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New perspectives into Gluconobacter-catalysed biotransformations. Biotechnol Adv 2023; 65:108127. [PMID: 36924811 DOI: 10.1016/j.biotechadv.2023.108127] [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: 10/22/2022] [Revised: 03/02/2023] [Accepted: 03/08/2023] [Indexed: 03/17/2023]
Abstract
Different from other aerobic microorganisms that oxidise carbon sources to water and carbon dioxide, Gluconobacter catalyses the incomplete oxidation of various substrates with regio- and stereoselectivity. This ability, as well as its capacity to release the resulting products into the reaction media, place Gluconobacter as a privileged member of a non-model microorganism class that may boost industrial biotechnology. Knowledge of new technologies applied to Gluconobacter has been piling up in recent years. Advancements in its genetic modification, application of immobilisation tools and careful designs of the transformations, have improved productivities and stabilities of Gluconobacter strains or enabled new bioconversions for the production of valuable marketable chemicals. In this work, the latest advancements applied to Gluconobacter-catalysed biotransformations are summarised with a special focus on recent available tools to improve them. From genetic and metabolic engineering to bioreactor design, the most recent works on the topic are analysed in depth to provide a comprehensive resource not only for scientists and technologists working on/with Gluconobacter, but for the general biotechnologist.
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Riese CN, Wittchen M, Jérôme V, Freitag R, Busche T, Kalinowski J, Schüler D. The transcriptomic landscape of Magnetospirillum gryphiswaldense during magnetosome biomineralization. BMC Genomics 2022; 23:699. [PMID: 36217140 PMCID: PMC9549626 DOI: 10.1186/s12864-022-08913-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 09/23/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND One of the most complex prokaryotic organelles are magnetosomes, which are formed by magnetotactic bacteria as sensors for navigation in the Earth's magnetic field. In the alphaproteobacterium Magnetospirillum gryphiswaldense magnetosomes consist of chains of magnetite crystals (Fe3O4) that under microoxic to anoxic conditions are biomineralized within membrane vesicles. To form such an intricate structure, the transcription of > 30 specific structural genes clustered within the genomic magnetosome island (MAI) has to be coordinated with the expression of an as-yet unknown number of auxiliary genes encoding several generic metabolic functions. However, their global regulation and transcriptional organization in response to anoxic conditions most favorable for magnetite biomineralization are still unclear. RESULTS Here, we compared transcriptional profiles of anaerobically grown magnetosome forming cells with those in which magnetosome biosynthesis has been suppressed by aerobic condition. Using whole transcriptome shotgun sequencing, we found that transcription of about 300 of the > 4300 genes was significantly enhanced during magnetosome formation. About 40 of the top upregulated genes are directly or indirectly linked to aerobic and anaerobic respiration (denitrification) or unknown functions. The mam and mms gene clusters, specifically controlling magnetosome biosynthesis, were highly transcribed, but constitutively expressed irrespective of the growth condition. By Cappable-sequencing, we show that the transcriptional complexity of both the MAI and the entire genome decreased under anaerobic conditions optimal for magnetosome formation. In addition, predominant promoter structures were highly similar to sigma factor σ70 dependent promoters in other Alphaproteobacteria. CONCLUSIONS Our transcriptome-wide analysis revealed that magnetite biomineralization relies on a complex interplay between generic metabolic processes such as aerobic and anaerobic respiration, cellular redox control, and the biosynthesis of specific magnetosome structures. In addition, we provide insights into global regulatory features that have remained uncharacterized in the widely studied model organism M. gryphiswaldense, including a comprehensive dataset of newly annotated transcription start sites and genome-wide operon detection as a community resource (GEO Series accession number GSE197098).
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Affiliation(s)
- Cornelius N Riese
- Department of Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Manuel Wittchen
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Valérie Jérôme
- Chair for Process Biotechnology, University of Bayreuth, Bayreuth, Germany
| | - Ruth Freitag
- Chair for Process Biotechnology, University of Bayreuth, Bayreuth, Germany
| | - Tobias Busche
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Dirk Schüler
- Department of Microbiology, University of Bayreuth, Bayreuth, Germany.
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FNR-Type Regulator GoxR of the Obligatorily Aerobic Acetic Acid Bacterium Gluconobacter oxydans Affects Expression of Genes Involved in Respiration and Redox Metabolism. Appl Environ Microbiol 2021; 87:AEM.00195-21. [PMID: 33741613 DOI: 10.1128/aem.00195-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/09/2021] [Indexed: 12/13/2022] Open
Abstract
Gene expression in the obligately aerobic acetic acid bacterium Gluconobacter oxydans responds to oxygen limitation, but the regulators involved are unknown. In this study, we analyzed a transcriptional regulator named GoxR (GOX0974), which is the only member of the fumarate-nitrate reduction regulator (FNR) family in this species. Evidence that GoxR contains an iron-sulfur cluster was obtained, suggesting that GoxR functions as an oxygen sensor similar to FNR. The direct target genes of GoxR were determined by combining several approaches, including a transcriptome comparison of a ΔgoxR mutant with the wild-type strain and detection of in vivo GoxR binding sites by chromatin affinity purification and sequencing (ChAP-Seq). Prominent targets were the cioAB genes encoding a cytochrome bd oxidase with low O2 affinity, which were repressed by GoxR, and the pnt operon, which was activated by GoxR. The pnt operon encodes a transhydrogenase (pntA1A2B), an NADH-dependent oxidoreductase (GOX0313), and another oxidoreductase (GOX0314). Evidence was obtained for GoxR being active despite a high dissolved oxygen concentration in the medium. We suggest a model in which the very high respiration rates of G. oxydans due to periplasmic oxidations cause an oxygen-limited cytoplasm and insufficient reoxidation of NAD(P)H in the respiratory chain, leading to inhibited cytoplasmic carbohydrate degradation. GoxR-triggered induction of the pnt operon enhances fast interconversion of NADPH and NADH by the transhydrogenase and NADH reoxidation by the GOX0313 oxidoreductase via reduction of acetaldehyde formed by pyruvate decarboxylase to ethanol. In fact, small amounts of ethanol were formed by G. oxydans under oxygen-restricted conditions in a GoxR-dependent manner.IMPORTANCE Gluconobacter oxydans serves as a cell factory for oxidative biotransformations based on membrane-bound dehydrogenases and as a model organism for elucidating the metabolism of acetic acid bacteria. Surprisingly, to our knowledge none of the more than 100 transcriptional regulators encoded in the genome of G. oxydans has been studied experimentally until now. In this work, we analyzed the function of a regulator named GoxR, which belongs to the FNR family. Members of this family serve as oxygen sensors by means of an oxygen-sensitive [4Fe-4S] cluster and typically regulate genes important for growth under anoxic conditions by anaerobic respiration or fermentation. Because G. oxydans has an obligatory aerobic respiratory mode of energy metabolism, it was tempting to elucidate the target genes regulated by GoxR. Our results show that GoxR affects the expression of genes that support the interconversion of NADPH and NADH and the NADH reoxidation by reduction of acetaldehyde to ethanol.
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Fricke PM, Klemm A, Bott M, Polen T. On the way toward regulatable expression systems in acetic acid bacteria: target gene expression and use cases. Appl Microbiol Biotechnol 2021; 105:3423-3456. [PMID: 33856535 PMCID: PMC8102297 DOI: 10.1007/s00253-021-11269-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/24/2021] [Accepted: 04/04/2021] [Indexed: 01/06/2023]
Abstract
Acetic acid bacteria (AAB) are valuable biocatalysts for which there is growing interest in understanding their basics including physiology and biochemistry. This is accompanied by growing demands for metabolic engineering of AAB to take advantage of their properties and to improve their biomanufacturing efficiencies. Controlled expression of target genes is key to fundamental and applied microbiological research. In order to get an overview of expression systems and their applications in AAB, we carried out a comprehensive literature search using the Web of Science Core Collection database. The Acetobacteraceae family currently comprises 49 genera. We found overall 6097 publications related to one or more AAB genera since 1973, when the first successful recombinant DNA experiments in Escherichia coli have been published. The use of plasmids in AAB began in 1985 and till today was reported for only nine out of the 49 AAB genera currently described. We found at least five major expression plasmid lineages and a multitude of further expression plasmids, almost all enabling only constitutive target gene expression. Only recently, two regulatable expression systems became available for AAB, an N-acyl homoserine lactone (AHL)-inducible system for Komagataeibacter rhaeticus and an L-arabinose-inducible system for Gluconobacter oxydans. Thus, after 35 years of constitutive target gene expression in AAB, we now have the first regulatable expression systems for AAB in hand and further regulatable expression systems for AAB can be expected. KEY POINTS: • Literature search revealed developments and usage of expression systems in AAB. • Only recently 2 regulatable plasmid systems became available for only 2 AAB genera. • Further regulatable expression systems for AAB are in sight.
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Affiliation(s)
- Philipp Moritz Fricke
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Angelika Klemm
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Michael Bott
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Tino Polen
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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Chen Y, Liu L, Yu S, Li J, Zhou J, Chen J. Identification of Gradient Promoters of Gluconobacter oxydans and Their Applications in the Biosynthesis of 2-Keto-L-Gulonic Acid. Front Bioeng Biotechnol 2021; 9:673844. [PMID: 33898410 PMCID: PMC8064726 DOI: 10.3389/fbioe.2021.673844] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 03/22/2021] [Indexed: 12/19/2022] Open
Abstract
The acetic acid bacterium Gluconobacter oxydans is known for its unique incomplete oxidation and therefore widely applied in the industrial production of many compounds, e.g., 2-keto-L-gulonic acid (2-KLG), the direct precursor of vitamin C. However, few molecular tools are available for metabolically engineering G. oxydans, which greatly limit the strain development. Promoters are one of vital components to control and regulate gene expression at the transcriptional level for boosting production. In this study, the low activity of SDH was found to hamper the high yield of 2-KLG, and enhancing the expression of SDH was achieved by screening the suitable promoters based on RNA sequencing data. We obtained 97 promoters from G. oxydans’s genome, including two strong shuttle promoters and six strongest promoters. Among these promoters, P3022 and P0943 revealed strong activities in both Escherichia coli and G. oxydans, and the activity of the strongest promoter (P2703) was about threefold that of the other reported strong promoters of G. oxydans. These promoters were used to overexpress SDH in G. oxydans WSH-003. The titer of 2-KLG reached 3.7 g/L when SDH was under the control of strong promoters P2057 and P2703. This study obtained a series of gradient promoters, including two strong shuttle promoters, and expanded the toolbox of available promoters for the application in metabolic engineering of G. oxydans for high-value products.
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Affiliation(s)
- Yue Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, China.,Science Center for Future Foods, Jiangnan University, Wuxi, China.,Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, China
| | - Li Liu
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, China.,Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, China
| | - Shiqin Yu
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, China.,Science Center for Future Foods, Jiangnan University, Wuxi, China.,Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, China
| | - Jianghua Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,Science Center for Future Foods, Jiangnan University, Wuxi, China
| | - Jingwen Zhou
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, China.,Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, China
| | - Jian Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, China.,National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, China
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Hövels M, Kosciow K, Kniewel J, Jakob F, Deppenmeier U. High yield production of levan-type fructans by Gluconobacter japonicus LMG 1417. Int J Biol Macromol 2020; 164:295-303. [DOI: 10.1016/j.ijbiomac.2020.07.105] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 06/29/2020] [Accepted: 07/09/2020] [Indexed: 12/24/2022]
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Kißling L, Schneider C, Seibel K, Dorjjugder N, Busche T, Kalinowski J, Mack M. The roseoflavin producer
Streptomyces davaonensis
has a high catalytic capacity and specific genetic adaptations with regard to the biosynthesis of riboflavin. Environ Microbiol 2020; 22:3248-3265. [DOI: 10.1111/1462-2920.15066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/06/2020] [Accepted: 05/10/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Lena Kißling
- Institute for Technical Microbiology, Department of Biotechnology Mannheim University of Applied Sciences Mannheim 68163 Germany
| | - Carmen Schneider
- Institute for Technical Microbiology, Department of Biotechnology Mannheim University of Applied Sciences Mannheim 68163 Germany
| | - Katharina Seibel
- Institute for Technical Microbiology, Department of Biotechnology Mannheim University of Applied Sciences Mannheim 68163 Germany
| | - Nasanjargal Dorjjugder
- Institute for Technical Microbiology, Department of Biotechnology Mannheim University of Applied Sciences Mannheim 68163 Germany
| | - Tobias Busche
- Center for Biotechnology Bielefeld University Bielefeld 33594 Germany
| | - Jörn Kalinowski
- Center for Biotechnology Bielefeld University Bielefeld 33594 Germany
| | - Matthias Mack
- Institute for Technical Microbiology, Department of Biotechnology Mannheim University of Applied Sciences Mannheim 68163 Germany
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Towards control of cellulose biosynthesis by Komagataeibacter using systems-level and strain engineering strategies: current progress and perspectives. Appl Microbiol Biotechnol 2020; 104:6565-6585. [PMID: 32529377 PMCID: PMC7347698 DOI: 10.1007/s00253-020-10671-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 12/29/2022]
Abstract
The strains of the Komagataeibacter genus have been shown to be the most efficient bacterial nanocellulose producers. Although exploited for many decades, the studies of these species focused mainly on the optimisation of cellulose synthesis process through modification of culturing conditions in the industrially relevant settings. Molecular physiology of Komagataeibacter was poorly understood and only a few studies explored genetic engineering as a strategy for strain improvement. Only since recently the systemic information of the Komagataeibacter species has been accumulating in the form of omics datasets representing sequenced genomes, transcriptomes, proteomes and metabolomes. Genetic analyses of the mutants generated in the untargeted strain modification studies have drawn attention to other important proteins, beyond those of the core catalytic machinery of the cellulose synthase complex. Recently, modern molecular and synthetic biology tools have been developed which showed the potential for improving targeted strain engineering. Taking the advantage of the gathered knowledge should allow for better understanding of the genotype–phenotype relationship which is necessary for robust modelling of metabolism as well as selection and testing of new molecular engineering targets. In this review, we discuss the current progress in the area of Komagataeibacter systems biology and its impact on the research aimed at scaled-up cellulose synthesis as well as BNC functionalisation.Key points • The accumulated omics datasets advanced the systemic understanding of Komagataeibacter physiology at the molecular level. • Untargeted and targeted strain modification approaches have been applied to improve nanocellulose yield and properties. • The development of modern molecular and synthetic biology tools presents a potential for enhancing targeted strain engineering. • The accumulating omic information should improve modelling of Komagataeibacter’s metabolism as well as selection and testing of new molecular engineering targets. |
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9
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Battling S, Wohlers K, Igwe C, Kranz A, Pesch M, Wirtz A, Baumgart M, Büchs J, Bott M. Novel plasmid-free Gluconobacter oxydans strains for production of the natural sweetener 5-ketofructose. Microb Cell Fact 2020; 19:54. [PMID: 32131833 PMCID: PMC7055074 DOI: 10.1186/s12934-020-01310-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/17/2020] [Indexed: 12/14/2022] Open
Abstract
Background 5-Ketofructose (5-KF) has recently been identified as a promising non-nutritive natural sweetener. Gluconobacter oxydans strains have been developed that allow efficient production of 5-KF from fructose by plasmid-based expression of the fructose dehydrogenase genes fdhSCL of Gluconobacter japonicus. As plasmid-free strains are preferred for industrial production of food additives, we aimed at the construction of efficient 5-KF production strains with the fdhSCL genes chromosomally integrated. Results For plasmid-free 5-KF production, we selected four sites in the genome of G. oxydans IK003.1 and inserted the fdhSCL genes under control of the strong P264 promoter into each of these sites. All four recombinant strains expressed fdhSCL and oxidized fructose to 5-KF, but site-specific differences were observed suggesting that the genomic vicinity influenced gene expression. For further improvement, a second copy of the fdhSCL genes under control of P264 was inserted into the second-best insertion site to obtain strain IK003.1::fdhSCL2. The 5-KF production rate and the 5-KF yield obtained with this double-integration strain were considerably higher than for the single integration strains and approached the values of IK003.1 with plasmid-based fdhSCL expression. Conclusion We identified four sites in the genome of G. oxydans suitable for expression of heterologous genes and constructed a strain with two genomic copies of the fdhSCL genes enabling efficient plasmid-free 5-KF production. This strain will serve as basis for further metabolic engineering strategies aiming at the use of alternative carbon sources for 5-KF production and for bioprocess optimization.
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Affiliation(s)
- Svenja Battling
- AVT-Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Karen Wohlers
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Chika Igwe
- AVT-Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Angela Kranz
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Matthias Pesch
- AVT-Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Astrid Wirtz
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Meike Baumgart
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Jochen Büchs
- AVT-Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074, Aachen, Germany.
| | - Michael Bott
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425, Jülich, Germany.
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Dostálová H, Busche T, Holátko J, Rucká L, Štěpánek V, Barvík I, Nešvera J, Kalinowski J, Pátek M. Overlap of Promoter Recognition Specificity of Stress Response Sigma Factors SigD and SigH in Corynebacterium glutamicum ATCC 13032. Front Microbiol 2019; 9:3287. [PMID: 30687273 PMCID: PMC6338062 DOI: 10.3389/fmicb.2018.03287] [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: 09/13/2018] [Accepted: 12/17/2018] [Indexed: 12/27/2022] Open
Abstract
Corynebacterium glutamicum ATCC 13032 harbors five sigma subunits of RNA polymerase belonging to Group IV, also called extracytoplasmic function (ECF) σ factors. These factors σC, σD, σE, σH, and σM are mostly involved in stress responses. The role of σD consists in the control of cell wall integrity. The σD regulon is involved in the synthesis of components of the mycomembrane which is part of the cell wall in C. glutamicum. RNA sequencing of the transcriptome from a strain overexpressing the sigD gene provided 29 potential σD-controlled genes and enabled us to precisely localize their transcriptional start sites. Analysis of the respective promoters by both in vitro transcription and the in vivo two-plasmid assay confirmed that transcription of 11 of the tested genes is directly σD-dependent. The key sequence elements of all these promoters were found to be identical or closely similar to the motifs -35 GTAACA/G and -10 GAT. Surprisingly, nearly all of these σD-dependent promoters were also active to a much lower extent with σHin vivo and one (Pcg0607) also in vitro, although the known highly conserved consensus sequence of the σH-dependent promoters is different (-35 GGAAT/C and -10 GTT). In addition to the activity of σH at the σD-controlled promoters, we discovered separated or overlapping σA- or σB-regulated or σH-regulated promoters within the upstream region of 8 genes of the σD-regulon. We found that phenol in the cultivation medium acts as a stress factor inducing expression of some σD-dependent genes. Computer modeling revealed that σH binds to the promoter DNA in a similar manner as σD to the analogous promoter elements. The homology models together with mutational analysis showed that the key amino acids, Ala 60 in σD and Lys 53 in σH, bind to the second nucleotide within the respective -10 promoter elements (GAT and GTT, respectively). The presented data obtained by integrating in vivo, in vitro and in silico approaches demonstrate that most of the σD-controlled genes also belong to the σH-regulon and are also transcribed from the overlapping or closely located housekeeping (σA-regulated) and/or general stress (σB-regulated) promoters.
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Affiliation(s)
- Hana Dostálová
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
| | - Tobias Busche
- Centrum für Biotechnologie, Universität Bielefeld, Bielefeld, Germany
| | - Jiří Holátko
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
| | - Lenka Rucká
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
| | - Václav Štěpánek
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
| | - Ivan Barvík
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czechia
| | - Jan Nešvera
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
| | - Jörn Kalinowski
- Centrum für Biotechnologie, Universität Bielefeld, Bielefeld, Germany
| | - Miroslav Pátek
- Institute of Microbiology of the CAS, v. v. i., Prague, Czechia
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11
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Kranz A, Steinmann A, Degner U, Mengus-Kaya A, Matamouros S, Bott M, Polen T. Global mRNA decay and 23S rRNA fragmentation in Gluconobacter oxydans 621H. BMC Genomics 2018; 19:753. [PMID: 30326828 PMCID: PMC6191907 DOI: 10.1186/s12864-018-5111-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 09/25/2018] [Indexed: 12/14/2022] Open
Abstract
Background Gluconobacter oxydans is a strictly aerobic Gram-negative acetic acid bacterium used industrially for oxidative biotransformations due to its exceptional type of catabolism. It incompletely oxidizes a wide variety of carbohydrates regio- and stereoselectively in the periplasm using membrane-bound dehydrogenases with accumulation of the products in the medium. As a consequence, only a small fraction of the carbon and energy source enters the cell, resulting in a low biomass yield. Additionally, central carbon metabolism is characterized by the absence of a functional glycolysis and absence of a functional tricarboxylic acid (TCA) cycle. Due to these features, G. oxydans is a highly interesting model organism. Here we analyzed global mRNA decay in G. oxydans to describe its characteristic features and to identify short-lived mRNAs representing potential bottlenecks in the metabolism for further growth improvement by metabolic engineering. Results Using DNA microarrays we estimated the mRNA half-lives in G. oxydans. Overall, the mRNA half-lives ranged mainly from 3 min to 25 min with a global mean of 5.7 min. The transcripts encoding GroES and GroEL required for proper protein folding ranked at the top among transcripts exhibiting both long half-lives and high abundance. The F-type H+-ATP synthase transcripts involved in energy metabolism ranked among the transcripts with the shortest mRNA half-lives. RNAseq analysis revealed low expression levels for genes of the incomplete TCA cycle and also the mRNA half-lives of several of those were short and below the global mean. The mRNA decay analysis also revealed an apparent instability of full-length 23S rRNA. Further analysis of the ribosome-associated rRNA revealed a 23S rRNA fragmentation pattern exhibiting new cleavage regions in 23S rRNAs which were previously not known. Conclusions The very short mRNA half-lives of the H+-ATP synthase, which is likely responsible for the ATP-proton motive force interconversion in G. oxydans under many or most conditions, is notably in contrast to mRNA decay data from other bacteria. Together with the short mRNA half-lives and low expression of some other central metabolic genes it could limit intended improvements of G. oxydans’ biomass yield by metabolic engineering. Also, further studies are needed to unravel the multistep process of the 23S rRNA fragmentation in G. oxydans. Electronic supplementary material The online version of this article (10.1186/s12864-018-5111-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Angela Kranz
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.,The Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Andrea Steinmann
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.,The Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Ursula Degner
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Aliye Mengus-Kaya
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Susana Matamouros
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Michael Bott
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.,The Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Tino Polen
- IBG-1: Biotechnology, Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany. .,The Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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