrupts the stoichiometry and biogenesis of new ribosomes and causes the accumulation of aberrant ribosome precursors. Collectively, our results provide a comprehensive, global analysis of endoribonuclease-based toxin-antitoxin systems in E. coli and support the conclusion that, despite their diversity, each disrupts translation and ribosome biogenesis.
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23
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Kumar N, Sharma S, Kaushal PS. Protein synthesis in Mycobacterium tuberculosis as a potential target for therapeutic interventions. Mol Aspects Med 2021; 81:101002. [PMID: 34344520 DOI: 10.1016/j.mam.2021.101002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 07/11/2021] [Accepted: 07/16/2021] [Indexed: 12/18/2022]
Abstract
Mycobacterium tuberculosis (Mtb) causes one of humankind's deadliest diseases, tuberculosis. Mtb protein synthesis machinery possesses several unique species-specific features, including its ribosome that carries two mycobacterial specific ribosomal proteins, bL37 and bS22, and ribosomal RNA segments. Since the protein synthesis is a vital cellular process that occurs on the ribosome, a detailed knowledge of the structure and function of mycobacterial ribosomes is essential to understand the cell's proteome by translation regulation. Like in many bacterial species such as Bacillus subtilis and Streptomyces coelicolor, two distinct populations of ribosomes have been identified in Mtb. Under low-zinc conditions, Mtb ribosomal proteins S14, S18, L28, and L33 are replaced with their non-zinc binding paralogues. Depending upon the nature of physiological stress, species-specific modulation of translation by stress factors and toxins that interact with the ribosome have been reported. In addition, about one-fourth of messenger RNAs in mycobacteria have been reported to be leaderless, i.e., without 5' UTR regions. However, the mechanism by which they are recruited to the Mtb ribosome is not understood. In this review, we highlight the mycobacteria-specific features of the translation apparatus and propose exploiting these features to improve the efficacy and specificity of existing antibiotics used to treat tuberculosis.
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Affiliation(s)
- Niraj Kumar
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India
| | - Shivani Sharma
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India
| | - Prem S Kaushal
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India.
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24
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Cushman J, Freeman E, McCallister S, Schumann A, Hutchison KW, Molloy SD. Increased whiB7 expression and antibiotic resistance in Mycobacterium chelonae carrying two prophages. BMC Microbiol 2021; 21:176. [PMID: 34107872 PMCID: PMC8191103 DOI: 10.1186/s12866-021-02224-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 05/05/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The global rise in the incidence of non-tuberculosis mycobacterial infections is of increasing concern due their high levels of intrinsic antibiotic resistance. Although integrated viral genomes, called prophage, are linked to increased antibiotic resistance in some bacterial species, we know little of their role in mycobacterial drug resistance. RESULTS We present here for the first time, evidence of increased antibiotic resistance and expression of intrinsic antibiotic resistance genes in a strain of Mycobacterium chelonae carrying prophage. Strains carrying the prophage McProf demonstrated increased resistance to amikacin. Resistance in these strains was further enhanced by exposure to sub-inhibitory concentrations of the antibiotic, acivicin, or by the presence of a second prophage, BPs. Increased expression of the virulence gene, whiB7, was observed in strains carrying both prophages, BPs and McProf, relative to strains carrying a single prophage or no prophages. CONCLUSIONS This study provides evidence that prophage alter expression of important mycobacterial intrinsic antibiotic resistance genes and additionally offers insight into the role prophage may play in mycobacterial adaptation to stress.
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Affiliation(s)
- Jaycee Cushman
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
| | - Emma Freeman
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
- The Honors College, University of Maine, Orono, ME, United States
| | - Sarah McCallister
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
| | - Anna Schumann
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
| | - Keith W Hutchison
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
- The Honors College, University of Maine, Orono, ME, United States
| | - Sally D Molloy
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States.
- The Honors College, University of Maine, Orono, ME, United States.
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25
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Abstract
A putative type II toxin-antitoxin (TA) module almost exclusively associated with conjugative IncC plasmids is homologous to the higBA family of TA systems found in chromosomes and plasmids of several species of bacteria. Despite the clinical significance and strong association with high-profile antimicrobial resistance (AMR) genes, the TA system of IncC plasmids remains largely uncharacterized. In this study, we present evidence that IncC plasmids encode a bona fide HigB-like toxin that strongly inhibits bacterial growth and results in cell elongation in Escherichia coli. IncC HigB toxin acts as a ribosome-dependent endoribonuclease that significantly reduces the transcript abundance of a subset of adenine-rich mRNA transcripts. A glycine residue at amino acid position 64 is highly conserved in HigB toxins from different bacterial species, and its replacement with valine (G64V) abolishes the toxicity and the mRNA cleavage activity of the IncC HigB toxin. The IncC plasmid higBA TA system functions as an effective addiction module that maintains plasmid stability in an antibiotic-free environment. This higBA addiction module is the only TA system that we identified in the IncC backbone and appears essential for the stable maintenance of IncC plasmids. We also observed that exposure to subinhibitory concentrations of ciprofloxacin, a DNA-damaging fluoroquinolone antibiotic, results in elevated higBA expression, which raises interesting questions about its regulatory mechanisms. A better understanding of this higBA-type TA module potentially allows for its subversion as part of an AMR eradication strategy. IMPORTANCE Toxin-antitoxin (TA) systems play vital roles in maintaining plasmids in bacteria. Plasmids with incompatibility group C are large plasmids that disseminate via conjugation and carry high-profile antibiotic resistance genes. We present experimental evidence that IncC plasmids carry a TA system that functions as an effective addiction module and maintains plasmid stability in an antibiotic-free environment. The toxin of IncC plasmids acts as an endoribonuclease that targets a subset of mRNA transcripts. Overexpressing the IncC toxin gene strongly inhibits bacterial growth and results in cell elongation in Escherichia coli hosts. We also identify a conserved amino acid residue in the toxin protein that is essential for its toxicity and show that the expression of this TA system is activated by a DNA-damaging antibiotic, ciprofloxacin. This mobile TA system may contribute to managing bacterial stress associated with DNA-damaging antibiotics.
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26
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Interactions of the Streptococcus pneumoniae Toxin-Antitoxin RelBE Proteins with Their Target DNA. Microorganisms 2021; 9:microorganisms9040851. [PMID: 33921033 PMCID: PMC8071376 DOI: 10.3390/microorganisms9040851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/17/2022] Open
Abstract
Type II bacterial toxin-antitoxin (TA) systems are found in most bacteria, archaea, and mobile genetic elements. TAs are usually found as a bi-cistronic operon composed of an unstable antitoxin and a stable toxin that targets crucial cellular functions like DNA supercoiling, cell-wall synthesis or mRNA translation. The type II RelBE system encoded by the pathogen Streptococcus pneumoniae is highly conserved among different strains and participates in biofilm formation and response to oxidative stress. Here, we have analyzed the participation of the RelB antitoxin and the RelB:RelE protein complex in the self-regulation of the pneumococcal relBE operon. RelB acted as a weak repressor, whereas RelE performed the role of a co-repressor. By DNA footprinting experiments, we show that the proteins bind to a region that encompasses two palindromic sequences that are located around the -10 sequences of the single promoter that directs the synthesis of the relBE mRNA. High-resolution footprinting assays showed the distribution of bases whose deoxyriboses are protected by the bound proteins, demonstrating that RelB and RelB:RelE contacted the DNA backbone on one face of the DNA helix and that these interactions extended beyond the palindromic sequences. Our findings suggest that the binding of the RelBE proteins to its DNA target would lead to direct inhibition of the binding of the host RNA polymerase to the relBE promoter.
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27
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Müller C, Crowe-McAuliffe C, Wilson DN. Ribosome Rescue Pathways in Bacteria. Front Microbiol 2021; 12:652980. [PMID: 33815344 PMCID: PMC8012679 DOI: 10.3389/fmicb.2021.652980] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/23/2021] [Indexed: 12/18/2022] Open
Abstract
Ribosomes that become stalled on truncated or damaged mRNAs during protein synthesis must be rescued for the cell to survive. Bacteria have evolved a diverse array of rescue pathways to remove the stalled ribosomes from the aberrant mRNA and return them to the free pool of actively translating ribosomes. In addition, some of these pathways target the damaged mRNA and the incomplete nascent polypeptide chain for degradation. This review highlights the recent developments in our mechanistic understanding of bacterial ribosomal rescue systems, including drop-off, trans-translation mediated by transfer-messenger RNA and small protein B, ribosome rescue by the alternative rescue factors ArfA and ArfB, as well as Bacillus ribosome rescue factor A, an additional rescue system found in some Gram-positive bacteria, such as Bacillus subtilis. Finally, we discuss the recent findings of ribosome-associated quality control in particular bacterial lineages mediated by RqcH and RqcP. The importance of rescue pathways for bacterial survival suggests they may represent novel targets for the development of new antimicrobial agents against multi-drug resistant pathogenic bacteria.
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Affiliation(s)
| | | | - Daniel N. Wilson
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
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28
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Kang S, Jin C, Kim D, Park SJ, Han S, Lee B. Structure-based design of peptides that trigger Streptococcus pneumoniae cell death. FEBS J 2021; 288:1546-1564. [PMID: 32770723 PMCID: PMC7984235 DOI: 10.1111/febs.15514] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 06/30/2020] [Accepted: 08/06/2020] [Indexed: 01/08/2023]
Abstract
Toxin-antitoxin (TA) systems regulate key cellular functions in bacteria. Here, we report a unique structure of the Streptococcus pneumoniae HigBA system and a novel antimicrobial agent that activates HigB toxin, which results in mRNA degradation as an antibacterial strategy. In this study, protein structure-based peptides were designed and successfully penetrated the S. pneumoniae cell membrane and exerted bactericidal activity. This result represents the time during which inhibitors triggered S. pneumoniae cell death via the TA system. This discovery is a remarkable milestone in the treatment of antibiotic-resistant S. pneumoniae, and the mechanism of bactericidal activity is completely different from those of current antibiotics. Furthermore, we found that the HigBA complex shows a crossed-scissor interface with two intermolecular β-sheets at both the N and C termini of the HigA antitoxin. Our biochemical and structural studies provided valuable information regarding the transcriptional regulation mechanisms associated with the structural variability of HigAs. Our in vivo study also revealed the potential catalytic residues of HigB and their functional relationships. An inhibition study with peptides additionally proved that peptide binding may allosterically inhibit HigB activity. Overall, our results provide insights into the molecular basis of HigBA TA systems in S. pneumoniae, which can be applied for the development of new antibacterial strategies. DATABASES: Structural data are available in the PDB database under the accession number 6AF4.
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Affiliation(s)
- Sung‐Min Kang
- Research Institute of Pharmaceutical Sciences, College of PharmacySeoul National UniversityGwanak‐guSeoulKorea
| | - Chenglong Jin
- Research Institute of Pharmaceutical Sciences, College of PharmacySeoul National UniversityGwanak‐guSeoulKorea
| | - Do‐Hee Kim
- College of PharmacyJeju National UniversityJejuKorea
- Interdisciplinary Graduate Program in Advanced Convergence Technology & ScienceJeju National UniversityJejuKorea
| | - Sung Jean Park
- Gachon Institute of Pharmaceutical Sciences, College of PharmacyGachon UniversityIncheonKorea
| | - Sang‐Woo Han
- Research Institute of Pharmaceutical Sciences, College of PharmacySeoul National UniversityGwanak‐guSeoulKorea
| | - Bong‐Jin Lee
- Research Institute of Pharmaceutical Sciences, College of PharmacySeoul National UniversityGwanak‐guSeoulKorea
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29
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Klemenčič M, Halužan Vasle A, Dolinar M. The Cysteine Protease MaOC1, a Prokaryotic Caspase Homolog, Cleaves the Antitoxin of a Type II Toxin-Antitoxin System. Front Microbiol 2021; 12:635684. [PMID: 33679669 PMCID: PMC7935541 DOI: 10.3389/fmicb.2021.635684] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/01/2021] [Indexed: 01/26/2023] Open
Abstract
The bloom-forming cyanobacterium Microcystis aeruginosa is known for its global distribution and for the production of toxic compounds. In the genome of M. aeruginosa PCC 7806, we discovered that the gene coding for MaOC1, a caspase homolog protease, is followed by a toxin-antitoxin module, flanked on each side by a direct repeat. We therefore investigated their possible interaction at the protein level. Our results suggest that this module belongs to the ParE/ParD-like superfamily of type II toxin-antitoxin systems. In solution, the antitoxin is predominantly alpha-helical and dimeric. When coexpressed with its cognate toxin and isolated from Escherichia coli, it forms a complex, as revealed by light scattering and affinity purification. The active site of the toxin is restricted to the C-terminus of the molecule. Its truncation led to normal cell growth, while the wild-type form prevented bacterial growth in liquid medium. The orthocaspase MaOC1 was able to cleave the antitoxin so that it could no longer block the toxin activity. The most likely target of the protease was the C-terminus of the antitoxin with two sections of basic amino acid residues. E. coli cells in which MaOC1 was expressed simultaneously with the toxin-antitoxin pair were unable to grow. In contrast, no effect on cell growth was found when using a proteolytically inactive MaOC1 mutant. We thus present the first case of a cysteine protease that regulates the activity of a toxin-antitoxin module, since all currently known activating proteases are of the serine type.
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Affiliation(s)
- Marina Klemenčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Ana Halužan Vasle
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Marko Dolinar
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
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30
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Abstract
Bacterial endoribonuclease toxins belong to a protein family that inhibits bacterial growth by degrading mRNA or rRNA sequences. The toxin genes are organized in pairs with its cognate antitoxins in the chromosome and thus the activities of the toxins are antagonized by antitoxin proteins or RNAs during active translation. In response to a variety of cellular stresses, the endoribonuclease toxins appear to be released from antitoxin molecules via proteolytic cleavage of antitoxin proteins or preferential degradation of antitoxin RNAs and cleave a diverse range of mRNA or rRNA sequences in a sequence-specific or codon-specific manner, resulting in various biological phenomena such as antibiotic tolerance and persister cell formation. Given that substrate specificity of each endoribonuclease toxin is determined by its structure and the composition of active site residues, we summarize the biology, structure, and substrate specificity of the updated bacterial endoribonuclease toxins.
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Affiliation(s)
- Yoontak Han
- Department of Life Sciences, Korea University, Seoul 02481, Korea
| | - Eun-Jin Lee
- Department of Life Sciences, Korea University, Seoul 02481, Korea
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31
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Abaeva IS, Vicens Q, Bochler A, Soufari H, Simonetti A, Pestova TV, Hashem Y, Hellen CUT. The Halastavi árva Virus Intergenic Region IRES Promotes Translation by the Simplest Possible Initiation Mechanism. Cell Rep 2020; 33:108476. [PMID: 33296660 DOI: 10.1016/j.celrep.2020.108476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/05/2020] [Accepted: 11/12/2020] [Indexed: 01/01/2023] Open
Abstract
Dicistrovirus intergenic region internal ribosomal entry sites (IGR IRESs) do not require initiator tRNA, an AUG codon, or initiation factors and jumpstart translation from the middle of the elongation cycle via formation of IRES/80S complexes resembling the pre-translocation state. eEF2 then translocates the [codon-anticodon]-mimicking pseudoknot I (PKI) from ribosomal A sites to P sites, bringing the first sense codon into the decoding center. Halastavi árva virus (HalV) contains an IGR that is related to previously described IGR IRESs but lacks domain 2, which enables these IRESs to bind to individual 40S ribosomal subunits. By using in vitro reconstitution and cryoelectron microscopy (cryo-EM), we now report that the HalV IGR IRES functions by the simplest initiation mechanism that involves binding to 80S ribosomes such that PKI is placed in the P site, so that the A site contains the first codon that is directly accessible for decoding without prior eEF2-mediated translocation of PKI.
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Affiliation(s)
- Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA
| | - Quentin Vicens
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Anthony Bochler
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France; Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Heddy Soufari
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France
| | - Angelita Simonetti
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 15 rue René Descartes, 67000 Strasbourg, France
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA.
| | - Yaser Hashem
- INSERM U1212 Acides Nucléiques: Régulations Naturelle et Artificielle, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France.
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, 450 Clarkson Avenue, MSC 44, Brooklyn, NY 11203, USA.
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32
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Abstract
In life's constant battle for survival, it takes one to kill but two to conquer. Toxin-antitoxin or toxin-antidote (TA) elements are genetic dyads that cheat the laws of inheritance to guarantee their transmission to the next generation. This seemingly simple genetic arrangement—a toxin linked to its antidote—is capable of quickly spreading and persisting in natural populations. TA elements were first discovered in bacterial plasmids in the 1980s and have recently been characterized in fungi, plants, and animals, where they underlie genetic incompatibilities and sterility in crosses between wild isolates. In this review, we provide a unified view of TA elements in both prokaryotic and eukaryotic organisms and highlight their similarities and differences at the evolutionary, genetic, and molecular levels. Finally, we propose several scenarios that could explain the paradox of the evolutionary origin of TA elements and argue that these elements may be key evolutionary players and that the full scope of their roles is only beginning to be uncovered.
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Affiliation(s)
- Alejandro Burga
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Eyal Ben-David
- Department of Human Genetics, Department of Biological Chemistry, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, USA
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University School of Medicine, Jerusalem 91120, Israel
| | - Leonid Kruglyak
- Department of Human Genetics, Department of Biological Chemistry, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, USA
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33
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2.09 Å Resolution structure of E. coli HigBA toxin-antitoxin complex reveals an ordered DNA-binding domain and intrinsic dynamics in antitoxin. Biochem J 2020; 477:4001-4019. [PMID: 33000860 DOI: 10.1042/bcj20200363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/15/2020] [Accepted: 09/30/2020] [Indexed: 12/24/2022]
Abstract
The toxin-antitoxin (TA) systems are small operon systems that are involved in important physiological processes in bacteria such as stress response and persister cell formation. Escherichia coli HigBA complex belongs to the type II TA systems and consists of a protein toxin called HigB and a protein antitoxin called HigA. The toxin HigB is a ribosome-dependent endoribonuclease that cleaves the translating mRNAs at the ribosome A site. The antitoxin HigA directly binds the toxin HigB, rendering the HigBA complex catalytically inactive. The existing biochemical and structural studies had revealed that the HigBA complex forms a heterotetrameric assembly via dimerization of HigA antitoxin. Here, we report a high-resolution crystal structure of E. coli HigBA complex that revealed a well-ordered DNA binding domain in HigA antitoxin. Using SEC-MALS and ITC methods, we have determined the stoichiometry of complex formation between HigBA and a 33 bp DNA and report that HigBA complex as well as HigA homodimer bind to the palindromic DNA sequence with nano molar affinity. Using E. coli growth assays, we have probed the roles of key, putative active site residues in HigB. Spectroscopic methods (CD and NMR) and molecular dynamics simulations study revealed intrinsic dynamic in antitoxin in HigBA complex, which may explain the large conformational changes in HigA homodimer in free and HigBA complexes observed previously. We also report a truncated, heterodimeric form of HigBA complex that revealed possible cleavage sites in HigBA complex, which can have implications for its cellular functions.
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34
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Rapid growth inhibitory activity of a YafQ-family endonuclease toxin of the Helicobacter pylori tfs4 integrative and conjugative element. Sci Rep 2020; 10:18171. [PMID: 33097748 PMCID: PMC7584586 DOI: 10.1038/s41598-020-72063-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/07/2020] [Indexed: 12/19/2022] Open
Abstract
Prokaryotic and archaeal chromosomes encode a diversity of toxin–antitoxin (TA) systems that contribute to a variety of stress-induced cellular processes in addition to stability and maintenance of mobile elements. Here, we find DinJ-YafQ family TA systems to be broadly distributed amongst diverse phyla, consistent with other ParE/RelE superfamily TAs, but more unusually occurring as a multiplicity of species-specific subtypes. In the gastric pathogen Helicobacter pylori we identify six distinct subtypes, of which three are predominantly associated with the mobilome, including the disease-associated integrative and conjugative element (ICE), tfs4. Whereas, the ICE-encoded proteins have characteristic features of DinJ-YafQ family Type II TA systems in general, the toxin component is distinguished by a broad metal-ion-dependent endonuclease activity with specificity for both RNA and DNA. We show that the remarkably rapid growth inhibitory activity of the ICE toxin is a correlate of a C-terminal lysine doublet which likely augments catalytic activity by increasing the positive electrostatic potential in the vicinity of the conserved active site. Our collective results reveal a structural feature of an ICE TA toxin that influences substrate catalysis and toxin function which may be relevant to specific TA-mediated responses in diverse genera of bacteria.
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35
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Hiller DA, Dunican BF, Nallur S, Li NS, Piccirilli JA, Strobel SA. The Positively Charged Active Site of the Bacterial Toxin RelE Causes a Large Shift in the General Base p Ka. Biochemistry 2020; 59:1665-1671. [PMID: 32320214 DOI: 10.1021/acs.biochem.9b01047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bacterial toxin RelE cleaves mRNA in the ribosomal A site. Although it shares a global fold with other microbial RNases, the active site contains several positively charged residues instead of histidines and glutamates that are typical of ribonucleases. The pH dependences of wild-type and mutant RelE indicate it uses general acid-base catalysis, but either the general acid (proposed to be R81) or the general base must have a substantially downshifted pKa. However, which group is shifted cannot be determined using available structural and biochemical data. Here, we use a phosphorothiolate at the scissile phosphate to remove the need for a general acid. We show this modification rescues nearly all of the defect of the R81A mutation, supporting R81 as the general acid. We also find that the observed pKa of the general base is dependent on the charge of the side chain at position 81. This indicates that positive charge in the active site contributes to a general base pKa downshifted by more than 5 units. Although this modestly reduces the effectiveness of general acid-base catalysis, it is strongly supplemented by the role of the positive charge in stabilizing the transition state for cleavage. Furthermore, we show that the ribosome is required for cleavage but not binding of mRNA by RelE. Ribosome functional groups do not directly contact the scissile phosphate, indicating that positioning and charge interactions dominate RelE catalysis. The unusual RelE active site catalyzes phosphoryl transfer at a rate comparable to those of similar enzymes, but in a ribosome-dependent fashion.
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Affiliation(s)
- David A Hiller
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry and Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Brian F Dunican
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Sunitha Nallur
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry and Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Nan-Sheng Li
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Joseph A Piccirilli
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry and Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
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36
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Jurėnas D, Van Melderen L. The Variety in the Common Theme of Translation Inhibition by Type II Toxin-Antitoxin Systems. Front Genet 2020; 11:262. [PMID: 32362907 PMCID: PMC7180214 DOI: 10.3389/fgene.2020.00262] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
Type II Toxin-antitoxin (TA) modules are bacterial operons that encode a toxic protein and its antidote, which form a self-regulating genetic system. Antitoxins put a halter on toxins in many ways that distinguish different types of TA modules. In type II TA modules, toxin and antitoxin are proteins that form a complex which physically sequesters the toxin, thereby preventing its toxic activity. Type II toxins inhibit various cellular processes, however, the translation process appears to be their favorite target and nearly every step of this complex process is inhibited by type II toxins. The structural features, enzymatic activities and target specificities of the different toxin families are discussed. Finally, this review emphasizes that the structural folds presented by these toxins are not restricted to type II TA toxins or to one particular cellular target, and discusses why so many of them evolved to target translation as well as the recent developments regarding the role(s) of these systems in bacterial physiology and evolution.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille Université, Marseille, France
| | - Laurence Van Melderen
- Cellular and Molecular Microbiology, Faculté des Sciences, Université libre de Bruxelles, Gosselies, Belgium
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37
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A competence-regulated toxin-antitoxin system in Haemophilus influenzae. PLoS One 2020; 15:e0217255. [PMID: 31931516 PMCID: PMC6957337 DOI: 10.1371/journal.pone.0217255] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 12/16/2019] [Indexed: 12/28/2022] Open
Abstract
Natural competence allows bacteria to respond to environmental and nutritional cues by taking up free DNA from their surroundings, thus gaining both nutrients and genetic information. In the Gram-negative bacterium Haemophilus influenzae, the genes needed for DNA uptake are induced by the CRP and Sxy transcription factors in response to lack of preferred carbon sources and nucleotide precursors. Here we show that one of these genes, HI0659, encodes the antitoxin of a competence-regulated toxin-antitoxin operon (‘toxTA’), likely acquired by horizontal gene transfer from a Streptococcus species. Deletion of the putative toxin (HI0660) restores uptake to the antitoxin mutant. The full toxTA operon was present in only 17 of the 181 strains we examined; complete deletion was seen in 22 strains and deletions removing parts of the toxin gene in 142 others. In addition to the expected Sxy- and CRP-dependent-competence promoter, HI0659/660 transcript analysis using RNA-seq identified an internal antitoxin-repressed promoter whose transcription starts within toxT and will yield nonfunctional protein. We propose that the most likely effect of unopposed toxin expression is non-specific cleavage of mRNAs and arrest or death of competent cells in the culture. Although the high frequency of toxT and toxTA deletions suggests that this competence-regulated toxin-antitoxin system may be mildly deleterious, it could also facilitate downregulation of protein synthesis and recycling of nucleotides under starvation conditions. Although our analyses were focused on the effects of toxTA, the RNA-seq dataset will be a useful resource for further investigations into competence regulation.
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Kurylo CM, Parks MM, Juette MF, Zinshteyn B, Altman RB, Thibado JK, Vincent CT, Blanchard SC. Endogenous rRNA Sequence Variation Can Regulate Stress Response Gene Expression and Phenotype. Cell Rep 2020; 25:236-248.e6. [PMID: 30282032 PMCID: PMC6312700 DOI: 10.1016/j.celrep.2018.08.093] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 08/16/2018] [Accepted: 08/30/2018] [Indexed: 11/30/2022] Open
Abstract
Prevailing dogma holds that ribosomes are uniform in composition and function. Here, we show that nutrient limitation-induced stress in E. coli changes the relative expression of rDNA operons to alter the rRNA composition within the actively translating ribosome pool. The most upregulated operon encodes the unique 16S rRNA, rrsH, distinguished by conserved sequence variation within the small ribosomal subunit. rrsH-bearing ribosomes affect the expression of functionally coherent gene sets and alter the levels of the RpoS sigma factor, the master regulator of the general stress response. These impacts are associated with phenotypic changes in antibiotic sensitivity, biofilm formation, and cell motility and are regulated by stress response proteins, RelA and RelE, as well as the metabolic enzyme and virulence-associated protein, AdhE. These findings establish that endogenously encoded, naturally occurring rRNA sequence variation can modulate ribosome function, central aspects of gene expression regulation, and cellular physiology. Most organisms encode multiple, distinct copies of rRNA genes, rendering the composition of the ribosome pool intrinsically heterogeneous. Here, Kurylo et al. show that nutrient limitation in E. coli upregulates the expression of ribosomes bearing conserved sequence variation in 16S rRNA that can regulate gene expression and phenotype.
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Affiliation(s)
- Chad M Kurylo
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Matthew M Parks
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Manuel F Juette
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Boris Zinshteyn
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Roger B Altman
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Jordana K Thibado
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - C Theresa Vincent
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA; Tri-Institutional Training Program in Chemical Biology, Weill Cornell Medicine, New York, NY, USA.
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Pavelich IJ, Maehigashi T, Hoffer ED, Ruangprasert A, Miles SJ, Dunham CM. Monomeric YoeB toxin retains RNase activity but adopts an obligate dimeric form for thermal stability. Nucleic Acids Res 2019; 47:10400-10413. [PMID: 31501867 PMCID: PMC6821326 DOI: 10.1093/nar/gkz760] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/13/2019] [Accepted: 08/21/2019] [Indexed: 11/30/2022] Open
Abstract
Chromosomally-encoded toxin-antitoxin complexes are ubiquitous in bacteria and regulate growth through the release of the toxin component typically in a stress-dependent manner. Type II ribosome-dependent toxins adopt a RelE-family RNase fold and inhibit translation by degrading mRNAs while bound to the ribosome. Here, we present biochemical and structural studies of the Escherichia coli YoeB toxin interacting with both a UAA stop and an AAU sense codon in pre- and post-mRNA cleavage states to provide insights into possible mRNA substrate selection. Both mRNAs undergo minimal changes during the cleavage event in contrast to type II ribosome-dependent RelE toxin. Further, the 16S rRNA decoding site nucleotides that monitor the mRNA in the aminoacyl(A) site adopt different orientations depending upon which toxin is present. Although YoeB is a RelE family member, it is the sole ribosome-dependent toxin that is dimeric. We show that engineered monomeric YoeB is active against mRNAs bound to both the small and large subunit. However, the stability of monomeric YoeB is reduced ∼20°C, consistent with potential YoeB activation during heat shock in E. coli as previously demonstrated. These data provide a molecular basis for the ability of YoeB to function in response to thermal stress.
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Affiliation(s)
- Ian J Pavelich
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.,Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Tatsuya Maehigashi
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Eric D Hoffer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | - Stacey J Miles
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Christine M Dunham
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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40
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Qian H, Yu H, Li P, Zhu E, Yao Q, Tai C, Deng Z, Gerdes K, He X, Gan J, Ou HY. Toxin-antitoxin operon kacAT of Klebsiella pneumoniae is regulated by conditional cooperativity via a W-shaped KacA-KacT complex. Nucleic Acids Res 2019; 47:7690-7702. [PMID: 31260525 PMCID: PMC6698736 DOI: 10.1093/nar/gkz563] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/28/2019] [Accepted: 06/20/2019] [Indexed: 12/05/2022] Open
Abstract
Bacterial toxin–antitoxin pairs play important roles in bacterial multidrug tolerance. Gcn5-related N-acetyltransferase (GNAT) toxins inhibit translation by acetylation of aminoacyl-tRNAs and are counteracted by direct contacts with cognate ribbon–helix–helix (RHH) antitoxins. Our previous analysis showed that the GNAT toxin KacT and RHH antitoxin KacA of Klebsiella pneumoniae form a heterohexamer in solution and that the complex interacts with the cognate promoter DNA, resulting in negative autoregulation of kacAT transcription. Here, we present the crystal structure of DNA-bound KacAT complex at 2.2 Å resolution. The crystal structure revealed the formation of a unique heterohexamer, KacT–KacA2–KacA2–KacT. The direct interaction of KacA and KacT involves a unique W-shaped structure with the two KacT molecules at opposite ends. Inhibition of KacT is achieved by the binding of four KacA proteins that preclude the formation of an active KacT dimer. The kacAT operon is auto-regulated and we present an experimentally supported molecular model proposing that the KacT:KacA ratio controls kacAT transcription by conditional cooperativity. These results yield a profound understanding of how transcription GNAT–RHH pairs are regulated.
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Affiliation(s)
- Hongliang Qian
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Hao Yu
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Peifei Li
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - E Zhu
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Qingqing Yao
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Cui Tai
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Kenn Gerdes
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Xinyi He
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Jianhua Gan
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Hong-Yu Ou
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
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Convergent Evolution of the Barnase/EndoU/Colicin/RelE (BECR) Fold in Antibacterial tRNase Toxins. Structure 2019; 27:1660-1674.e5. [PMID: 31515004 DOI: 10.1016/j.str.2019.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 08/03/2019] [Accepted: 08/20/2019] [Indexed: 11/20/2022]
Abstract
Contact-dependent growth inhibition (CDI) is a form of interbacterial competition mediated by CdiB-CdiA two-partner secretion systems. CdiA effector proteins carry polymorphic C-terminal toxin domains (CdiA-CT), which are neutralized by specific CdiI immunity proteins to prevent self-inhibition. Here, we present the crystal structures of CdiA-CT⋅CdiI complexes from Klebsiella pneumoniae 342 and Escherichia coli 3006. The toxins adopt related folds that resemble the ribonuclease domain of colicin D, and both are isoacceptor-specific tRNases that cleave the acceptor stem of deacylated tRNAGAUIle. Although the toxins are similar in structure and substrate specificity, CdiA-CTKp342 activity requires translation factors EF-Tu and EF-Ts, whereas CdiA-CTEC3006 is intrinsically active. Furthermore, the corresponding immunity proteins are unrelated in sequence and structure. CdiIKp342 forms a dimeric β sandwich, whereas CdiIEC3006 is an α-solenoid monomer. Given that toxin-immunity genes co-evolve as linked pairs, these observations suggest that the similarities in toxin structure and activity reflect functional convergence.
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Burke JR, La Clair JJ, Philippe RN, Pabis A, Corbella M, Jez JM, Cortina GA, Kaltenbach M, Bowman ME, Louie GV, Woods KB, Nelson AT, Tawfik DS, Kamerlin SC, Noel JP. Bifunctional Substrate Activation via an Arginine Residue Drives Catalysis in Chalcone Isomerases. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01926] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jason R. Burke
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - James J. La Clair
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - Ryan N. Philippe
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - Anna Pabis
- Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, S-751 24 Uppsala, Sweden
| | - Marina Corbella
- Department of Chemistry−BMC, Uppsala University, BMC Box 576, S-751 23 Uppsala, Sweden
| | - Joseph M. Jez
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - George A. Cortina
- Department of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - Miriam Kaltenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Marianne E. Bowman
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - Gordon V. Louie
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - Katherine B. Woods
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
| | - Andrew T. Nelson
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Dan S. Tawfik
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Shina C.L. Kamerlin
- Department of Chemistry−BMC, Uppsala University, BMC Box 576, S-751 23 Uppsala, Sweden
| | - Joseph P. Noel
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
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A ParDE-family toxin antitoxin system in major resistance plasmids of Enterobacteriaceae confers antibiotic and heat tolerance. Sci Rep 2019; 9:9872. [PMID: 31285520 PMCID: PMC6614396 DOI: 10.1038/s41598-019-46318-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 06/26/2019] [Indexed: 11/16/2022] Open
Abstract
Toxin-antitoxin (TA) systems were initially discovered as plasmid addiction systems on low-copy-number plasmids. Thousands of TA loci have since been identified on chromosomes, plasmids and mobile elements in bacteria and archaea with diverse roles in bacterial physiology and in maintenance of genetic elements. Here, we identified and characterised a plasmid mediated type II TA system in Enterobacteriaceae as a member of the ParDE super family. This system (hereafter, ParDEI) is distributed among IncI and IncF-type antibiotic resistance and virulence plasmids found in avian and human-source Escherichia coli and Salmonella. It is found that ParDEI is a plasmid stability and stress response module that increases tolerance of aminoglycoside, quinolone and β-lactam antibiotics in E. coli by ~100–1,000-fold, and thus to levels beyond those achievable in the course of antibiotic therapy for human infections. ParDEI also confers a clear survival advantage at 42 °C and expression of the ParEI toxin in trans induces the SOS response, inhibits cell division and promotes biofilm formation. This transmissible high-level antibiotic tolerance is likely to be an important factor in the success of the IncI and IncF plasmids which carry it and the important pathogens in which these are resident.
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44
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General Mechanisms Leading to Persister Formation and Awakening. Trends Genet 2019; 35:401-411. [DOI: 10.1016/j.tig.2019.03.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/20/2019] [Accepted: 03/27/2019] [Indexed: 11/18/2022]
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45
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Abstract
Regulatory RNAs, present in many bacterial genomes and particularly in pathogenic bacteria such as Staphylococcus aureus, control the expression of genes encoding virulence factors or metabolic proteins. They are extremely diverse and include noncoding RNAs (sRNA), antisense RNAs, and some 5' or 3' untranslated regions of messenger RNAs that act as sensors for metabolites, tRNAs, or environmental conditions (e.g., temperature, pH). In this review we focus on specific examples of sRNAs of S. aureus that illustrate how numerous sRNAs and associated proteins are embedded in complex networks of regulation. In addition, we discuss the CRISPR-Cas systems defined as an RNA-interference-like mechanism, which also exist in staphylococcal strains.
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46
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Ferrari A, Maggi S, Montanini B, Levante A, Lazzi C, Yamaguchi Y, Rivetti C, Folli C. Identification and first characterization of DinJ-YafQ toxin-antitoxin systems in Lactobacillus species of biotechnological interest. Sci Rep 2019; 9:7645. [PMID: 31114007 PMCID: PMC6529426 DOI: 10.1038/s41598-019-44094-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 05/09/2019] [Indexed: 11/18/2022] Open
Abstract
DinJ-YafQ is a type II TA system comprising the ribosome-dependent RNase YafQ toxin and the DinJ antitoxin protein. Although the module has been extensively characterized in Escherichia coli, little information is available for homologous systems in lactic acid bacteria. In this study, we employed bioinformatics tools to identify DinJ-YafQ systems in Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus species, commonly used in biotechnological processes. Among a total of nineteen systems found, two TA modules from Lactobacillus paracasei and two modules from Lactobacillus rhamnosus wild strains were isolated and their activity was verified by growth assays in Escherichia coli either in liquid and solid media. The RNase activity of the YafQ toxins was verified in vivo by probing mRNA dynamics and metabolism with single-cell Thioflavin T fluorescence. Our findings demonstrate that, albeit DinJ-YafQ TA systems are widely distributed in lactic acid bacteria, only few are fully functional, while others have lost toxicity even though they maintain high sequence identity with wild type YafQ and a likely functional antitoxin protein.
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Affiliation(s)
- Alberto Ferrari
- Department of Food and Drug, University of Parma, 43124, Parma, Italy
| | - Stefano Maggi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124, Parma, Italy
| | - Barbara Montanini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124, Parma, Italy
| | - Alessia Levante
- Department of Food and Drug, University of Parma, 43124, Parma, Italy
| | - Camilla Lazzi
- Department of Food and Drug, University of Parma, 43124, Parma, Italy
| | - Yoshihiro Yamaguchi
- The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - Claudio Rivetti
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124, Parma, Italy.
| | - Claudia Folli
- Department of Food and Drug, University of Parma, 43124, Parma, Italy.
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The Origin and Evolution of Release Factors: Implications for Translation Termination, Ribosome Rescue, and Quality Control Pathways. Int J Mol Sci 2019; 20:ijms20081981. [PMID: 31018531 PMCID: PMC6514570 DOI: 10.3390/ijms20081981] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 04/18/2019] [Accepted: 04/18/2019] [Indexed: 01/26/2023] Open
Abstract
The evolution of release factors catalyzing the hydrolysis of the final peptidyl-tRNA bond and the release of the polypeptide from the ribosome has been a longstanding paradox. While the components of the translation apparatus are generally well-conserved across extant life, structurally unrelated release factor peptidyl hydrolases (RF-PHs) emerged in the stems of the bacterial and archaeo-eukaryotic lineages. We analyze the diversification of RF-PH domains within the broader evolutionary framework of the translation apparatus. Thus, we reconstruct the possible state of translation termination in the Last Universal Common Ancestor with possible tRNA-like terminators. Further, evolutionary trajectories of the several auxiliary release factors in ribosome quality control (RQC) and rescue pathways point to multiple independent solutions to this problem and frequent transfers between superkingdoms including the recently characterized ArfT, which is more widely distributed across life than previously appreciated. The eukaryotic RQC system was pieced together from components with disparate provenance, which include the long-sought-after Vms1/ANKZF1 RF-PH of bacterial origin. We also uncover an under-appreciated evolutionary driver of innovation in rescue pathways: effectors deployed in biological conflicts that target the ribosome. At least three rescue pathways (centered on the prfH/RFH, baeRF-1, and C12orf65 RF-PH domains), were likely innovated in response to such conflicts.
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Muthuramalingam M, White JC, Murphy T, Ames JR, Bourne CR. The toxin from a ParDE toxin-antitoxin system found in Pseudomonas aeruginosa offers protection to cells challenged with anti-gyrase antibiotics. Mol Microbiol 2019; 111:441-454. [PMID: 30427086 PMCID: PMC6368863 DOI: 10.1111/mmi.14165] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2018] [Indexed: 12/13/2022]
Abstract
Toxin-antitoxin systems are mediators of diverse activities in bacterial physiology. For the ParE-type toxins, their reported role of gyrase inhibition utilized during plasmid-segregation killing indicates they are toxic. However, their location throughout chromosomes leads to questions about function, including potential non-toxic outcomes. The current study has characterized a ParDE system from the opportunistic human pathogen Pseudomonas aeruginosa (Pa). We identified a protective function for this ParE toxin, PaParE, against effects of quinolone and other antibiotics. However, higher concentrations of PaParE are themselves toxic to cells, indicating the phenotypic outcome can vary based on its concentration. Our assays confirmed PaParE inhibition of gyrase-mediated supercoiling of DNA with an IC50 value in the low micromolar range, a species-specificity that resulted in more efficacious inhibition of Escherichia coli derived gyrase versus Pa gyrase, and overexpression in the absence of antitoxin yielded an expected filamentous morphology with multi-foci nucleic acid material. Additional data revealed that the PaParE toxin is monomeric and interacts with dimeric PaParD antitoxin with a KD in the lower picomolar range, yielding a heterotetramer. This work provides novel insights into chromosome-encoded ParE function, whereby its expression can impart partial protection to cultures from selected antibiotics.
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Affiliation(s)
- Meenakumari Muthuramalingam
- The University of Oklahoma, Department of Chemistry and BiochemistryNorman73019OKUSA
- Present address:
Department of Pharmaceutical ChemistryUniversity of KansasLawrence66047 KSUSA
| | - John C. White
- The University of Oklahoma, Department of Chemistry and BiochemistryNorman73019OKUSA
| | - Tamiko Murphy
- The University of Oklahoma, Department of Chemistry and BiochemistryNorman73019OKUSA
| | - Jessica R. Ames
- The University of Oklahoma, Department of Chemistry and BiochemistryNorman73019OKUSA
| | - Christina R. Bourne
- The University of Oklahoma, Department of Chemistry and BiochemistryNorman73019OKUSA
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Skjerning RB, Senissar M, Winther KS, Gerdes K, Brodersen DE. The RES domain toxins of RES-Xre toxin-antitoxin modules induce cell stasis by degrading NAD+. Mol Microbiol 2018; 111:221-236. [PMID: 30315706 DOI: 10.1111/mmi.14150] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2018] [Indexed: 12/18/2022]
Abstract
Type II toxin-antitoxin (TA) modules, which are important cellular regulators in prokaryotes, usually encode two proteins, a toxin that inhibits cell growth and a nontoxic and labile inhibitor (antitoxin) that binds to and neutralizes the toxin. Here, we demonstrate that the res-xre locus from Photorhabdus luminescens and other bacterial species function as bona fide TA modules in Escherichia coli. The 2.2 Å crystal structure of the intact Pseudomonas putida RES-Xre TA complex reveals an unusual 2:4 stoichiometry in which a central RES toxin dimer binds two Xre antitoxin dimers. The antitoxin dimers each expose two helix-turn-helix DNA-binding domains of the Cro repressor type, suggesting the TA complex is capable of binding the upstream promoter sequence on DNA. The toxin core domain shows structural similarity to ADP-ribosylating enzymes such as diphtheria toxin but has an atypical NAD+ -binding pocket suggesting an alternative function. We show that activation of the toxin in vivo causes a depletion of intracellular NAD+ levels eventually leading to inhibition of cell growth in E. coli and inhibition of global macromolecular biosynthesis. Both structure and activity are unprecedented among bacterial TA systems, suggesting the functional scope of bacterial TA toxins is much wider than previously appreciated.
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Affiliation(s)
- Ragnhild Bager Skjerning
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Meriem Senissar
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Kristoffer S Winther
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Kenn Gerdes
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Ditlev E Brodersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
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50
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ClpAP protease is a universal factor that activates the parDE toxin-antitoxin system from a broad host range RK2 plasmid. Sci Rep 2018; 8:15287. [PMID: 30327496 PMCID: PMC6191456 DOI: 10.1038/s41598-018-33726-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/04/2018] [Indexed: 12/12/2022] Open
Abstract
The activity of type II toxin-antitoxin systems (TA), which are responsible for many important features of bacterial cells, is based on the differences between toxin and antitoxin stabilities. The antitoxin lability results from bacterial protease activity. Here, we investigated how particular Escherichia coli cytosolic proteases, namely, Lon, ClpAP, ClpXP, and ClpYQ, affect the stability of both the toxin and antitoxin components of the parDE system from the broad host range plasmid RK2. The results of our in vivo and in vitro experiments show that the ParD antitoxin is degraded by the ClpAP protease, and dsDNA stimulates this process. The ParE toxin is not degraded by any of these proteases and can therefore cause growth inhibition of plasmid-free cells after an unequal plasmid distribution during cell division. We also demonstrate that the ParE toxin interaction with ParD prevents antitoxin proteolysis by ClpAP; however, this interaction does not prevent the ClpAP interaction with ParD. We show that ClpAP protease homologs affect plasmid stability in other bacterial species, indicating that ClpAP is a universal activator of the parDE system and that ParD is a universal substrate for ClpAP.
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