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Wang Z, Li Y, Gao X, Xing J, Wang R, Zhu D, Shen G. Comparative genomic analysis of Halomonas campaniensis wild-type and ultraviolet radiation-mutated strains reveal genomic differences associated with increased ectoine production. Int Microbiol 2023; 26:1009-1020. [PMID: 37067733 PMCID: PMC10622362 DOI: 10.1007/s10123-023-00356-y] [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: 11/01/2022] [Revised: 04/01/2023] [Accepted: 04/05/2023] [Indexed: 04/18/2023]
Abstract
Ectoine is a natural amino acid derivative and one of the most widely used compatible solutes produced by Halomonas species that affects both cellular growth and osmotic equilibrium. The positive effects of UV mutagenesis on both biomass and ectoine content production in ectoine-producing strains have yet to be reported. In this study, the wild-type H. campaniensis strain XH26 (CCTCCM2019776) was subjected to UV mutagenesis to increase ectoine production. Eight rounds of mutagenesis were used to generate mutated XH26 strains with different UV-irradiation exposure times. Ectoine extract concentrations were then evaluated among all strains using high-performance liquid chromatography analysis, alongside whole genome sequencing with the PacBio RS II platform and comparison of the wild-type strain XH26 and the mutant strain G8-52 genomes. The mutant strain G8-52 (CCTCCM2019777) exhibited the highest cell growth rate and ectoine yields among mutated strains in comparison with strain XH26. Further, ectoine levels in the aforementioned strain significantly increased to 1.51 ± 0.01 g L-1 (0.65 g g-1 of cell dry weight), representing a twofold increase compared to wild-type cells (0.51 ± 0.01 g L-1) when grown in culture medium for ectoine accumulation. Concomitantly, electron microscopy revealed that mutated strain G8-52 cells were obviously shorter than wild-type strain XH26 cells. Moreover, strain G8-52 produced a relatively stable ectoine yield (1.50 g L-1) after 40 days of continuous subculture. Comparative genomics analysis suggested that strain XH26 harbored 24 mutations, including 10 nucleotide insertions, 10 nucleotide deletions, and unique single nucleotide polymorphisms. Notably, the genes orf00723 and orf02403 (lipA) of the wild-type strain mutated to davT and gabD in strain G8-52 that encoded for 4-aminobutyrate-2-oxoglutarate transaminase and NAD-dependent succinate-semialdehyde dehydrogenase, respectively. Consequently, these genes may be involved in increased ectoine yields. These results suggest that continuous multiple rounds of UV mutation represent a successful strategy for increasing ectoine production, and that the mutant strain G8-52 is suitable for large-scale fermentation applications.
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Affiliation(s)
- Zhibo Wang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Yongzhen Li
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Xiang Gao
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Jiangwa Xing
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Rong Wang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Derui Zhu
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Guoping Shen
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China.
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2
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Zou D, Chen J, Zhang C, Kao SJ, Liu H, Li M. Diversity and salinity adaptations of ammonia oxidizing archaea in three estuaries of China. Appl Microbiol Biotechnol 2023; 107:6897-6909. [PMID: 37702790 DOI: 10.1007/s00253-023-12761-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 07/22/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023]
Abstract
Ammonia-oxidizing archaea (AOA) are ubiquitously found in diverse habitats and play pivotal roles in the nitrogen and carbon cycle, especially in estuarine and coastal environments. Despite the fact that the diversity and distribution of AOA are thought to be tightly linked to habitats, little is known about the relationship that underpins their genomic traits, adaptive potentials, and ecological niches. Here, we have characterized and compared the AOA community in three estuaries of China using metagenomics. AOA were the dominant ammonia oxidizers in the three estuaries. Through phylogenetic analyses, five major AOA groups were identified, including the Nitrosomarinus-like, Nitrosopumilus-like, Aestuariumsis-like, Nitrosarchaeum-like, and Nitrosopelagicus-like groups. Statistical analyses showed that the aquatic and sedimentary AOA communities were mainly influenced by spatial factors (latitude and water depth) and environmental factors (salinity, pH, and dissolved oxygen) in estuaries, respectively. Compared to AOA dwelling in terrestrial and marine habitats, estuarine AOA encoded more genes involved in glucose and amino acid metabolism, transport systems, osmotic control, and cell motility. The low proteome isoelectric points (pI), high content of acidic amino acids, and the presence of potassium ion and mechanosensitive channels suggest a "salt-in" strategy for estuarine AOA to counteract high osmolarity in their surroundings. Our findings have indicated potential adaptation strategies and highlighted their importance in the estuarine nitrogen and carbon cycles. KEY POINTS: • Spatial and environmental factors influence water and sediment AOA respectively. • Estuarine AOA share low proteome isoelectric value and high acid amino acids content. • AOA adaptation to estuaries is likely resulted from their unique genomic features.
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Affiliation(s)
- Dayu Zou
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
| | - Jianfang Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China
| | - Chuanlun Zhang
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Southern University of Science and Technology, Shenzhen, 518000, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 510000, China
| | - Shuh-Ji Kao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361000, China
| | - Hongbin Liu
- Department of Ocean Science and Hong Kong Branch of Southern Marine Science & Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China.
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China.
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Zhang W, Liu K, Kong F, Ye T, Wang T. Multiple Functions of Compatible Solute Ectoine and Strategies for Constructing Overproducers for Biobased Production. Mol Biotechnol 2023:10.1007/s12033-023-00827-7. [PMID: 37488320 DOI: 10.1007/s12033-023-00827-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/14/2023] [Indexed: 07/26/2023]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes initially found in the hyperhalophilic bacterium Ectothiorhodospira halochloris, which inhabits the desert in Egypt. The habitat of ectoine producers implies the primary function of ectoine as a cytoprotectant against harsh conditions such as high salinity, drought, and high radiation. More extensive and in-depth studies have revealed the multiple functions of ectoine in its native producer bacterial cells and other types of cells and its biomolecular components (such as proteins and DNA) as a general protective agent. Its chemical properties as a bio-based amino acid derivative make it attractive for basic scientific research and related industries, such as the food/agricultural industry, cosmetic manufacturing, biologics, and therapeutic agent preparation. This article first discusses the functions and applications of ectoine and 5-hydroxyectoine. Subsequently, more emphasis was placed on advances in bio-based ectoine and/or 5-hydroxyectoine production. Strategies for developing more robust cell factories for highly efficient ectoine and/or 5-hydroxyectoine production are further discussed. We hope this review will provide a valuable reference for studies on the bio-based production of ectoine and 5-hydroxyectoine.
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Affiliation(s)
- Wei Zhang
- College of Life Sciences, Xinyang Normal University, Xinyang, 464000, People's Republic of China
| | - Kun Liu
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Fang Kong
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tao Ye
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tianwen Wang
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China.
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Shu Z, Zhang X, Wang R, Xing J, Li Y, Zhu D, Shen G. Metabolic engineering of Halomonas campaniensis strain XH26 to remove competing pathways to enhance ectoine production. Sci Rep 2023; 13:9732. [PMID: 37322079 PMCID: PMC10272175 DOI: 10.1038/s41598-023-36975-8] [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: 02/01/2023] [Accepted: 06/13/2023] [Indexed: 06/17/2023] Open
Abstract
Ectoine has gained considerable attention as a high-value chemical with significant application potential and market demand. This study aimed to increase ectoine yields by blocking the metabolic shunt pathway of L-aspartate-4-semialdehyde, the precursor substrate in ectoine synthesis. The homoserine dehydrogenase encoded by hom in H. campaniensis strain XH26 is responsible for the metabolic shunt of L-aspartate-4-semialdehyde to glycine. CRISPR/Cas9 technology was used to seamlessly knockout hom, blocking the metabolic shunt pathway to increase ectoine yields. The ectoine yield of XH26/Δhom was 351.13 mg (g CDW)-1 after 48 h of incubation in 500 mL shake flasks using optimal medium with 1.5 mol L-1 NaCl, which was significantly higher than the 239.18 mg (g CDW)-1 of the wild-type strain. Additionally, the absence of the ectoine metabolic shunt pathway affects betaine synthesis, and thus the betaine yields of XH26/Δhom was 19.98 mg (g CDW)-1, considerably lower than the 69.58 mg (g CDW)-1 of the wild-type strain. Batch fermentation parameters were optimized, and the wild-type strain and XH26/Δhom were fermented in 3 L fermenters, resulting in a high ectoine yield of 587.09 mg (g CDW)-1 for the defective strain, which was significantly greater than the ectoine yield of 385.03 mg (g CDW)-1 of the wild-type strain. This study showed that blocking the metabolic shunt of synthetic substrates effectively increases ectoine production, and a reduction in the competitively compatible solute betaine appears to promote increased ectoine synthesis.
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Affiliation(s)
- Zhiwan Shu
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Xin Zhang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Rong Wang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Jiangwa Xing
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Yongzhen Li
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Derui Zhu
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Guoping Shen
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China.
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5
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Cantera S, Di Benedetto F, Tumulero BF, Sousa DZ. Microbial conversion of carbon dioxide and hydrogen into the fine chemicals hydroxyectoine and ectoine. BIORESOURCE TECHNOLOGY 2023; 374:128753. [PMID: 36801441 DOI: 10.1016/j.biortech.2023.128753] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/11/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
This study explores a novel conversion of CO2 into the chemicals hydroxyectoine and ectoine, which are compounds with high retail values in the pharmaceutical industry. Firstly, 11 species of microbes able to use CO2 and H2 and that have the genes for ectoines synthesis (ectABCD) were identified through literature search and genomic mining. Laboratory tests were then conducted to ascertain the capacity of these microbes to produce ectoines from CO2. Results showed that the most promising bacteria for CO2 to ectoines bioconversion areHydrogenovibrio marinus, Rhodococcus opacus, and Hydrogenibacillus schlegelii.Upon salinity and H2/CO2/O2 ratio optimization,H. marinus accumulated 85 mg of ectoine g biomass-1. Interestingly, R.opacusand H. schlegelii mainly produced hydroxyectoine (53 and 62 mg g biomass-1), which has a higher commercial value. Overall, these results constitute the first proof of a novel valorization platform of CO2 and lay the foundation for a new economic niche aimed at CO2 recircularization into pharmaceuticals.
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Affiliation(s)
- Sara Cantera
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands.
| | - Francesca Di Benedetto
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Ben F Tumulero
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
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Chiriac MC, Haber M, Salcher MM. Adaptive genetic traits in pelagic freshwater microbes. Environ Microbiol 2023; 25:606-641. [PMID: 36513610 DOI: 10.1111/1462-2920.16313] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 12/12/2022] [Indexed: 12/15/2022]
Abstract
Pelagic microbes have adopted distinct strategies to inhabit the pelagial of lakes and oceans and can be broadly categorized in two groups: free-living, specialized oligotrophs and patch-associated generalists or copiotrophs. In this review, we aim to identify genomic traits that enable pelagic freshwater microbes to thrive in their habitat. To do so, we discuss the main genetic differences of pelagic marine and freshwater microbes that are both dominated by specialized oligotrophs and the difference to freshwater sediment microbes, where copiotrophs are more prevalent. We phylogenomically analysed a collection of >7700 metagenome-assembled genomes, classified habitat preferences on different taxonomic levels, and compared the metabolic traits of pelagic freshwater, marine, and freshwater sediment microbes. Metabolic differences are mainly associated with transport functions, environmental information processing, components of the electron transport chain, osmoregulation and the isoelectric point of proteins. Several lineages with known habitat transitions (Nitrososphaeria, SAR11, Methylophilaceae, Synechococcales, Flavobacteriaceae, Planctomycetota) and the underlying mechanisms in this process are discussed in this review. Additionally, the distribution, ecology and genomic make-up of the most abundant freshwater prokaryotes are described in details in separate chapters for Actinobacteriota, Bacteroidota, Burkholderiales, Verrucomicrobiota, Chloroflexota, and 'Ca. Patescibacteria'.
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Affiliation(s)
| | - Markus Haber
- Institute of Hydrobiology, Biology Centre CAS, Ceske Budejovice, Czechia
| | - Michaela M Salcher
- Institute of Hydrobiology, Biology Centre CAS, Ceske Budejovice, Czechia
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7
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Production and Recovery of Ectoine: A Review of Current State and Future Prospects. Processes (Basel) 2023. [DOI: 10.3390/pr11020339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a revolutionizing substance with vast applications in the cosmetic and food industries. Ectoine is often sourced from halobacteria. The increasing market demand for ectoine has urged the development of cost-effective and sustainable large-scale production of ectoine from microbial sources. This review describes the existing and potential microbial sources of ectoine and its derivatives, as well as microbial production and fermentation approaches for ectoine recovery. In addition, conventional methods and emerging technologies for enhanced production and recovery of ectoine from microbial fermentation with a focus on the aqueous biphasic system (ABS) are discussed. The ABS is a practically feasible approach for the integration of fermentation, cell disruption, bioconversion, and clarification of various biomolecules in a single-step operation. Nonetheless, the implementation of the ABS on an industrial-scale basis for the enhanced production and recovery of ectoine is yet to be exploited. Therefore, the feasibility of the ABS to integrate the production and direct recovery of ectoine from microbial sources is also highlighted in this review.
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8
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Ma Z, Wu C, Zhu L, Chang R, Ma W, Deng Y, Chen X. Bioactivity profiling of the extremolyte ectoine as a promising protectant and its heterologous production. 3 Biotech 2022; 12:331. [PMID: 36311375 PMCID: PMC9606177 DOI: 10.1007/s13205-022-03370-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 09/20/2022] [Indexed: 11/28/2022] Open
Abstract
Ectoine is a compatible solutes that is diffusely dispersed in bacteria and archaea. It plays a significant role as protectant against various external pressures, such as high temperature, high osmolarity, dryness and radiation, in cells. Ectoine can be utilized in cosmetics due to its properties of moisturizing and antiultraviolet. It can also be used in the pharmaceutical industry for treating various diseases. Therefore, strong protection of ectoine creates a high commercial value. Its current market value is approximately US$1000 kg-1. However, traditional ectoine production in high-salinity media causes high costs of equipment loss and wastewater treatment. There is a growing attention to reduce the salinity of the fermentation broth without sacrificing the production of ectoine. Thus, heterologous production of ectoine in nonhalophilic microorganisms may represent the new generation of the industrial production of ectoine. In this review, we summarized and discussed the biological activities of ectoine on cell and human health protection and its heterologous production.
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Affiliation(s)
- Zhi Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Chutian Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Linjiang Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Renjie Chang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Weilin Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Yanfeng Deng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Xiaolong Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
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Czech L, Gertzen C, Smits SHJ, Bremer E. Guilty by association: importers, exporters and
MscS
‐type mechanosensitive channels encoded in biosynthetic gene clusters for the stress‐protectant ectoine. Environ Microbiol 2022; 24:5306-5331. [DOI: 10.1111/1462-2920.16203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/07/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Czech
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
- Department of Chemistry and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
| | - Christoph Gertzen
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Pharmaceutical and Medicinal Chemistry Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
| | - Sander H. J. Smits
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Biochemistry Heinrich Heine University Düsseldorf Düsseldorf Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
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Ren M, Wang J. Phylogenetic divergence and adaptation of Nitrososphaeria across lake depths and freshwater ecosystems. THE ISME JOURNAL 2022; 16:1491-1501. [PMID: 35091647 PMCID: PMC9123079 DOI: 10.1038/s41396-022-01199-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 01/05/2022] [Accepted: 01/17/2022] [Indexed: 04/29/2023]
Abstract
Thaumarchaeota (now the class Nitrososphaeria in the phylum Thermoproteota in GTDB taxonomy) are abundant across marine and soil habitats; however, their genomic diversity and evolutionary history in freshwater environments remain elusive. Here, we reconstructed 17 high-quality metagenome-assembled genomes of Nitrososphaeria from a deep lake and two great rivers, and compared all available genomes between freshwater and marine habitats regarding their phylogenetic positions, relative abundance, and genomic content. We found that freshwater Nitrososphaeria were dominated by the family Nitrosopumilaceae and could be grouped into three distinct clades closely related to the genera Nitrosopumilus, Nitrosoarchaeum, and Nitrosotenuis. The Nitrosopumilus-like clade was exclusively from deep lakes, while the Nitrosoarchaeum-like clade was dominated by species from deep lakes and rivers, and the Nitrosotenuis-like clade was mainly from rivers, deep lakes, and estuaries. Interestingly, there was vertical niche separation between two clades in deep lakes, showing that the Nitrosopumilus-like species dominated shallow layers, whereas the relative abundance of the Nitrosoarchaeum-like clade increased toward deep waters. Phylogenetic clustering patterns in the Nitrosopumilaceae supported at least one freshwater-to-marine and two marine-to-freshwater transitions, the former of which refined the potential terrestrial-to-marine evolutionary path as previously proposed. The occurrence of the two marine-to-freshwater transitions were accompanied by horizontal transfer of the genes involved in nutrition regulation, osmoregulation, and cell motility during their colonization to freshwater habitats. Specifically, the Nitrosopumilus-like clade showed losses of genes encoding flagella assembly and ion transport, whereas the Nitrosoarchaeum-like clade had losses of intact genes involved in urea uptake and utilization and gains of genes encoding osmolarity-mediated mechanosensitive channels. Collectively, our results reveal for the first time the high genomic diversity of the class Nitrososphaeria across freshwater ecosystems and provide novel insights into their adaptive mechanisms and evolutionary histories.
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Affiliation(s)
- Minglei Ren
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Jianjun Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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11
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Functional Insights of Salinity Stress-Related Pathways in Metagenome-Resolved Methanothrix Genomes. Appl Environ Microbiol 2022; 88:e0244921. [PMID: 35477253 PMCID: PMC9128505 DOI: 10.1128/aem.02449-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Recently, methanogenic archaea belonging to the genus Methanothrix were reported to have a fundamental role in maintaining stable ecosystem functioning in anaerobic bioreactors under different configurations/conditions. In this study, we reconstructed three Methanothrix metagenome-assembled genomes (MAGs) from granular sludge collected from saline upflow anaerobic sludge blanket (UASB) reactors, where Methanothrix harundinacea was previously implicated with the formation of compact and stable granules under elevated salinity levels (up to 20 g/L Na+). Genome annotation and pathway analysis of the Methanothrix MAGs revealed a genetic repertoire supporting their growth under high salinity. Specifically, the most dominant Methanothrix (MAG_279), classified as a subspecies of Methanothrix_A harundinacea_D, had the potential to augment its salinity resistance through the production of different glycoconjugates via the N-glycosylation process, and via the production of compatible solutes as Nε-acetyl-β-lysine and ectoine. The stabilization and reinforcement of the cell membrane via the production of isoprenoids was identified as an additional stress-related pathway in this microorganism. The improved understanding of the salinity stress-related mechanisms of M. harundinacea highlights its ecological niche in extreme conditions, opening new perspectives for high-efficiency methanisation of organic waste at high salinities, as well as the possible persistence of this methanogen in highly-saline natural anaerobic environments. IMPORTANCE Using genome-centric metagenomics, we discovered a new Methanothrix harundinacea subspecies that appears to be a halotolerant acetoclastic methanogen with the flexibility for adaptation in the anaerobic digestion process both at low (5 g/L Na+) and high salinity conditions (20 g/L Na+). Annotation of the recovered M. harundinacea genome revealed salinity stress-related functions, including the modification of EPS glycoconjugates and the production of compatible solutes. This is the first study reporting these genomic features within a Methanothrix sp., a milestone further supporting previous studies that identified M. harundinacea as a key-driver in anaerobic granulation under high salinity stress.
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12
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Zhang T, Cui T, Cao Y, Li Y, Li F, Zhu D, Xing J. Whole genome sequencing of the halophilic Halomonas qaidamensis XH36, a novel species strain with high ectoine production. Antonie Van Leeuwenhoek 2022; 115:545-559. [PMID: 35243586 DOI: 10.1007/s10482-022-01709-9] [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: 10/23/2021] [Accepted: 01/18/2022] [Indexed: 10/18/2022]
Abstract
Here, we report the whole genome of a novel halophilic Halomonas species strain XH36 with high ectoine production potential. The genome was 3,818,310 bp in size with a GC content of 51.97%, and contained 3533 genes, 61 tRNAs and 18 rRNAs. The phylogenetic analysis using the 16s rRNA genes, the UBCGs and the TYGS database indicated that XH36 belongs to a novel Halomonas species, which we named as Halomonas qaidamensis. Osmoadaptation related genes including Na(+) and K(+) transport and compatible solute accumulation were both present in the XH36 genome, the latter of which mainly contained ectoine, 5-hydroxyectoine and betaine. HPLC validation studies showed that H. qaidamensis XH36 accumulated ectoine to cope with salt stress, and the content of ectoine could be as high as 315 mg/g CDW under 3 mol/l NaCl. Our results show that XH36 is a new promising industrial strain for ectoine production, and the genomic analysis will guide us to better understand its salt-induced osmoadaptation mechanisms, and provide theoretical references for future application research of ectoine.
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Affiliation(s)
- Tiantian Zhang
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Tianqi Cui
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Yaning Cao
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Yongzhen Li
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Fenghui Li
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Derui Zhu
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China
| | - Jiangwa Xing
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, China.
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13
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Sun X, Zhao J, Zhou X, Bei Q, Xia W, Zhao B, Zhang J, Jia Z. Salt tolerance-based niche differentiation of soil ammonia oxidizers. THE ISME JOURNAL 2022; 16:412-422. [PMID: 34389794 PMCID: PMC8776802 DOI: 10.1038/s41396-021-01079-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 07/20/2021] [Accepted: 07/26/2021] [Indexed: 02/03/2023]
Abstract
Ammonia oxidizers are key players in the global nitrogen cycle, yet little is known about their ecological performances and adaptation strategies for growth in saline terrestrial ecosystems. This study combined 13C-DNA stable-isotope probing (SIP) microcosms with amplicon and shotgun sequencing to reveal the composition and genomic adaptations of active ammonia oxidizers in a saline-sodic (solonetz) soil with high salinity and pH (20.9 cmolc exchangeable Na+ kg-1 soil and pH 9.64). Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) exhibited strong nitrification activities, although AOB performed most of the ammonia oxidation observed in the solonetz soil and in the farmland soil converted from solonetz soil. Members of the Nitrosococcus, which are more often associated with aquatic habitats, were identified as the dominant ammonia oxidizers in the solonetz soil with the first direct labeling evidence, while members of the Nitrosospira were the dominant ammonia oxidizers in the farmland soil, which had much lower salinity and pH. Metagenomic analysis of "Candidatus Nitrosococcus sp. Sol14", a new species within the Nitrosococcus lineage, revealed multiple genomic adaptations predicted to facilitate osmotic and pH homeostasis in this extreme habitat, including direct Na+ extrusion/H+ import and the ability to increase intracellular osmotic pressure by accumulating compatible solutes. Comparative genomic analysis revealed that variation in salt-tolerance mechanisms was the primary driver for the niche differentiation of ammonia oxidizers in saline-sodic soils. These results demonstrate how ammonia oxidizers can adapt to saline-sodic soil with excessive Na+ content and provide new insights on the nitrogen cycle in extreme terrestrial ecosystems.
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Affiliation(s)
- Xiangxin Sun
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jun Zhao
- grid.15276.370000 0004 1936 8091Institute for Food and Agricultural Sciences (IFAS), Department of Microbiology & Cell Science, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL USA
| | - Xue Zhou
- grid.257065.30000 0004 1760 3465College of Agricultural Science and Engineering, Hohai University, Nanjing, Jiangsu Province China
| | - Qicheng Bei
- grid.419554.80000 0004 0491 8361Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Weiwei Xia
- grid.260478.f0000 0000 9249 2313College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu Province China
| | - Bingzi Zhao
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jiabao Zhang
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Zhongjun Jia
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
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14
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Genome-Resolved Metagenomic Insights into Massive Seasonal Ammonia-Oxidizing Archaea Blooms in San Francisco Bay. mSystems 2022; 7:e0127021. [PMID: 35076275 PMCID: PMC8788347 DOI: 10.1128/msystems.01270-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ammonia-oxidizing archaea (AOA) are key for the transformation of ammonia to oxidized forms of nitrogen in aquatic environments around the globe, including nutrient-rich coastal and estuarine waters such as San Francisco Bay (SFB). Using metagenomics and 16S rRNA gene amplicon libraries, we found that AOA are more abundant than ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), except in the freshwater stations in SFB. In South SFB, we observed recurrent AOA blooms of “Candidatus Nitrosomarinus catalina” SPOT01-like organisms, which account for over 20% of 16S rRNA gene amplicons in both surface and bottom waters and co-occur with weeks of high nitrite concentrations (>10 μM) in the oxic water column. We observed pronounced nitrite peaks occurring in the autumn for 7 of the last 9 years (2012 to 2020), suggesting that seasonal AOA blooms are common in South SFB. We recovered two high-quality AOA metagenome-assembled genomes (MAGs), including a Nitrosomarinus-like genome from the South SFB bloom and another Nitrosopumilus genome originating from Suisun Bay in North SFB. Both MAGs cluster with genomes from other estuarine/coastal sites. Analysis of Nitrosomarinus-like genomes show that they are streamlined, with low GC content and high coding density, and harbor urease genes. Our findings support the unique niche of Nitrosomarinus-like organisms which dominate coastal/estuarine waters and provide insights into recurring AOA blooms in SFB. IMPORTANCE Ammonia-oxidizing archaea (AOA) carry out key transformations of ammonia in estuarine systems such as San Francisco Bay (SFB)—the largest estuary on the west coast of North America—and play a significant role in both local and global nitrogen cycling. Using metagenomics and 16S rRNA gene amplicon libraries, we document a massive, recurrent AOA bloom in South SFB that co-occurs with months of high nitrite concentrations in the oxic water column. Our study is the first to generate metagenome-assembled genomes (MAGs) from SFB, and through this process we recovered two high-quality AOA MAGs, one of which originated from bloom samples. These AOA MAGs yield new insight into the Nitrosopumilus and Nitrosomarinus-like lineages and their potential niches in coastal and estuarine systems. Nitrosomarinus-like AOA are abundant in coastal regions around the globe, and we highlight the common occurrence of urease genes, low GC content, and range of salinity tolerances within this lineage.
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15
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Durán-Viseras A, Sánchez-Porro C, Ventosa A. Genomic Insights Into New Species of the Genus Halomicroarcula Reveals Potential for New Osmoadaptative Strategies in Halophilic Archaea. Front Microbiol 2021; 12:751746. [PMID: 34803972 PMCID: PMC8600319 DOI: 10.3389/fmicb.2021.751746] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 10/11/2021] [Indexed: 12/02/2022] Open
Abstract
Metagenomic studies on prokaryotic diversity of hypersaline soils from the Odiel saltmarshes, South-west Spain, revealed a high proportion of genomic sequences not related to previously cultivated taxa, that might be related to haloarchaea with a high environmental and nutritional flexibility. In this study, we used a culturomics approach in order to isolate new haloarchaeal microorganisms from these hypersaline soils. Four haloarchaeal strains, designated strains F24AT, F28, F27T, and F13T, phylogenetically related to the genus Halomicroarcula, were isolated and characterized in detail. The phylogenomic tree based on the 100 orthologous single-copy genes present in the genomes of these four strains as well as those of the type strains of the species Halomicroarcula pellucida CECT 7537T, Halomicroarcula salina JCM 18369T and Halomicroarcula limicola JCM 18640T, that were determined in this study, revealed that these four new isolates clustered on three groups, with strains F24AT and F28 within a single cluster, and altogether with the species of Halomicroarcula. Additionally, Orthologous Average Nucleotide Identity (OrthoANI), digital DNA-DNA hybridization (dDDH) and Average Amino-acid Identity (AAI) values, likewise phenotypic characteristics, including their polar lipids profiles, permitted to determine that they represent three new species, for which we propose the names Halomicroarcula rubra sp. nov. (type strain F13T), Halomicroarcula nitratireducens sp. nov. (type strain F27T) and Halomicroarcula salinisoli sp. nov. (type strain F24AT). An in deep comparative genomic analysis of species of the genus Halomicroarcula, including their metabolism, their capability to biosynthesize secondary metabolites and their osmoregulatory adaptation mechanisms was carried out. Although they use a salt-in strategy, the identification of the complete pathways for the biosynthesis of the compatible solutes trehalose and glycine betaine, not identified before in any other haloarchaea, might suggest alternative osmoadaptation strategies for this group. This alternative osmoregulatory mechanism would allow this group of haloarchaea to be versatile and eco-physiologically successful in hypersaline environments and would justify the capability of the species of this genus to grow not only on environments with high salt concentrations [up to 30% (w/v) salts], but also under intermediate to low salinities.
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Affiliation(s)
- Ana Durán-Viseras
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Sevilla, Sevilla, Spain
| | - Cristina Sánchez-Porro
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Sevilla, Sevilla, Spain
| | - Antonio Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Sevilla, Sevilla, Spain
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16
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Kang JY, Lee B, Kim JA, Kim MS, Kim CH. Identification and characterization of an ectoine biosynthesis gene cluster from Aestuariispira ectoiniformans sp. nov., isolated from seawater. Microbiol Res 2021; 254:126898. [PMID: 34710834 DOI: 10.1016/j.micres.2021.126898] [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: 02/15/2021] [Revised: 09/16/2021] [Accepted: 10/19/2021] [Indexed: 11/26/2022]
Abstract
An ectoine-producing bacterium, designated SWCN16T, was isolated from seawater and could be grown in a medium containing up to 12 % NaCl. A phylogenetic analysis based on 16S rRNA gene sequences revealed that strain SWCN16T belonged to the genus Aestuariispira, class Alphaproteobacteria, and shared the highest 16S rRNA gene sequence similarity of 96.8% with Aestuariispira insulae CECT 8488T. The phenotypic, chemotaxonomic, and genotypic characteristics findings of this study suggested that strain SWCN16T represented a novel species of the genus Aestuariispira. We propose the name Aestuariispira ectoiniformans sp. nov. for this species. Whole-genome sequencing analysis of the isolate revealed a putative ectABC gene cluster for ectoine biosynthesis. These genes were found to be functional using ectoine synthesis testing and S16-ectBAC cells, which were pET21a-ectBAC-transformed E. coli BL21 cells. We found that S16-ectBAC synthesized about 1.67 g/L extracellular ectoine and about 0.59 g/L intracellular ectoine via bioconversion at optimum conditions.
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Affiliation(s)
- Ji Young Kang
- Industrial Microbiology and Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, 580-185, Republic of Korea.
| | - Binna Lee
- Industrial Microbiology and Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, 580-185, Republic of Korea.
| | - Jeong Ah Kim
- Industrial Microbiology and Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, 580-185, Republic of Korea.
| | - Min-Soo Kim
- Industrial Microbiology and Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, 580-185, Republic of Korea.
| | - Chul Ho Kim
- Industrial Microbiology and Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, 580-185, Republic of Korea.
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17
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Frikha-Dammak D, Ayadi H, Hakim-Rekik I, Belbahri L, Maalej S. Genome analysis of the salt-resistant Paludifilum halophilum DSM 102817 T reveals genes involved in flux-tuning of ectoines and unexplored bioactive secondary metabolites. World J Microbiol Biotechnol 2021; 37:178. [PMID: 34549358 DOI: 10.1007/s11274-021-03147-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/14/2021] [Indexed: 10/20/2022]
Abstract
Paludifilum halophilum DSM 102817T is the first member of the genus Paludifilum in the Thermoactinomycetaceae family. The thermohalophilic bacterium was isolated from the solar saltern of Sfax, Tunisia and was shown to be able to produce ectoines with a relatively high-yield and to cope with salt stress conditions. In this study, the whole genome of P. halophilum was sequenced and analysed. Analysis revealed 3,789,765 base pairs with an average GC% content of 51.5%. A total of 3775 genes were predicted of which 3616 were protein-coding genes and 73 were RNA genes. The genes encoding key enzymes for ectoines (ectoine and hydroxyectoine) synthesis (ectABCD) were identified from the bacterial genome next to a gene cluster (ehuABCD) encoding a binding-protein-dependent ABC transport system responsible for ectoines mobility through the cell membrane. With the aid of KEGG analysis, we found that the central catabolic network of P. halophilum comprises the pathways of glycolysis, tricarboxylic acid cycle, and pentose phosphate. In addition, anaplerotic pathways replenishing oxaloacetate and glutamate synthesis from central metabolism needed for high ectoines biosynthetic fluxes were identified through several key enzymes. Furthermore, a total of 18 antiSMASH-predicted putative biosynthetic gene clusters for secondary metabolites with high novelty and diversity were identified in P. halophilum genome, including biosynthesis of colabomycine-A, fusaricidin-E, zwittermycin A, streptomycin, mycosubtilin and meilingmycin. Based on these data, P. halophilum emerged as a promising source for ectoines and antimicrobials with the potential to be scaled up for industrial production, which could benefit the pharmaceutical and cosmetic industries.
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Affiliation(s)
- Donyez Frikha-Dammak
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia
| | - Houda Ayadi
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia
| | - Imen Hakim-Rekik
- Unité de Génomique Fonctionnelle et Physiologie des Plantes, Université de Sfax, Institut Supérieur de Biotechnologie de Sfax, BP 1175, 3000, Sfax, Tunisia
| | - Lassaad Belbahri
- Laboratory of Soil Biology, University of Neuchatel, 11 Rue Emile Argand, 2000, Neuchâtel, Switzerland
| | - Sami Maalej
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia.
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18
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Andrys J, Heider J, Borowski T. Comparison of different approaches to derive classical bonded force-field parameters for a transition metal cofactor: a case study for non-heme iron site of ectoine synthase. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02796-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractComputational investigations into the structure and function of metalloenzymes with transition metal cofactors require proper preparation of the model, which requires obtaining reliable force field parameters for the cofactor. Here, we present a test case where several methods were used to derive amber force field parameters for a bonded model of the Fe(II) cofactor of ectoine synthase. Moreover, the spin of the ground state of the cofactor was probed by DFT and post-HF methods, which consistently indicated the quintet state is lowest in energy and well separated from triplet and singlet. The performance of the obtained force field parameter sets, derived for the quintet spin state, was scrutinized and compared taking into account metrics focused on geometric features of the models as well as their energetics. The main conclusion of this study is that Hessian-based methods yield parameters which represent the geometry around the metal ion, but poorly reproduce energy variance with geometrical changes. On the other hand, the energy-based method yields parameters accurately reproducing energy-structure relationships, but with bad performance in geometry optimization. Preliminary tests show that admixing geometrical criteria to energy-based methods may allow to derive parameters with acceptable performance for both energy and geometry.
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19
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Law KP, He W, Tao J, Zhang C. Characterization of the Exometabolome of Nitrosopumilus maritimus SCM1 by Liquid Chromatography-Ion Mobility Mass Spectrometry. Front Microbiol 2021; 12:658781. [PMID: 34276593 PMCID: PMC8281238 DOI: 10.3389/fmicb.2021.658781] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/04/2021] [Indexed: 11/13/2022] Open
Abstract
Marine Thaumarchaeota (formerly known as the marine group I archaea) have received much research interest in recent years since these chemolithoautotrophic organisms are abundant in the subsurface ocean and oxidize ammonium to nitrite, which makes them a major contributor to the marine carbon and nitrogen cycles. However, few studies have investigated the chemical composition of their exometabolome and their contributions to the pool of dissolved organic matter (DOM) in seawater. This study exploits the recent advances in ion mobility mass spectrometry (IM-MS) and integrates this instrumental capability with bioinformatics to reassess the exometabolome of a model ammonia-oxidizing archaeon, Nitrosopumilus maritimus strain SCM1. Our method has several advantages over the conventional approach using an Orbitrap or ion cyclotron resonance mass analyzer and allows assignments or annotations of spectral features to known metabolites confidently and indiscriminately, as well as distinction of biological molecules from background organics. Consistent with the results of a previous report, the SPE-extracted exometabolome of N. maritimus is dominated by biologically active nitrogen-containing metabolites, in addition to peptides secreted extracellularly. Cobalamin and associated intermediates, including α-ribazole and α-ribazole 5′-phosphate, are major components of the SPE-extracted exometabolome of N. maritimus. This supports the proposition that Thaumarchaeota have the capacity of de novo biosynthesizing cobalamin. Other biologically significant metabolites, such as agmatidine and medicagenate, predicted by genome screening are also detected, which indicates that Thaumarchaeota have remarkable metabolic potentials, underlining their importance in driving elemental cycles critical to biological processes in the ocean.
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Affiliation(s)
- Kai P Law
- SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China.,Shenzhen Key Laboratory of Marine Geo-Omics Research, Southern University of Science and Technology, Shenzhen, China.,Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Wei He
- Shenzhen Key Laboratory of Marine Geo-Omics Research, Southern University of Science and Technology, Shenzhen, China.,Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Jianchang Tao
- Shenzhen Key Laboratory of Marine Geo-Omics Research, Southern University of Science and Technology, Shenzhen, China.,Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Chuanlun Zhang
- Shenzhen Key Laboratory of Marine Geo-Omics Research, Southern University of Science and Technology, Shenzhen, China.,Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,Shanghai Sheshan National Geophysical Observatory, Shanghai, China
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20
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Hermann L, Mais CN, Czech L, Smits SHJ, Bange G, Bremer E. The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient. Biol Chem 2021; 401:1443-1468. [PMID: 32755967 DOI: 10.1515/hsz-2020-0223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.
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Affiliation(s)
- Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Biochemistry and Synthetic Biology of Microbial Metabolism Group, Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch Str. 10, D-35043 Marburg, Germany
| | - Christopher-Nils Mais
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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21
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Wang Y, Qin W, Jiang X, Ju F, Mao Y, Zhang A, Stahl DA, Zhang T. Seasonal Prevalence of Ammonia-Oxidizing Archaea in a Full-Scale Municipal Wastewater Treatment Plant Treating Saline Wastewater Revealed by a 6-Year Time-Series Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:2662-2673. [PMID: 33539079 DOI: 10.1021/acs.est.0c07703] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Although several molecular-based studies have demonstrated the involvement of ammonia-oxidizing archaea (AOA) in ammonia oxidation in wastewater treatment plants (WWTPs), factors affecting the persistence and growth of AOA in these engineered systems have not been resolved. Here, we show a seasonal prevalence of AOA in a full-scale WWTP (Shatin, Hong Kong SAR) over a 6-year period of observation, even outnumbering ammonia-oxidizing bacteria in the seasonal peaks in 3 years, which may be due to the high bioavailable copper concentrations. Comparative analysis of three metagenome-assembled genomes of group I.1a AOA obtained from the activated sludge and 16S rRNA gene sequences recovered from marine sediments suggested that the seawater used for toilet flushing was the primary source of the WWTP AOA. A rare AOA population in the estuarine source water became transiently abundant in the WWTP with a metagenome-based relative abundance of up to 1.3% over three seasons of observation. Correlation-based network analysis revealed a robust co-occurrence relationship between these AOA and organisms potentially active in nitrite oxidation. Moreover, a strong correlation between the dominant AOA and an abundant proteobacterial organism suggested that capacity for extracellular polymeric substance production by the proteobacterium could provide a niche for AOA within bioaggregates. Together, the study highlights the importance of long-term observation in identifying biotic and abiotic factors governing population dynamics in open systems such as full-scale WWTPs.
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Affiliation(s)
- Yulin Wang
- Environmental Microbiome Engineering and Biotechnology Laboratory, The University of Hong Kong, Hong Kong SAR, China
| | - Wei Qin
- School of Oceanography, University of Washington, Seattle 98195, Washington, United States
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman 73019, Oklahoma, United States
| | - Xiaotao Jiang
- Environmental Microbiome Engineering and Biotechnology Laboratory, The University of Hong Kong, Hong Kong SAR, China
| | - Feng Ju
- School of Engineering, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China
| | - Yanping Mao
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, Guangdong, China
| | - Anni Zhang
- Environmental Microbiome Engineering and Biotechnology Laboratory, The University of Hong Kong, Hong Kong SAR, China
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle 98195, Washington, United States
| | - Tong Zhang
- Environmental Microbiome Engineering and Biotechnology Laboratory, The University of Hong Kong, Hong Kong SAR, China
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22
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Gregory GJ, Boyd EF. Stressed out: Bacterial response to high salinity using compatible solute biosynthesis and uptake systems, lessons from Vibrionaceae. Comput Struct Biotechnol J 2021; 19:1014-1027. [PMID: 33613867 PMCID: PMC7876524 DOI: 10.1016/j.csbj.2021.01.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/19/2022] Open
Abstract
Bacteria have evolved mechanisms that allow them to adapt to changes in osmolarity and some species have adapted to live optimally in high salinity environments such as in the marine ecosystem. Most bacteria that live in high salinity do so by the biosynthesis and/or uptake of compatible solutes, small organic molecules that maintain the turgor pressure of the cell. Osmotic stress response mechanisms and their regulation among marine heterotrophic bacteria are poorly understood. In this review, we discuss what is known about compatible solute metabolism and transport and new insights gained from studying marine bacteria belonging to the family Vibrionaceae.
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Affiliation(s)
| | - E. Fidelma Boyd
- Corresponding author at: Department of Biological Sciences, 341 Wolf Hall, University of Delaware, Newark, DE 19716, United States.
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23
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Bethlehem L, van Echten-Deckert G. Ectoines as novel anti-inflammatory and tissue protective lead compounds with special focus on inflammatory bowel disease and lung inflammation. Pharmacol Res 2020; 164:105389. [PMID: 33352226 DOI: 10.1016/j.phrs.2020.105389] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/16/2020] [Accepted: 12/14/2020] [Indexed: 01/06/2023]
Abstract
The compatible solute ectoine is one of the most abundant and powerful cytoprotectant in the microbial world. Due to its unique ability to stabilize biological membranes and macromolecules it has been successfully commercialized as ingredient of various over-the-counter drugs, achieving primarily epithelial protection. While trying to elucidate the mechanism of its cell protective properties in in-vitro studies, a significant anti-inflammatory effect was documented for the small molecule. The tissue protective potential of ectoine considerably improved organ quality during preservation. In addition, ectoine and derivatives have been demonstrated to significantly decrease inflammatory cytokine production, thereby alleviating the inflammatory response following organ transplantation, and launching new therapeutic options for pathologies such as Inflammatory Bowel Disease (IBD) and Chronic Obstructive Pulmonary Disease (COPD). In this review, we aim to summarize the knowledge of this fairly nascent field of the anti-inflammatory potential of diverse ectoines. We also point out that this promising field faces challenges in its biochemical and molecular substantiations, including defining the molecular mechanisms of the observed effects and their regulation. However, based on their potent cytoprotective, anti-inflammatory, and non-toxic properties we believe that ectoines represent promising candidates for risk free interventions in inflammatory pathologies with steeply increasing demands for new therapeutics.
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Affiliation(s)
- Lukas Bethlehem
- Institute for Microbiology & Biotechnology, University Bonn, Germany.
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Pfeifer K, Ergal İ, Koller M, Basen M, Schuster B, Rittmann SKMR. Archaea Biotechnology. Biotechnol Adv 2020; 47:107668. [PMID: 33271237 DOI: 10.1016/j.biotechadv.2020.107668] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/13/2022]
Abstract
Archaea are a domain of prokaryotic organisms with intriguing physiological characteristics and ecological importance. In Microbial Biotechnology, archaea are historically overshadowed by bacteria and eukaryotes in terms of public awareness, industrial application, and scientific studies, although their biochemical and physiological properties show a vast potential for a wide range of biotechnological applications. Today, the majority of microbial cell factories utilized for the production of value-added and high value compounds on an industrial scale are bacterial, fungal or algae based. Nevertheless, archaea are becoming ever more relevant for biotechnology as their cultivation and genetic systems improve. Some of the main advantages of archaeal cell factories are the ability to cultivate many of these often extremophilic organisms under non-sterile conditions, and to utilize inexpensive feedstocks often toxic to other microorganisms, thus drastically reducing cultivation costs. Currently, the only commercially available products of archaeal cell factories are bacterioruberin, squalene, bacteriorhodopsin and diether-/tetraether-lipids, all of which are produced utilizing halophiles. Other archaeal products, such as carotenoids and biohydrogen, as well as polyhydroxyalkanoates and methane are in early to advanced development stages, respectively. The aim of this review is to provide an overview of the current state of Archaea Biotechnology by describing the actual state of research and development as well as the industrial utilization of archaeal cell factories, their role and their potential in the future of sustainable bioprocessing, and to illustrate their physiological and biotechnological potential.
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Affiliation(s)
- Kevin Pfeifer
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria; Institute of Synthetic Bioarchitectures, Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Wien, Austria
| | - İpek Ergal
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria
| | - Martin Koller
- Office of Research Management and Service, c/o Institute of Chemistry, University of Graz, Austria
| | - Mirko Basen
- Microbial Physiology Group, Division of Microbiology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Bernhard Schuster
- Institute of Synthetic Bioarchitectures, Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Wien, Austria
| | - Simon K-M R Rittmann
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Wien, Austria.
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Ancestral Reconstructions Decipher Major Adaptations of Ammonia-Oxidizing Archaea upon Radiation into Moderate Terrestrial and Marine Environments. mBio 2020; 11:mBio.02371-20. [PMID: 33051370 PMCID: PMC7554672 DOI: 10.1128/mbio.02371-20] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Unlike all other archaeal lineages, ammonia-oxidizing archaea (AOA) of the phylum Thaumarchaeota are widespread and abundant in all moderate and oxic environments on Earth. The evolutionary adaptations that led to such unprecedented ecological success of a microbial clade characterized by highly conserved energy and carbon metabolisms have, however, remained underexplored. Here, we reconstructed the genomic content and growth temperature of the ancestor of all AOA, as well as the ancestors of the marine and soil lineages, based on 39 available complete or nearly complete genomes of AOA. Our evolutionary scenario depicts an extremely thermophilic, autotrophic, aerobic ancestor from which three independent lineages of a marine and two terrestrial groups radiated into moderate environments. Their emergence was paralleled by (i) a continuous acquisition of an extensive collection of stress tolerance genes mostly involved in redox maintenance and oxygen detoxification, (ii) an expansion of regulatory capacities in transcription and central metabolic functions, and (iii) an extended repertoire of cell appendages and modifications related to adherence and interactions with the environment. Our analysis provides insights into the evolutionary transitions and key processes that enabled the conquest of the diverse environments in which contemporary AOA are found.
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Kumar S, Paul D, Bhushan B, Wakchaure GC, Meena KK, Shouche Y. Traversing the "Omic" landscape of microbial halotolerance for key molecular processes and new insights. Crit Rev Microbiol 2020; 46:631-653. [PMID: 32991226 DOI: 10.1080/1040841x.2020.1819770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Post-2005, the biology of the salt afflicted habitats is predominantly studied employing high throughput "Omic" approaches comprising metagenomics, transcriptomics, metatranscriptomics, metabolomics, and proteomics. Such "Omic-based" studies have deciphered the unfamiliar details about microbial salt-stress biology. The MAGs (Metagenome-assembled genomes) of uncultured halophilic microbial lineages such as Nanohaloarchaea and haloalkaliphilic members within CPR (Candidate Phyla Radiation) have been reconstructed from diverse hypersaline habitats. The study of MAGs of such uncultured halophilic microbial lineages has unveiled the genomic basis of salt stress tolerance in "yet to culture" microbial lineages. Furthermore, functional metagenomic approaches have been used to decipher the novel genes from uncultured microbes and their possible role in microbial salt-stress tolerance. The present review focuses on the new insights into microbial salt-stress biology gained through different "Omic" approaches. This review also summarizes the key molecular processes that underlie microbial salt-stress response, and their role in microbial salt-stress tolerance has been confirmed at more than one "Omic" levels.
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Affiliation(s)
- Satish Kumar
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India.,ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Dhiraj Paul
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India
| | - Bharat Bhushan
- ICAR-National Bureau of Plant Genetic Resources, New Delhi, India
| | - G C Wakchaure
- ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Kamlesh K Meena
- ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Yogesh Shouche
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India
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Reshetnikov AS, Rozova ON, Trotsenko YA, But SY, Khmelenina VN, Mustakhimov II. Ectoine degradation pathway in halotolerant methylotrophs. PLoS One 2020; 15:e0232244. [PMID: 32353000 PMCID: PMC7192451 DOI: 10.1371/journal.pone.0232244] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 04/10/2020] [Indexed: 12/03/2022] Open
Abstract
Background Microorganisms living in saline environments are forced to regulate turgor via the synthesis of organic osmoprotective compounds. Microbial adaptation to fluctuations in external salinity includes degradation of compatible solutes. Here we have examined the biochemical pathway of degradation of the cyclic imino acid ectoine, the major osmoprotector in halotolerant methane-utilizing bacteria. Methods The BLAST search of the genes involved in ectoine degradation in the halotolerant methanotroph Methylotuvimicrobium alcaliphilum 20Z was performed with the reference sequences of Halomonas elongata. The genes for the key enzymes of the pathway were disrupted by insertion mutagenesis and the cellular metabolites in the methanol extracts of mutant cells were analyzed by HPLC. The doeA gene from Mm. alcaliphilum 20Z was heterologously expressed in Escherichia coli to identify the product of ectoine hydrolysis catalyzed by ectoine hydrolase DoeA. Results We have shown that the halotolerant methanotroph Mm. alcaliphilum 20Z possesses the doeBDAC gene cluster coding for putative ectoine hydrolase (DoeA), Nα-acetyl-L-2,4-diaminobutyrate deacetylase (DoeB), diaminobutyrate transaminase (DoeD) and aspartate-semialdehyde dehydrogenase (DoeC). The deletion of the doeA gene resulted in accumulation of the higher level of ectoine compared to the wild type strain. Nγ-acetyl-L-2,4-diaminobutyrate (Nγ-acetyl-DAB), a substrate for ectoine synthase, was found in the cytoplasm of the wild type strain. Nα-acetyl-L-2,4-diaminobutyrate (Nα-acetyl-DAB), a substrate for the DoeB enzyme, appeared in the cells as a result of exposure of the doeB mutant to low osmotic pressure. The genes for the enzymes involved in ectoine degradation were found in all aerobic methylotrophs capable of ectoine biosynthesis. These results provide the first evidence for the in vivo operation of the ectoine degradation pathway in methanotrophs and thus expand our understanding of the regulation mechanisms of bacterial osmoadaptation. Conclusions During adaptation to the changes in external osmolarity, halophilic and halotolerant methylotrophs cleave ectoine, thereby entering the carbon and nitrogen of the compatible solute to the central metabolic pathways. The biochemical route of ectoine degradation in the halotolerant methanotroph Mm. alcaliphilum 20Z is similar to that in heterotrophic halophiles. We have shown that ectoine hydrolase DoeA in this methanotroph hydrolyzes ectoine with the formation of the only isomer: Nα-acetyl-DAB. All aerobic methylotrophs capable of ectoine biosynthesis harbor the genetic determinants for ectoine degradation.
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Affiliation(s)
- Aleksander S. Reshetnikov
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Olga N. Rozova
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Yuri A. Trotsenko
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Sergey Yu. But
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Valentina N. Khmelenina
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
- * E-mail:
| | - Ildar I. Mustakhimov
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
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Microbial ecology and biogeochemistry of hypersaline sediments in Orca Basin. PLoS One 2020; 15:e0231676. [PMID: 32315331 PMCID: PMC7173876 DOI: 10.1371/journal.pone.0231676] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/28/2020] [Indexed: 11/21/2022] Open
Abstract
In deep ocean hypersaline basins, the combination of high salinity, unusual ionic composition and anoxic conditions represents significant challenges for microbial life. We used geochemical porewater characterization and DNA sequencing based taxonomic surveys to enable environmental and microbial characterization of anoxic hypersaline sediments and brines in the Orca Basin, the largest brine basin in the Gulf of Mexico. Full-length bacterial 16S rRNA gene clone libraries from hypersaline sediments and the overlying brine were dominated by the uncultured halophilic KB1 lineage, Deltaproteobacteria related to cultured sulfate-reducing halophilic genera, and specific lineages of heterotrophic Bacteroidetes. Archaeal clones were dominated by members of the halophilic methanogen genus Methanohalophilus, and the ammonia-oxidizing Marine Group I (MG-I) within the Thaumarchaeota. Illumina sequencing revealed higher phylum- and subphylum-level complexity, especially in lower-salinity sediments from the Orca Basin slope. Illumina and clone library surveys consistently detected MG-I Thaumarchaeota and halotolerant Deltaproteobacteria in the hypersaline anoxic sediments, but relative abundances of the KB1 lineage differed between the two sequencing methods. The stable isotopic composition of dissolved inorganic carbon and methane in porewater, and sulfate concentrations decreasing downcore indicated methanogenesis and sulfate reduction in the anoxic sediments. While anaerobic microbial processes likely occur at low rates near their maximal salinity thresholds in Orca Basin, long-term accumulation of reaction products leads to high methane concentrations and reducing conditions within the Orca Basin brine and sediments.
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Contribution of mechanosensitive channels to osmoadaptation and ectoine excretion in Halomonas elongata. Extremophiles 2020; 24:421-432. [PMID: 32266565 PMCID: PMC7174268 DOI: 10.1007/s00792-020-01168-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/24/2020] [Indexed: 12/05/2022]
Abstract
For osmoadaptation the halophilic bacterium Halomonas elongata synthesizes as its main compatible solute the aspartate derivative ectoine. H. elongata does not rely entirely on synthesis but can accumulate ectoine by uptake from the surrounding environment with the help of the osmoregulated transporter TeaABC. Disruption of the TeaABC-mediated ectoine uptake creates a strain that is constantly losing ectoine to the medium. However, the efflux mechanism of ectoine in H. elongata is not yet understood. H. elongata possesses four genes encoding mechanosensitive channels all of which belong to the small conductance type (MscS). Analysis by qRT-PCR revealed a reduction in transcription of the mscS genes with increasing salinity. The response of H. elongata to hypo- and hyperosmotic shock never resulted in up-regulation but rather in down-regulation of mscS transcription. Deletion of all four mscS genes created a mutant that was unable to cope with hypoosmotic shock. However, the knockout mutant grew significantly faster than the wildtype at high salinity of 2 M NaCl, and most importantly, still exported 80% of the ectoine compared to the wildtype. We thus conclude that a yet unknown system, which is independent of mechanosensitive channels, is the major export route for ectoine in H. elongata.
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Hillier HT, Altermark B, Leiros I. The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway. FEBS J 2020; 287:4641-4658. [PMID: 32112674 DOI: 10.1111/febs.15265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/30/2020] [Accepted: 02/26/2020] [Indexed: 01/13/2023]
Abstract
l-2,4-diaminobutyric acid (DABA) aminotransferases can catalyze the formation of amines at the distal ω-position of substrates, and is the intial and rate-limiting enzyme in the biosynthesis pathway of the cytoprotecting molecule (S)-2-methyl-1,4,5,6-tetrahydro-4-pyrimidine carboxylic acid (ectoine). Although there is an industrial interest in the biosynthesis of ectoine, the DABA aminotransferases remain poorly characterized. Herein, we present the crystal structure of EctB (2.45 Å), a DABA aminotransferase from Chromohalobacter salexigens DSM 3043, a well-studied organism with respect to osmoadaptation by ectoine biosynthesis. We investigate the enzyme's oligomeric state to show that EctB from C. salexigens is a tetramer of two functional dimers, and suggest conserved recognition sites for dimerization that also includes the characteristic gating loop that helps shape the active site of the neighboring monomer. Although ω-transaminases are known to have two binding pockets to accommodate for their dual substrate specificity, we herein provide the first description of two binding pockets in the active site that may account for the catalytic character of DABA aminotransferases. Furthermore, our biochemical data reveal that the EctB enzyme from C. salexigens is a thermostable, halotolerant enzyme with a broad pH tolerance which may be linked to its tetrameric state. Put together, this study creates a solid foundation for a deeper structural understanding of DABA aminotransferases and opening up for future downstream studies of EctB's catalytic character and its redesign as a better catalyst for ectoine biosynthesis. In summary, we believe that the EctB enzyme from C. salexigens can serve as a benchmark enzyme for characterization of DABA aminotransferases. DATABASE: Structural data are available in PDB database under the accession number 6RL5.
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Affiliation(s)
- Heidi Therese Hillier
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Bjørn Altermark
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Ingar Leiros
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
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Richter AA, Kobus S, Czech L, Hoeppner A, Zarzycki J, Erb TJ, Lauterbach L, Dickschat JS, Bremer E, Smits SHJ. The architecture of the diaminobutyrate acetyltransferase active site provides mechanistic insight into the biosynthesis of the chemical chaperone ectoine. J Biol Chem 2020; 295:2822-2838. [PMID: 31969391 DOI: 10.1074/jbc.ra119.011277] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/19/2020] [Indexed: 12/17/2022] Open
Abstract
Ectoine is a solute compatible with the physiologies of both prokaryotic and eukaryotic cells and is widely synthesized by bacteria as an osmotic stress protectant. Because it preserves functional attributes of proteins and macromolecular complexes, it is considered a chemical chaperone and has found numerous practical applications. However, the mechanism of its biosynthesis is incompletely understood. The second step in ectoine biosynthesis is catalyzed by l-2,4-diaminobutyrate acetyltransferase (EctA; EC 2.3.1.178), which transfers the acetyl group from acetyl-CoA to EctB-formed l-2,4-diaminobutyrate (DAB), yielding N-γ-acetyl-l-2,4-diaminobutyrate (N-γ-ADABA), the substrate of ectoine synthase (EctC). Here, we report the biochemical and structural characterization of the EctA enzyme from the thermotolerant bacterium Paenibacillus lautus (Pl). We found that (Pl)EctA forms a homodimer whose enzyme activity is highly regiospecific by producing N-γ-ADABA but not the ectoine catabolic intermediate N-α-acetyl-l-2,4-diaminobutyric acid. High-resolution crystal structures of (Pl)EctA (at 1.2-2.2 Å resolution) (i) for its apo-form, (ii) in complex with CoA, (iii) in complex with DAB, (iv) in complex with both CoA and DAB, and (v) in the presence of the product N-γ-ADABA were obtained. To pinpoint residues involved in DAB binding, we probed the structure-function relationship of (Pl)EctA by site-directed mutagenesis. Phylogenomics shows that EctA-type proteins from both Bacteria and Archaea are evolutionarily highly conserved, including catalytically important residues. Collectively, our biochemical and structural findings yielded detailed insights into the catalytic core of the EctA enzyme that laid the foundation for unraveling its reaction mechanism.
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Affiliation(s)
- Alexandra A Richter
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Stefanie Kobus
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Jan Zarzycki
- Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
| | - Tobias J Erb
- SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany; Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
| | - Lukas Lauterbach
- Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-University Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-University Bonn, D-53121 Bonn, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany; Institute of Biochemistry, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany.
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Fenizia S, Thume K, Wirgenings M, Pohnert G. Ectoine from Bacterial and Algal Origin Is a Compatible Solute in Microalgae. Mar Drugs 2020; 18:E42. [PMID: 31935955 PMCID: PMC7024275 DOI: 10.3390/md18010042] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 02/03/2023] Open
Abstract
Osmoregulation in phytoplankton is attributed to several highly polar low-molecular-weight metabolites. A widely accepted model considers dimethylsulfoniopropionate (DMSP) as the most important and abundant osmotically active metabolite. Using an optimized procedure for the extraction and detection of highly polar metabolites, we expand the group of phytoplankton osmolytes by identifying ectoine in several microalgae. Ectoine is known as a bacterial compatible solute, but, to the best of our knowledge, was never considered as a phytoplankton-derived product. Given the ability of microalgae to take up zwitterions, such as DMSP, we tested the hypothesis that the algal ectoine is derived from associated bacteria. We therefore analyzed methanol extracts of xenic and axenic cultures of two different species of microalgae and could detect elevated concentrations of ectoine in those that harbor associated bacteria. However, also microalgae without an associated microbiome contain ectoine in smaller amounts, pointing towards a dual origin of this metabolite in the algae from their own biosynthesis as well as from uptake. We also tested the role of ectoine in the osmoadaptation of microalgae. In the model diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, elevated amounts of ectoine were found when cultivated in seawater with salinities of 50 PSU compared to the standard culture conditions of 35 PSU. Therefore, we add ectoine to the family of osmoadaptive metabolites in phytoplankton and prove a new, potentially synergistic metabolic interplay of bacteria and algae.
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Affiliation(s)
- Simona Fenizia
- Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, D-07743 Jena, Germany; (S.F.); (K.T.); (M.W.)
- Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany
| | - Kathleen Thume
- Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, D-07743 Jena, Germany; (S.F.); (K.T.); (M.W.)
| | - Marino Wirgenings
- Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, D-07743 Jena, Germany; (S.F.); (K.T.); (M.W.)
| | - Georg Pohnert
- Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, D-07743 Jena, Germany; (S.F.); (K.T.); (M.W.)
- Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany
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Richter AA, Mais CN, Czech L, Geyer K, Hoeppner A, Smits SHJ, Erb TJ, Bange G, Bremer E. Biosynthesis of the Stress-Protectant and Chemical Chaperon Ectoine: Biochemistry of the Transaminase EctB. Front Microbiol 2019; 10:2811. [PMID: 31921013 PMCID: PMC6915088 DOI: 10.3389/fmicb.2019.02811] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/20/2019] [Indexed: 12/20/2022] Open
Abstract
Bacteria frequently adapt to high osmolarity surroundings through the accumulation of compatible solutes. Ectoine is a prominent member of these types of stress protectants and is produced via an evolutionarily conserved biosynthetic pathway beginning with the L-2,4-diaminobutyrate (DAB) transaminase (TA) EctB. Here, we studied EctB from the thermo-tolerant Gram-positive bacterium Paenibacillus lautus (Pl) and show that this tetrameric enzyme is highly tolerant to salt, pH, and temperature. During ectoine biosynthesis, EctB converts L-glutamate and L-aspartate-beta-semialdehyde into 2-oxoglutarate and DAB, but it also catalyzes the reverse reaction. Our analysis unravels that EctB enzymes are mechanistically identical to the PLP-dependent gamma-aminobutyrate TAs (GABA-TAs) and only differ with respect to substrate binding. Inspection of the genomic context of the ectB gene in P. lautus identifies an unusual arrangement of juxtapositioned genes for ectoine biosynthesis and import via an Ehu-type binding-protein-dependent ABC transporter. This operon-like structure suggests the operation of a highly coordinated system for ectoine synthesis and import to maintain physiologically adequate cellular ectoine pools under osmotic stress conditions in a resource-efficient manner. Taken together, our study provides an in-depth mechanistic and physiological description of EctB, the first enzyme of the ectoine biosynthetic pathway.
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Affiliation(s)
- Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Christopher-Nils Mais
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Kyra Geyer
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tobias J Erb
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Gert Bange
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
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Czech L, Wilcken S, Czech O, Linne U, Brauner J, Smits SHJ, Galinski EA, Bremer E. Exploiting Substrate Promiscuity of Ectoine Hydroxylase for Regio- and Stereoselective Modification of Homoectoine. Front Microbiol 2019; 10:2745. [PMID: 31827466 PMCID: PMC6890836 DOI: 10.3389/fmicb.2019.02745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 11/13/2022] Open
Abstract
Extant enzymes are not only highly efficient biocatalysts for a single, or a group of chemically closely related substrates but often have retained, as a mark of their evolutionary history, a certain degree of substrate ambiguity. We have exploited the substrate ambiguity of the ectoine hydroxylase (EctD), a member of the non-heme Fe(II)-containing and 2-oxoglutarate-dependent dioxygenase superfamily, for such a task. Naturally, the EctD enzyme performs a precise regio- and stereoselective hydroxylation of the ubiquitous stress protectant and chemical chaperone ectoine (possessing a six-membered pyrimidine ring structure) to yield trans-5-hydroxyectoine. Using a synthetic ectoine derivative, homoectoine, which possesses an expanded seven-membered diazepine ring structure, we were able to selectively generate, both in vitro and in vivo, trans-5-hydroxyhomoectoine. For this transformation, we specifically used the EctD enzyme from Pseudomonas stutzeri in a whole cell biocatalyst approach, as this enzyme exhibits high catalytic efficiency not only for its natural substrate ectoine but also for homoectoine. Molecular docking approaches with the crystal structure of the Sphingopyxis alaskensis EctD protein predicted the formation of trans-5-hydroxyhomoectoine, a stereochemical configuration that we experimentally verified by nuclear-magnetic resonance spectroscopy. An Escherichia coli cell factory expressing the P. stutzeri ectD gene from a synthetic promoter imported homoectoine via the ProU and ProP compatible solute transporters, hydroxylated it, and secreted the formed trans-5-hydroxyhomoectoine, independent from all currently known mechanosensitive channels, into the growth medium from which it could be purified by high-pressure liquid chromatography.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Sarah Wilcken
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Oliver Czech
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Uwe Linne
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Jarryd Brauner
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany.,Center for Structural Studies, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany
| | - Erwin A Galinski
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-Universität Marburg, Marburg, Germany
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High ectoine production by an engineered Halomonas hydrothermalis Y2 in a reduced salinity medium. Microb Cell Fact 2019; 18:184. [PMID: 31655591 PMCID: PMC6815383 DOI: 10.1186/s12934-019-1230-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/11/2019] [Indexed: 12/02/2022] Open
Abstract
Background As an attracted compatible solute, 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) showed great potentials in various field. However, lower productivity and high saline medium seriously hinder its wide applications. Results The entire ectoine metabolism, including pathways for ectoine synthesis and catabolism, was identified in the genome of an ectoine-excreting strain Halomonas hydrothermalis Y2. By in-frame deletion of genes encoding ectoine hydroxylase (EctD) and (or) ectoine hydrolase (DoeA) that responsible for ectoine catabolism, the pathways for ectoine utilization were disrupted and resulted in an obviously enhanced productivity. Using an optimized medium containing 100 g L−1 NaCl in a 500-mL flask, the double mutant of Y2/ΔectD/ΔdoeA synthesized 3.13 g L−1 ectoine after 30 h cultivation. This is much higher than that of the wild type strain (1.91 g L−1), and also exceeds the production of Y2/ΔectD (2.21 g L−1). The remarkably enhanced accumulation of ectoine by Y2/ΔectD/ΔdoeA implied a critical function of Doe pathway in the ectoine catabolism. Furthermore, to reduce the salinity of fermentation medium and overcome the wastewater treatment difficulty, mutants that lacking key Na+/H+ antiporter, Mrp and (or) NhaD2, were constructed based on strain Y2/ΔectD/ΔdoeA. As a result, the Mrp-deficient strain could synthesize equal amount of ectoine (around 7 g L−1 or 500 mg (g DCW) −1) in the medium containing lower concentration of NaCl. During a fed-batch fermentation process with 60 g L−1 NaCl stress, a maximum 10.5 g L−1 ectoine was accumulated by the Mrp-deficient strain, with a specific production of 765 mg (g DCW)−1 and a yield of 0.21 g g−1 monosodium glutamate. Conclusion The remarkably enhanced production of ectoine by Y2/ΔectD/ΔdoeA implied the critical function of Doe pathway in the ectoine catabolism. Moreover, the reduced salinity requirement of Mrp-deficient strain implied a feasible protocol for many compatible solute biosynthesis, i.e., by silencing some Na+/H+ antiporters in their halophilic producers and thus lowering the medium salinity.![]()
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Ren M, Feng X, Huang Y, Wang H, Hu Z, Clingenpeel S, Swan BK, Fonseca MM, Posada D, Stepanauskas R, Hollibaugh JT, Foster PG, Woyke T, Luo H. Phylogenomics suggests oxygen availability as a driving force in Thaumarchaeota evolution. ISME JOURNAL 2019; 13:2150-2161. [PMID: 31024152 DOI: 10.1038/s41396-019-0418-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 03/07/2019] [Accepted: 04/03/2019] [Indexed: 11/09/2022]
Abstract
Ammonia-oxidizing archaea (AOA) of the phylum Thaumarchaeota are widespread in marine and terrestrial habitats, playing a major role in the global nitrogen cycle. However, their evolutionary history remains unexplored, which limits our understanding of their adaptation mechanisms. Here, our comprehensive phylogenomic tree of Thaumarchaeota supports three sequential events: origin of AOA from terrestrial non-AOA ancestors, colonization of the shallow ocean, and expansion to the deep ocean. Careful molecular dating suggests that these events coincided with the Great Oxygenation Event around 2300 million years ago (Mya), and oxygenation of the shallow and deep ocean around 800 and 635-560 Mya, respectively. The first transition was likely enabled by the gain of an aerobic pathway for energy production by ammonia oxidation and biosynthetic pathways for cobalamin and biotin that act as cofactors in aerobic metabolism. The first transition was also accompanied by the loss of dissimilatory nitrate and sulfate reduction, loss of oxygen-sensitive pyruvate oxidoreductase, which reduces pyruvate to acetyl-CoA, and loss of the Wood-Ljungdahl pathway for anaerobic carbon fixation. The second transition involved gain of a K+ transporter and of the biosynthetic pathway for ectoine, which may function as an osmoprotectant. The third transition was accompanied by the loss of the uvr system for repairing ultraviolet light-induced DNA lesions. We conclude that oxygen availability drove the terrestrial origin of AOA and their expansion to the photic and dark oceans, and that the stressors encountered during these events were partially overcome by gene acquisitions from Euryarchaeota and Bacteria, among other sources.
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Affiliation(s)
- Minglei Ren
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong.,Shenzhen Research Institute, The Chinese University of Hong Kong, 518000, Shenzhen, China
| | - Xiaoyuan Feng
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Yongjie Huang
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong.,Shenzhen Research Institute, The Chinese University of Hong Kong, 518000, Shenzhen, China
| | - Hui Wang
- Biology Department, College of Science, Shantou University, 515063, Shantou, China
| | - Zhong Hu
- Biology Department, College of Science, Shantou University, 515063, Shantou, China
| | | | - Brandon K Swan
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, 04544, USA.,National Biodefense Analysis and Countermeasures Center, Frederick, MD, 21702, USA
| | - Miguel M Fonseca
- CINBIO and Department of Biochemistry, Genetics and Immunology, University of Vigo, 36310, Vigo, Spain
| | - David Posada
- CINBIO and Department of Biochemistry, Genetics and Immunology, University of Vigo, 36310, Vigo, Spain
| | | | - James T Hollibaugh
- Department of Marine Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Peter G Foster
- Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK
| | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Haiwei Luo
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong. .,Shenzhen Research Institute, The Chinese University of Hong Kong, 518000, Shenzhen, China.
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37
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Illuminating the catalytic core of ectoine synthase through structural and biochemical analysis. Sci Rep 2019; 9:364. [PMID: 30674920 PMCID: PMC6344544 DOI: 10.1038/s41598-018-36247-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/16/2018] [Indexed: 11/26/2022] Open
Abstract
Ectoine synthase (EctC) is the signature enzyme for the production of ectoine, a compatible solute and chemical chaperone widely synthesized by bacteria as a cellular defense against the detrimental effects of osmotic stress. EctC catalyzes the last step in ectoine synthesis through cyclo-condensation of the EctA-formed substrate N-gamma-acetyl-L-2,4-diaminobutyric acid via a water elimination reaction. We have biochemically and structurally characterized the EctC enzyme from the thermo-tolerant bacterium Paenibacillus lautus (Pl). EctC is a member of the cupin superfamily and forms dimers, both in solution and in crystals. We obtained high-resolution crystal structures of the (Pl)EctC protein in forms that contain (i) the catalytically important iron, (ii) iron and the substrate N-gamma-acetyl-L-2,4-diaminobutyric acid, and (iii) iron and the enzyme reaction product ectoine. These crystal structures lay the framework for a proposal for the EctC-mediated water-elimination reaction mechanism. Residues involved in coordinating the metal, the substrate, or the product within the active site of ectoine synthase are highly conserved among a large group of EctC-type proteins. Collectively, the biochemical, mutational, and structural data reported here yielded detailed insight into the structure-function relationship of the (Pl)EctC enzyme and are relevant for a deeper understanding of the ectoine synthase family as a whole.
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38
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Jung MY, Islam MA, Gwak JH, Kim JG, Rhee SK. Nitrosarchaeum koreense gen. nov., sp. nov., an aerobic and mesophilic, ammonia-oxidizing archaeon member of the phylum Thaumarchaeota isolated from agricultural soil. Int J Syst Evol Microbiol 2018; 68:3084-3095. [PMID: 30124400 DOI: 10.1099/ijsem.0.002926] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A mesophilic, chemolithoautotrophic, neutrophilic and aerobic ammonia-oxidizing archaeon, designated strain MY1T, was isolated from agricultural soil. Microscopic observation revealed short, rod-shaped cells with a diameter of 0.3-0.5 µm and length of 0.6-1.0 µm. The isolate had no flagella and pili, and possessed no genes associated with archaeal flagella synthesis. The major membrane lipids consisted mainly of the glycerol dibiphytanyl glycerol tetraether (GDGT) lipids GDGT-0 to GDGT-4 and crenarchaeol. The major intact polar lipids (IPLs) were determined as hexose plus phosphohexose IPL and dihexose IPL. Strain MY1T obtains energy by aerobically oxidizing ammonia and carbon by fixing CO2. An optimal growth was observed at 25 °C, at pH 7 and with 0.2-0.4 % (w/v) salinity that corresponds with its terrestrial habitat. The addition of α-keto acids was necessary to stimulate growth. The strain tolerated ammonium and nitrite concentrations up to 10 and 5 mM, respectively. The MY1T genome has a DNA G+C content of 32.7 mol%. Phylogenetic analysis based on the 16S rRNA gene showed that strain MY1T belongs to the family Nitrosopumilaceaeof the phylum Thaumarchaeota, sharing the highest 16S rRNA gene sequence similarity (96.6-97.1 %) with marine isolates of the genus Nitrosopumilus. The average nucleotide identity was 78 % between strain MY1T and Nitrosopumilus maritimus SCM1T, indicating distant relatedness. Based on the phenotypic, phylogenetic and genomic analyses, it was concluded that strain MY1T belongs to the novel genus Nitrosarchaeum, under which the name Nitrosarchaeum koreense sp. nov. is proposed as the type species. The type strain is MY1T (=JCM 31640T=KCTC 4249T).
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Affiliation(s)
- Man-Young Jung
- 1Department of Microbiology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea.,2Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Md Arafat Islam
- 1Department of Microbiology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea
| | - Joo-Han Gwak
- 1Department of Microbiology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea
| | - Jong-Geol Kim
- 1Department of Microbiology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea
| | - Sung-Keun Rhee
- 1Department of Microbiology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea
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39
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Gagliano MC, Neu TR, Kuhlicke U, Sudmalis D, Temmink H, Plugge CM. EPS Glycoconjugate Profiles Shift as Adaptive Response in Anaerobic Microbial Granulation at High Salinity. Front Microbiol 2018; 9:1423. [PMID: 30013532 PMCID: PMC6036115 DOI: 10.3389/fmicb.2018.01423] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/11/2018] [Indexed: 11/22/2022] Open
Abstract
Anaerobic granulation at elevated salinities has been discussed in several analytical and engineering based studies. They report either enhanced or decreased efficiencies in relation to different Na+ levels. To evaluate this discrepancy, we focused on the microbial and structural dynamics of granules formed in two upflow anaerobic sludge blanket (UASB) reactors treating synthetic wastewater at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Granules were successfully formed in both conditions, but at high salinity, the start-up inoculum quickly formed larger granules having a thicker gel layer in comparison to granules developed at low salinity. Granules retained high concentrations of sodium without any negative effect on biomass activity and structure. 16S rRNA gene analysis and Fluorescence in Situ Hybridization (FISH) identified the acetotrophic Methanosaeta harundinacea as the dominant microorganism at both salinities. Fluorescence lectin bar coding (FLBC) screening highlighted a significant shift in the glycoconjugate pattern between granules grown at 5 and 20 g/L of Na+, and the presence of different extracellular domains. The excretion of a Mannose-rich cloud-like glycoconjugate matrix, which seems to form a protective layer for some methanogenic cells clusters, was found to be the main distinctive feature of the microbial community grown at high salinity conditions.
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Affiliation(s)
- Maria C Gagliano
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Thomas R Neu
- Helmholtz Centre for Environmental Research, Magdeburg, Germany
| | - Ute Kuhlicke
- Helmholtz Centre for Environmental Research, Magdeburg, Germany
| | - Dainis Sudmalis
- Sub-department of Environmental Technology, Wageningen University & Research, Wageningen, Netherlands
| | - Hardy Temmink
- Sub-department of Environmental Technology, Wageningen University & Research, Wageningen, Netherlands
| | - Caroline M Plugge
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, Netherlands
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40
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Li F, Xie W, Yuan Q, Luo H, Li P, Chen T, Zhao X, Wang Z, Ma H. Genome-scale metabolic model analysis indicates low energy production efficiency in marine ammonia-oxidizing archaea. AMB Express 2018; 8:106. [PMID: 29946801 PMCID: PMC6038301 DOI: 10.1186/s13568-018-0635-y] [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: 02/02/2018] [Accepted: 06/18/2018] [Indexed: 12/02/2022] Open
Abstract
Marine ammonia-oxidizing archaea (AOA) play an important role in the global nitrogen cycle by obtaining energy for biomass production from CO2 via oxidation of ammonium. The isolation of Candidatus “Nitrosopumilus maritimus” strain SCM1, which represents the globally distributed AOA in the ocean, provided an opportunity for uncovering the contributions of those AOA to carbon and nitrogen cycles in ocean. Although several ammonia oxidation pathways have been proposed for SCM1, little is known about its ATP production efficiency. Here, based on the published genome of Nitrosopumilus maritimus SCM1, a genome-scale metabolic model named NmrFL413 was reconstructed. Based on the model NmrFL413, the estimated ATP/NH4+ yield (0.149–0.276 ATP/NH4+) is tenfold lower than the calculated theoretical yield of the proposed ammonia oxidation pathways in marine AOA (1.5–1.75 ATP/NH4+), indicating a low energy production efficiency of SCM1. Our model also suggested the minor contribution of marine AOA to carbon cycle comparing with their significant contribution to nitrogen cycle in the ocean.
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41
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Czech L, Hermann L, Stöveken N, Richter AA, Höppner A, Smits SHJ, Heider J, Bremer E. Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis. Genes (Basel) 2018; 9:genes9040177. [PMID: 29565833 PMCID: PMC5924519 DOI: 10.3390/genes9040177] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 01/26/2023] Open
Abstract
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Lucas Hermann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Nadine Stöveken
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
- Institute of Biochemistry, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
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Gunde-Cimerman N, Plemenitaš A, Oren A. Strategies of adaptation of microorganisms of the three domains of life to high salt concentrations. FEMS Microbiol Rev 2018. [DOI: 10.1093/femsre/fuy009] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Nina Gunde-Cimerman
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia
| | - Ana Plemenitaš
- Institute of Biochemistry, Medical Faculty, University of Ljubljana, Vrazov trg 1, SI-1000 Ljubljana, Slovenia
| | - Aharon Oren
- Department of Plant and Environmental Sciences, The Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
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León MJ, Hoffmann T, Sánchez-Porro C, Heider J, Ventosa A, Bremer E. Compatible Solute Synthesis and Import by the Moderate Halophile Spiribacter salinus: Physiology and Genomics. Front Microbiol 2018; 9:108. [PMID: 29497403 PMCID: PMC5818414 DOI: 10.3389/fmicb.2018.00108] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022] Open
Abstract
Members of the genus Spiribacter are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations. Spiribacter salinus M19-40 is the type species of this genus and its first cultivated representative. In the habitats of S. salinus M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the in silico mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes. S. salinus M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical ectABC operon. Instead, they are scrambled (ectAC; ectB) and are physically separated from each other on the S. salinus M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the ect genes. S. salinus M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations. In silico genome mining revealed that S. salinus M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that S. salinus M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in salt-stressed cells in unmodified form and suppressed the synthesis of ectoine. In conclusion, the data presented here allow us to derive a genome-scale picture of the cellular adjustment strategy of a species that represents an environmentally abundant group of ecophysiologically important halophilic microorganisms.
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Affiliation(s)
- María J León
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany
| | - Cristina Sánchez-Porro
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
| | - Antonio Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
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44
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A Single Mechanosensitive Channel Protects Francisella tularensis subsp. holarctica from Hypoosmotic Shock and Promotes Survival in the Aquatic Environment. Appl Environ Microbiol 2018; 84:AEM.02203-17. [PMID: 29269496 DOI: 10.1128/aem.02203-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/15/2017] [Indexed: 01/01/2023] Open
Abstract
Francisella tularensis subsp. holarctica is found in North America and much of Europe and causes the disease tularemia in humans and animals. An aquatic cycle has been described for this subspecies, which has caused waterborne outbreaks of tularemia in at least 10 countries. In this study, we sought to identify the mechanosensitive channel(s) required for the bacterium to survive the transition from mammalian hosts to freshwater, which is likely essential for the transmission of the bacterium between susceptible hosts. A single 165-amino-acid MscS-type mechanosensitive channel (FtMscS) was found to protect F. tularensis subsp. holarctica from hypoosmotic shock, despite lacking much of the cytoplasmic vestibule domain found in well-characterized MscS proteins from other organisms. The deletion of this channel did not affect virulence within the mammalian host; however, FtMscS was required to survive the transition from the host niche to freshwater. The deletion of FtMscS did not alter the sensitivity of F. tularensis subsp. holarctica to detergents, H2O2, or antibiotics, suggesting that the role of FtMscS is specific to protection from hypoosmotic shock. The deletion of FtMscS also led to a reduced average cell size without altering gross cell morphology. The mechanosensitive channel identified and characterized in this study likely contributes to the transmission of tularemia between hosts by allowing the bacterium to survive the transition from mammalian hosts to freshwater.IMPORTANCE The contamination of freshwater by Francisella tularensis subsp. holarctica has resulted in a number of outbreaks of tularemia. Invariably, the contamination originates from the carcasses or excreta of infected animals and thus involves an abrupt osmotic downshock as the bacteria enter freshwater. How F. tularensis survives this drastic change in osmolarity has not been clear, but here we report that a single mechanosensitive channel protects the bacterium from osmotic downshock. This channel is functional despite lacking much of the cytoplasmic vestibule domain that is present in better-studied organisms such as Escherichia coli; this report builds on previous studies that have suggested that parts of this domain are dispensable for downshock protection. These findings extend our understanding of the aquatic cycle and ecological persistence of F. tularensis, with further implications for mechanosensitive channel biology.
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Abstract
The cellular adjustment of Bacteria and Archaea to high-salinity habitats is well studied and has generally been classified into one of two strategies. These are to accumulate high levels either of ions (the “salt-in” strategy) or of physiologically compliant organic osmolytes, the compatible solutes (the “salt-out” strategy). Halophilic protists are ecophysiological important inhabitants of salt-stressed ecosystems because they are not only very abundant but also represent the majority of eukaryotic lineages in nature. However, their cellular osmostress responses have been largely neglected. Recent reports have now shed new light on this issue using the geographically widely distributed halophilic heterotrophic protists Halocafeteria seosinensis, Pharyngomonas kirbyi, and Schmidingerothrix salinarum as model systems. Different approaches led to the joint conclusion that these unicellular Eukarya use the salt-out strategy to cope successfully with the persistent high salinity in their habitat. They accumulate various compatible solutes, e.g., glycine betaine, myo-inositol, and ectoines. The finding of intron-containing biosynthetic genes for ectoine and hydroxyectoine, their salt stress–responsive transcription in H. seosinensis, and the production of ectoine and its import by S. salinarum come as a considerable surprise because ectoines have thus far been considered exclusive prokaryotic compatible solutes. Phylogenetic considerations of the ectoine/hydroxyectoine biosynthetic genes of H. seosinensis suggest that they have been acquired via lateral gene transfer by these bacterivorous Eukarya from ectoine/hydroxyectoine-producing food bacteria that populate the same habitat.
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Affiliation(s)
- Laura Czech
- Department of Biology, Laboratory for Molecular Microbiology, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Molecular Microbiology, Philipps-University Marburg, Marburg, Germany
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Marburg, Germany
- * E-mail:
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Tinkering with Osmotically Controlled Transcription Allows Enhanced Production and Excretion of Ectoine and Hydroxyectoine from a Microbial Cell Factory. Appl Environ Microbiol 2018; 84:AEM.01772-17. [PMID: 29101191 DOI: 10.1128/aem.01772-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/28/2017] [Indexed: 12/21/2022] Open
Abstract
Ectoine and hydroxyectoine are widely synthesized by members of the Bacteria and a few members of the Archaea as potent osmostress protectants. We have studied the salient features of the osmostress-responsive promoter directing the transcription of the ectoine/hydroxyectoine biosynthetic gene cluster from the plant-root-associated bacterium Pseudomonas stutzeri by transferring it into Escherichia coli, an enterobacterium that does not produce ectoines naturally. Using ect-lacZ reporter fusions, we found that the heterologous ect promoter reacted with exquisite sensitivity in its transcriptional profile to graded increases in sustained high salinity, responded to a true osmotic signal, and required the buildup of an osmotically effective gradient across the cytoplasmic membrane for its induction. The involvement of the -10, -35, and spacer regions of the sigma-70-type ect promoter in setting promoter strength and response to osmotic stress was assessed through site-directed mutagenesis. Moderate changes in the ect promoter sequence that increase its resemblance to housekeeping sigma-70-type promoters of E. coli afforded substantially enhanced expression, both in the absence and in the presence of osmotic stress. Building on this set of ect promoter mutants, we engineered an E. coli chassis strain for the heterologous production of ectoines. This synthetic cell factory lacks the genes for the osmostress-responsive synthesis of trehalose and the compatible solute importers ProP and ProU, and it continuously excretes ectoines into the growth medium. By combining appropriate host strains and different plasmid variants, excretion of ectoine, hydroxyectoine, or a mixture of both compounds was achieved under mild osmotic stress conditions.IMPORTANCE Ectoines are compatible solutes, organic osmolytes that are used by microorganisms to fend off the negative consequences of high environmental osmolarity on cellular physiology. An understanding of the salient features of osmostress-responsive promoters directing the expression of the ectoine/hydroxyectoine biosynthetic gene clusters is lacking. We exploited the ect promoter from an ectoine/hydroxyectoine-producing soil bacterium for such a study by transferring it into a surrogate bacterial host. Despite the fact that E. coli does not synthesize ectoines naturally, the ect promoter retained its exquisitely sensitive osmotic control, indicating that osmoregulation of ect transcription is an inherent feature of the promoter and its flanking sequences. These sequences were narrowed to a 116-bp DNA fragment. Ectoines have interesting commercial applications. Building on data from a site-directed mutagenesis study of the ect promoter, we designed a synthetic cell factory that secretes ectoine, hydroxyectoine, or a mixture of both compounds into the growth medium.
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Qin W, Heal KR, Ramdasi R, Kobelt JN, Martens-Habbena W, Bertagnolli AD, Amin SA, Walker CB, Urakawa H, Könneke M, Devol AH, Moffett JW, Armbrust EV, Jensen GJ, Ingalls AE, Stahl DA. Nitrosopumilus maritimus gen. nov., sp. nov., Nitrosopumilus cobalaminigenes sp. nov., Nitrosopumilus oxyclinae sp. nov., and Nitrosopumilus ureiphilus sp. nov., four marine ammonia-oxidizing archaea of the phylum Thaumarchaeota. Int J Syst Evol Microbiol 2017; 67:5067-5079. [PMID: 29034851 DOI: 10.1099/ijsem.0.002416] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Four mesophilic, neutrophilic, and aerobic marine ammonia-oxidizing archaea, designated strains SCM1T, HCA1T, HCE1T and PS0T, were isolated from a tropical marine fish tank, dimly lit deep coastal waters, the lower euphotic zone of coastal waters, and near-surface sediment in the Puget Sound estuary, respectively. Cells are straight or slightly curved small rods, 0.15-0.26 µm in diameter and 0.50-1.59 µm in length. Motility was not observed, although strain PS0T possesses genes associated with archaeal flagella and chemotaxis, suggesting it may be motile under some conditions. Cell membranes consist of glycerol dibiphytanyl glycerol tetraether (GDGT) lipids, with crenarchaeol as the major component. Strain SCM1T displays a single surface layer (S-layer) with p6 symmetry, distinct from the p3-S-layer reported for the soil ammonia-oxidizing archaeon Nitrososphaera viennensis EN76T. Respiratory quinones consist of fully saturated and monounsaturated menaquinones with 6 isoprenoid units in the side chain. Cells obtain energy from ammonia oxidation and use carbon dioxide as carbon source; addition of an α-keto acid (α-ketoglutaric acid) was necessary to sustain growth of strains HCA1T, HCE1T, and PS0T. Strain PS0T uses urea as a source of ammonia for energy production and growth. All strains synthesize vitamin B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), and B12 (cobalamin). Optimal growth occurs between 25 and 32 °C, between pH 6.8 and 7.3, and between 25 and 37 ‰ salinity. All strains have a low mol% G+C content of 33.0-34.2. Strains are related by 98 % or greater 16S rRNA gene sequence identity, sharing ~85 % 16S rRNA gene sequence identity with Nitrososphaera viennensis EN76T. All four isolates are well separated by phenotypic and genotypic characteristics and are here assigned to distinct species within the genus Nitrosopumilus gen. nov. Isolates SCM1T (=ATCC TSD-97T =NCIMB 15022T), HCA1T (=ATCC TSD-96T), HCE1T (=ATCC TSD-98T), and PS0T (=ATCC TSD-99T) are type strains of the species Nitrosopumilusmaritimus sp. nov., Nitrosopumilus cobalaminigenes sp. nov., Nitrosopumilus oxyclinae sp. nov., and Nitrosopumilus ureiphilus sp. nov., respectively. In addition, we propose the family Nitrosopumilaceae fam. nov. and the order Nitrosopumilales ord. nov. within the class Nitrososphaeria.
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Affiliation(s)
- Wei Qin
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Katherine R Heal
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Rasika Ramdasi
- Division of Biology, California Institute of Technology, Pasadena, CA, USA
| | - Julia N Kobelt
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Willm Martens-Habbena
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
- Department of Microbiology and Cell Science and Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Florida, FL, USA
| | - Anthony D Bertagnolli
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Shady A Amin
- Department of Chemistry, New York University Abu Dhabi, Abu Dhabi, UAE
| | - Christopher B Walker
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Hidetoshi Urakawa
- Department of Marine and Ecological Sciences, Florida Gulf Coast University, Fort Myers, FL, USA
| | - Martin Könneke
- Marine Archaea Group, MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Allan H Devol
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - James W Moffett
- Departments of Biological Sciences and Earth Sciences and Civil and Environmental Engineering, University of Southern California, Los Angeles, CA, USA
| | | | - Grant J Jensen
- Division of Biology, California Institute of Technology, Pasadena, CA, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | - Anitra E Ingalls
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
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Schulz A, Hermann L, Freibert SA, Bönig T, Hoffmann T, Riclea R, Dickschat JS, Heider J, Bremer E. Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues. Environ Microbiol 2017; 19:4599-4619. [PMID: 28892254 DOI: 10.1111/1462-2920.13924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 01/04/2023]
Abstract
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, Philipps-University Marburg, Robert-Koch Str. 6, D-35032 Marburg, Germany
| | - Tobias Bönig
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Ramona Riclea
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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49
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Bownik A, Stępniewska Z. Ectoine as a promising protective agent in humans and animals. Arh Hig Rada Toksikol 2017; 67:260-265. [PMID: 28033102 DOI: 10.1515/aiht-2016-67-2837] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 11/01/2016] [Indexed: 12/18/2022] Open
Abstract
Ectoine is a compatible water molecule-binding solute (osmoprotectant) produced by several bacterial species in response to osmotic stress and unfavourable environmental conditions. This amino acid derivative can accumulate inside cells at high concentrations without interfering with natural processes and can protect the cell against radiation or osmotic stress. This brief review presents the current state of knowledge about the effects of ectoine on animals and focuses on its practical use for enzyme stabilisation, human skin protection, anti-inflammatory treatment, inhibitory effects in neurodegenerative diseases, and other therapeutic potential in human or veterinary medicine.
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Schulz A, Stöveken N, Binzen IM, Hoffmann T, Heider J, Bremer E. Feeding on compatible solutes: A substrate-induced pathway for uptake and catabolism of ectoines and its genetic control by EnuR. Environ Microbiol 2016; 19:926-946. [PMID: 27318028 DOI: 10.1111/1462-2920.13414] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/19/2016] [Indexed: 01/19/2023]
Abstract
Ectoine and 5-hydroxyectoine are widely synthesized microbial osmostress protectants. They are also versatile nutrients but their catabolism and the genetic regulation of the corresponding genes are incompletely understood. Using the marine bacterium Ruegeria pomeroyi DSS-3, we investigated the utilization of ectoines and propose a seven steps comprising catabolic route that entails an initial conversion of 5-hydroxyectoine to ectoine, the opening of the ectoine ring, and the subsequent degradation of this intermediate to l-aspartate. The catabolic genes are co-transcribed with three genes encoding a 5-hydroxyectoine/ectoine-specific TRAP transporter. A chromosomal deletion of this entire gene cluster abolishes the utilization of ectoines as carbon and nitrogen sources. The presence of ectoines in the growth medium triggers enhanced expression of the importer and catabolic operon, a process dependent on a substrate-inducible promoter that precedes this gene cluster. EnuR, a member of the MocR/GabR-type transcriptional regulators, controls the activity of this promoter and functions as a repressor. EnuR contains a covalently bound pyridoxal-5'-phosphate, and we suggest that this co-factor is critical for the substrate-mediated induction of the 5-hydroxyectoine/ectoine import and catabolic genes. Bioinformatics showed that ectoine consumers are restricted to the Proteobacteria and that EnuR is likely a central regulator for most ectoine/5-hydroxyectoine catabolic genes.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Nadine Stöveken
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
| | - Ina M Binzen
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
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