1
|
Miralles-Robledillo JM, Martínez-Espinosa RM, Pire C. Transcriptomic profiling of haloarchaeal denitrification through RNA-Seq analysis. Appl Environ Microbiol 2024; 90:e0057124. [PMID: 38814058 PMCID: PMC11218638 DOI: 10.1128/aem.00571-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 04/26/2024] [Indexed: 05/31/2024] Open
Abstract
Denitrification, a crucial biochemical pathway prevalent among haloarchaea in hypersaline ecosystems, has garnered considerable attention in recent years due to its ecological implications. Nevertheless, the underlying molecular mechanisms and genetic regulation governing this respiration/detoxification process in haloarchaea remain largely unexplored. In this study, RNA-sequencing was used to compare the transcriptomes of the haloarchaeon Haloferax mediterranei under oxic and denitrifying conditions, shedding light on the intricate metabolic alterations occurring within the cell, such as the accurate control of the metal homeostasis. Furthermore, the investigation identifies several genes encoding transcriptional regulators and potential accessory proteins with putative roles in denitrification. Among these are bacterioopsin-like transcriptional activators, proteins harboring a domain of unknown function (DUF2249), and cyanoglobin. In addition, the study delves into the genetic regulation of denitrification, finding a regulatory motif within promoter regions that activates numerous denitrification-related genes. This research serves as a starting point for future molecular biology studies in haloarchaea, offering a promising avenue to unravel the intricate mechanisms governing haloarchaeal denitrification, a pathway of paramount ecological importance.IMPORTANCEDenitrification, a fundamental process within the nitrogen cycle, has been subject to extensive investigation due to its close association with anthropogenic activities, and its contribution to the global warming issue, mainly through the release of N2O emissions. Although our comprehension of denitrification and its implications is generally well established, most studies have been conducted in non-extreme environments with mesophilic microorganisms. Consequently, there is a significant knowledge gap concerning extremophilic denitrifiers, particularly those inhabiting hypersaline environments. The significance of this research was to delve into the process of haloarchaeal denitrification, utilizing the complete denitrifier haloarchaeon Haloferax mediterranei as a model organism. This research led to the analysis of the metabolic state of this microorganism under denitrifying conditions and the identification of regulatory signals and genes encoding proteins potentially involved in this pathway, serving as a valuable resource for future molecular studies.
Collapse
Affiliation(s)
- Jose María Miralles-Robledillo
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
| | - Rosa María Martínez-Espinosa
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies “Ramón Margalef”, University of Alicante, Alicante, Spain
| | - Carmen Pire
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies “Ramón Margalef”, University of Alicante, Alicante, Spain
| |
Collapse
|
2
|
Xu T, Mitra R, Tan D, Li Z, Zhou C, Chen T, Xie Z, Han J. Utilization of gene manipulation system for advancing the biotechnological potential of halophiles: A review. Biotechnol Adv 2024; 70:108302. [PMID: 38101552 DOI: 10.1016/j.biotechadv.2023.108302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/02/2023] [Accepted: 12/09/2023] [Indexed: 12/17/2023]
Abstract
Halophiles are salt-loving microorganisms known to have their natural resistance against media contamination even when cultivated in nonsterile and continuous bioprocess system, thus acting as promising cell factories for Next Generation of Industrial Biotechnology (NGIB). NGIB - a successor to the traditional industrial biotechnology, is a more sustainable and efficient bioprocess technology while saving energy and water in a more convenient way as well as reducing the investment cost and skilled workforce requirement. Numerous studies have achieved intriguing outcomes during synthesis of different metabolite using halophiles such as polyhydroxyalkanoates (PHA), ectoine, biosurfactants, and carotenoids. Present-day development in genetic maneuverings have shown optimistic effects on the industrial applications of halophiles. However, viable and competent genetic manipulation system and gene editing tools are critical to accelerate the process of halophile engineering. With the aid of such powerful gene manipulation systems, exclusive microbial chassis are being crafted with desirable features to breed another innovative area of research such as synthetic biology. This review provides an aerial perspective on how the expansion of adaptable gene manipulation toolkits in halophiles are contributing towards biotechnological advancement, and also focusses on their subsequent application for production improvement. This current methodical and comprehensive review will definitely help the scientific fraternity to bridge the gap between challenges and opportunities in halophile engineering.
Collapse
Affiliation(s)
- Tong Xu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
| | - Ruchira Mitra
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; International College, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Dan Tan
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Zhengjun Li
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Cheng Zhou
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; College of Biochemical Engineering, Beijing Union University, Beijing 100023, People's Republic of China
| | - Tao Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Zhengwei Xie
- Peking University International Cancer Institute, Health Science Center, Peking University, Beijing 100191, People's Republic of China
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
| |
Collapse
|
3
|
Alberti L, König P, Zeidler S, Poehlein A, Daniel R, Averhoff B, Müller V. Identification and characterization of a novel pathway for aldopentose degradation in Acinetobacter baumannii. Environ Microbiol 2023; 25:2416-2430. [PMID: 37522309 DOI: 10.1111/1462-2920.16471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 07/14/2023] [Indexed: 08/01/2023]
Abstract
The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L-arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α-ketoglutarate. Molecular, genetic, and biochemical experiments revealed one branch to be specific for L-arabonate oxidation, and the other for D-xylonate and D-ribonate. Both clusters also encode an uptake system and a regulator that acts as activator (L-arabonate) or repressor (D-xylonate and D-ribonate). Genes encoding the initial oxidation of pentose to pentonate were not part of the clusters, but our data are consistent with the hypothesis of a promiscous, pyrroloquinoline quinone (PQQ)-dependent, periplasmic pentose dehydrogenase, followed by the uptake of the pentonates and their degradation by specific pathways. However, there is a cross-talk between the two different pathways since the isoenzymes can replace each other. Growth on pentoses was found only in pathogenic Acinetobacter species but not in non-pathogenic such as Acinetobacter baylyi. However, mutants impaired in growth on pentoses were not affected in traits important for infection, but growth on L-arabinose was beneficial for long-term survival and desiccation resistance in A. baumannii ATCC 19606.
Collapse
Affiliation(s)
- Lydia Alberti
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Patricia König
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Sabine Zeidler
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| |
Collapse
|
4
|
Rados T, Andre K, Cerletti M, Bisson A. A sweet new set of inducible and constitutive promoters in Haloferax volcanii. Front Microbiol 2023; 14:1204876. [PMID: 37637112 PMCID: PMC10448506 DOI: 10.3389/fmicb.2023.1204876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/27/2023] [Indexed: 08/29/2023] Open
Abstract
Inducible promoters are one of cellular and molecular biology's most important technical tools. The ability to deplete, replete, and overexpress genes on demand is the foundation of most functional studies. Here, we developed and characterized a new xylose-responsive promoter (Pxyl), the second inducible promoter system for the model haloarcheon Haloferax volcanii. Generating RNA-seq datasets from cultures in the presence of four historically used inducers (arabinose, xylose, maltose, and IPTG), we mapped upregulated genomic regions primarily repressed in the absence of the above inducers. We found a highly upregulated promoter that controls the expression of the xacEA (HVO_B0027-28) operon in the pHV3 chromosome. To characterize this promoter region, we cloned msfGFP (monomeric superfold green fluorescent protein) under the control of two upstream regions into a modified pTA962 vector: the first 250 bp (P250) and the whole 750 bp intergenic fragments (P750). The P250 sequence drove the expression of msfGFP constitutively, and its expression did not respond to the presence or absence of xylose. However, the P750 promoter showed not only to be repressed in the absence of xylose but also expressed higher levels of msfGFP than the previously described inducible promoter PtnaA in the presence of the inducer. Finally, we validated the inducible Pxyl promoter by reproducing morphological phenotypes already described in the literature. By overexpressing the tubulin-like FtsZ1 and FtsZ2, we observed similar but slightly more pronounced morphological defects than the tryptophan-inducible promoter PtnaA. FtsZ1 overexpression created larger, deformed cells, whereas cells overexpressing FtsZ2 were smaller but mostly retained their shape. In summary, this work contributes a new xylose-inducible promoter that could be used simultaneously with the well-established PtnaA in functional studies in H. volcanii in the future.
Collapse
Affiliation(s)
- Theopi Rados
- Department of Biology, Brandeis University, Waltham, MA, United States
| | - Katherine Andre
- Department of Biology, Brandeis University, Waltham, MA, United States
| | - Micaela Cerletti
- Department of Biology, Brandeis University, Waltham, MA, United States
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Alex Bisson
- Department of Biology, Brandeis University, Waltham, MA, United States
| |
Collapse
|
5
|
Johnsen U, Ortjohann M, Reinhardt A, Turner JM, Stratton C, Weber KR, Sanchez KM, Maupin-Furlow J, Davies C, Schönheit P. Discovery of a novel transcriptional regulator of sugar catabolism in archaea. Mol Microbiol 2023; 120:224-240. [PMID: 37387308 PMCID: PMC10838023 DOI: 10.1111/mmi.15114] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 07/01/2023]
Abstract
The haloarchaeon Haloferax volcanii degrades D-glucose via the semiphosphorylative Entner-Doudoroff pathway and D-fructose via a modified Embden-Meyerhof pathway. Here, we report the identification of GfcR, a novel type of transcriptional regulator that functions as an activator of both D-glucose and D-fructose catabolism. We find that in the presence of D-glucose, GfcR activates gluconate dehydratase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase and also acts as activator of the phosphotransferase system and of fructose-1,6-bisphosphate aldolase, which are involved in uptake and degradation of D-fructose. In addition, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase are activated by GfcR in the presence of D-fructose and also during growth on D-galactose and glycerol. Electrophoretic mobility shift assays indicate that GfcR binds directly to promoters of regulated genes. Specific intermediates of the degradation pathways of the three hexoses and of glycerol were identified as inducer molecules of GfcR. GfcR is composed of a phosphoribosyltransferase (PRT) domain with an N-terminal helix-turn-helix motif and thus shows homology to PurR of Gram-positive bacteria that is involved in the transcriptional regulation of nucleotide biosynthesis. We propose that GfcR of H. volcanii evolved from a PRT-like enzyme to attain a function as a transcriptional regulator of central sugar catabolic pathways in archaea.
Collapse
Affiliation(s)
- Ulrike Johnsen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Marius Ortjohann
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Andreas Reinhardt
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Jonathan M. Turner
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Caleb Stratton
- Department of Biochemistry & Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Katherine R. Weber
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
| | - Karol M. Sanchez
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
| | - Julie Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
- Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Christopher Davies
- Department of Biochemistry & Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Peter Schönheit
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| |
Collapse
|
6
|
Open Issues for Protein Function Assignment in Haloferax volcanii and Other Halophilic Archaea. Genes (Basel) 2021; 12:genes12070963. [PMID: 34202810 PMCID: PMC8305020 DOI: 10.3390/genes12070963] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/10/2021] [Accepted: 06/15/2021] [Indexed: 12/14/2022] Open
Abstract
Background: Annotation ambiguities and annotation errors are a general challenge in genomics. While a reliable protein function assignment can be obtained by experimental characterization, this is expensive and time-consuming, and the number of such Gold Standard Proteins (GSP) with experimental support remains very low compared to proteins annotated by sequence homology, usually through automated pipelines. Even a GSP may give a misleading assignment when used as a reference: the homolog may be close enough to support isofunctionality, but the substrate of the GSP is absent from the species being annotated. In such cases, the enzymes cannot be isofunctional. Here, we examined a variety of such issues in halophilic archaea (class Halobacteria), with a strong focus on the model haloarchaeon Haloferax volcanii. Results: Annotated proteins of Hfx. volcanii were identified for which public databases tend to assign a function that is probably incorrect. In some cases, an alternative, probably correct, function can be predicted or inferred from the available evidence, but this has not been adopted by public databases because experimental validation is lacking. In other cases, a probably invalid specific function is predicted by homology, and while there is evidence that this assigned function is unlikely, the true function remains elusive. We listed 50 of those cases, each with detailed background information, so that a conclusion about the most likely biological function can be drawn. For reasons of brevity and comprehension, only the key aspects are listed in the main text, with detailed information being provided in a corresponding section of the Supplementary Materials. Conclusions: Compiling, describing and summarizing these open annotation issues and functional predictions will benefit the scientific community in the general effort to improve the evaluation of protein function assignments and more thoroughly detail them. By highlighting the gaps and likely annotation errors currently in the databases, we hope this study will provide a framework for experimentalists to systematically confirm (or disprove) our function predictions or to uncover yet more unexpected functions.
Collapse
|
7
|
Tästensen JB, Johnsen U, Reinhardt A, Ortjohann M, Schönheit P. D-galactose catabolism in archaea: operation of the DeLey-Doudoroff pathway in Haloferax volcanii. FEMS Microbiol Lett 2021; 367:5736015. [PMID: 32055827 DOI: 10.1093/femsle/fnaa029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/11/2020] [Indexed: 11/12/2022] Open
Abstract
The haloarchaeon Haloferax volcanii was found to grow on D-galactose as carbon and energy source. Here we report a comprehensive analysis of D-galactose catabolism in H. volcanii. Genome analyses indicated a cluster of genes encoding putative enzymes of the DeLey-Doudoroff pathway for D-galactose degradation including galactose dehydrogenase, galactonate dehydratase, 2-keto-3-deoxygalactonate kinase and 2-keto-3-deoxy-6-phosphogalactonate (KDPGal) aldolase. The recombinant galactose dehydrogenase and galactonate dehydratase showed high specificity for D-galactose and galactonate, respectively, whereas KDPGal aldolase was promiscuous in utilizing KDPGal and also the C4 epimer 2-keto-3-deoxy-6-phosphogluconate as substrates. Growth studies with knock-out mutants indicated the functional involvement of galactose dehydrogenase, galactonate dehydratase and KDPGal aldolase in D-galactose degradation. Further, the transcriptional regulator GacR was identified, which was characterized as an activator of genes of the DeLey-Doudoroff pathway. Finally, genes were identified encoding components of an ABC transporter and a knock-out mutant of the substrate binding protein indicated the functional involvement of this transporter in D-galactose uptake. This is the first report of D-galactose degradation via the DeLey-Doudoroff pathway in the domain of archaea.
Collapse
Affiliation(s)
- Julia-Beate Tästensen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Ulrike Johnsen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Andreas Reinhardt
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Marius Ortjohann
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Peter Schönheit
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| |
Collapse
|
8
|
Zhao Z, Xian M, Liu M, Zhao G. Biochemical routes for uptake and conversion of xylose by microorganisms. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:21. [PMID: 32021652 PMCID: PMC6995148 DOI: 10.1186/s13068-020-1662-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/21/2020] [Indexed: 05/23/2023]
Abstract
Xylose is a major component of lignocellulose and the second most abundant sugar present in nature. Efficient utilization of xylose is required for the development of economically viable processes to produce biofuels and chemicals from biomass. However, there are still some bottlenecks in the bioconversion of xylose, including the fact that some microorganisms cannot assimilate xylose naturally and that the uptake and metabolism of xylose are inhibited by glucose, which is usually present with xylose in lignocellulose hydrolysate. To overcome these issues, numerous efforts have been made to discover, characterize, and engineer the transporters and enzymes involved in xylose utilization to relieve glucose inhibition and to develop recombinant microorganisms to produce fuels and chemicals from xylose. Here we describe a recent advancement focusing on xylose-utilizing pathways, biosynthesis of chemicals from xylose, and engineering strategies used to improve the conversion efficiency of xylose.
Collapse
Affiliation(s)
- Zhe Zhao
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Mo Xian
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 China
| | - Min Liu
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 China
| | - Guang Zhao
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 China
| |
Collapse
|
9
|
d-Ribose Catabolism in Archaea: Discovery of a Novel Oxidative Pathway in Haloarcula Species. J Bacteriol 2020; 202:JB.00608-19. [PMID: 31712277 DOI: 10.1128/jb.00608-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 10/29/2019] [Indexed: 11/20/2022] Open
Abstract
The Haloarcula species H. marismortui and H. hispanica were found to grow on d-ribose, d-xylose, and l-arabinose. Here, we report the discovery of a novel promiscuous oxidative pathway of pentose degradation based on genome analysis, identification and characterization of enzymes, transcriptional analysis, and growth experiments with knockout mutants. Together, the data indicate that in Haloarcula spp., d-ribose, d-xylose, and l-arabinose were degraded to α-ketoglutarate involving the following enzymes: (i) a promiscuous pentose dehydrogenase that catalyzed the oxidation of d-ribose, d-xylose, and l-arabinose; (ii) a promiscuous pentonolactonase that was involved in the hydrolysis of ribonolactone, xylonolactone, and arabinolactone; (iii) a highly specific dehydratase, ribonate dehydratase, which catalyzed the dehydration of ribonate, and a second enzyme, a promiscuous xylonate/gluconate dehydratase, which was involved in the conversion of xylonate, arabinonate, and gluconate. Phylogenetic analysis indicated that the highly specific ribonate dehydratase constitutes a novel sugar acid dehydratase family within the enolase superfamily; and (iv) finally, 2-keto-3-deoxypentanonate dehydratase and α-ketoglutarate semialdehyde dehydrogenase catalyzed the conversion of 2-keto-3-deoxypentanonate to α-ketoglutarate via α-ketoglutarate semialdehyde. We conclude that the expanded substrate specificities of the pentose dehydrogenase and pentonolactonase toward d-ribose and ribonolactone, respectively, and the presence of a highly specific ribonate dehydratase are prerequisites of the oxidative degradation of d-ribose in Haloarcula spp. This is the first characterization of an oxidative degradation pathway of d-ribose to α-ketoglutarate in archaea.IMPORTANCE The utilization and degradation of d-ribose in archaea, the third domain of life, have not been analyzed so far. We show that Haloarcula species utilize d-ribose, which is degraded to α-ketoglutarate via a novel oxidative pathway. Evidence is presented that the oxidative degradation of d-ribose involves novel promiscuous enzymes, pentose dehydrogenase and pentonolactonase, and a novel sugar acid dehydratase highly specific for ribonate. This is the first report of an oxidative degradation pathway of d-ribose in archaea, which differs from the canonical nonoxidative pathway of d-ribose degradation reported for most bacteria. The data contribute to our understanding of the unusual sugar degradation pathways and enzymes in archaea.
Collapse
|
10
|
The TK0271 Protein Activates Transcription of Aromatic Amino Acid Biosynthesis Genes in the Hyperthermophilic Archaeon Thermococcus kodakarensis. mBio 2019; 10:mBio.01213-19. [PMID: 31506306 PMCID: PMC6737238 DOI: 10.1128/mbio.01213-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms of transcriptional regulation in archaea are still poorly understood. In this study, we identified a transcriptional regulator in the hyperthermophilic archaeon Thermococcus kodakarensis that activates the transcription of three operons involved in the biosynthesis of aromatic amino acids. The study represents one of only a few that identifies a regulator in Archaea that activates transcription. The results also imply that transcriptional regulation of genes with the same function is carried out by diverse mechanisms in the archaea, depending on the lineage. TrpY from Methanothermobacter thermautotrophicus is a regulator that inhibits transcription of the Trp biosynthesis (trp) operon. Here, we show that the TrpY homolog in Thermococcus kodakarensis is not involved in such regulation. There are 87 genes on the T. kodakarensis genome predicted to encode transcriptional regulators (TRs). By screening for TRs that specifically bind to the promoter of the trp operon of T. kodakarensis, we identified TK0271. The gene resides in the aro operon, responsible for the biosynthesis of chorismate, a precursor for Trp, Tyr, and Phe. TK0271 was expressed in Escherichia coli, and the protein, here designated Tar (Thermococcalesaromatic amino acid regulator), was purified. Tar specifically bound to the trp promoter with a dissociation constant (Kd) value of approximately 5 nM. Tar also bound to the promoters of the Tyr/Phe biosynthesis (tyr-phe) and aro operons. The protein recognized a palindromic sequence (TGGACA-N8-TGTCCA) conserved in these promoters. In vitro transcription assays indicated that Tar activates transcription from all three promoters. We cultivated T. kodakarensis in amino acid-based medium and found that transcript levels of the trp, tyr-phe, and aro operons increased in the absence of Trp, Tyr, or Phe. We further constructed a TK0271 gene disruption strain (ΔTK0271). Growth of ΔTK0271 was similar to that of the host strain in medium including Trp, Tyr, and Phe but was significantly impaired in the absence of any one of these amino acids. The results suggest that Tar is responsible for the transcriptional activation of aromatic amino acid biosynthesis genes in T. kodakarensis.
Collapse
|
11
|
Reinhardt A, Johnsen U, Schönheit P. l-Rhamnose catabolism in archaea. Mol Microbiol 2019; 111:1093-1108. [PMID: 30707467 DOI: 10.1111/mmi.14213] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2019] [Indexed: 11/30/2022]
Abstract
The halophilic archaeon Haloferax volcanii utilizes l-rhamnose as a sole carbon and energy source. It is shown that l-rhamnose is taken up by an ABC transporter and is oxidatively degraded to pyruvate and l-lactate via the diketo-hydrolase pathway. The genes involved in l-rhamnose uptake and degradation form a l-rhamnose catabolism (rhc) gene cluster. The rhc cluster also contains a gene, rhcR, that encodes the transcriptional regulator RhcR which was characterized as an activator of all rhc genes. 2-keto-3-deoxy-l-rhamnonate, a metabolic intermediate of l-rhamnose degradation, was identified as inducer molecule of RhcR. The essential function of rhc genes for uptake and degradation of l-rhamnose was proven by the respective knockout mutants. Enzymes of the diketo-hydrolase pathway, including l-rhamnose dehydrogenase, l-rhamnonolactonase, l-rhamnonate dehydratase, 2-keto-3-deoxy-l-rhamnonate dehydrogenase and 2,4-diketo-3-deoxy-l-rhamnonate hydrolase, were characterized. Further, genes of the diketo-hydrolase pathway were also identified in the hyperthermophilic crenarchaeota Vulcanisaeta distributa and Sulfolobus solfataricus and selected enzymes were characterized, indicating the presence of the diketo-hydrolase pathway in these archaea. Together, this is the first comprehensive description of l-rhamnose catabolism in the domain of archaea.
Collapse
Affiliation(s)
- Andreas Reinhardt
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118, Kiel, Germany
| | - Ulrike Johnsen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118, Kiel, Germany
| | - Peter Schönheit
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118, Kiel, Germany
| |
Collapse
|
12
|
Conserved principles of transcriptional networks controlling metabolic flexibility in archaea. Emerg Top Life Sci 2018; 2:659-669. [PMID: 33525832 PMCID: PMC7289023 DOI: 10.1042/etls20180036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/05/2018] [Accepted: 11/08/2018] [Indexed: 12/13/2022]
Abstract
Gene regulation is intimately connected with metabolism, enabling the appropriate timing and tuning of biochemical pathways to substrate availability. In microorganisms, such as archaea and bacteria, transcription factors (TFs) often directly sense external cues such as nutrient substrates, metabolic intermediates, or redox status to regulate gene expression. Intense recent interest has characterized the functions of a large number of such regulatory TFs in archaea, which regulate a diverse array of unique archaeal metabolic capabilities. However, it remains unclear how the co-ordinated activity of the interconnected metabolic and transcription networks produces the dynamic flexibility so frequently observed in archaeal cells as they respond to energy limitation and intermittent substrate availability. In this review, we communicate the current state of the art regarding these archaeal networks and their dynamic properties. We compare the topology of these archaeal networks to those known for bacteria to highlight conserved and unique aspects. We present a new computational model for an exemplar archaeal network, aiming to lay the groundwork toward understanding general principles that unify the dynamic function of integrated metabolic-transcription networks across archaea and bacteria.
Collapse
|
13
|
Li M, Yin J, Mei S, Wang X, Tang XF, Tang B. Halolysin SptA, a Serine Protease, Contributes to Growth-Phase Transition of Haloarchaeon Natrinema sp. J7-2, and Its Expression Involves Cooperative Action of Multiple Cis-Regulatory Elements. Front Microbiol 2018; 9:1799. [PMID: 30123209 PMCID: PMC6085418 DOI: 10.3389/fmicb.2018.01799] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/17/2018] [Indexed: 12/18/2022] Open
Abstract
Many haloarchaea produce extracellular subtilisin-like proteases (halolysins) during late log phase; however, the physiological function and regulatory mechanism of growth phase-dependent production of halolysins are unknown. Halolysin SptA, the major extracellular protease of Natrinema sp. J7-2, is capable of intracellular self-activation to affect haloarchaeal growth. Here, we report that deletion of sptA leads to loss of extracellular and intracellular protease activities against azocasein and/or suc-AAPF-pNA, as well as a change in growth-phase transition of the haloarchaeon. Our results suggest that SptA is important for strain J7-2 to enter the stationary and death phases. Deletion and mutational analyses of the 5'-flanking region of sptA revealed two partially overlapping, semi-palindromic sequences upstream of the TATA box act as positive and negative cis-regulatory elements, respectively, to mediate sptA expression in late log phase. Additionally, a negative cis-regulatory element covering WW motif and a distant enhancer contribute to the modulation of sptA expression. Our results demonstrate that SptA functions both extracellularly and intracellularly, and that sptA expression relies on the cooperative action of multiple cis-regulatory elements, allowing SptA to exert its function properly at different growth stages in strain J7-2.
Collapse
Affiliation(s)
- Moran Li
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jing Yin
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Sha Mei
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xuhong Wang
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xiao-Feng Tang
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.,Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan, China
| | - Bing Tang
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.,Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan, China
| |
Collapse
|
14
|
Valdehuesa KNG, Ramos KRM, Nisola GM, Bañares AB, Cabulong RB, Lee WK, Liu H, Chung WJ. Everyone loves an underdog: metabolic engineering of the xylose oxidative pathway in recombinant microorganisms. Appl Microbiol Biotechnol 2018; 102:7703-7716. [PMID: 30003296 DOI: 10.1007/s00253-018-9186-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 11/25/2022]
Abstract
The D-xylose oxidative pathway (XOP) has recently been employed in several recombinant microorganisms for growth or for the production of several valuable compounds. The XOP is initiated by D-xylose oxidation to D-xylonolactone, which is then hydrolyzed into D-xylonic acid. D-Xylonic acid is then dehydrated to form 2-keto-3-deoxy-D-xylonic acid, which may be further dehydrated then oxidized into α-ketoglutarate or undergo aldol cleavage to form pyruvate and glycolaldehyde. This review introduces a brief discussion about XOP and its discovery in bacteria and archaea, such as Caulobacter crescentus and Haloferax volcanii. Furthermore, the current advances in the metabolic engineering of recombinant strains employing the XOP are discussed. This includes utilization of XOP for the production of diols, triols, and short-chain organic acids in Escherichia coli, Saccharomyces cerevisiae, and Corynebacterium glutamicum. Improving the D-xylose uptake, growth yields, and product titer through several metabolic engineering techniques bring some of these recombinant strains close to industrial viability. However, more developments are still needed to optimize the XOP pathway in the host strains, particularly in the minimization of by-product formation.
Collapse
Affiliation(s)
- Kris Niño G Valdehuesa
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Kristine Rose M Ramos
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Grace M Nisola
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Angelo B Bañares
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Rhudith B Cabulong
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Won-Keun Lee
- Division of Bioscience and Bioinformatics, Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea
| | - Huaiwei Liu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, Qingdao, 266237, People's Republic of China.
| | - Wook-Jin Chung
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 17058, Republic of Korea.
| |
Collapse
|
15
|
Sutter JM, Johnsen U, Schönheit P. Characterization of a pentonolactonase involved in D-xylose and L-arabinose catabolism in the haloarchaeon Haloferax volcanii. FEMS Microbiol Lett 2018; 364:3898818. [PMID: 28854683 DOI: 10.1093/femsle/fnx140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/27/2017] [Indexed: 12/25/2022] Open
Abstract
Haloferax volcanii degrades the pentoses D-xylose and L-arabinose via an oxidative pathway to α-ketoglutarate as an intermediate. The initial dehydrogenases of the pathway, D-xylose dehydrogenase (XDH) and L-arabinose dehydrogenase (L-AraDH) catalyze the NADP+ dependent D-xylose and L-arabinose oxidation. It is shown here that the pentoses are oxidized to the corresponding lactones, D-xylono-γ-lactone and L-arabino-γ-lactone, rather than to the respective sugar acids. A putative lactonase gene, xacC, located in genomic vicinity of XDH and L-AraDH, was found to be transcriptionally upregulated by both D-xylose and L-arabinose mediated by the pentose-specific regulator XacR. The recombinant lactonase catalyzed the hydrolysis of D-xylono-γ-lactone and L-arabino-γ-lactone. This is the first report of a functional lactonase involved in sugar catabolism in the domain of archaea.
Collapse
Affiliation(s)
- Jan-Moritz Sutter
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| | - Ulrike Johnsen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| | - Peter Schönheit
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| |
Collapse
|
16
|
Gene regulation of two ferredoxin:NADP + oxidoreductases by the redox-responsive regulator SurR in Thermococcus kodakarensis. Extremophiles 2017; 21:903-917. [PMID: 28688056 DOI: 10.1007/s00792-017-0952-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 07/02/2017] [Indexed: 01/21/2023]
Abstract
The redox-responsive regulator SurR in the hyperthermophilic archaea Pyrococcus furiosus and Thermococcus kodakarensis binds to the SurR-binding consensus sequence (SBS) by responding to the presence of elemental sulfur. Here we constructed a surR gene disruption strain (DTS) in T. kodakarensis, and identified the genes that were under SurR control by comparing the transcriptomes of DTS and parent strains. Among these genes, transcript levels of ferredoxin:NADP+ oxidoreductases 1 and 2 (FNOR1 and FNOR2) genes displayed opposite responses to surR deletion, indicating that SurR repressed FNOR1 transcription while enhancing FNOR2 transcription. Each promoter region contains an SBS upstream (uSBS) and downstream (dSBS) of TATA. In addition to in vitro binding assays, we examined the roles of each SBS in vivo. In FNOR1, mutations in either one of the SBSs resulted in a complete loss of repression, indicating that the presence of both SBSs was essential for repression. In FNOR2, uSBS indeed functioned to enhance gene expression, whereas dSBS functioned in gene repression. SurR bound to uSBS2 of FNOR2 more efficiently than to dSBS2 in vitro, which may explain why SurR overall enhances FNOR2 transcription. Further analyses indicated the importance in the distance between uSBS and TATA for transcriptional activation in FNOR2.
Collapse
|
17
|
Schönheit P, Buckel W, Martin WF. On the Origin of Heterotrophy. Trends Microbiol 2016; 24:12-25. [DOI: 10.1016/j.tim.2015.10.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/28/2015] [Accepted: 10/07/2015] [Indexed: 10/22/2022]
|