1
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Pu H, Chen Y, Zhao X, Dai L, Tong A, Tang D, Chen Q, Yu Y. A toxin-antitoxin system provides phage defense via DNA damage and repair. Nat Commun 2025; 16:3141. [PMID: 40169592 PMCID: PMC11961720 DOI: 10.1038/s41467-025-58540-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2024] [Accepted: 03/19/2025] [Indexed: 04/03/2025] Open
Abstract
Widespread in bacteria and archaea, toxin-antitoxin (TA) systems have been recently demonstrated to function in phage defense. Here we characterize the anti-phage function of a type IV TA system, ShosTA. Using structural and biochemical approaches, we show that ShosT couples phosphoribosyltransferase and pyrophosphatase activities to disrupt purine metabolism, resulting in DNA duplication, cell filamentation and ultimate cell death. ShosA binds DNA and likely recruits other proteins to facilitate DNA homologous recombination to antagonize ShosT's toxicity. We identify Gp0.7 of T7 phage as a trigger for ShosTA system via shutting off the protein synthesis, and the C-terminus-mediated intrinsic instability of ShosA releases the toxicity of the existing ShosT proteins. Collectively, our results provide a novel toxin-antitoxin mechanism for anti-phage immunity and shed light on the triggering of this TA system.
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Affiliation(s)
- Huan Pu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yuxin Chen
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xinjun Zhao
- National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Lunzhi Dai
- National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Aiping Tong
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Dongmei Tang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Qiang Chen
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Yamei Yu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
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2
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Lee D, Gunamalai L, Kannan J, Vickery K, Yaacov O, Onuchic-Whitford AC, Chakravarti A, Kapoor A. Massively parallel reporter assays identify functional enhancer variants at QT interval GWAS loci. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.03.11.642686. [PMID: 40161821 PMCID: PMC11952420 DOI: 10.1101/2025.03.11.642686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 04/02/2025]
Abstract
Genome-wide association studies (GWAS) have identified >30 loci with multiple common noncoding variants explaining interindividual electrocardiographic QT interval (QTi) variation. Of the many types of noncoding functional elements, here we sought to identify transcriptional enhancers with sequence variation and their cognate transcription factors (TFs) that alter the expression of proximal cardiac genes to affect QTi variation. We used massively parallel reporter assays (MPRA) in mouse cardiomyocyte HL-1 cells to screen for functional enhancer variants among 1,018 QTi-associated GWAS variants that overlap candidate cardiac enhancers across 31 loci. We identified 445 GWAS variant-containing enhancers of which 79 showed significant allelic difference in enhancer activity across 21 GWAS loci, with multiple enhancer variants per locus. Of these, we predicted differential binding by cardiac TFs, including AP-1, ATF-1, GATA2, MEF2, NKX2.5, SRF and TBX5 which are known to play key roles in development and homeostasis, at 49 enhancer variants. Finally, we used expression quantitative trait locus mapping and predicted promoter-enhancer contacts to identify 14 candidate target genes through analyses of 36 enhancer variants at 16 loci. This study provides strong evidence for 14 cardiac genes, 10 of them novel, impacting on QTi variation, beyond explaining observed genetic associations.
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Affiliation(s)
- Dongwon Lee
- Department of Pediatrics, Division of Nephrology, Boston Children’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - Lavanya Gunamalai
- Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jeerthi Kannan
- Department of Pediatrics, Division of Nephrology, Boston Children’s Hospital, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - Kyla Vickery
- Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Or Yaacov
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
| | - Ana C. Onuchic-Whitford
- Department of Pediatrics, Division of Nephrology, Boston Children’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Renal division, Brigham and Women’s Hospital, Boston, MA, USA
| | - Aravinda Chakravarti
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
| | - Ashish Kapoor
- Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
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3
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Sim M, Nguyen J, Škopová K, Yoo K, Tai CH, Knipling L, Chen Q, Kim D, Nolan S, Elaksher R, Majdalani N, Lorenzi H, Stibitz S, Moon K, Hinton DM. A highly conserved sRNA downregulates multiple genes, including a σ 54 transcriptional activator, in the virulence mode of Bordetella pertussis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.11.19.624354. [PMID: 39803429 PMCID: PMC11722255 DOI: 10.1101/2024.11.19.624354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/24/2025]
Abstract
Bacterial sRNAs together with the RNA chaperone Hfq post-transcriptionally regulate gene expression by affecting ribosome binding or mRNA stability. In the human pathogen Bordetella pertussis, the causative agent of whooping cough, hundreds of sRNAs have been identified, but their roles in B. pertussis biology are mostly unknown. Here we characterize a Hfq-dependent sRNA (S17), whose level is dramatically higher in the virulence (Bvg+) mode. We show that transcription from a σA-dependent promoter yields a long form of 190 nucleotides (nts) that is processed by RNase E to generate a shorter, more stable form (S17S) of 67 nts. Using RNA-seq and RT-qPCR, we identify 92 genes whose expression significantly increases in the absence of S17. Of these genes, 70 contain sequences at/near their ribosome binding sites (RBSs) that are complementary to single-stranded (ss) regions (Sites 1 or 2) of S17S. The identified genes include those encoding multiple transporters and 3 transcriptional regulators. Using a lacZ translational reporter system, we demonstrate that S17S directly represses one of these genes, BP2158, a σ54-dependent transcriptional regulator, suggesting the repression of a σ54 regulon in the Bvg+ mode. We find that the S17S region containing Sites 1 and 2 is 100% conserved throughout various Betaproteobacteria species, and the S17S target sites are often conserved in the homologs of the B. pertussis target genes. We speculate that S17S regulation represents a highly conserved process that fine-tunes gene expression in the Bvg+ mode of B. pertussis and perhaps under other conditions in related bacteria.
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Affiliation(s)
- Minji Sim
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jeffers Nguyen
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Karolína Škopová
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Kyungyoon Yoo
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Chin-Hsien Tai
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, USA
| | - Leslie Knipling
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Qing Chen
- Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - David Kim
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Summer Nolan
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Rawan Elaksher
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Nadim Majdalani
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, USA
| | - Hernan Lorenzi
- Tri-Lab Bioinformatics Core, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Scott Stibitz
- Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Kyung Moon
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Deborah M Hinton
- Gene Expression and Regulation Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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4
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Nyerges A, Chiappino-Pepe A, Budnik B, Baas-Thomas M, Flynn R, Yan S, Ostrov N, Liu M, Wang M, Zheng Q, Hu F, Chen K, Rudolph A, Chen D, Ahn J, Spencer O, Ayalavarapu V, Tarver A, Harmon-Smith M, Hamilton M, Blaby I, Yoshikuni Y, Hajian B, Jin A, Kintses B, Szamel M, Seregi V, Shen Y, Li Z, Church GM. Synthetic genomes unveil the effects of synonymous recoding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.16.599206. [PMID: 38915524 PMCID: PMC11195188 DOI: 10.1101/2024.06.16.599206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Engineering the genetic code of an organism provides the basis for (i) making any organism safely resistant to natural viruses and (ii) preventing genetic information flow into and out of genetically modified organisms while (iii) allowing the biosynthesis of genetically encoded unnatural polymers1-4. Achieving these three goals requires the reassignment of multiple of the 64 codons nature uses to encode proteins. However, synonymous codon replacement-recoding-is frequently lethal, and how recoding impacts fitness remains poorly explored. Here, we explore these effects using whole-genome synthesis, multiplexed directed evolution, and genome-transcriptome-translatome-proteome co-profiling on multiple recoded genomes. Using this information, we assemble a synthetic Escherichia coli genome in seven sections using only 57 codons to encode proteins. By discovering the rules responsible for the lethality of synonymous recoding and developing a data-driven multi-omics-based genome construction workflow that troubleshoots synthetic genomes, we overcome the lethal effects of 62,007 synonymous codon swaps and 11,108 additional genomic edits. We show that synonymous recoding induces transcriptional noise including new antisense RNAs, leading to drastic transcriptome and proteome perturbation. As the elimination of select codons from an organism's genetic code results in the widespread appearance of cryptic promoters, we show that synonymous codon choice may naturally evolve to minimize transcriptional noise. Our work provides the first genome-scale description of how synonymous codon changes influence organismal fitness and paves the way for the construction of functional genomes that provide genetic firewalls from natural ecosystems and safely produce biopolymers, drugs, and enzymes with an expanded chemistry.
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Affiliation(s)
- Akos Nyerges
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | | | - Bogdan Budnik
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | | | - Regan Flynn
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Shirui Yan
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- BGI Research, Shenzhen 518083, China
| | - Nili Ostrov
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Min Liu
- GenScript USA Inc., Piscataway, NJ 08854, USA
| | | | | | | | | | - Alexandra Rudolph
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Dawn Chen
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Jenny Ahn
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Owen Spencer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | | | - Angela Tarver
- DOE Joint Genome Institute (JGI), Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Miranda Harmon-Smith
- DOE Joint Genome Institute (JGI), Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Matthew Hamilton
- DOE Joint Genome Institute (JGI), Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ian Blaby
- DOE Joint Genome Institute (JGI), Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Yasuo Yoshikuni
- DOE Joint Genome Institute (JGI), Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Behnoush Hajian
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Adeline Jin
- GenScript USA Inc., Piscataway, NJ 08854, USA
| | - Balint Kintses
- Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, 6726, Hungary
| | - Monika Szamel
- Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, 6726, Hungary
| | - Viktoria Seregi
- Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, 6726, Hungary
| | - Yue Shen
- BGI Research, Shenzhen 518083, China
- BGI Research, Changzhou 213299, China
- Guangdong Provincial Key Laboratory of Genome Read and Write, BGI Research, Shenzhen 518083, China
| | - Zilong Li
- GenScript USA Inc., Piscataway, NJ 08854, USA
| | - George M. Church
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
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5
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Schmitt DS, Siegel SD, Selle K. Applications of designer phage encoding recombinant gene payloads. Trends Biotechnol 2024; 42:326-338. [PMID: 37833198 DOI: 10.1016/j.tibtech.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/17/2023] [Accepted: 09/19/2023] [Indexed: 10/15/2023]
Abstract
Advances in genetic engineering, synthetic biology, and DNA sequencing have transformed the re-emergent therapeutic bacteriophage field. The increasing rate of multidrug resistant (MDR) infections and the speed at which new bacteriophages can be isolated, sequenced, characterized, and engineered has reinvigorated phage therapy and unlocked new applications of phages for modulating bacteria. The methods used to genetically engineer bacteriophages are undergoing significant development, but identification of heterologous gene payloads with desirable activity and determination of their impact on bacteria or human cells in translationally relevant applications remain underexplored areas. Here, we discuss and categorize recombinant gene payloads for their potential outcome on phage-bacteria interactions when genetically engineered into phage genomes for expression in their bacterial hosts.
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Affiliation(s)
- Daniel S Schmitt
- Biomanufacturing Training and Education Center, North Carolina State University, Raleigh, NC, USA
| | - Sara D Siegel
- Biomanufacturing Training and Education Center, North Carolina State University, Raleigh, NC, USA
| | - Kurt Selle
- Biomanufacturing Training and Education Center, North Carolina State University, Raleigh, NC, USA.
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6
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Choi W, Maharjan A, Im HG, Park JY, Park JT, Park JH. Identification and Characterization of HEPN-MNT Type II TA System from Methanothermobacter thermautotrophicus ΔH. J Microbiol 2023; 61:411-421. [PMID: 37071293 DOI: 10.1007/s12275-023-00041-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 04/19/2023]
Abstract
Toxin-antitoxin (TA) systems are widespread in bacteria and archaea plasmids and genomes to regulate DNA replication, gene transcription, or protein translation. Higher eukaryotic and prokaryotic nucleotide-binding (HEPN) and minimal nucleotidyltransferase (MNT) domains are prevalent in prokaryotic genomes and constitute TA pairs. However, three gene pairs (MTH304/305, 408/409, and 463/464) of Methanothermobacter thermautotropicus ΔH HEPN-MNT family have not been studied as TA systems. Among these candidates, our study characterizes the MTH463/MTH464 TA system. MTH463 expression inhibited Escherichia coli growth, whereas MTH464 did not and blocked MTH463 instead. Using site-directed MTH463 mutagenesis, we determined that amino acids R99G, H104A, and Y106A from the R[ɸX]4-6H motif are involved with MTH463 cell toxicity. Furthermore, we established that purified MTH463 could degrade MS2 phage RNA, whereas purified MTH464 neutralized MTH463 activity in vitro. Our results indicate that the endonuclease toxin MTH463 (encoding a HEPN domain) and its cognate antitoxin MTH464 (encoding the MNT domain) may act as a type II TA system in M. thermautotropicus ΔH. This study provides initial and essential information studying TA system functions, primarily archaea HEPN-MNT family.
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Affiliation(s)
- Wonho Choi
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
- 4D Convergence Technology Institute (National Key Technology Institute in University), Korea National University of Transportation, Jungpyeong, 27909, Republic of Korea
| | - Anoth Maharjan
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
| | - Hae Gang Im
- BIORCHESTRA Co., LTD., Daejeon, 34013, Republic of Korea
| | - Ji-Young Park
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
| | - Jong-Tae Park
- Department of Food Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea.
| | - Jung-Ho Park
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea.
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7
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Stokar-Avihail A, Fedorenko T, Hör J, Garb J, Leavitt A, Millman A, Shulman G, Wojtania N, Melamed S, Amitai G, Sorek R. Discovery of phage determinants that confer sensitivity to bacterial immune systems. Cell 2023; 186:1863-1876.e16. [PMID: 37030292 DOI: 10.1016/j.cell.2023.02.029] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 01/09/2023] [Accepted: 02/20/2023] [Indexed: 04/10/2023]
Abstract
Over the past few years, numerous anti-phage defense systems have been discovered in bacteria. Although the mechanism of defense for some of these systems is understood, a major unanswered question is how these systems sense phage infection. To systematically address this question, we isolated 177 phage mutants that escape 15 different defense systems. In many cases, these escaper phages were mutated in the gene sensed by the defense system, enabling us to map the phage determinants that confer sensitivity to bacterial immunity. Our data identify specificity determinants of diverse retron systems and reveal phage-encoded triggers for multiple abortive infection systems. We find general themes in phage sensing and demonstrate that mechanistically diverse systems have converged to sense either the core replication machinery of the phage, phage structural components, or host takeover mechanisms. Combining our data with previous findings, we formulate key principles on how bacterial immune systems sense phage invaders.
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Affiliation(s)
- Avigail Stokar-Avihail
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Taya Fedorenko
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jens Hör
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jeremy Garb
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Azita Leavitt
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Adi Millman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gabriela Shulman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nicole Wojtania
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sarah Melamed
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gil Amitai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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8
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Kelly A, Arrowsmith TJ, Went SC, Blower TR. Toxin-antitoxin systems as mediators of phage defence and the implications for abortive infection. Curr Opin Microbiol 2023; 73:102293. [PMID: 36958122 DOI: 10.1016/j.mib.2023.102293] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/14/2023] [Accepted: 02/21/2023] [Indexed: 03/25/2023]
Abstract
Bacteria have evolved a broad range of defence mechanisms to protect against infection by their viral parasites, bacteriophages (phages). Toxin-antitoxin (TA) systems are small loci found throughout bacteria and archaea that in some cases provide phage defence. The recent explosion in phage defence system discovery has identified multiple novel TA systems with antiphage activity. Due to inherent toxicity, TA systems are thought to mediate abortive infection (Abi), wherein the host cell dies in response to phage infection, removing the phage, and protecting clonal siblings. Recent studies, however, have uncovered molecular mechanisms by which TA systems are activated by phages, how they mediate toxicity, and how phages escape the defences. These new models reveal dazzling complexity in phage-host interactions and provide further evidence that TA systems do not in all cases inherently perform classic Abi, suggesting an evolved conceptual definition is required.
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Affiliation(s)
- Abigail Kelly
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK
| | - Tom J Arrowsmith
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK
| | - Sam C Went
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK
| | - Tim R Blower
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK.
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9
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Malik T, Klenow L, Karyolaimos A, Gier JWD, Daniels R. Silencing Transcription from an Influenza Reverse Genetics Plasmid in E. coli Enhances Gene Stability. ACS Synth Biol 2023; 12:432-445. [PMID: 36716395 PMCID: PMC9942234 DOI: 10.1021/acssynbio.2c00358] [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] [Indexed: 02/01/2023]
Abstract
Reverse genetics (RG) systems have been instrumental for determining the molecular aspects of viral replication, pathogenesis, and for the development of therapeutics. Here, we demonstrate that genes encoding the influenza surface antigens hemagglutinin and neuraminidase have varying stability when cloned into a common RG plasmid and transformed into Escherichia coli. Using GFP as a reporter, we demonstrate that E. coli expresses the target genes in the RG plasmid at low levels. Incorporating lac operators or a transcriptional terminator into the plasmid reduced expression and stabilized the viral genes to varying degrees. Sandwiching the viral gene between two lac operators provided the largest contribution to stability and we confirmed the stabilization is Lac repressor-dependent and crucial for subsequent plasmid propagations in E. coli. Viruses rescued from the lac operator-stabilized plasmid displayed similar kinetics and titers to the original plasmid in two different viral backbones. Together, these results indicate that silencing transcription from the plasmid in E. coli helps to maintain the correct influenza gene sequence and that the lac operator addition does not impair virus production. It is envisaged that sandwiching DNA segments between lac operators can be used for reducing DNA segment instability in any plasmid that is propagated in E. coli which express the Lac repressor.
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Affiliation(s)
- Tahir Malik
- Division
of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | - Laura Klenow
- Division
of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | - Alexandros Karyolaimos
- Department
of Biochemistry and Biophysics, Stockholm
University, 10691 Stockholm, Sweden
| | - Jan-Willem de Gier
- Department
of Biochemistry and Biophysics, Stockholm
University, 10691 Stockholm, Sweden
| | - Robert Daniels
- Division
of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States,
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10
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Millman A, Melamed S, Leavitt A, Doron S, Bernheim A, Hör J, Garb J, Bechon N, Brandis A, Lopatina A, Ofir G, Hochhauser D, Stokar-Avihail A, Tal N, Sharir S, Voichek M, Erez Z, Ferrer JLM, Dar D, Kacen A, Amitai G, Sorek R. An expanded arsenal of immune systems that protect bacteria from phages. Cell Host Microbe 2022; 30:1556-1569.e5. [DOI: 10.1016/j.chom.2022.09.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/15/2022] [Accepted: 09/28/2022] [Indexed: 01/16/2023]
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11
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Rousset F, Depardieu F, Miele S, Dowding J, Laval AL, Lieberman E, Garry D, Rocha EPC, Bernheim A, Bikard D. Phages and their satellites encode hotspots of antiviral systems. Cell Host Microbe 2022; 30:740-753.e5. [PMID: 35316646 PMCID: PMC9122126 DOI: 10.1016/j.chom.2022.02.018] [Citation(s) in RCA: 159] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 01/27/2022] [Accepted: 02/23/2022] [Indexed: 11/18/2022]
Abstract
Bacteria carry diverse genetic systems to defend against viral infection, some of which are found within prophages where they inhibit competing viruses. Phage satellites pose additional pressures on phages by hijacking key viral elements to their own benefit. Here, we show that E. coli P2-like phages and their parasitic P4-like satellites carry hotspots of genetic variation containing reservoirs of anti-phage systems. We validate the activity of diverse systems and describe PARIS, an abortive infection system triggered by a phage-encoded anti-restriction protein. Antiviral hotspots participate in inter-viral competition and shape dynamics between the bacterial host, P2-like phages, and P4-like satellites. Notably, the anti-phage activity of satellites can benefit the helper phage during competition with virulent phages, turning a parasitic relationship into a mutualistic one. Anti-phage hotspots are present across distant species and constitute a substantial source of systems that participate in the competition between mobile genetic elements.
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Affiliation(s)
- François Rousset
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France.
| | - Florence Depardieu
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Solange Miele
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Julien Dowding
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Anne-Laure Laval
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | | | | | - Eduardo P C Rocha
- Institut Pasteur, Université de Paris, CNRS UMR 3525, Microbial Evolutionary Genomics, 75015 Paris, France
| | - Aude Bernheim
- Université de Paris, INSERM, IAME, 75006 Paris, France
| | - David Bikard
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France.
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12
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Korniakova V, Devinck A, Groleau MC, Déziel E, Perreault J. Fluoride-Controlled Riboswitch-Based Dampening of Gene Expression for Cloning Potent Promoters. Front Genet 2022; 12:591543. [PMID: 35126444 PMCID: PMC8814607 DOI: 10.3389/fgene.2021.591543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/15/2021] [Indexed: 11/29/2022] Open
Abstract
Bioreporter systems based on detectable enzyme activity, such as that of beta-galactosidase or luciferase, are key in novel bacterial promoter discovery and study. While these systems permit quantification of gene expression, their use is limited by the toxicity of the expressed reporter enzymes in a given host. Indeed, the most potent promoters may be overlooked if their activity causes a lethal overproduction of the reporter genes when screening for transcriptional activity of potential promoter sequences with the luxCDABE cassette. To overcome this limitation, a variation of the mini-CTX-lux plasmid has been designed which allows reduction of promoter activity via the addition of an adjacent fluoride riboswitch. The riboswitch adds a layer of regulation between the promoter and the reporter gene, allowing cloning of stronger promoters by weakening expression, while giving the potential to induce with fluoride to provide a good signal for weaker promoters, thus circumventing limitations associated with reporter toxicity. We noticed the riboswitch potential portability issues between species, suggesting caution when using riboswitches non-native to the species where it is being used. This study introduces a new molecular biology tool which will allow for the identification of previously unverifiable or uncharacterized potent promoters and also provides a cloning vector for translational fusion with luciferase in a plasmid compatible with many species such as from the genera Burkholderia and Pseudomonas.
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13
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Andreopoulos WB, Geller AM, Lucke M, Balewski J, Clum A, Ivanova NN, Levy A. Deeplasmid: deep learning accurately separates plasmids from bacterial chromosomes. Nucleic Acids Res 2021; 50:e17. [PMID: 34871418 PMCID: PMC8860608 DOI: 10.1093/nar/gkab1115] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 10/11/2021] [Accepted: 10/23/2021] [Indexed: 11/13/2022] Open
Abstract
Plasmids are mobile genetic elements that play a key role in microbial ecology and evolution by mediating horizontal transfer of important genes, such as antimicrobial resistance genes. Many microbial genomes have been sequenced by short read sequencers and have resulted in a mix of contigs that derive from plasmids or chromosomes. New tools that accurately identify plasmids are needed to elucidate new plasmid-borne genes of high biological importance. We have developed Deeplasmid, a deep learning tool for distinguishing plasmids from bacterial chromosomes based on the DNA sequence and its encoded biological data. It requires as input only assembled sequences generated by any sequencing platform and assembly algorithm and its runtime scales linearly with the number of assembled sequences. Deeplasmid achieves an AUC–ROC of over 89%, and it was more accurate than five other plasmid classification methods. Finally, as a proof of concept, we used Deeplasmid to predict new plasmids in the fish pathogen Yersinia ruckeri ATCC 29473 that has no annotated plasmids. Deeplasmid predicted with high reliability that a long assembled contig is part of a plasmid. Using long read sequencing we indeed validated the existence of a 102 kb long plasmid, demonstrating Deeplasmid's ability to detect novel plasmids.
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Affiliation(s)
- William B Andreopoulos
- Joint Genome Institute, US Department of Energy, LBNL Berkeley, CA, USA.,Department of Computer Science, San Jose State University, CA, USA
| | - Alexander M Geller
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Miriam Lucke
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Jan Balewski
- National Energy Research Scientific Computing Center (NERSC), Berkeley, CA, USA
| | - Alicia Clum
- Joint Genome Institute, US Department of Energy, LBNL Berkeley, CA, USA
| | - Natalia N Ivanova
- Joint Genome Institute, US Department of Energy, LBNL Berkeley, CA, USA
| | - Asaf Levy
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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14
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Bhandari BK, Lim CS, Remus DM, Chen A, van Dolleweerd C, Gardner PP. Analysis of 11,430 recombinant protein production experiments reveals that protein yield is tunable by synonymous codon changes of translation initiation sites. PLoS Comput Biol 2021; 17:e1009461. [PMID: 34610008 PMCID: PMC8519471 DOI: 10.1371/journal.pcbi.1009461] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/15/2021] [Accepted: 09/19/2021] [Indexed: 12/16/2022] Open
Abstract
Recombinant protein production is a key process in generating proteins of interest in the pharmaceutical industry and biomedical research. However, about 50% of recombinant proteins fail to be expressed in a variety of host cells. Here we show that the accessibility of translation initiation sites modelled using the mRNA base-unpairing across the Boltzmann's ensemble significantly outperforms alternative features. This approach accurately predicts the successes or failures of expression experiments, which utilised Escherichia coli cells to express 11,430 recombinant proteins from over 189 diverse species. On this basis, we develop TIsigner that uses simulated annealing to modify up to the first nine codons of mRNAs with synonymous substitutions. We show that accessibility captures the key propensity beyond the target region (initiation sites in this case), as a modest number of synonymous changes is sufficient to tune the recombinant protein expression levels. We build a stochastic simulation model and show that higher accessibility leads to higher protein production and slower cell growth, supporting the idea of protein cost, where cell growth is constrained by protein circuits during overexpression.
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Affiliation(s)
- Bikash K. Bhandari
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Chun Shen Lim
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Daniela M. Remus
- Callaghan Innovation Protein Science and Engineering, University of Canterbury, Christchurch, New Zealand
| | - Augustine Chen
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Craig van Dolleweerd
- Biomolecular Interaction Center, University of Canterbury, Christchurch, New Zealand
| | - Paul P. Gardner
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Biomolecular Interaction Center, University of Canterbury, Christchurch, New Zealand
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15
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Gu Q, He P, Wang D, Ma J, Zhong X, Zhu Y, Zhang Y, Bai Q, Pan Z, Yao H. An Auto-Regulating Type II Toxin-Antitoxin System Modulates Drug Resistance and Virulence in Streptococcus suis. Front Microbiol 2021; 12:671706. [PMID: 34475853 PMCID: PMC8406773 DOI: 10.3389/fmicb.2021.671706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements that play an essential role in multidrug tolerance and virulence of bacteria. So far, little is known about the TA systems in Streptococcus suis. In this study, the Xress-MNTss TA system, composed of the MNTss toxin in the periplasmic space and its interacting Xress antitoxin, was identified in S. suis. β-galactosidase activity and electrophoretic mobility shift assay (EMSA) revealed that Xress and the Xress-MNTss complex could bind directly to the Xress-MNTss promoter as well as downregulate streptomycin adenylyltransferase ZY05719_RS04610. Interestingly, the Xress deletion mutant was less pathogenic in vivo following a challenge in mice. Transmission electron microscopy and adhesion assays pointed to a significantly thinner capsule but greater biofilm-formation capacity in ΔXress than in the wild-type strain. These results indicate that Xress-MNTss, a new type II TA system, plays an important role in antibiotic resistance and pathogenicity in S. suis.
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Affiliation(s)
- Qibing Gu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Peijuan He
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Dan Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Jiale Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Xiaojun Zhong
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Yinchu Zhu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yue Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Qiankun Bai
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Zihao Pan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Huochun Yao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
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16
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Wen X, Zhang Y, Cheng H, An J, Guo Y, Wang L, Wang M. A CRISPR/dCas9-assisted system to clone toxic genes in Escherichia coli. Biochim Biophys Acta Gen Subj 2021; 1865:129994. [PMID: 34450195 DOI: 10.1016/j.bbagen.2021.129994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/26/2021] [Accepted: 08/22/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND The cloning of toxic genes in E. coli requires strict regulation of the target genes' leaky expression. Many methods facilitating successful gene cloning of toxic genes are commonly exploited, but the applicability is severely limited. METHODS A CRISPR/dCas9-assisted system was used to clone toxic genes in E. coli. The plasmid-based and genome-integrated systems were designed in this study. And the green fluorescent protein characterization system was used to test the repression efficiency of the two systems. RESULTS We optimized the plasmid-based CRISPR/dCas9-assisted repression system via testing different sgRNAs targeting the Ptrc promoter and achieved inhibition efficiency up to 64.8%. The genome-integrated system represented 35.9% decreased GFP expression and was successfully employed to cloned four toxic genes from Corynebacterium glutamicum in E. coli. CONCLUSIONS Using this method, we successfully cloned four C. glutamicum-derived toxic genes that had been failed to clone in conventional ways. The CRISPR/dCas9-assisted gene cloning method was a promising tool to facilitate precise gene cloning of different origins in E. coli. GENERAL SIGNIFICANCE This system will be useful for cloning toxic genes from different origins in E. coli, and can accelerate the related research of gene characterization and heterologous expression in the metagenomic era.
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Affiliation(s)
- Xiao Wen
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Yue Zhang
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Haijiao Cheng
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Jingjing An
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Yanmei Guo
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Lixian Wang
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Meng Wang
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
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17
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Marques F, Luzhetskyy A, Mendes MV. Engineering Corynebacterium glutamicum with a comprehensive genomic library and phage-based vectors. Metab Eng 2020; 62:221-234. [DOI: 10.1016/j.ymben.2020.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/17/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022]
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18
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Bhat S, Bialy D, Sealy JE, Sadeyen JR, Chang P, Iqbal M. A ligation and restriction enzyme independent cloning technique: an alternative to conventional methods for cloning hard-to-clone gene segments in the influenza reverse genetics system. Virol J 2020; 17:82. [PMID: 32576218 PMCID: PMC7309217 DOI: 10.1186/s12985-020-01358-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 06/17/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Reverse genetics is used in many laboratories around the world and enables the creation of tailor-made influenza viruses with a desired genotype or phenotype. However, the process is not flawless, and difficulties remain during cloning of influenza gene segments into reverse genetics vectors (pHW2000, pHH21, pCAGGS). Reverse genetics begins with making cDNA copies of influenza gene segments and cloning them into bi-directional (pHW2000) or uni-directional plasmids (pHH21, pCAGGS) followed by transfection of the recombinant plasmid(s) to HEK-293 T or any other suitable cells which are permissive to transfection. However, the presence of internal restriction sites in the gene segments of many field isolates of avian influenza viruses makes the cloning process difficult, if employing conventional methods. Further, the genetic instability of influenza gene-containing plasmids in bacteria (especially Polymerase Basic 2 and Polymerase Basic 1 genes; PB2 and PB1) also leads to erroneous incorporation of bacterial genomic sequences into the influenza gene of interest. METHODS Herein, we report an easy and efficient ligation and restriction enzyme independent (LREI) cloning method for cloning influenza gene segments into pHW2000 vector. The method involves amplification of megaprimers followed by PCR amplification of megaprimers using a bait plasmid, DpnI digestion and transformation. RESULTS Hard-to-clone genes: PB2 of A/chicken/Bangladesh/23527/2014 (H9N2) and PB1 of A/chicken/Bangladesh/23527/2014 (H9N2), A/chicken/Jiangxi/02.05YGYXG023-P/2015 (H5N6) and A/Chicken/Vietnam/H7F-14-BN4-315/2014 (H9N2) were cloned into pHW2000 using our LREI method and recombinant viruses were subsequently rescued. CONCLUSION The LREI cloning procedure represents an alternative strategy for cloning influenza gene segments which have internal restriction sites for the enzymes used in reverse genetics. Further, the problem of genetic instability in bacteria can be alleviated by growing recombinant bacterial cultures at a lower temperature. This technique can be applied to clone any influenza gene segment using universal primers, which would help in rapid generation of influenza viruses and facilitate influenza research and vaccine development.
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19
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Talukdar PK, Negretti NM, Turner KL, Konkel ME. Molecular Dissection of the Campylobacter jejuni CadF and FlpA Virulence Proteins in Binding to Host Cell Fibronectin. Microorganisms 2020; 8:E389. [PMID: 32168837 PMCID: PMC7143056 DOI: 10.3390/microorganisms8030389] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/07/2020] [Accepted: 03/09/2020] [Indexed: 02/07/2023] Open
Abstract
Campylobacter jejuni, a zoonotic pathogen that frequently colonizes poultry, possesses two Microbial Surface Components Recognizing Adhesive Matrix Molecule(s) (MSCRAMMs) termed CadF and FlpA that bind to the glycoprotein fibronectin (FN). Previous to this study, it was not known whether the CadF and FlpA proteins were functionally redundant or if both were required to potentiate host cell binding and signaling processes. We addressed these questions by generating a complete repertoire of cadF and flpA mutants and complemented isolates, and performing multiple phenotypic assays. Both CadF and FlpA were found to be necessary for the maximal binding of C. jejuni to FN and to host cells. In addition, both CadF and FlpA are required for the delivery of the C. jejuni Cia effector proteins into the cytosol of host target cells, which in turn activates the MAPK signaling pathway (Erk 1/2) that is required for the C. jejuni invasion of host cells. These data demonstrate the non-redundant and bi-functional nature of these two C. jejuni FN-binding proteins. Taken together, the C. jejuni CadF and FlpA adhesins facilitate the binding of C. jejuni to the host cells, permit delivery of effector proteins into the cytosol of a host target cell, and aid in the rewiring of host cell signaling pathways to alter host cell behavior.
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Affiliation(s)
| | | | | | - Michael E. Konkel
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7520, USA; (P.K.T.); (N.M.N.); (K.L.T.)
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20
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Dobrzanski T, Pobre V, Moreno LF, Barbosa HCDS, Monteiro RA, de Oliveira Pedrosa F, de Souza EM, Arraiano CM, Steffens MBR. In silico prediction and expression profile analysis of small non-coding RNAs in Herbaspirillum seropedicae SmR1. BMC Genomics 2020; 21:134. [PMID: 32039705 PMCID: PMC7011215 DOI: 10.1186/s12864-019-6402-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Herbaspirillum seropedicae is a diazotrophic bacterium from the β-proteobacteria class that colonizes endophytically important gramineous species, promotes their growth through phytohormone-dependent stimulation and can express nif genes and fix nitrogen inside plant tissues. Due to these properties this bacterium has great potential as a commercial inoculant for agriculture. The H. seropedicae SmR1 genome is completely sequenced and annotated but despite the availability of diverse structural and functional analysis of this genome, studies involving small non-coding RNAs (sRNAs) has not yet been done. We have conducted computational prediction and RNA-seq analysis to select and confirm the expression of sRNA genes in the H. seropedicae SmR1 genome, in the presence of two nitrogen independent sources and in presence of naringenin, a flavonoid secreted by some plants. RESULTS This approach resulted in a set of 117 sRNAs distributed in riboswitch, cis-encoded and trans-encoded categories and among them 20 have Rfam homologs. The housekeeping sRNAs tmRNA, ssrS and 4.5S were found and we observed that a large number of sRNAs are more expressed in the nitrate condition rather than the control condition and in the presence of naringenin. Some sRNAs expression were confirmed in vitro and this work contributes to better understand the post transcriptional regulation in this bacterium. CONCLUSIONS H. seropedicae SmR1 express sRNAs in the presence of two nitrogen sources and/or in the presence of naringenin. The functions of most of these sRNAs remains unknown but their existence in this bacterium confirms the evidence that sRNAs are involved in many different cellular activities to adapt to nutritional and environmental changes.
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Affiliation(s)
- Tatiane Dobrzanski
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil
| | - Vânia Pobre
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
| | - Leandro Ferreira Moreno
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil
| | - Helba Cirino de Souza Barbosa
- Graduate Program in Bioinformatics, Universidade Federal do Paraná (UFPR), Rua Alcides Vieira Arcoverde, 1225, Curitiba, 81520-260, Brazil
| | - Rose Adele Monteiro
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil.,Graduate Program in Bioinformatics, Universidade Federal do Paraná (UFPR), Rua Alcides Vieira Arcoverde, 1225, Curitiba, 81520-260, Brazil
| | - Fábio de Oliveira Pedrosa
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil
| | - Emanuel Maltempi de Souza
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil
| | - Cecília Maria Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Maria Berenice Reynaud Steffens
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná (UFPR), Av. Coronel. Francisco H. dos Santos, 210, PoBox 19046, Curitiba, 81.531-980, Paraná, Brazil.
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21
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Cataldo VF, Salgado V, Saa PA, Agosin E. Genomic integration of unclonable gene expression cassettes in Saccharomyces cerevisiae using rapid cloning-free workflows. Microbiologyopen 2020; 9:e978. [PMID: 31944620 PMCID: PMC7066455 DOI: 10.1002/mbo3.978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/22/2019] [Accepted: 11/22/2019] [Indexed: 11/11/2022] Open
Abstract
Most DNA assembly methods require bacterial amplification steps, which restrict its application to genes that can be cloned in the bacterial host without significant toxic effects. However, genes that cannot be cloned in bacteria do not necessarily exert toxic effects on the final host. In order to tackle this issue, we adapted two DNA assembly workflows for rapid, cloning-free construction and genomic integration of expression cassettes in Saccharomyces cerevisiae. One method is based on a modified Gibson assembly, while the other relies on a direct assembly and integration of linear PCR products by yeast homologous recombination. The methods require few simple experimental steps, and their performance was evaluated for the assembly and integration of unclonable zeaxanthin epoxidase expression cassettes in yeast. Results showed that up to 95% integration efficiency can be reached with minimal experimental effort. The presented workflows can be employed as rapid gene integration tools for yeast, especially tailored for integrating unclonable genes.
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Affiliation(s)
- Vicente F Cataldo
- Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valeria Salgado
- Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pedro A Saa
- Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Eduardo Agosin
- Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
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22
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Genome-Wide Screening for Identification of Novel Toxin-Antitoxin Systems in Staphylococcus aureus. Appl Environ Microbiol 2019; 85:AEM.00915-19. [PMID: 31375497 DOI: 10.1128/aem.00915-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 07/11/2019] [Indexed: 01/24/2023] Open
Abstract
Toxin-antitoxin (TA) systems consist of toxin-inhibiting diverse cellular functions (e.g., DNA replication, transcription, and translation) and a noncoding RNA or protein antitoxin. TA systems are associated with various cellular events, such as stress responses, programmed cell death, and bacterial pathogenicity. Recent advances in genome sequencing and bioinformatics research have demonstrated that most bacteria harbor various kinds of TA modules on their chromosomes; however, there is little understanding of chromosomally encoded TA systems in the Gram-positive pathogen Staphylococcus aureus Here, we report on newly discovered S. aureus TA systems, each of which is composed of two proteins. Manual search and gene operon prediction analysis identified eight 2-gene operons as potential candidates for TA systems. Subsequently, using an Escherichia coli host killing and rescue assay, we demonstrated that four of the eight candidates worked as TA systems, designated tsaAT, tsbAT, tscAT, and tsdAT Moreover, the TsaT, TsbT, TscT, and TsdT toxins inhibited S. aureus growth, and the toxicity of TsbT was neutralized by coexpressing the tsbA gene in the native host, S. aureus Further, the bioinformatics analysis of the gene clusters revealed that TsaAT, TsbAT, TscAT, and TsdAT did not exhibit sequence similarity to known bacterial TA systems, and their homologues were present only within Staphylococcus species and not among any other bacteria. Our results further advance not only the understanding of S. aureus TA systems but also the study of unannotated TA systems in various bacterial species.IMPORTANCE Recent advances in genome sequencing and bioinformatics research have demonstrated that most pathogenic bacteria harbor a large number of chromosomally encoded toxin-antitoxin (TA) modules. However, little is known about the TA systems in S. aureus Here, we newly identified four S. aureus TA systems using a combination of manual base-by-base screening and functional analysis in E. coli Moreover, all toxins of the identified TA systems caused growth inhibition in the native host S. aureus Although the newly identified TA systems did not exhibit sequence similarity with known bacterial TA systems, their orthologues were conserved only among other Staphylococcus species, indicating their uniqueness to staphylococci. Our approach opens the possibility for studying unannotated TA systems in various bacterial species.
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Sass AM, De Waele S, Daled S, Devreese B, Deforce D, Van Nieuwerburgh F, Coenye T. Small RNA NcS27 co-regulates utilization of carbon sources in Burkholderia cenocepacia J2315. MICROBIOLOGY-SGM 2019; 165:1135-1150. [PMID: 31464662 DOI: 10.1099/mic.0.000848] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Small non-coding sRNAs have versatile roles in regulating bacterial metabolism. Four short homologous Burkholderia cenocepacia sRNAs strongly expressed under conditions of growth arrest were recently identified. Here we report the detailed investigation of one of these, NcS27. sRNA NcS27 contains a short putative target recognition sequence, which is conserved throughout the order Burkholderiales. This sequence is the reverse complement of the Shine-Dalgarno sequence of a large number of genes involved in transport and metabolism of amino acids and carbohydrates. Overexpression of NcS27 sRNA had a distinct impact on growth, attenuating growth on a variety of substrates such as phenylalanine, tyrosine, glycerol and galactose, while having no effect on growth on other substrates. Transcriptomics and proteomics of NcS27 overexpression and silencing mutants revealed numerous predicted targets changing expression, notably of genes involved in degradation of aromatic amino acids phenylalanine and tyrosine, and in transport of carbohydrates. The conserved target recognition sequence was essential for growth phenotypes and gene expression changes. Cumulatively, our data point to a role of NcS27 in regulating the shutdown of metabolism upon nutrient deprivation in B. cenocepacia. We propose Burkholderiadouble-hairpin sRNA regulator bdhR1 as designation for ncS27.
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Affiliation(s)
- Andrea M Sass
- Laboratory of Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Stijn De Waele
- Laboratory for Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Simon Daled
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Bart Devreese
- Laboratory for Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Dieter Deforce
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Filip Van Nieuwerburgh
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
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Kumar A, Kumar V, Kumar A. Functional characterization of host toxic EcdB transcription factor protein of echinocandin B biosynthetic gene cluster. Biotechnol Appl Biochem 2019; 66:626-633. [PMID: 31069846 DOI: 10.1002/bab.1763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 05/07/2019] [Indexed: 11/09/2022]
Abstract
The ecdB is a transcription factor, located in the echinocandin B biosynthetic gene cluster of Emericella rugulosa NRRL11440. Here, we validated the ecdB mRNA sequence for functional expression and to explore the role of EcdB protein in the echinocandin B regulation. The sequence alignment study revealed that the ecdB coding sequence was found 75 bp shorter than the reference mRNA sequence. This coding sequence encodes for EcdB protein and comprises three conserved domains; DNA binding domain (DBD), coiled-coil domain, and signature middle homology region. The full-length and DBD (truncated) DNA sequences were expressed in Escherichia coli BL21(DE3) under different tested conditions. The expression of EcdB protein was found to be toxic, which curbs the cell growth. In contrast to truncated protein (GST:EcdB1-54), the full-length (GST:EcdB) protein was expressed at very low titer and not detectable in SDS-PAGE under the varying isopropyl β-d-1-thiogalactopyranoside (IPTG), temperature, and media conditions. However, GST:EcdB1-54 was successfully purified under standard conditions (0.5 mM IPTG at 0.5OD) with 33 kDa expected size. The functionality of GST:EcdB1-54 was attained by electrophoretic mobility shift assay study as a clear band shifting showed with ecdA promoter. Taken together, we conclude that EcdB interacts with the ecdA promoter that reflected to require for echinocandin B regulation.
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Affiliation(s)
- Arvind Kumar
- Department of Biotechnology, Central University of South Bihar, Panchanpur, Gaya, India
| | - Vinay Kumar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Antresh Kumar
- Department of Biotechnology, Central University of South Bihar, Panchanpur, Gaya, India
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Chemical synthesis rewriting of a bacterial genome to achieve design flexibility and biological functionality. Proc Natl Acad Sci U S A 2019; 116:8070-8079. [PMID: 30936302 PMCID: PMC6475421 DOI: 10.1073/pnas.1818259116] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The fundamental biological functions of a living cell are stored within the DNA sequence of its genome. Classical genetic approaches dissect the functioning of biological systems by analyzing individual genes, yet uncovering the essential gene set of an organism has remained very challenging. It is argued that the rewriting of entire genomes through the process of chemical synthesis provides a powerful and complementary research concept to understand how essential functions are programed into genomes. Understanding how to program biological functions into artificial DNA sequences remains a key challenge in synthetic genomics. Here, we report the chemical synthesis and testing of Caulobacter ethensis-2.0 (C. eth-2.0), a rewritten bacterial genome composed of the most fundamental functions of a bacterial cell. We rebuilt the essential genome of Caulobacter crescentus through the process of chemical synthesis rewriting and studied the genetic information content at the level of its essential genes. Within the 785,701-bp genome, we used sequence rewriting to reduce the number of encoded genetic features from 6,290 to 799. Overall, we introduced 133,313 base substitutions, resulting in the rewriting of 123,562 codons. We tested the biological functionality of the genome design in C. crescentus by transposon mutagenesis. Our analysis revealed that 432 essential genes of C. eth-2.0, corresponding to 81.5% of the design, are equal in functionality to natural genes. These findings suggest that neither changing mRNA structure nor changing the codon context have significant influence on biological functionality of synthetic genomes. Discovery of 98 genes that lost their function identified essential genes with incorrect annotation, including a limited set of 27 genes where we uncovered noncoding control features embedded within protein-coding sequences. In sum, our results highlight the promise of chemical synthesis rewriting to decode fundamental genome functions and its utility toward the design of improved organisms for industrial purposes and health benefits.
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Induction of a Toxin-Antitoxin Gene Cassette under High Hydrostatic Pressure Enables Markerless Gene Disruption in the Hyperthermophilic Archaeon Pyrococcus yayanosii. Appl Environ Microbiol 2019; 85:AEM.02662-18. [PMID: 30504216 DOI: 10.1128/aem.02662-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 11/28/2018] [Indexed: 11/20/2022] Open
Abstract
The discovery of hyperthermophiles has dramatically changed our understanding of the habitats in which life can thrive. However, the extreme high temperatures in which these organisms live have severely restricted the development of genetic tools. The archaeon Pyrococcus yayanosii A1 is a strictly anaerobic and piezophilic hyperthermophile that is an ideal model for studies of extreme environmental adaptation. In the present study, we identified a high hydrostatic pressure (HHP)-inducible promoter (P hhp ) that controls target gene expression under HHP. We developed an HHP-inducible toxin-antitoxin cassette (HHP-TAC) containing (i) a counterselectable marker in which a gene encoding a putative toxin (virulence-associated protein C [PF0776 {VapC}]) controlled by the HHP-inducible promoter was used in conjunction with the gene encoding antitoxin PF0775 (VapB), which was fused to a constitutive promoter (P hmtB ), and (ii) a positive marker with the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase-encoding gene from P. furiosus controlled by the constitutive promoter P gdh The HHP-TAC was constructed to realize markerless gene disruption directly in P. yayanosii A1 in rich medium. The pop-out recombination step was performed using an HHP-inducible method. As proof, the PYCH_13690 gene, which encodes a 4-α-glucanotransferase, was successfully deleted from the strain P. yayanosii A1. The results showed that the capacity for starch hydrolysis in the Δ1369 mutant decreased dramatically compared to that in the wild-type strain. The inducible toxin-antitoxin system developed in this study greatly increases the genetic tools available for use in hyperthermophiles.IMPORTANCE Genetic manipulations in hyperthermophiles have been studied for over 20 years. However, the extremely high temperatures under which these organisms grow have limited the development of genetic tools. In this study, an HHP-inducible promoter was used to control the expression of a toxin. Compared to sugar-inducible and cold-shock-inducible promoters, the HHP-inducible promoter rarely has negative effects on the overall physiology and central metabolism of microorganisms, especially piezophilic hyperthermophiles. Previous studies have used auxotrophic strains as hosts, which may interfere with studies of adaptation and metabolism. Using an inducible toxin-antitoxin (TA) system as a counterselectable marker enables the generation of a markerless gene disruption strain without the use of auxotrophic mutants and counterselection with 5-fluoroorotic acid. TA systems are widely distributed in bacteria and archaea and can be used to overcome the limitations of high growth temperatures and dramatically extend the selectivity of genetic tools in hyperthermophiles.
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A novel method for cloning of coding sequences of highly toxic proteins. Biochim Biophys Acta Gen Subj 2018; 1863:521-527. [PMID: 30578833 DOI: 10.1016/j.bbagen.2018.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 11/26/2018] [Accepted: 12/17/2018] [Indexed: 11/20/2022]
Abstract
BACKGROUND During standard gene cloning, the recombinant protein appearing in bacteria as the result of expression leakage very often inhibits cell proliferation leading to blocking of the cloning procedure. Although different approaches can reduce transgene basal expression, the recombinant proteins, which even in trace amounts inhibit bacterial growth, can completely prevent the cloning process. METHODS Working to solve the problem of DNase II-like cDNA cloning, we developed a novel cloning approach. The method is based on separate cloning of the 5' and 3' fragments of target cDNA into a vector in such a way that the short Multiple Cloning Site insertion remaining between both fragments changes the reading frame and prevents translation of mRNA arising as a result of promoter leakage. Subsequently, to get the vector with full, uninterrupted Open Reading Frame, the Multiple Cloning Site insertion is removed by in vitro restriction/ligation reactions, utilizing the unique restriction site present in native cDNA. RESULTS Using this designed method, we cloned a coding sequence of AcDNase II that is extremely toxic for bacteria cells. Then, we demonstrated the usefulness of the construct prepared in this way for overexpression of AcDNase II in eukaryotic cells. CONCLUSIONS The designed method allows cloning of toxic protein coding sequences that cannot be cloned by standard methods. GENERAL SIGNIFICANCE Cloning of cDNAs encoding toxic proteins is still a troublesome problem that hinders the progress of numerous studies. The method described here is a convenient solution to cloning problems that are common in research on toxic proteins.
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Abstract
BACKGROUND Deciphering the history of life on Earth has long been regarded as one of the most central tasks in biology. In past years, widespread discordance between the evolutionary histories of different groups of orthologous genes of prokaryotes have been revealed, primarily due to horizontal gene transfers (HGTs). Nonetheless, evidence that support a strong tree-like signal of evolution have been uncovered, despite the presence of HGT events. Therefore, a challenging task is to distill this tree-like signal from the noise induced by all sources of non-tree-like events. RESULTS In this work we tackle this question, using real and simulated data. We first tighten a recent related theoretical result in this field. In a simulation study, we infer individual quartet topologies, and then use the inferred quartets to reconstruct simulated species trees. We demonstrate that accurate tree reconstruction is feasible despite surprisingly high rates of HGT. In a real data study, we construct phylogenies of two sets of prokaryotes, and show that our tree reconstruction scheme is comparable with (and complementary better than) other commonly used methods. CONCLUSIONS Using a blend of theoretical and empirical investigations, our study proves the feasibility of accurate quartet-based phylogenetic reconstruction, the vast impact of HGT events notwithstanding.
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Affiliation(s)
- Eliran Avni
- Department of Evolutionary Biology, University of Haifa, 199 Aba Khoushy Ave. Mount Carmel, Haifa, 3498838, Israel
| | - Sagi Snir
- Department of Evolutionary Biology, University of Haifa, 199 Aba Khoushy Ave. Mount Carmel, Haifa, 3498838, Israel.
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Leis B, Held C, Andreeßen B, Liebl W, Graubner S, Schulte LP, Schwarz WH, Zverlov VV. Optimizing the composition of a synthetic cellulosome complex for the hydrolysis of softwood pulp: identification of the enzymatic core functions and biochemical complex characterization. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:220. [PMID: 30116297 PMCID: PMC6083626 DOI: 10.1186/s13068-018-1220-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/31/2018] [Indexed: 05/30/2023]
Abstract
BACKGROUND The development of efficient cellulase blends is a key factor for cost-effectively valorizing biomass in a new bio-economy. Today, the enzymatic hydrolysis of plant-derived polysaccharides is mainly accomplished with fungal cellulases, whereas potentially equally effective cellulose-degrading systems from bacteria have not been developed. Particularly, a thermostable multi-enzyme cellulase complex, the cellulosome from the anaerobic cellulolytic bacterium Clostridium thermocellum is promising of being applied as cellulolytic nano-machinery for the production of fermentable sugars from cellulosic biomass. RESULTS In this study, 60 cellulosomal components were recombinantly produced in E. coli and systematically permuted in synthetic complexes to study the function-activity relationship of all available enzymes on Kraft pulp from pine wood as the substrate. Starting from a basic exo/endoglucanase complex, we were able to identify additional functional classes such as mannanase and xylanase for optimal activity on the substrate. Based on these results, we predicted a synthetic cellulosome complex consisting of seven single components (including the scaffoldin protein and a β-glucosidase) and characterized it biochemically. We obtained a highly thermostable complex with optimal activity around 60-65 °C and an optimal pH in agreement with the optimum of the native cellulosome (pH 5.8). Remarkably, a fully synthetic complex containing 47 single cellulosomal components showed comparable activity with a commercially available fungal enzyme cocktail on the softwood pulp substrate. CONCLUSIONS Our results show that synthetic bacterial multi-enzyme complexes based on the cellulosome of C. thermocellum can be applied as a versatile platform for the quick adaptation and efficient degradation of a substrate of interest.
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Affiliation(s)
- Benedikt Leis
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
- Present Address: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Winchester Str. 2, 35394 Gießen, Germany
| | - Claudia Held
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Björn Andreeßen
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Wolfgang Liebl
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Sigrid Graubner
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Louis-Philipp Schulte
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Wolfgang H. Schwarz
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Vladimir V. Zverlov
- Department of Microbiology, Technische Universität München, TUM School of Life Sciences Weihenstephan, Emil-Ramann-Str. 4, 85354 Freising, Germany
- Institute of Molecular Genetics, Russian Academy of Science, Kurchatov Sq. 2, Moscow, 123182 Russia
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Westmann CA, Alves LDF, Silva-Rocha R, Guazzaroni ME. Mining Novel Constitutive Promoter Elements in Soil Metagenomic Libraries in Escherichia coli. Front Microbiol 2018; 9:1344. [PMID: 29973927 PMCID: PMC6019500 DOI: 10.3389/fmicb.2018.01344] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 05/31/2018] [Indexed: 11/13/2022] Open
Abstract
Although functional metagenomics has been widely employed for the discovery of genes relevant to biotechnology and biomedicine, its potential for assessing the diversity of transcriptional regulatory elements of microbial communities has remained poorly explored. Here, we experimentally mined novel constitutive promoter sequences in metagenomic libraries by combining a bi-directional reporter vector, high-throughput fluorescence assays and predictive computational methods. Through the expression profiling of fluorescent clones from two independent soil sample libraries, we have analyzed the regulatory dynamics of 260 clones with candidate promoters as a set of active metagenomic promoters in the host Escherichia coli. Through an in-depth analysis of selected clones, we were able to further explore the architecture of metagenomic fragments and to report the presence of multiple promoters per fragment with a dominant promoter driving the expression profile. These approaches resulted in the identification of 33 novel active promoters from metagenomic DNA originated from very diverse phylogenetic groups. The in silico and in vivo analysis of these individual promoters allowed the generation of a constitutive promoter consensus for exogenous sequences recognizable by E. coli in metagenomic studies. The results presented here demonstrates the potential of functional metagenomics for exploring environmental bacterial communities as a source of novel regulatory genetic parts to expand the toolbox for microbial engineering.
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Affiliation(s)
- Cauã A Westmann
- Department of Cellular and Molecular Biology, FMRP, University of São Paulo, Ribeirão Preto, Brazil
| | - Luana de Fátima Alves
- Department of Biology, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil.,Department of Biochemistry, FMRP, University of São Paulo, Ribeirão Preto, Brazil
| | - Rafael Silva-Rocha
- Department of Cellular and Molecular Biology, FMRP, University of São Paulo, Ribeirão Preto, Brazil
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Jia X, Yao J, Gao Z, Liu G, Dong YH, Wang X, Zhang H. Structure-function analyses reveal the molecular architecture and neutralization mechanism of a bacterial HEPN-MNT toxin-antitoxin system. J Biol Chem 2018; 293:6812-6823. [PMID: 29555683 PMCID: PMC5936836 DOI: 10.1074/jbc.ra118.002421] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/13/2018] [Indexed: 11/06/2022] Open
Abstract
Toxin-antitoxin (TA) loci in bacteria are small genetic modules that regulate various cellular activities, including cell growth and death. The two-gene module encoding a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domain and a cognate MNT (minimal nucleotidyltransferase) domain have been predicted to represent a novel type II TA system prevalent in archaea and bacteria. However, the neutralization mechanism and cellular targets of the TA family remain unclear. The toxin SO_3166 having a HEPN domain and its cognate antitoxin SO_3165 with an MNT domain constitute a typical type II TA system that regulates cell motility and confers plasmid stability in the bacterium Shewanella oneidensis Here, we report the crystal structure and solution conformation of the SO_3166-SO_3165 pair, representing the first complex structures in this TA family. The structures revealed that SO_3165 and SO_3166 form a tight heterooctamer (at a 2:6 ratio), an organization that is very rare in other TA systems. We also observed that SO_3166 dimerization enables the formation of a deep cleft at the HEPN-domain interface harboring a composite RX4-6H active site that functions as an RNA-cleaving RNase. SO_3165 bound SO_3166 mainly through its two α-helices (α2 and α4), functioning as molecular recognition elements. Moreover, their insertion into the SO_3166 cleft sterically blocked the RX4-6H site or narrowed the cleft to inhibit RNA substrate binding. Structure-based mutagenesis confirmed the important roles of these α-helices in SO_3166 binding and inhibition. Our structure-function analysis provides first insights into the neutralization mechanism of the HEPN-MNT TA family.
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Affiliation(s)
- Xuanyan Jia
- From the Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601
| | - Jianyun Yao
- the CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301
| | - Zengqiang Gao
- the Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, and
| | - Guangfeng Liu
- the National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yu-Hui Dong
- the Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, and
| | - Xiaoxue Wang
- the CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301,
| | - Heng Zhang
- the Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, and
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Wu J, Deng A, Sun Q, Bai H, Sun Z, Shang X, Zhang Y, Liu Q, Liang Y, Liu S, Che Y, Wen T. Bacterial Genome Editing via a Designed Toxin-Antitoxin Cassette. ACS Synth Biol 2018; 7:822-831. [PMID: 28094982 DOI: 10.1021/acssynbio.6b00287] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Manipulating the bacterial genomes in an efficient manner is essential to biological and biotechnological research. Here, we reprogrammed the bacterial TA systems as the toxin counter-selectable cassette regulated by an antitoxin switch (TCCRAS) for genetic modifications in the extensively studied and utilized Gram-positive bacteria, B. subtilis and Corynebacterium glutamicum. In the five characterized type II TA systems, the RelBE complex can specifically and efficiently regulate cell growth and death by the conditionally controlled antitoxin RelB switch, thereby serving as a novel counter-selectable cassette to establish the TCCRAS system. Using a single vector, such a system has been employed to perform in-frame deletion, functional knock-in, gene replacement, precise point mutation, large-scale insertion, and especially, deletion of the fragments up to 194.9 kb in B. subtilis. In addition, the biosynthesis of lycopene was first achieved in B. subtilis using TCCRAS to integrate a 5.4-kb fusion cluster ( P spac- crtI- crtE- crtB). The system was further adapted for gene knockdown and replacement, and large-scale deletion of the fragments up to 179.8 kb in C. glutamicum, with the mutation efficiencies increased by 0.8-1.0-fold compared to the conventional SacB method. TCCRAS thus holds promise as an effective and versatile genome-scale engineering technology for metabolic engineering and synthetic genomics research in a broad range of the Gram-positive bacteria.
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Affiliation(s)
- Jie Wu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Aihua Deng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Qinyun Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Hua Bai
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Zhaopeng Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Xiuling Shang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Yun Zhang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Qian Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Yong Liang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Shuwen Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Yongsheng Che
- State Key Laboratory of Toxicology & Medical Countermeasures , Beijing Institute of Pharmacology & Toxicology , Beijing 100850 , China
| | - Tingyi Wen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology , Chinese Academy of Sciences , Beijing 100101 , China
- Savaid medical school , University of Chinese Academy of Sciences , Beijing 100049 , China
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Sass A, Kiekens S, Coenye T. Identification of small RNAs abundant in Burkholderia cenocepacia biofilms reveal putative regulators with a potential role in carbon and iron metabolism. Sci Rep 2017; 7:15665. [PMID: 29142288 PMCID: PMC5688073 DOI: 10.1038/s41598-017-15818-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 11/02/2017] [Indexed: 12/23/2022] Open
Abstract
Small RNAs play a regulatory role in many central metabolic processes of bacteria, as well as in developmental processes such as biofilm formation. Small RNAs of Burkholderia cenocepacia, an opportunistic pathogenic beta-proteobacterium, are to date not well characterised. To address that, we performed genome-wide transcriptome structure analysis of biofilm grown B. cenocepacia J2315. 41 unannotated short transcripts were identified in intergenic regions of the B. cenocepacia genome. 15 of these short transcripts, highly abundant in biofilms, widely conserved in Burkholderia sp. and without known function, were selected for in-depth analysis. Expression profiling showed that most of these sRNAs are more abundant in biofilms than in planktonic cultures. Many are also highly abundant in cells grown in minimal media, suggesting they are involved in adaptation to nutrient limitation and growth arrest. Their computationally predicted targets include a high proportion of genes involved in carbon metabolism. Expression and target genes of one sRNA suggest a potential role in regulating iron homoeostasis. The strategy used for this study to detect sRNAs expressed in B. cenocepacia biofilms has successfully identified sRNAs with a regulatory function.
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Affiliation(s)
- Andrea Sass
- Department of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Sanne Kiekens
- Department of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Tom Coenye
- Department of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
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Avni E, Snir S. Toxic genes present a unique phylogenetic signature. Mol Phylogenet Evol 2017; 116:141-148. [PMID: 28842276 DOI: 10.1016/j.ympev.2017.08.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 10/19/2022]
Abstract
Horizontal gene transfer (HGT) is a major part of the evolution of Archaea and Bacteria, to the extent that the validity of the Tree of Life concept for prokaryotes has been seriously questioned. The patterns and routes of HGT remain a subject of intense study and debate. It was discovered that while several genes exhibit rampant HGT across the whole prokaryotic tree of life, others are lethal to certain organisms and therefore cannot be successfully transferred to them. We distinguish between these two classes of genes and show analytically that genes found to be toxic to a specific species (E. coli) also resist HGT in general. Several tools we employ show evidence to support that claim. One of those tools is the quartet plurality distribution (QPD), a mathematical tool that measures tendency to HGT over a large set of genes and species. When aggregated over a collection of genes, it can reveal important properties of this collection. We conclude that evidence of toxicity of certain genes to a wide variety of prokaryotes are revealed using the new tool of quartet plurality distribution.
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Affiliation(s)
- Eliran Avni
- Dept. of Evolutionary Biology, University of Haifa, Haifa 31905, Israel.
| | - Sagi Snir
- Dept. of Evolutionary Biology, University of Haifa, Haifa 31905, Israel.
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Shidore T, Triplett LR. Toxin-Antitoxin Systems: Implications for Plant Disease. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:161-179. [PMID: 28525308 DOI: 10.1146/annurev-phyto-080516-035559] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Toxin-antitoxin (TA) systems are gene modules that are ubiquitous in free-living prokaryotes. Diverse in structure, cellular function, and fitness roles, TA systems are defined by the presence of a toxin gene that suppresses bacterial growth and a toxin-neutralizing antitoxin gene, usually encoded in a single operon. Originally viewed as DNA maintenance modules, TA systems are now thought to function in many roles, including bacterial stress tolerance, virulence, phage defense, and biofilm formation. However, very few studies have investigated the significance of TA systems in the context of plant-microbe interactions. This review discusses the potential impact and application of TA systems in plant-associated bacteria, guided by insights gained from animal-pathogenic model systems.
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Affiliation(s)
- T Shidore
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06511:
| | - L R Triplett
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06511:
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Abstract
Evolution of bacteria and archaea involves an incessant arms race against an enormous diversity of genetic parasites. Accordingly, a substantial fraction of the genes in most bacteria and archaea are dedicated to antiparasite defense. The functions of these defense systems follow several distinct strategies, including innate immunity; adaptive immunity; and dormancy induction, or programmed cell death. Recent comparative genomic studies taking advantage of the expanding database of microbial genomes and metagenomes, combined with direct experiments, resulted in the discovery of several previously unknown defense systems, including innate immunity centered on Argonaute proteins, bacteriophage exclusion, and new types of CRISPR-Cas systems of adaptive immunity. Some general principles of function and evolution of defense systems are starting to crystallize, in particular, extensive gain and loss of defense genes during the evolution of prokaryotes; formation of genomic defense islands; evolutionary connections between mobile genetic elements and defense, whereby genes of mobile elements are repeatedly recruited for defense functions; the partially selfish and addictive behavior of the defense systems; and coupling between immunity and dormancy induction/programmed cell death.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894;
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894;
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894;
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Burkholderia cepacia Complex Regulation of Virulence Gene Expression: A Review. Genes (Basel) 2017; 8:genes8010043. [PMID: 28106859 PMCID: PMC5295037 DOI: 10.3390/genes8010043] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/11/2017] [Accepted: 01/12/2017] [Indexed: 12/31/2022] Open
Abstract
Burkholderia cepacia complex (Bcc) bacteria emerged as opportunistic pathogens in cystic fibrosis and immunocompromised patients. Their eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. Bcc bacteria have large and complex genomes, composed of two to four replicons, with variable numbers of insertion sequences. The complexity of Bcc genomes confers a high genomic plasticity to these bacteria, allowing their adaptation and survival to diverse habitats, including the human host. In this work, we review results from recent studies using omics approaches to elucidate in vivo adaptive strategies and virulence gene regulation expression of Bcc bacteria when infecting the human host or subject to conditions mimicking the stressful environment of the cystic fibrosis lung.
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Benureau Y, Colin P, Staropoli I, Gonzalez N, Garcia-Perez J, Alcami J, Arenzana-Seisdedos F, Lagane B. Guidelines for cloning, expression, purification and functional characterization of primary HIV-1 envelope glycoproteins. J Virol Methods 2016; 236:184-195. [PMID: 27451265 DOI: 10.1016/j.jviromet.2016.07.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/13/2016] [Accepted: 07/19/2016] [Indexed: 12/14/2022]
Abstract
The trimeric HIV-1 envelope (Env) glycoproteins gp120 and gp41 mediate virus entry into target cells by engaging CD4 and the coreceptors CCR5 or CXCR4 at the cell surface and driving membrane fusion. Receptor/gp120 interactions regulate the virus life cycle, HIV infection transmission and pathogenesis. Env is also the target of neutralizing antibodies. Efforts have thus been made to produce soluble HIV-1 glycoproteins to develop vaccines and study the role and mechanisms of HIV/receptor interactions. However, production and purification of Env glycoproteins and their functional assessment has to cope with multiple obstacles. These include difficulties in amplifying and cloning env sequences and setting up receptor binding assays that are suitable for studies on large collections of glycoproteins, flexible enough to adapt to Env and receptor structural heterogeneities, and allow recapitulating the receptor binding properties of virion-associated Env trimers. Here we identify these difficulties and present protocols to produce primary gp120 and determination of their binding properties to receptors. The receptor binding assays confirmed that the produced glycoproteins are competent for binding CD4 and undergo proper CD4-induced conformational changes required for interaction with CCR5. These assays may help elucidate the role of gp120/receptor interactions in the pathophysiology of HIV infection and develop HIV-1 entry inhibitors.
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Affiliation(s)
- Yann Benureau
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Philippe Colin
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Isabelle Staropoli
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Nuria Gonzalez
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Javier Garcia-Perez
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Jose Alcami
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Fernando Arenzana-Seisdedos
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Bernard Lagane
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
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Young REB, Purton S. Codon reassignment to facilitate genetic engineering and biocontainment in the chloroplast of Chlamydomonas reinhardtii. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:1251-60. [PMID: 26471875 PMCID: PMC5102678 DOI: 10.1111/pbi.12490] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/08/2015] [Accepted: 09/13/2015] [Indexed: 05/18/2023]
Abstract
There is a growing interest in the use of microalgae as low-cost hosts for the synthesis of recombinant products such as therapeutic proteins and bioactive metabolites. In particular, the chloroplast, with its small, genetically tractable genome (plastome) and elaborate metabolism, represents an attractive platform for genetic engineering. In Chlamydomonas reinhardtii, none of the 69 protein-coding genes in the plastome uses the stop codon UGA, therefore this spare codon can be exploited as a useful synthetic biology tool. Here, we report the assignment of the codon to one for tryptophan and show that this can be used as an effective strategy for addressing a key problem in chloroplast engineering: namely, the assembly of expression cassettes in Escherichia coli when the gene product is toxic to the bacterium. This problem arises because the prokaryotic nature of chloroplast promoters and ribosome-binding sites used in such cassettes often results in transgene expression in E. coli, and is a potential issue when cloning genes for metabolic enzymes, antibacterial proteins and integral membrane proteins. We show that replacement of tryptophan codons with the spare codon (UGG→UGA) within a transgene prevents functional expression in E. coli and in the chloroplast, and that co-introduction of a plastidial trnW gene carrying a modified anticodon restores function only in the latter by allowing UGA readthrough. We demonstrate the utility of this system by expressing two genes known to be highly toxic to E. coli and discuss its value in providing an enhanced level of biocontainment for transplastomic microalgae.
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Affiliation(s)
- Rosanna E B Young
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, London, UK
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40
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Zhang C, Tsoi R, You L. Addressing biological uncertainties in engineering gene circuits. Integr Biol (Camb) 2015; 8:456-64. [PMID: 26674800 DOI: 10.1039/c5ib00275c] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Synthetic biology has grown tremendously over the past fifteen years. It represents a new strategy to develop biological understanding and holds great promise for diverse practical applications. Engineering of a gene circuit typically involves computational design of the circuit, selection of circuit components, and test and optimization of circuit functions. A fundamental challenge in this process is the predictable control of circuit function due to multiple layers of biological uncertainties. These uncertainties can arise from different sources. We categorize these uncertainties into incomplete quantification of parts, interactions between heterologous components and the host, or stochastic dynamics of chemical reactions and outline potential design strategies to minimize or exploit them.
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Affiliation(s)
- Carolyn Zhang
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
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41
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Designing overall stoichiometric conversions and intervening metabolic reactions. Sci Rep 2015; 5:16009. [PMID: 26530953 PMCID: PMC4632160 DOI: 10.1038/srep16009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/07/2015] [Indexed: 02/07/2023] Open
Abstract
Existing computational tools for de novo metabolic pathway assembly, either based on mixed integer linear programming techniques or graph-search applications, generally only find linear pathways connecting the source to the target metabolite. The overall stoichiometry of conversion along with alternate co-reactant (or co-product) combinations is not part of the pathway design. Therefore, global carbon and energy efficiency is in essence fixed with no opportunities to identify more efficient routes for recycling carbon flux closer to the thermodynamic limit. Here, we introduce a two-stage computational procedure that both identifies the optimum overall stoichiometry (i.e., optStoic) and selects for (non-)native reactions (i.e., minRxn/minFlux) that maximize carbon, energy or price efficiency while satisfying thermodynamic feasibility requirements. Implementation for recent pathway design studies identified non-intuitive designs with improved efficiencies. Specifically, multiple alternatives for non-oxidative glycolysis are generated and non-intuitive ways of co-utilizing carbon dioxide with methanol are revealed for the production of C2+ metabolites with higher carbon efficiency.
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42
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Sass AM, Van Acker H, Förstner KU, Van Nieuwerburgh F, Deforce D, Vogel J, Coenye T. Genome-wide transcription start site profiling in biofilm-grown Burkholderia cenocepacia J2315. BMC Genomics 2015; 16:775. [PMID: 26462475 PMCID: PMC4603805 DOI: 10.1186/s12864-015-1993-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 10/06/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Burkholderia cenocepacia is a soil-dwelling Gram-negative Betaproteobacterium with an important role as opportunistic pathogen in humans. Infections with B. cenocepacia are very difficult to treat due to their high intrinsic resistance to most antibiotics. Biofilm formation further adds to their antibiotic resistance. B. cenocepacia harbours a large, multi-replicon genome with a high GC-content, the reference genome of strain J2315 includes 7374 annotated genes. This study aims to annotate transcription start sites and identify novel transcripts on a whole genome scale. METHODS RNA extracted from B. cenocepacia J2315 biofilms was analysed by differential RNA-sequencing and the resulting dataset compared to data derived from conventional, global RNA-sequencing. Transcription start sites were annotated and further analysed according to their position relative to annotated genes. RESULTS Four thousand ten transcription start sites were mapped over the whole B. cenocepacia genome and the primary transcription start site of 2089 genes expressed in B. cenocepacia biofilms were defined. For 64 genes a start codon alternative to the annotated one was proposed. Substantial antisense transcription for 105 genes and two novel protein coding sequences were identified. The distribution of internal transcription start sites can be used to identify genomic islands in B. cenocepacia. A potassium pump strongly induced only under biofilm conditions was found and 15 non-coding small RNAs highly expressed in biofilms were discovered. CONCLUSIONS Mapping transcription start sites across the B. cenocepacia genome added relevant information to the J2315 annotation. Genes and novel regulatory RNAs putatively involved in B. cenocepacia biofilm formation were identified. These findings will help in understanding regulation of B. cenocepacia biofilm formation.
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Affiliation(s)
- Andrea M Sass
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
| | - Heleen Van Acker
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
| | - Konrad U Förstner
- Core Unit Systems Medicine, University of Würzburg, Würzburg, Germany.
| | | | - Dieter Deforce
- Laboratory of Pharmaceutical Biotechnology, Ghent University, Ghent, Belgium.
| | - Jörg Vogel
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany.
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
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Yao J, Guo Y, Zeng Z, Liu X, Shi F, Wang X. Identification and characterization of a HEPN-MNT family type II toxin-antitoxin in Shewanella oneidensis. Microb Biotechnol 2015; 8:961-73. [PMID: 26112399 PMCID: PMC4621449 DOI: 10.1111/1751-7915.12294] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 04/20/2015] [Accepted: 05/02/2015] [Indexed: 11/30/2022] Open
Abstract
Toxin-antitoxin (TA) systems are prevalent in bacteria and archaea. However, related studies in the ecologically and bioelectrochemically important strain Shewanella oneidensis are limited. Here, we show that SO_3166, a member of the higher eukaryotes and prokaryotes nucleotide-binding (HEPN) superfamily, strongly inhibited cell growth in S. oneidensis and Escherichia coli. SO_3165, a putative minimal nucleotidyltransferase (MNT), neutralized the toxicity of SO_3166. Gene SO_3165 lies upstream of SO_3166, and they are co-transcribed. Moreover, the SO_3165 and SO_3166 proteins interact with each other directly in vivo, and antitoxin SO_3165 bound to the promoter of the TA operon and repressed its activity. Finally, the conserved Rx4-6H domain in HEPN family was identified in SO_3166. Mutating either the R or H abolished SO_3166 toxicity, confirming that Rx4-6H domain is critical for SO_3166 activity. Taken together, these results demonstrate that SO_3166 and SO_3165 in S. oneidensis form a typical type II TA pair. This TA pair plays a critical role in regulating bacterial functions because its disruption led to impaired cell motility in S. oneidensis. Thus, we demonstrated for the first time that HEPN-MNT can function as a TA system, thereby providing important insights into the understanding of the function and regulation of HEPNs and MNTs in prokaryotes.
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Affiliation(s)
- Jianyun Yao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunxue Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Zhenshun Zeng
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoxiao Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Fei Shi
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
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Antimicrobial compounds from seaweeds-associated bacteria and fungi. Appl Microbiol Biotechnol 2014; 99:1571-86. [PMID: 25549621 DOI: 10.1007/s00253-014-6334-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/14/2014] [Accepted: 12/15/2014] [Indexed: 12/22/2022]
Abstract
In recent decade, seaweeds-associated microbial communities have been significantly evaluated for functional and chemical analyses. Such analyses let to conclude that seaweeds-associated microbial communities are highly diverse and rich sources of bioactive compounds of exceptional molecular structure. Extracting bioactive compounds from seaweed-associated microbial communities have been recently increased due to their broad-spectrum antimicrobial activities including antibacterial, antifungal, antiviral, anti-settlement, antiprotozoan, antiparasitic, and antitumor. These allelochemicals not only provide protection to host from other surrounding pelagic microorganisms, but also ensure their association with the host. Antimicrobial compounds from marine sources are promising and priority targets of biotechnological and pharmaceutical applications. This review describes the bioactive metabolites reported from seaweed-associated bacterial and fungal communities and illustrates their bioactivities. Biotechnological application of metagenomic approach for identifying novel bioactive metabolites is also dealt, in view of their future development as a strong tool to discover novel drug targets from seaweed-associated microbial communities.
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45
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Nielsen AAK, Voigt CA. Multi-input CRISPR/Cas genetic circuits that interface host regulatory networks. Mol Syst Biol 2014; 10:763. [PMID: 25422271 PMCID: PMC4299604 DOI: 10.15252/msb.20145735] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/26/2014] [Accepted: 10/29/2014] [Indexed: 12/24/2022] Open
Abstract
Genetic circuits require many regulatory parts in order to implement signal processing or execute algorithms in cells. A potentially scalable approach is to use dCas9, which employs small guide RNAs (sgRNAs) to repress genetic loci via the programmability of RNA:DNA base pairing. To this end, we use dCas9 and designed sgRNAs to build transcriptional logic gates and connect them to perform computation in living cells. We constructed a set of NOT gates by designing five synthetic Escherichia coli σ70 promoters that are repressed by corresponding sgRNAs, and these interactions do not exhibit crosstalk between each other. These sgRNAs exhibit high on-target repression (56- to 440-fold) and negligible off-target interactions (< 1.3-fold). These gates were connected to build larger circuits, including the Boolean-complete NOR gate and a 3-gate circuit consisting of four layered sgRNAs. The synthetic circuits were connected to the native E. coli regulatory network by designing output sgRNAs to target an E. coli transcription factor (malT). This converts the output of a synthetic circuit to a switch in cellular phenotype (sugar utilization, chemotaxis, phage resistance).
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Affiliation(s)
- Alec A K Nielsen
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Christopher A Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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46
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Chaisson MJP, Huddleston J, Dennis MY, Sudmant PH, Malig M, Hormozdiari F, Antonacci F, Surti U, Sandstrom R, Boitano M, Landolin JM, Stamatoyannopoulos JA, Hunkapiller MW, Korlach J, Eichler EE. Resolving the complexity of the human genome using single-molecule sequencing. Nature 2014; 517:608-11. [PMID: 25383537 DOI: 10.1038/nature13907] [Citation(s) in RCA: 538] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/30/2014] [Indexed: 12/11/2022]
Abstract
The human genome is arguably the most complete mammalian reference assembly, yet more than 160 euchromatic gaps remain and aspects of its structural variation remain poorly understood ten years after its completion. To identify missing sequence and genetic variation, here we sequence and analyse a haploid human genome (CHM1) using single-molecule, real-time DNA sequencing. We close or extend 55% of the remaining interstitial gaps in the human GRCh37 reference genome--78% of which carried long runs of degenerate short tandem repeats, often several kilobases in length, embedded within (G+C)-rich genomic regions. We resolve the complete sequence of 26,079 euchromatic structural variants at the base-pair level, including inversions, complex insertions and long tracts of tandem repeats. Most have not been previously reported, with the greatest increases in sensitivity occurring for events less than 5 kilobases in size. Compared to the human reference, we find a significant insertional bias (3:1) in regions corresponding to complex insertions and long short tandem repeats. Our results suggest a greater complexity of the human genome in the form of variation of longer and more complex repetitive DNA that can now be largely resolved with the application of this longer-read sequencing technology.
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Affiliation(s)
- Mark J P Chaisson
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - John Huddleston
- 1] Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
| | - Megan Y Dennis
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Peter H Sudmant
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Maika Malig
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Fereydoun Hormozdiari
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Francesca Antonacci
- Dipartimento di Biologia, Università degli Studi di Bari 'Aldo Moro', Bari 70125, Italy
| | - Urvashi Surti
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - Richard Sandstrom
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Matthew Boitano
- Pacific Biosciences of California, Inc., Menlo Park, California 94025, USA
| | - Jane M Landolin
- Pacific Biosciences of California, Inc., Menlo Park, California 94025, USA
| | - John A Stamatoyannopoulos
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | | | - Jonas Korlach
- Pacific Biosciences of California, Inc., Menlo Park, California 94025, USA
| | - Evan E Eichler
- 1] Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
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47
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High-resolution crystal structure reveals a HEPN domain at the C-terminal region of S. cerevisiae RNA endonuclease Swt1. Biochem Biophys Res Commun 2014; 453:826-32. [PMID: 25450355 DOI: 10.1016/j.bbrc.2014.10.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/09/2014] [Indexed: 11/21/2022]
Abstract
Swt1 is an RNA endonuclease that plays an important role in quality control of nuclear messenger ribonucleoprotein particles (mRNPs) in eukaryotes; however, its structural details remain to be elucidated. Here, we report the crystal structure of the C-terminal (CT) domain of Swt1 from Saccharomyces cerevisiae, which shares common characteristics of higher eukaryotes and prokaryotes nucleotide binding (HEPN) domain superfamily. To study in detail the full-length protein structure, we analyzed the low-resolution architecture of Swt1 in solution using small angle X-ray scattering (SAXS) method. Both the CT domain and middle domain exhibited a good fit upon superimposing onto the molecular envelope of Swt1. Our study provides the necessary structural information for detailed analysis of the functional role of Swt1, and its importance in the process of nuclear mRNP surveillance.
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Lu S, Le S, Tan Y, Li M, Liu C, Zhang K, Huang J, Chen H, Rao X, Zhu J, Zou L, Ni Q, Li S, Wang J, Jin X, Hu Q, Yao X, Zhao X, Zhang L, Huang G, Hu F. Unlocking the mystery of the hard-to-sequence phage genome: PaP1 methylome and bacterial immunity. BMC Genomics 2014; 15:803. [PMID: 25233860 PMCID: PMC4177049 DOI: 10.1186/1471-2164-15-803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 09/16/2014] [Indexed: 12/02/2022] Open
Abstract
Background Whole-genome sequencing is an important method to understand the genetic information, gene function, biological characteristics and survival mechanisms of organisms. Sequencing large genomes is very simple at present. However, we encountered a hard-to-sequence genome of Pseudomonas aeruginosa phage PaP1. Shotgun sequencing method failed to complete the sequence of this genome. Results After persevering for 10 years and going over three generations of sequencing techniques, we successfully completed the sequence of the PaP1 genome with a length of 91,715 bp. Single-molecule real-time sequencing results revealed that this genome contains 51 N-6-methyladenines and 152 N-4-methylcytosines. Three significant modified sequence motifs were predicted, but not all of the sites found in the genome were methylated in these motifs. Further investigations revealed a novel immune mechanism of bacteria, in which host bacteria can recognise and repel modified bases containing inserts in a large scale. This mechanism could be accounted for the failure of the shotgun method in PaP1 genome sequencing. This problem was resolved using the nfi- mutant of Escherichia coli DH5α as a host bacterium to construct a shotgun library. Conclusions This work provided insights into the hard-to-sequence phage PaP1 genome and discovered a new mechanism of bacterial immunity. The methylome of phage PaP1 is responsible for the failure of shotgun sequencing and for bacterial immunity mediated by enzyme Endo V activity; this methylome also provides a valuable resource for future studies on PaP1 genome replication and modification, as well as on gene regulation and host interaction. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-803) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Fuquan Hu
- Department of Microbiology, College of Basic Medical Science, Third Military Medical University, Chongqing 400038, P, R, China.
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Sagy O, Shamir R, Rechavi O. Examination of exhaustive cloning attempts reveals that C. elegans piRNAs, transposons, and repeat sequences are efficiently cloned in yeast, but not in bacteria. Front Genet 2014; 5:275. [PMID: 25221566 PMCID: PMC4148067 DOI: 10.3389/fgene.2014.00275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/26/2014] [Indexed: 11/13/2022] Open
Abstract
Genome sequencing requires insertion of random fragments of the sequenced organism’s DNA into a unicellular host, most often Escherichia coli bacteria. This manipulation was found in the past to be analogous to naturally occurring horizontal gene transfer, and moreover has proved valuable to understanding toxicity of foreign genetic elements to E. coli. Sequencing of the Caenorhabditis elegans genome was similarly achieved via DNA transformation into E. coli. However, numerous attempts have proven a significant percentage of the genome unclonable using bacteria, although clonable via yeast. We examined the genomic segments that were not clonable in bacteria but were clonable in yeast, and observed that, in line with previous hypotheses, such sequences are more repetitive on average compared with the entire C. elegans genome. In addition, we found that these gap-sequences encode significantly more for DNA transposons. Surprisingly, we discovered that although the vast majority of the C. elegans genome is clonable in bacteria (77.5%), almost all the thousands of sequences that encode for PIWI-interacting small RNAs, or 21U-RNAs (91.6%) were only clonable in yeast. These results might help understanding why most piRNAs in C. elegans are physically clustered on particular loci on chromosome IV. In worms and in a large number of other organisms, piRNAs serve to distinguish “Self” from “Non-Self” sequences, and thus to protect the integrity of the genome against foreign genetic elements, such as transposons. We discuss the possible implications of these discoveries.
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Affiliation(s)
- Or Sagy
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University Tel Aviv, Israel
| | - Ron Shamir
- Blavatnik School of Computer Science, Tel Aviv University Tel Aviv, Israel
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University Tel Aviv, Israel
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Renda BA, Hammerling MJ, Barrick JE. Engineering reduced evolutionary potential for synthetic biology. MOLECULAR BIOSYSTEMS 2014; 10:1668-78. [PMID: 24556867 DOI: 10.1039/c3mb70606k] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The field of synthetic biology seeks to engineer reliable and predictable behaviors in organisms from collections of standardized genetic parts. However, unlike other types of machines, genetically encoded biological systems are prone to changes in their designed sequences due to mutations in their DNA sequences after these devices are constructed and deployed. Thus, biological engineering efforts can be confounded by undesired evolution that rapidly breaks the functions of parts and systems, particularly when they are costly to the host cell to maintain. Here, we explain the fundamental properties that determine the evolvability of biological systems. Then, we use this framework to review current efforts to engineer the DNA sequences that encode synthetic biology devices and the genomes of their microbial hosts to reduce their ability to evolve and therefore increase their genetic reliability so that they maintain their intended functions over longer timescales.
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Affiliation(s)
- Brian A Renda
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
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