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Kretz J, Israel V, McIntosh M. Design-Build-Test of Synthetic Promoters for Inducible Gene Regulation in Alphaproteobacteria. ACS Synth Biol 2023; 12:2663-2675. [PMID: 37561940 DOI: 10.1021/acssynbio.3c00251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Inducible gene expression is useful for biotechnological applications and for studying gene regulation and function in bacteria. Many inducible systems that perform in model organisms such as the Gammaproteobacterium Escherichia coli do not perform well in other bacteria that are of biotechnological interest. Typical problems include weak or leaky expression. Here, we describe an invention named ACIT (Alphaproteobacteria chromosomally integrating transcription-control cassette) that is carried on a suicide plasmid to enable insertion into the chromosome of the host. ACIT consists of multiple DNA fragments specifically arranged in a cassette that allows tight transcription control over any gene or gene cluster of interest following homologous recombination. At the heart of the invention is the ability to modify or exchange parts, e.g., promoters, to suit particular bacteria and growth conditions, allowing for customized gene expression control. Furthermore, ACIT provides a basis for a design-build-test approach for controlling gene expression in less studied bacteria. We describe examples of its control over pigment and exopolysaccharide production, growth, cell form, and social behavior in various Alphaproteobacteria.
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Affiliation(s)
- Jonas Kretz
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
| | - Vera Israel
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
| | - Matthew McIntosh
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
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2
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Hanko EKR, Joosab Noor Mahomed TA, Stoney RA, Breitling R. TFBMiner: A User-Friendly Command Line Tool for the Rapid Mining of Transcription Factor-Based Biosensors. ACS Synth Biol 2023; 12:1497-1507. [PMID: 37053505 DOI: 10.1021/acssynbio.2c00679] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Transcription factors responsive to small molecules are essential elements in synthetic biology designs. They are often used as genetically encoded biosensors with applications ranging from the detection of environmental contaminants and biomarkers to microbial strain engineering. Despite our efforts to expand the space of compounds that can be detected using biosensors, the identification and characterization of transcription factors and their corresponding inducer molecules remain labor- and time-intensive tasks. Here, we introduce TFBMiner, a new data mining and analysis pipeline that enables the automated and rapid identification of putative metabolite-responsive transcription factor-based biosensors (TFBs). This user-friendly command line tool harnesses a heuristic rule-based model of gene organization to identify both gene clusters involved in the catabolism of user-defined molecules and their associated transcriptional regulators. Ultimately, biosensors are scored based on how well they fit the model, providing wet-lab scientists with a ranked list of candidates that can be experimentally tested. We validated the pipeline using a set of molecules for which TFBs have been reported previously, including sensors responding to sugars, amino acids, and aromatic compounds, among others. We further demonstrated the utility of TFBMiner by identifying a biosensor for S-mandelic acid, an aromatic compound for which a responsive transcription factor had not been found previously. Using a combinatorial library of mandelate-producing microbial strains, the newly identified biosensor was able to distinguish between low- and high-producing strain candidates. This work will aid in the unraveling of metabolite-responsive microbial gene regulatory networks and expand the synthetic biology toolbox to allow for the construction of more sophisticated self-regulating biosynthetic pathways.
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Affiliation(s)
- Erik K R Hanko
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Tariq A Joosab Noor Mahomed
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Ruth A Stoney
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Rainer Breitling
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
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3
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Teng ZJ, Qin QL, Zhang W, Li J, Fu HH, Wang P, Lan M, Luo G, He J, McMinn A, Wang M, Chen XL, Zhang YZ, Chen Y, Li CY. Biogeographic traits of dimethyl sulfide and dimethylsulfoniopropionate cycling in polar oceans. MICROBIOME 2021; 9:207. [PMID: 34654476 PMCID: PMC8520302 DOI: 10.1186/s40168-021-01153-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Dimethyl sulfide (DMS) is the dominant volatile organic sulfur in global oceans. The predominant source of oceanic DMS is the cleavage of dimethylsulfoniopropionate (DMSP), which can be produced by marine bacteria and phytoplankton. Polar oceans, which represent about one fifth of Earth's surface, contribute significantly to the global oceanic DMS sea-air flux. However, a global overview of DMS and DMSP cycling in polar oceans is still lacking and the key genes and the microbial assemblages involved in DMSP/DMS transformation remain to be fully unveiled. RESULTS Here, we systematically investigated the biogeographic traits of 16 key microbial enzymes involved in DMS/DMSP cycling in 60 metagenomic samples from polar waters, together with 174 metagenome and 151 metatranscriptomes from non-polar Tara Ocean dataset. Our analyses suggest that intense DMS/DMSP cycling occurs in the polar oceans. DMSP demethylase (DmdA), DMSP lyases (DddD, DddP, and DddK), and trimethylamine monooxygenase (Tmm, which oxidizes DMS to dimethylsulfoxide) were the most prevalent bacterial genes involved in global DMS/DMSP cycling. Alphaproteobacteria (Pelagibacterales) and Gammaproteobacteria appear to play prominent roles in DMS/DMSP cycling in polar oceans. The phenomenon that multiple DMS/DMSP cycling genes co-occurred in the same bacterial genome was also observed in metagenome assembled genomes (MAGs) from polar oceans. The microbial assemblages from the polar oceans were significantly correlated with water depth rather than geographic distance, suggesting the differences of habitats between surface and deep waters rather than dispersal limitation are the key factors shaping microbial assemblages involved in DMS/DMSP cycling in polar oceans. CONCLUSIONS Overall, this study provides a global overview of the biogeographic traits of known bacterial genes involved in DMS/DMSP cycling from the Arctic and Antarctic oceans, laying a solid foundation for further studies of DMS/DMSP cycling in polar ocean microbiome at the enzymatic, metabolic, and processual levels. Video Abstract.
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Affiliation(s)
- Zhao-Jie Teng
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
| | - Qi-Long Qin
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
| | - Weipeng Zhang
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
| | - Jian Li
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
| | - Hui-Hui Fu
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266373, China
| | - Peng Wang
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266373, China
| | - Musheng Lan
- The Key Laboratory for Polar Science MNR, Polar Research Institute of China, Shanghai, 200136, China
| | - Guangfu Luo
- The Key Laboratory for Polar Science MNR, Polar Research Institute of China, Shanghai, 200136, China
| | - Jianfeng He
- The Key Laboratory for Polar Science MNR, Polar Research Institute of China, Shanghai, 200136, China
| | - Andrew McMinn
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Min Wang
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
| | - Xiu-Lan Chen
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266373, China
| | - Yu-Zhong Zhang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266373, China
| | - Yin Chen
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China.
- School of Life Sciences, University of Warwick, Coventry, UK.
| | - Chun-Yang Li
- College of Marine Life Sciences, Institute for Advanced Ocean Study, Ocean University of China, Qingdao, 266003, China.
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266373, China.
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4
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Reshetnikov AS, But SY, Rozova ON, Mustakhimov II, Khmelenina VN. Alteration of cofactor specificity of the acrylyl-CoA reductase from Escherichia coli. Biotechnol Lett 2021; 43:1421-1427. [PMID: 33860390 DOI: 10.1007/s10529-021-03130-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 04/08/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Alteration of the cofactor specificity of acrylyl-CoA reductase (AcuI) catalyzing the NAD(P)H-dependent reduction of acrylyl-CoA to propionyl-CoA is often desirable for designing of artificial metabolic pathways of various appointments. RESULTS Several variants of AcuIs from Escherichia coli K-12 with multiple amino acid substitutions to alter the cofactor preference were obtained by site directed mutagenesis and the modified enzymes as His6-tagged proteins were characterized. The simultaneous substitutions of arginine-180, arginine-198 and serine-178 residues by alanine in the enzyme pocket sequence as well as other amino acid changes decreased both NADPH- and NADH-dependent activities in comparison to the wild-type enzyme. The replacement of serine-156 by glutamic acid decreased NADPH-dependent activity at least 7000-fold but NADH-dependent activity only by threefold. The replacement of serine-156 by aspartic acid decreased NADPH-dependent activity 70-fold with fair preservation of activity and specificity to NADH. CONCLUSIONS These results demonstrated a relevance of Asp156 in the interaction of AcuI from E. coli K-12 with NADH as a coenzyme. These findings may provide reference information for shifting coenzyme specificity of acrylyl-CoA reductases.
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Affiliation(s)
- Aleksander S Reshetnikov
- Laboratory of Methylotrophy, Federal Research Center, "Pushchino Scientific Center for Biological Research, Russian Academy of Sciences" IBPM RAS, Pushchino, Moscow Region, Russia, 142290
| | - Sergey Y But
- Laboratory of Methylotrophy, Federal Research Center, "Pushchino Scientific Center for Biological Research, Russian Academy of Sciences" IBPM RAS, Pushchino, Moscow Region, Russia, 142290
| | - Olga N Rozova
- Laboratory of Methylotrophy, Federal Research Center, "Pushchino Scientific Center for Biological Research, Russian Academy of Sciences" IBPM RAS, Pushchino, Moscow Region, Russia, 142290
| | - Ildar I Mustakhimov
- Laboratory of Methylotrophy, Federal Research Center, "Pushchino Scientific Center for Biological Research, Russian Academy of Sciences" IBPM RAS, Pushchino, Moscow Region, Russia, 142290
| | - Valentina N Khmelenina
- Laboratory of Methylotrophy, Federal Research Center, "Pushchino Scientific Center for Biological Research, Russian Academy of Sciences" IBPM RAS, Pushchino, Moscow Region, Russia, 142290.
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5
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Engineered protein switches for exogenous control of gene expression. Biochem Soc Trans 2020; 48:2205-2212. [DOI: 10.1042/bst20200441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 02/02/2023]
Abstract
There is an ongoing need in the synthetic biology community for novel ways to regulate gene expression. Protein switches, which sense biological inputs and respond with functional outputs, represent one way to meet this need. Despite the fact that there is already a large pool of transcription factors and signaling proteins available, the pool of existing switches lacks the substrate specificities and activities required for certain applications. Therefore, a large number of techniques have been applied to engineer switches with novel properties. Here we discuss some of these techniques by broadly organizing them into three approaches. We show how novel switches can be created through mutagenesis, domain swapping, or domain insertion. We then briefly discuss their use as biosensors and in complex genetic circuits.
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6
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Construction of a switchable synthetic Escherichia coli for aromatic amino acids by a tunable switch. J Ind Microbiol Biotechnol 2020; 47:233-242. [PMID: 31989326 DOI: 10.1007/s10295-020-02262-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/18/2020] [Indexed: 10/25/2022]
Abstract
Escherichia coli, a model microorganism for which convenient metabolic engineering tools are available and that grows quickly in cheap media, has been widely used in the production of valuable chemicals, including aromatic amino acids. As the three aromatic amino acids, L-tryptophan, L-tyrosine, and L-phenylalanine, share the same precursors, to increase the titer of a specific aromatic amino acid, the branch pathways to the others are usually permanently inactivated, which leads to the generation of auxotrophic strains. In this study, a tunable switch that can toggle between different states was constructed. Then, a switchable and non-auxotrophic E. coli strain for synthesis of aromatic amino acids was constructed using this tunable switch. By adding different inducers to cultures, three different production patterns of aromatic amino acids by the engineered strain could be observed. This tunable switch can also be applied in regulating other branch pathways and in other bacteria.
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7
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Complete genome sequence of Rhodococcus sp. NJ-530, a DMSP-degrading actinobacterium isolated from Antarctic sea ice. 3 Biotech 2019; 9:363. [PMID: 31576282 DOI: 10.1007/s13205-019-1889-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/27/2019] [Indexed: 10/26/2022] Open
Abstract
Dimethylsulfide (DMS), a climatically important gas generated by dimethylsulfoniopropionate (DMSP) degradation, plays an important role in the global sulfur cycle and affects the global climate. Marine bacteria are the primary mediators of DMSP degradation and DMS production. Here, we present the complete genome sequence of Rhodococcus sp. NJ-530, isolated from Antarctic sea ice, which utilizes DMSP as a sole carbon and energy source, degrading DMSP into DMS. The genome of strain NJ-530 consists of 7371 protein-coding sequences (CDSs) with 54 tRNA genes and 15 rRNA operons as 5S-16S-23S rRNA. The strain has one circular chromosome of 6,408,544 bp with 6331 CDSs and 62.41% GC content. Genomic annotation revealed that Rhodococcus sp. NJ-530 may have a DMSP cleavage gene cluster, including dddD, dddB and dddC, suggesting the existence of the DddD-type DMSP cleavage pathway. The complete genome sequence of Rhodococcus sp. NJ-530 will provide useful information for better understanding of the molecular mechanism underlying marine DMSP degradation and Antarctic DMS production.
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8
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González JM, Hernández L, Manzano I, Pedrós-Alió C. Functional annotation of orthologs in metagenomes: a case study of genes for the transformation of oceanic dimethylsulfoniopropionate. ISME JOURNAL 2019; 13:1183-1197. [PMID: 30643200 DOI: 10.1038/s41396-019-0347-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/22/2018] [Accepted: 12/25/2018] [Indexed: 11/09/2022]
Abstract
Dimethylsulfoniopropionate (DMSP) is produced mainly by phytoplankton and bacteria. It is relatively abundant and ubiquitous in the marine environment, where bacterioplankton make use of it readily as both carbon and sulfur sources. In one transformation pathway, part of the molecule becomes dimethylsulfide (DMS), which escapes into the atmosphere and plays an important role in the sulfur exchange between oceans and atmosphere. Through its other dominant catabolic pathway, bacteria are able to use it as sulfur source. During the past few years, a number of genes involved in its transformation have been characterized. Identifying genes in taxonomic groups not amenable to conventional methods of cultivation is challenging. Indeed, functional annotation of genes in environmental studies is not straightforward, considering that particular taxa are not well represented in the available sequence databases. Furthermore, many genes belong to families of paralogs with similar sequences but perhaps different functions. In this study, we develop in silico approaches to infer protein function of an environmentally important gene (dmdA) that carries out the first step in the sulfur assimilation from DMSP. The method combines a set of tools to annotate a targeted gene in genome databases and metagenome assemblies. The method will be useful to identify genes that carry out key biochemical processes in the environment.
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Affiliation(s)
- José M González
- Department of Microbiology, University of La Laguna, La Laguna, Spain.
| | - Laura Hernández
- Department of Microbiology, University of La Laguna, La Laguna, Spain
| | - Iris Manzano
- Department of Microbiology, University of La Laguna, La Laguna, Spain
| | - Carlos Pedrós-Alió
- Systems Biology Program, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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9
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Functional Genetic Elements for Controlling Gene Expression in Cupriavidus necator H16. Appl Environ Microbiol 2018; 84:AEM.00878-18. [PMID: 30030234 PMCID: PMC6146998 DOI: 10.1128/aem.00878-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
A robust and predictable control of gene expression plays an important role in synthetic biology and biotechnology applications. Development and quantitative evaluation of functional genetic elements, such as constitutive and inducible promoters as well as ribosome binding sites (RBSs), are required. In this study, we designed, built, and tested promoters and RBSs for controlling gene expression in the model lithoautotroph Cupriavidus necator H16. A series of variable-strength, insulated, constitutive promoters exhibiting predictable activity within a >700-fold dynamic range was compared to the native P phaC , with the majority of promoters displaying up to a 9-fold higher activity. Positively (AraC/P araBAD -l-arabinose and RhaRS/P rhaBAD -l-rhamnose) and negatively (AcuR/P acuRI -acrylate and CymR/P cmt -cumate) regulated inducible systems were evaluated. By supplying different concentrations of inducers, a >1,000-fold range of gene expression levels was achieved. Application of inducible systems for controlling expression of the isoprene synthase gene ispS led to isoprene yields that exhibited a significant correlation to the reporter protein synthesis levels. The impact of designed RBSs and other genetic elements, such as mRNA stem-loop structure and A/U-rich sequence, on gene expression was also evaluated. A second-order polynomial relationship was observed between the RBS activities and isoprene yields. This report presents quantitative data on regulatory genetic elements and expands the genetic toolbox of C. necatorIMPORTANCE This report provides tools for robust and predictable control of gene expression in the model lithoautotroph C. necator H16. To address a current need, we designed, built, and tested promoters and RBSs for controlling gene expression in C. necator H16. To answer a question on how existing and newly developed inducible systems compare, two positively (AraC/P araBAD -l-arabinose and RhaRS/P rhaBAD -l-rhamnose) and two negatively (AcuR/P acuRI -acrylate and CymR/P cmt -cumate) regulated inducible systems were quantitatively evaluated and their induction kinetics analyzed. To establish if gene expression can be further improved, the effect of genetic elements, such as mRNA stem-loop structure and A/U-rich sequence, on gene expression was evaluated. Using isoprene production as an example, the study investigated if and to what extent chemical compound yield correlates to the level of gene expression of product-synthesizing enzyme.
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10
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Abstract
ABSTRACT
Previously, leaderless mRNAs (lmRNAs) were perceived to make up only a minor fraction of the transcriptome in bacteria. However, advancements in RNA sequencing technology are uncovering vast numbers of lmRNAs, particularly in archaea,
Actinobacteria
, and extremophiles and thus underline their significance in cellular physiology and regulation. Due to the absence of conventional ribosome binding signals, lmRNA translation initiation is distinct from canonical mRNAs and can therefore be differentially regulated. The ribosome’s inherent ability to bind a 5′-terminal AUG can stabilize and protect the lmRNA from degradation or allow ribosomal loading for downstream initiation events. As a result, lmRNAs remain translationally competent during a variety of physiological conditions, allowing them to contribute to multiple regulatory mechanisms. Furthermore, the abundance of lmRNAs can increase during adverse conditions through the upregulation of lmRNA transcription from alternative promoters or by the generation of lmRNAs from canonical mRNAs cleaved by an endonucleolytic toxin. In these ways, lmRNA translation can continue during stress and contribute to regulation, illustrating their importance in the cell. Due to their presence in all domains of life and their ability to be translated by heterologous hosts, lmRNAs appear further to represent ancestral transcripts that might allow us to study the evolution of the ribosome and the translational process.
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11
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Lei L, Cherukuri KP, Alcolombri U, Meltzer D, Tawfik DS. The Dimethylsulfoniopropionate (DMSP) Lyase and Lyase-Like Cupin Family Consists of Bona Fide DMSP lyases as Well as Other Enzymes with Unknown Function. Biochemistry 2018; 57:3364-3377. [DOI: 10.1021/acs.biochem.8b00097] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lei Lei
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Uria Alcolombri
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Diana Meltzer
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Dan S. Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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Cao HY, Wang P, Xu F, Li PY, Xie BB, Qin QL, Zhang YZ, Li CY, Chen XL. Molecular Insight into the Acryloyl-CoA Hydration by AcuH for Acrylate Detoxification in Dimethylsulfoniopropionate-Catabolizing Bacteria. Front Microbiol 2017; 8:2034. [PMID: 29089943 PMCID: PMC5651017 DOI: 10.3389/fmicb.2017.02034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 10/05/2017] [Indexed: 11/13/2022] Open
Abstract
Microbial cleavage of dimethylsulfoniopropionate (DMSP) producing dimethyl sulfide (DMS) and acrylate is an important step in global sulfur cycling. Acrylate is toxic for cells, and thus should be metabolized effectively for detoxification. There are two proposed pathways for acrylate metabolism in DMSP-catabolizing bacteria, the AcuN-AcuK pathway and the PrpE-AcuI pathway. AcuH is an acryloyl-CoA hydratase in DMSP-catabolizing bacteria and can catalyze the hydration of toxic acryloyl-CoA to produce 3-hydroxypropionyl-CoA (3-HP-CoA) in both the AcuN-AcuK pathway and the side path of the PrpE-AcuI pathway. However, the structure and catalytic mechanism of AcuH remain unknown. Here, we cloned a putative acuH gene from Roseovarius nubinhibens ISM, a typical DMSP-catabolizing bacterium, and expressed it (RdAcuH) in Escherichia coli. The activity of RdAcuH toward acryloyl-CoA was detected by liquid chromatography-mass spectrometry (LC-MS), which suggests that RdAcuH is a functional acryloyl-CoA hydratase. Then we solved the crystal structure of RdAcuH. Each asymmetric unit in the crystal of RdAcuH contains a dimer of trimers and each RdAcuH monomer contains an N-terminal domain (NTD) and a C-terminal domain (CTD). There are three active centers in each trimer and each active center is located between the NTD of a subunit and the CTD of the neighboring subunit. Site-directed mutagenesis analysis indicates that two highly conserved glutamates, Glu112 and Glu132, in the active center are essential for catalysis. Based on our results and previous research, we analyzed the catalytic mechanism of AcuH to hydrate acryloyl-CoA, in which Glu132 acts as the catalytic base. This study sheds light on the mechanism of acrylate detoxification in DMSP-catabolizing bacteria.
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Affiliation(s)
- Hai-Yan Cao
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Peng Wang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Fei Xu
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Ping-Yi Li
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Bin-Bin Xie
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Qi-Long Qin
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Yu-Zhong Zhang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Chun-Yang Li
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Institute of Marine Science and Technology, Shandong University, Jinan, China
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13
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Rampley CPN, Davison PA, Qian P, Preston GM, Hunter CN, Thompson IP, Wu LJ, Huang WE. Development of SimCells as a novel chassis for functional biosensors. Sci Rep 2017; 7:7261. [PMID: 28775370 PMCID: PMC5543166 DOI: 10.1038/s41598-017-07391-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/28/2017] [Indexed: 01/31/2023] Open
Abstract
This work serves as a proof-of-concept for bacterially derived SimCells (Simple Cells), which contain the cell machinery from bacteria and designed DNA (or potentially a simplified genome) to instruct the cell to carry out novel, specific tasks. SimCells represent a reprogrammable chassis without a native chromosome, which can host designed DNA to perform defined functions. In this paper, the use of Escherichia coli MC1000 ∆minD minicells as a non-reproducing chassis for SimCells was explored, as demonstrated by their ability to act as sensitive biosensors for small molecules. Highly purified minicells derived from E. coli strains containing gene circuits for biosensing were able to transduce the input signals from several small molecules (glucarate, acrylate and arabinose) into the production of green fluorescent protein (GFP). A mathematical model was developed to fit the experimental data for induction of gene expression in SimCells. The intracellular ATP level was shown to be important for SimCell function. A purification and storage protocol was developed to prepare SimCells which could retain their functions for an extended period of time. This study demonstrates that SimCells are able to perform as ‘smart bioparticles’ controlled by designed gene circuits.
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Affiliation(s)
- Cordelia P N Rampley
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
| | - Paul A Davison
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Pu Qian
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Gail M Preston
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, Oxford, United Kingdom
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Ian P Thompson
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
| | - Ling Juan Wu
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, United Kingdom
| | - Wei E Huang
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom.
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Wang P, Cao HY, Chen XL, Li CY, Li PY, Zhang XY, Qin QL, Todd JD, Zhang YZ. Mechanistic insight into acrylate metabolism and detoxification in marine dimethylsulfoniopropionate-catabolizing bacteria. Mol Microbiol 2017; 105:674-688. [PMID: 28598523 DOI: 10.1111/mmi.13727] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2017] [Indexed: 12/24/2022]
Abstract
Dimethylsulfoniopropionate (DMSP) cleavage, yielding dimethyl sulfide (DMS) and acrylate, provides vital carbon sources to marine bacteria, is a key component of the global sulfur cycle and effects atmospheric chemistry and potentially climate. Acrylate and its metabolite acryloyl-CoA are toxic if allowed to accumulate within cells. Thus, organisms cleaving DMSP require effective systems for both the utilization and detoxification of acrylate. Here, we examine the mechanism of acrylate utilization and detoxification in Roseobacters. We propose propionate-CoA ligase (PrpE) and acryloyl-CoA reductase (AcuI) as the key enzymes involved and through structural and mutagenesis analyses, provide explanations of their catalytic mechanisms. In most cases, DMSP lyases and DMSP demethylases (DmdAs) have low substrate affinities, but AcuIs have very high substrate affinities, suggesting that an effective detoxification system for acylate catabolism exists in DMSP-catabolizing Roseobacters. This study provides insight on acrylate metabolism and detoxification and a possible explanation for the high Km values that have been noted for some DMSP lyases. Since acrylate/acryloyl-CoA is probably produced by other metabolism, and AcuI and PrpE are conserved in many organisms across all domains of life, the detoxification system is likely relevant to many metabolic processes and environments beyond DMSP catabolism.
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Affiliation(s)
- Peng Wang
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Hai-Yan Cao
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Xiu-Lan Chen
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Chun-Yang Li
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Ping-Yi Li
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Xi-Ying Zhang
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Qi-Long Qin
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China
| | - Jonathan D Todd
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Yu-Zhong Zhang
- Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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15
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Bullock HA, Luo H, Whitman WB. Evolution of Dimethylsulfoniopropionate Metabolism in Marine Phytoplankton and Bacteria. Front Microbiol 2017; 8:637. [PMID: 28469605 PMCID: PMC5395565 DOI: 10.3389/fmicb.2017.00637] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 03/28/2017] [Indexed: 11/13/2022] Open
Abstract
The elucidation of the pathways for dimethylsulfoniopropionate (DMSP) synthesis and metabolism and the ecological impact of DMSP have been studied for nearly 70 years. Much of this interest stems from the fact that DMSP metabolism produces the climatically active gas dimethyl sulfide (DMS), the primary natural source of sulfur to the atmosphere. DMSP plays many important roles for marine life, including use as an osmolyte, antioxidant, predator deterrent, and cryoprotectant for phytoplankton and as a reduced carbon and sulfur source for marine bacteria. DMSP is hypothesized to have become abundant in oceans approximately 250 million years ago with the diversification of the strong DMSP producers, the dinoflagellates. This event coincides with the first genome expansion of the Roseobacter clade, known DMSP degraders. Structural and mechanistic studies of the enzymes of the bacterial DMSP demethylation and cleavage pathways suggest that exposure to DMSP led to the recruitment of enzymes from preexisting metabolic pathways. In some cases, such as DmdA, DmdD, and DddP, these enzymes appear to have evolved to become more specific for DMSP metabolism. By contrast, many of the other enzymes, DmdB, DmdC, and the acrylate utilization hydratase AcuH, have maintained broad functionality and substrate specificities, allowing them to carry out a range of reactions within the cell. This review will cover the experimental evidence supporting the hypothesis that, as DMSP became more readily available in the marine environment, marine bacteria adapted enzymes already encoded in their genomes to utilize this new compound.
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Affiliation(s)
- Hannah A Bullock
- Department of Microbiology, University of Georgia, AthensGA, USA
| | - Haiwei Luo
- School of Life Sciences, The Chinese University of Hong KongHong Kong, Hong Kong
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16
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Enzymology of Microbial Dimethylsulfoniopropionate Catabolism. STRUCTURAL AND MECHANISTIC ENZYMOLOGY 2017; 109:195-222. [DOI: 10.1016/bs.apcsb.2017.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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17
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Genetically encoded sensors enable real-time observation of metabolite production. Proc Natl Acad Sci U S A 2016; 113:2388-93. [PMID: 26858408 DOI: 10.1073/pnas.1600375113] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Engineering cells to produce valuable metabolic products is hindered by the slow and laborious methods available for evaluating product concentration. Consequently, many designs go unevaluated, and the dynamics of product formation over time go unobserved. In this work, we develop a framework for observing product formation in real time without the need for sample preparation or laborious analytical methods. We use genetically encoded biosensors derived from small-molecule responsive transcription factors to provide a fluorescent readout that is proportional to the intracellular concentration of a target metabolite. Combining an appropriate biosensor with cells designed to produce a metabolic product allows us to track product formation by observing fluorescence. With individual cells exhibiting fluorescent intensities proportional to the amount of metabolite they produce, high-throughput methods can be used to rank the quality of genetic variants or production conditions. We observe production of several renewable plastic precursors with fluorescent readouts and demonstrate that higher fluorescence is indeed an indicator of higher product titer. Using fluorescence as a guide, we identify process parameters that produce 3-hydroxypropionate at 4.2 g/L, 23-fold higher than previously reported. We also report, to our knowledge, the first engineered route from glucose to acrylate, a plastic precursor with global sales of $14 billion. Finally, we monitor the production of glucarate, a replacement for environmentally damaging detergents, and muconate, a renewable precursor to polyethylene terephthalate and nylon with combined markets of $51 billion, in real time, demonstrating that our method is applicable to a wide range of molecules.
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18
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Rogers JK, Guzman CD, Taylor ND, Raman S, Anderson K, Church GM. Synthetic biosensors for precise gene control and real-time monitoring of metabolites. Nucleic Acids Res 2015; 43:7648-60. [PMID: 26152303 PMCID: PMC4551912 DOI: 10.1093/nar/gkv616] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 04/20/2015] [Accepted: 06/01/2015] [Indexed: 12/19/2022] Open
Abstract
Characterization and standardization of inducible transcriptional regulators has transformed how scientists approach biology by allowing precise and tunable control of gene expression. Despite their utility, only a handful of well-characterized regulators exist, limiting the complexity of engineered biological systems. We apply a characterization pipeline to four genetically encoded sensors that respond to acrylate, glucarate, erythromycin and naringenin. We evaluate how the concentration of the inducing chemical relates to protein expression, how the extent of induction affects protein expression kinetics, and how the activation behavior of single cells relates to ensemble measurements. We show that activation of each sensor is orthogonal to the other sensors, and to other common inducible systems. We demonstrate independent control of three fluorescent proteins in a single cell, chemically defining eight unique transcriptional states. To demonstrate biosensor utility in metabolic engineering, we apply the glucarate biosensor to monitor product formation in a heterologous glucarate biosynthesis pathway and identify superior enzyme variants. Doubling the number of well-characterized inducible systems makes more complex synthetic biological circuits accessible. Characterizing sensors that transduce the intracellular concentration of valuable metabolites into fluorescent readouts enables high-throughput screening of biological catalysts and alleviates the primary bottleneck of the metabolic engineering design-build-test cycle.
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Affiliation(s)
- Jameson K Rogers
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02143, USA
| | - Christopher D Guzman
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA
| | - Noah D Taylor
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Srivatsan Raman
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Kelley Anderson
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA
| | - George M Church
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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19
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Curson ARJ, Burns OJ, Voget S, Daniel R, Todd JD, McInnis K, Wexler M, Johnston AWB. Screening of metagenomic and genomic libraries reveals three classes of bacterial enzymes that overcome the toxicity of acrylate. PLoS One 2014; 9:e97660. [PMID: 24848004 PMCID: PMC4029986 DOI: 10.1371/journal.pone.0097660] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/22/2014] [Indexed: 11/22/2022] Open
Abstract
Acrylate is produced in significant quantities through the microbial cleavage of the highly abundant marine osmoprotectant dimethylsulfoniopropionate, an important process in the marine sulfur cycle. Acrylate can inhibit bacterial growth, likely through its conversion to the highly toxic molecule acrylyl-CoA. Previous work identified an acrylyl-CoA reductase, encoded by the gene acuI, as being important for conferring on bacteria the ability to grow in the presence of acrylate. However, some bacteria lack acuI, and, conversely, many bacteria that may not encounter acrylate in their regular environments do contain this gene. We therefore sought to identify new genes that might confer tolerance to acrylate. To do this, we used functional screening of metagenomic and genomic libraries to identify novel genes that corrected an E. coli mutant that was defective in acuI, and was therefore hyper-sensitive to acrylate. The metagenomic libraries yielded two types of genes that overcame this toxicity. The majority encoded enzymes resembling AcuI, but with significant sequence divergence among each other and previously ratified AcuI enzymes. One other metagenomic gene, arkA, had very close relatives in Bacillus and related bacteria, and is predicted to encode an enoyl-acyl carrier protein reductase, in the same family as FabK, which catalyses the final step in fatty-acid biosynthesis in some pathogenic Firmicute bacteria. A genomic library of Novosphingobium, a metabolically versatile alphaproteobacterium that lacks both acuI and arkA, yielded vutD and vutE, two genes that, together, conferred acrylate resistance. These encode sequential steps in the oxidative catabolism of valine in a pathway in which, significantly, methacrylyl-CoA is a toxic intermediate. These findings expand the range of bacteria for which the acuI gene encodes a functional acrylyl-CoA reductase, and also identify novel enzymes that can similarly function in conferring acrylate resistance, likely, again, through the removal of the toxic product acrylyl-CoA.
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Affiliation(s)
- Andrew R. J. Curson
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
- * E-mail:
| | - Oliver J. Burns
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Sonja Voget
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Jonathan D. Todd
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Kathryn McInnis
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Margaret Wexler
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Andrew W. B. Johnston
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
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Abstract
The most common prokaryotic signal transduction mechanisms are the one-component systems in which a single polypeptide contains both a sensory domain and a DNA-binding domain. Among the >20 classes of one-component systems, the TetR family of regulators (TFRs) are widely associated with antibiotic resistance and the regulation of genes encoding small-molecule exporters. However, TFRs play a much broader role, controlling genes involved in metabolism, antibiotic production, quorum sensing, and many other aspects of prokaryotic physiology. There are several well-established model systems for understanding these important proteins, and structural studies have begun to unveil the mechanisms by which they bind DNA and recognize small-molecule ligands. The sequences for more than 200,000 TFRs are available in the public databases, and genomics studies are identifying their target genes. Three-dimensional structures have been solved for close to 200 TFRs. Comparison of these structures reveals a common overall architecture of nine conserved α helices. The most important open question concerning TFR biology is the nature and diversity of their ligands and how these relate to the biochemical processes under their control.
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Cuthbertson L, Ahn SK, Nodwell JR. Deglycosylation as a mechanism of inducible antibiotic resistance revealed using a global relational tree for one-component regulators. ACTA ACUST UNITED AC 2013; 20:232-40. [PMID: 23438752 DOI: 10.1016/j.chembiol.2012.11.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/22/2012] [Accepted: 11/27/2012] [Indexed: 10/27/2022]
Abstract
The ligands that interact with the vast majority of small-molecule binding transcription factors are unknown, a significant gap in our understanding of sensory perception by cells. TetR-family regulators (TFRs) are found in most prokaryotes and are involved in regulating virtually every aspect of prokaryotic life however only a few TFRs have been characterized. We report the application of phylogenomics to the identification of cognate ligands for TFRs. Using phylogenomics we identify a TFR, KijR, that responds to the antibiotic kijanimicin. We go on to show that KijR represses a gene, kijX, which confers resistance to kijanimicin. Finally we show that KijX inactivates kijanimicin by the hydrolytic removal of sugar residues. This is a demonstration of antibiotic resistance by deglycosylation.
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Affiliation(s)
- Leslie Cuthbertson
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
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22
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Acrylyl-coenzyme A reductase, an enzyme involved in the assimilation of 3-hydroxypropionate by Rhodobacter sphaeroides. J Bacteriol 2013; 195:4716-25. [PMID: 23955006 DOI: 10.1128/jb.00685-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The anoxygenic phototroph Rhodobacter sphaeroides uses 3-hydroxypropionate as a sole carbon source for growth. Previously, we showed that the gene (RSP_1434) known as acuI, which encodes a protein of the medium-chain dehydrogenase/reductase (MDR) superfamily, was involved in 3-hydroxypropionate assimilation via the reductive conversion to propionyl-coenzyme A (CoA). Based on these results, we speculated that acuI encoded acrylyl-CoA reductase. In this work, we characterize the in vitro enzyme activity of purified, recombinant AcuI using a coupled spectrophotometric assay. AcuI from R. sphaeroides catalyzes the NADPH-dependent acrylyl-CoA reduction to produce propionyl-CoA. Two other members of the MDR012 family within the MDR superfamily, the products of SPO_1914 from Ruegeria pomeroyi and yhdH from Escherichia coli, were shown to also be part of this new class of NADPH-dependent acrylyl-CoA reductases. The activities of the three enzymes were characterized by an extremely low Km for acrylyl-CoA (<3 μM) and turnover numbers of 45 to 80 s(-1). These homodimeric enzymes were highly specific for NADPH (Km = 18 to 33 μM), with catalytic efficiencies of more than 10-fold higher for NADPH than for NADH. The introduction of codon-optimized SPO_1914 or yhdH into a ΔacuI::kan mutant of R. sphaeroides on a plasmid complemented 3-hydroxypropionate-dependent growth. However, in their native hosts, SPO_1914 and yhdH are believed to function in the metabolism of substrates other than 3-hydroxypropionate, where acrylyl-CoA is an intermediate. Complementation of the ΔacuI::kan mutant phenotype by crotonyl-CoA carboxylase/reductase from R. sphaeroides was attributed to the fact that the enzyme also uses acrylyl-CoA as a substrate.
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23
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Reisch CR, Crabb WM, Gifford SM, Teng Q, Stoudemayer MJ, Moran MA, Whitman WB. Metabolism of dimethylsulphoniopropionate byRuegeria pomeroyi DSS-3. Mol Microbiol 2013; 89:774-91. [DOI: 10.1111/mmi.12314] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2013] [Indexed: 11/25/2022]
Affiliation(s)
- Chris R. Reisch
- Department of Microbiology; University of Georgia; Athens; GA; USA
| | - Warren M. Crabb
- Department of Microbiology; University of Georgia; Athens; GA; USA
| | - Scott M. Gifford
- Department of Marine sciences; University of Georgia; Athens; GA; USA
| | - Quincy Teng
- US Environmental Protection Agency; Athens; GA; USA
| | | | - Mary Ann Moran
- Department of Marine sciences; University of Georgia; Athens; GA; USA
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24
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Schlüter JP, Reinkensmeier J, Barnett MJ, Lang C, Krol E, Giegerich R, Long SR, Becker A. Global mapping of transcription start sites and promoter motifs in the symbiotic α-proteobacterium Sinorhizobium meliloti 1021. BMC Genomics 2013; 14:156. [PMID: 23497287 PMCID: PMC3616915 DOI: 10.1186/1471-2164-14-156] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/12/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sinorhizobium meliloti is a soil-dwelling α-proteobacterium that possesses a large, tripartite genome and engages in a nitrogen fixing symbiosis with its plant hosts. Although much is known about this important model organism, global characterization of genetic regulatory circuits has been hampered by a lack of information about transcription and promoters. RESULTS Using an RNAseq approach and RNA populations representing 16 different growth and stress conditions, we comprehensively mapped S. meliloti transcription start sites (TSS). Our work identified 17,001 TSS that we grouped into six categories based on the genomic context of their transcripts: mRNA (4,430 TSS assigned to 2,657 protein-coding genes), leaderless mRNAs (171), putative mRNAs (425), internal sense transcripts (7,650), antisense RNA (3,720), and trans-encoded sRNAs (605). We used this TSS information to identify transcription factor binding sites and putative promoter sequences recognized by seven of the 15 known S. meliloti σ factors σ70, σ54, σH1, σH2, σE1, σE2, and σE9). Altogether, we predicted 2,770 new promoter sequences, including 1,302 located upstream of protein coding genes and 722 located upstream of antisense RNA or trans-encoded sRNA genes. To validate promoter predictions for targets of the general stress response σ factor, RpoE2 (σE2), we identified rpoE2-dependent genes using microarrays and confirmed TSS for a subset of these by 5' RACE mapping. CONCLUSIONS By identifying TSS and promoters on a global scale, our work provides a firm foundation for the continued study of S. meliloti gene expression with relation to gene organization, σ factors and other transcription factors, and regulatory RNAs.
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Affiliation(s)
- Jan-Philip Schlüter
- Institute of Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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25
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Aseev LV, Chugunov AO, Efremov RG, Boni IV. A single missense mutation in a coiled-coil domain of Escherichia coli ribosomal protein S2 confers a thermosensitive phenotype that can be suppressed by ribosomal protein S1. J Bacteriol 2013; 195:95-104. [PMID: 23104805 PMCID: PMC3536177 DOI: 10.1128/jb.01305-12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Accepted: 10/21/2012] [Indexed: 01/01/2023] Open
Abstract
Ribosomal protein S2 is an essential component of translation machinery, and its viable mutated variants conferring distinct phenotypes serve as a valuable tool in studying the role of S2 in translation regulation. One of a few available rpsB mutants, rpsB1, shows thermosensitivity and ensures enhanced expression of leaderless mRNAs. In this study, we identified the nature of the rpsB1 mutation. Sequencing of the rpsB1 allele revealed a G-to-A transition in the part of the rpsB gene which encodes a coiled-coil domain of S2. The resulting E132K substitution resides in a highly conserved site, TKKE, a so-called N-terminal capping box, at the beginning of the second alpha helix. The protruding coiled-coil domain of S2 is known to provide binding with 16S rRNA in the head of the 30S subunit and, in addition, to interact with a key mRNA binding protein, S1. Molecular dynamics simulations revealed a detrimental impact of the E132K mutation on the coiled-coil structure and thereby on the interactions between S2 and 16S rRNA, providing a clue for the thermosensitivity of the rpsB1 mutant. Using a strain producing a leaderless lacZ transcript from the chromosomal lac promoter, we demonstrated that not only the rpsB1 mutation generating S2/S1-deficient ribosomes but also the rpsA::IS10 mutation leading to partial deficiency in S1 alone increased translation efficiency of the leaderless mRNA by about 10-fold. Moderate overexpression of S1 relieved all these effects and, moreover, suppressed the thermosensitive phenotype of rpsB1, indicating the role of S1 as an extragenic suppressor of the E132K mutation.
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Affiliation(s)
- Leonid V Aseev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russia
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26
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Todd JD, Curson ARJ, Sullivan MJ, Kirkwood M, Johnston AWB. The Ruegeria pomeroyi acuI gene has a role in DMSP catabolism and resembles yhdH of E. coli and other bacteria in conferring resistance to acrylate. PLoS One 2012; 7:e35947. [PMID: 22563425 PMCID: PMC3338564 DOI: 10.1371/journal.pone.0035947] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/23/2012] [Indexed: 11/17/2022] Open
Abstract
The Escherichia coli YhdH polypeptide is in the MDR012 sub-group of medium chain reductase/dehydrogenases, but its biological function was unknown and no phenotypes of YhdH− mutants had been described. We found that an E. coli strain with an insertional mutation in yhdH was hyper-sensitive to inhibitory effects of acrylate, and, to a lesser extent, to those of 3-hydroxypropionate. Close homologues of YhdH occur in many Bacterial taxa and at least two animals. The acrylate sensitivity of YhdH− mutants was corrected by the corresponding, cloned homologues from several bacteria. One such homologue is acuI, which has a role in acrylate degradation in marine bacteria that catabolise dimethylsulfoniopropionate (DMSP) an abundant anti-stress compound made by marine phytoplankton. The acuI genes of such bacteria are often linked to ddd genes that encode enzymes that cleave DMSP into acrylate plus dimethyl sulfide (DMS), even though these are in different polypeptide families, in unrelated bacteria. Furthermore, most strains of Roseobacters, a clade of abundant marine bacteria, cleave DMSP into acrylate plus DMS, and can also demethylate it, using DMSP demethylase. In most Roseobacters, the corresponding gene, dmdA, lies immediately upstream of acuI and in the model Roseobacter strain Ruegeria pomeroyi DSS-3, dmdA-acuI were co-regulated in response to the co-inducer, acrylate. These observations, together with findings by others that AcuI has acryloyl-CoA reductase activity, lead us to suggest that YdhH/AcuI enzymes protect cells against damaging effects of intracellular acryloyl-CoA, formed endogenously, and/or via catabolising exogenous acrylate. To provide “added protection” for bacteria that form acrylate from DMSP, acuI was recruited into clusters of genes involved in this conversion and, in the case of acuI and dmdA in the Roseobacters, their co-expression may underpin an interaction between the two routes of DMSP catabolism, whereby the acrylate product of DMSP lyases is a co-inducer for the demethylation pathway.
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Affiliation(s)
- Jonathan D Todd
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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27
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Ramachandran VK, Shearer N, Jacob JJ, Sharma CM, Thompson A. The architecture and ppGpp-dependent expression of the primary transcriptome of Salmonella Typhimurium during invasion gene expression. BMC Genomics 2012; 13:25. [PMID: 22251276 PMCID: PMC3293720 DOI: 10.1186/1471-2164-13-25] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 01/17/2012] [Indexed: 11/26/2022] Open
Abstract
Background Invasion of intestinal epithelial cells by Salmonella enterica serovar Typhimurium (S. Typhimurium) requires expression of the extracellular virulence gene expression programme (STEX), activation of which is dependent on the signalling molecule guanosine tetraphosphate (ppGpp). Recently, next-generation transcriptomics (RNA-seq) has revealed the unexpected complexity of bacterial transcriptomes and in this report we use differential RNA sequencing (dRNA-seq) to define the high-resolution transcriptomic architecture of wild-type S. Typhimurium and a ppGpp null strain under growth conditions which model STEX. In doing so we show that ppGpp plays a much wider role in regulating the S. Typhimurium STEX primary transcriptome than previously recognised. Results Here we report the precise mapping of transcriptional start sites (TSSs) for 78% of the S. Typhimurium open reading frames (ORFs). The TSS mapping enabled a genome-wide promoter analysis resulting in the prediction of 169 alternative sigma factor binding sites, and the prediction of the structure of 625 operons. We also report the discovery of 55 new candidate small RNAs (sRNAs) and 302 candidate antisense RNAs (asRNAs). We discovered 32 ppGpp-dependent alternative TSSs and determined the extent and level of ppGpp-dependent coding and non-coding transcription. We found that 34% and 20% of coding and non-coding RNA transcription respectively was ppGpp-dependent under these growth conditions, adding a further dimension to the role of this remarkable small regulatory molecule in enabling rapid adaptation to the infective environment. Conclusions The transcriptional architecture of S. Typhimurium and finer definition of the key role ppGpp plays in regulating Salmonella coding and non-coding transcription should promote the understanding of gene regulation in this important food borne pathogen and act as a resource for future research.
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Affiliation(s)
- Vinoy K Ramachandran
- Institute of Food Research, Norwich, UK, University of Würzburg, Josef-Schneider-Str, 2/Bau D15, 97080 Würzburg, Germany
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Rhodobacter sphaeroides uses a reductive route via propionyl coenzyme A to assimilate 3-hydroxypropionate. J Bacteriol 2011; 194:225-32. [PMID: 22056933 DOI: 10.1128/jb.05959-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
3-Hydroxypropionate is a product or intermediate of the carbon metabolism of organisms from all three domains of life. However, little is known about how carbon derived from 3-hydroxypropionate is assimilated by organisms that can utilize this C(3) compound as a carbon source. This work uses the model bacterium Rhodobacter sphaeroides to begin to elucidate how 3-hydroxypropionate can be incorporated into cell constituents. To this end, a quantitative assay for 3-hydroxypropionate was developed by using recombinant propionyl coenzyme A (propionyl-CoA) synthase from Chloroflexus aurantiacus. Using this assay, we demonstrate that R. sphaeroides can utilize 3-hydroxypropionate as the sole carbon source and energy source. We establish that acetyl-CoA is not the exclusive entry point for 3-hydroxypropionate into the central carbon metabolism and that the reductive conversion of 3-hydroxypropionate to propionyl-CoA is a necessary route for the assimilation of this molecule by R. sphaeroides. Our conclusion is based on the following findings: (i) crotonyl-CoA carboxylase/reductase, a key enzyme of the ethylmalonyl-CoA pathway for acetyl-CoA assimilation, was not essential for growth with 3-hydroxypropionate, as demonstrated by mutant analyses and enzyme activity measurements; (ii) the reductive conversion of 3-hydroxypropionate or acrylate to propionyl-CoA was detected in cell extracts of R. sphaeroides grown with 3-hydroxypropionate, and both activities were upregulated compared to the activities of succinate-grown cells; and (iii) the inactivation of acuI, encoding a candidate acrylyl-CoA reductase, resulted in a 3-hydroxypropionate-negative growth phenotype.
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Abstract
The compatible solute dimethylsulphoniopropionate (DMSP) has important roles in marine environments. It is an anti-stress compound made by many single-celled plankton, some seaweeds and a few land plants that live by the shore. Furthermore, in the oceans it is a major source of carbon and sulphur for marine bacteria that break it down to products such as dimethyl sulphide, which are important in their own right and have wide-ranging effects, from altering animal behaviour to seeding cloud formation. In this Review, we describe how recent genetic and genomic work on the ways in which several different bacteria, and some fungi, catabolize DMSP has provided new and surprising insights into the mechanisms, regulation and possible evolution of DMSP catabolism in microorganisms.
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