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Allert MJ, Kumar S, Wang Y, Beese LS, Hellinga HW. Accurate Identification of Periplasmic Urea-binding Proteins by Structure- and Genome Context-assisted Functional Analysis. J Mol Biol 2024; 436:168780. [PMID: 39241982 DOI: 10.1016/j.jmb.2024.168780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 08/29/2024] [Accepted: 08/31/2024] [Indexed: 09/09/2024]
Abstract
ABC transporters are ancient and ubiquitous nutrient transport systems in bacteria and play a central role in defining lifestyles. Periplasmic solute-binding proteins (SBPs) are components that deliver ligands to their translocation machinery. SBPs have diversified to bind a wide range of ligands with high specificity and affinity. However, accurate assignment of cognate ligands remains a challenging problem in SBPs. Urea metabolism plays an important role in the nitrogen cycle; anthropogenic sources account for more than half of global nitrogen fertilizer. We report identification of urea-binding proteins within a large SBP sequence family that encodes diverse functions. By combining genetic linkage between SBPs, ABC transporter components, enzymes or transcription factors, we accurately identified cognate ligands, as we verified experimentally by biophysical characterization of ligand binding and crystallographic determination of the urea complex of a thermostable urea-binding homolog. Using three-dimensional structure information, these functional assignments were extrapolated to other members in the sequence family lacking genetic linkage information, which revealed that only a fraction bind urea. Using the same combined approaches, we also inferred that other family members bind various short-chain amides, aliphatic amino acids (leucine, isoleucine, valine), γ-aminobutyrate, and as yet unknown ligands. Comparative structural analysis revealed structural adaptations that encode diversification in these SBPs. Systematic assignment of ligands to SBP sequence families is key to understanding bacterial lifestyles, and also provides a rich source of biosensors for clinical and environmental analysis, such as the thermostable urea-binding protein identified here.
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Affiliation(s)
- Malin J Allert
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Shivesh Kumar
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, MO 63110, USA.
| | - You Wang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Lorena S Beese
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Homme W Hellinga
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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Zhang S, Liu S, Chen M, Lu J, Ma Y. Characterization of urease active calcite-producing strain YX-3 combined with the whole genome. ENVIRONMENTAL RESEARCH 2024; 262:119855. [PMID: 39208972 DOI: 10.1016/j.envres.2024.119855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 08/13/2024] [Accepted: 08/26/2024] [Indexed: 09/04/2024]
Abstract
Urease found in a wide range of microorganisms plays a vital role in ureolytic induced calcite precipitation (UICP). However, the genomic information on urease-producing strains is limited, and there is a need for further in-depth studies on aspects such as the regulation of urease activity by nickel ligand residues. The present study delved into the elucidation of urease activity in a newly isolated strain YX-3 coupled with nickel-ligand residues by employing the genetic architecture of biomineralization-controlled growth, molecular docking, molecular dynamics simulation (MDS), and site-directed mutagenesis. Genome-wide sequencing showed the presence of urease gene clusters, comprising structural genes ureA, ureB, and ureC, alongside auxiliary genes ureD, ureE, ureF, and ureG. RT-qPCR analysis showed that the addition of NiCl2 resulted in a significant up-regulation of ureC expression. His267, His294, and Gly325 in the domain of UreC were further proved to coordinate with nickel ions and urea simultaneously through homology modeling and molecular docking, and molecular dynamics simulations (MDS) showed the urease-urea docking complexes exhibited degressive binding stability by four metrics including root mean square deviations (RMSD) when those residues were mutated into alanine respectively. Western blotting exhibited that mutations of H267A, H294A, and G325A led to a reduction in the relative expression of urease, wherein urease activity was about 62%, 45%, and 20% times that of the wild type (WT), respectively. The overexpression results further confirmed the importance of these residues for urease activity and CaCO3 precipitation. These results would help to deepen the understanding of urease-producing strains at a molecular level and expand the theoretical basis for modulating urease activity.
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Affiliation(s)
- Shuqi Zhang
- College of Life Science, Northwest University, 229 Tai bai North Rd, Xi'an, Shaanxi, 710069, China; Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Shichuang Liu
- College of Life Science, Northwest University, 229 Tai bai North Rd, Xi'an, Shaanxi, 710069, China
| | - Mengyao Chen
- College of Life Science, Northwest University, 229 Tai bai North Rd, Xi'an, Shaanxi, 710069, China
| | - Juncheng Lu
- College of Life Science, Northwest University, 229 Tai bai North Rd, Xi'an, Shaanxi, 710069, China
| | - Yanling Ma
- College of Life Science, Northwest University, 229 Tai bai North Rd, Xi'an, Shaanxi, 710069, China; Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, Shaanxi, 710069, China.
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Zhu H, Ye Z, Xu Z, Wei L. Transcriptomic Analysis Reveals the Effect of Urea on Metabolism of Nannochloropsis oceanica. Life (Basel) 2024; 14:797. [PMID: 39063552 PMCID: PMC11278182 DOI: 10.3390/life14070797] [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: 04/10/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 07/28/2024] Open
Abstract
The eukaryotic microalga Nannochloropsis oceanica represents a promising bioresource for the production of biofuels and pharmaceuticals. Urea, a crucial nutrient for the photosynthetic N. oceanica, stimulates the accumulation of substances such as lipids, which influence growth and physiology. However, the specific mechanisms by which N. oceanica responds and adapts to urea addition remain unknown. High-throughput mRNA sequencing and differential gene expression analysis under control and urea-added conditions revealed significant metabolic changes. This involved the differential expression of 2104 genes, with 1354 being upregulated and 750 downregulated, resulting in the reprogramming of crucial pathways such as carbon and nitrogen metabolism, photosynthesis, and lipid metabolism. The results specifically showed that genes associated with photosynthesis in N. oceanica were significantly downregulated, particularly those related to light-harvesting proteins. Interestingly, urea absorption and transport may depend not only on specialized transport channels such as urease but also on alternative transport channels such as the ABC transporter family and the CLC protein family. In addition, urea caused specific changes in carbon and lipid metabolism. Genes associated with the Calvin cycle and carbon concentration mechanisms were significantly upregulated. In lipid metabolism, the expression of genes associated with lipases and polyunsaturated fatty acid synthesis was highly activated. Furthermore, the expression of several genes involved in the tricarboxylic acid cycle and folate metabolism was enhanced, making important contributions to energy supply and the synthesis and modification of genes and macromolecules. Our observations indicate that N. oceanica actively and dynamically regulates the redistribution of carbon and nitrogen after urea addition, providing references for further research on the effects of urea on N. oceanica.
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Affiliation(s)
- Han Zhu
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou 571129, China
- International Science and Technology Cooperation Laboratory for Marine Microalgae Ecological Carbon Sinks, Hainan Normal University, Haikou 571158, China
| | - Zhenli Ye
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Zhengru Xu
- College of Foreign Language, Hainan Normal University, Haikou 571157, China
| | - Li Wei
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou 571129, China
- International Science and Technology Cooperation Laboratory for Marine Microalgae Ecological Carbon Sinks, Hainan Normal University, Haikou 571158, China
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Arya CK, Maurya S, Ramanathan G. Insight into the metabolic pathways of Paracoccus sp. strain DMF: a non-marine halotolerant methylotroph capable of degrading aliphatic amines/amides. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:125947-125964. [PMID: 38010547 DOI: 10.1007/s11356-023-30858-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 10/31/2023] [Indexed: 11/29/2023]
Abstract
Paracoccus sp. strain DMF (P. DMF from henceforth) is a gram-negative heterotroph known to tolerate and utilize high concentrations of N,N-dimethylformamide (DMF). The work presented here elaborates on the metabolic pathways involved in the degradation of C1 compounds, many of which are well-known pollutants and toxic to the environment. Investigations on microbial growth and detection of metabolic intermediates corroborate the outcome of the functional genome analysis. Several classes of C1 compounds, such as methanol, methylated amines, aliphatic amides, and naturally occurring quaternary amines like glycine betaine, were tested as growth substrates. The detailed growth and kinetic parameter analyses reveal that P. DMF can efficiently aerobically degrade trimethylamine (TMA) and grow on quaternary amines such as glycine betaine. The results show that the mechanism for halotolerant adaptation in the presence of glycine betaine is dissimilar from those observed for conventional trehalose-mediated halotolerance in heterotrophic bacteria. In addition, a close genomic survey revealed the presence of a Co(I)-based substrate-specific corrinoid methyltransferase operon, referred to as mtgBC. This demethylation system has been associated with glycine betaine catabolism in anaerobic methanogens and is unknown in denitrifying aerobic heterotrophs. This report on an anoxic-specific demethylation system in an aerobic heterotroph is unique. Our finding exposes the metabolic potential for the degradation of a variety of C1 compounds by P. DMF, making it a novel organism of choice for remediating a wide range of possible environmental contaminants.
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Affiliation(s)
- Chetan Kumar Arya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Shiwangi Maurya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Gurunath Ramanathan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
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Vaskevicius L, Malunavicius V, Jankunec M, Lastauskiene E, Talaikis M, Mikoliunaite L, Maneikis A, Gudiukaite R. Insights in MICP dynamics in urease-positive Staphylococcus sp. H6 and Sporosarcina pasteurii bacterium. ENVIRONMENTAL RESEARCH 2023; 234:116588. [PMID: 37423368 DOI: 10.1016/j.envres.2023.116588] [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: 04/05/2023] [Revised: 06/22/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Microbially induced calcite precipitation (MICP) is an efficient and eco-friendly technique that has attracted significant interest for resolving various problems in the soil (erosion, improving structural integrity and water retention, etc.), remediation of heavy metals, production of self-healing concrete or restoration of different concrete structures. The success of most common MICP methods depends on microorganisms degrading urea which leads to the formation of CaCO3 crystals. While Sporosarcina pasteurii is a well-known microorganism for MICP, other soil abundant microorganisms, such as Staphylococcus bacteria have not been thoroughly studied for its efficiency in bioconsolidation though MICP is a very important proccess which can ensure soil quality and health. This study aimed to analyze MICP process at the surface level in Sporosarcina pasteurii and a newly screened Staphylococcus sp. H6 bacterium as well as show the possibility of this new microorganism to perform MICP. It was observed that Staphylococcus sp. H6 culture precipitated 157.35 ± 3.3 mM of Ca2+ ions from 200 mM, compared to 176 ± 4.8 mM precipitated by S. pasteurii. The bioconsolidation of sand particles was confirmed by Raman spectroscopy and XRD analysis, which indicated the formation of CaCO3 crystals for both Staphylococcus sp. H6 and S. pasteurii cells. The water-flow test suggested a significant reduction in water permeability in bioconsolidated sand samples for both Staphylococcus sp. H6 and S. pasteurii. Notably, this study provides the first evidence that CaCO3 precipitation occurs on the surface of Staphylococcus and S. pasteurii cells within the initial 15-30 min after exposure to the biocementation solution. Furthermore, Atomic force microscopy (AFM) indicated rapid changes in cell roughness, with bacterial cells becoming completely coated with CaCO3 crystals after 90 min incubation with a biocementation solution. To our knowledge, this is the first time where atomic force microscopy was used to visualize the dynamic of MICP on cell surface.
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Affiliation(s)
- Laurynas Vaskevicius
- Department of Microbiology and Biotechnology, Institute of Biosciences, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania
| | - Vilius Malunavicius
- Department of Microbiology and Biotechnology, Institute of Biosciences, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania
| | - Marija Jankunec
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania
| | - Egle Lastauskiene
- Department of Microbiology and Biotechnology, Institute of Biosciences, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania
| | - Martynas Talaikis
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania
| | - Lina Mikoliunaite
- Department of Physical Chemistry, Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko St. 24, LT-03225, Vilnius, Lithuania; Laboratory of Spectroelectrochemistry, Department of Organic Chemistry, Center for Physical Sciences and Technology, Sauletekis Av. 3, LT-10257, Vilnius, Lithuania
| | - Andrius Maneikis
- Vilnius Gediminas Technical University, Sauletekis Av. 11, LT-10223, Vilnius, Lithuania
| | - Renata Gudiukaite
- Department of Microbiology and Biotechnology, Institute of Biosciences, Life Sciences Center, Vilnius University, Sauletekis Av. 7, LT-10257, Vilnius, Lithuania.
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Wang M, Shi Z, Gao N, Zhou Y, Ni X, Chen J, Liu J, Zhou W, Guo X, Xin B, Shen Y, Wang Y, Zheng P, Sun J. Sustainable and high-level microbial production of plant hemoglobin in Corynebacterium glutamicum. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:80. [PMID: 37170167 PMCID: PMC10176901 DOI: 10.1186/s13068-023-02337-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/03/2023] [Indexed: 05/13/2023]
Abstract
BACKGROUND Plant hemoglobin shows great potential as a food additive to circumvent the controversy of using animal materials. Microbial fermentation with engineered microorganisms is considered as a promising strategy for sustainable production of hemoglobin. As an endotoxin-free and GRAS (generally regarded as safe) bacterium, Corynebacterium glutamicum is an attractive host for hemoglobin biosynthesis. RESULTS Herein, C. glutamicum was engineered to efficiently produce plant hemoglobin. Hemoglobin genes from different sources including soybean and maize were selected and subjected to codon optimization. Interestingly, some candidates optimized for the codon usage bias of Escherichia coli outperformed those for C. glutamicum regarding the heterologous expression in C. glutamicum. Then, saturated synonymous mutation of the N-terminal coding sequences of hemoglobin genes and fluorescence-based high-throughput screening produced variants with 1.66- to 3.45-fold increase in hemoglobin expression level. To avoid the use of toxic inducers, such as isopropyl-β-D-thiogalactopyranoside, two native inducible expression systems based on food additives propionate and gluconate were developed. Promoter engineering improved the hemoglobin expression level by 2.2- to 12.2-fold. Combination of these strategies and plasmid copy number modification allowed intracellular production of hemoglobin up to approximately 20% of total protein. Transcriptome and proteome analyses of the hemoglobin-producing strain revealed the cellular response to excess hemoglobin accumulation. Several genes were identified as potential targets for further enhancing hemoglobin production. CONCLUSIONS In this study, production of plant hemoglobin in C. glutamicum was systematically engineered by combining codon optimization, promoter engineering, plasmid copy number modification, and multi-omics-guided novel target discovery. This study offers useful design principles to genetically engineer C. glutamicum for the production of hemoglobin and other recombinant proteins.
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Affiliation(s)
- Mengmeng Wang
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300222, China
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Zhong Shi
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
| | - Ning Gao
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yingyu Zhou
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300222, China
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Xiaomeng Ni
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Jiuzhou Chen
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Jiao Liu
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Wenjuan Zhou
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Xuan Guo
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Bo Xin
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300222, China
| | - Yanbing Shen
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300222, China
| | - Yu Wang
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ping Zheng
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Jibin Sun
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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Lascu I, Tănase AM, Jablonski P, Chiciudean I, Preda MI, Avramescu S, Irgum K, Stoica I. Revealing the Phenotypic and Genomic Background for PHA Production from Rapeseed-Biodiesel Crude Glycerol Using Photobacterium ganghwense C2.2. Int J Mol Sci 2022; 23:13754. [PMID: 36430242 PMCID: PMC9697146 DOI: 10.3390/ijms232213754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/12/2022] Open
Abstract
Polyhydroxyalkanoates (PHA) are promising biodegradable and biocompatible bioplastics, and extensive knowledge of the employed bacterial strain's metabolic capabilities is necessary in choosing economically feasible production conditions. This study aimed to create an in-depth view of the utilization of Photobacterium ganghwense C2.2 for PHA production by linking a wide array of characterization methods: metabolic pathway annotation from the strain's complete genome, high-throughput phenotypic tests, and biomass analyses through plate-based assays and flask and bioreactor cultivations. We confirmed, in PHA production conditions, urea catabolization, fatty acid degradation and synthesis, and high pH variation and osmotic stress tolerance. With urea as a nitrogen source, pure and rapeseed-biodiesel crude glycerol were analyzed comparatively as carbon sources for fermentation at 20 °C. Flask cultivations yielded 2.2 g/L and 2 g/L PHA at 120 h, respectively, with molecular weights of 428,629 g/mol and 81,515 g/mol. Bioreactor batch cultivation doubled biomass accumulation (10 g/L and 13.2 g/L) in 48 h, with a PHA productivity of 0.133 g/(L·h) and 0.05 g/(L·h). Thus, phenotypic and genomic analyses determined the successful use of Photobacterium ganghwense C2.2 for PHA production using urea and crude glycerol and 20 g/L NaCl, without pH adjustment, providing the basis for a viable fermentation process.
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Affiliation(s)
- Irina Lascu
- Department of Genetics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | - Ana Maria Tănase
- Department of Genetics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | - Piotr Jablonski
- Department of Chemistry, Faculty of Science and Technology, Umeå University, S-90187 Umeå, Sweden
| | - Iulia Chiciudean
- Department of Genetics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | - Maria Irina Preda
- Department of Genetics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | - Sorin Avramescu
- Department of Organic Chemistry, Biochemistry and Catalysis, Faculty of Chemistry, University of Bucharest, 030018 Bucharest, Romania
| | - Knut Irgum
- Department of Chemistry, Faculty of Science and Technology, Umeå University, S-90187 Umeå, Sweden
| | - Ileana Stoica
- Department of Genetics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
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Desulfovibrio desulfuricans AY5 Isolated from a Patient with Autism Spectrum Disorder Binds Iron in Low-Soluble Greigite and Pyrite. Microorganisms 2021; 9:microorganisms9122558. [PMID: 34946159 PMCID: PMC8705596 DOI: 10.3390/microorganisms9122558] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 01/25/2023] Open
Abstract
The sulphate-reducing bacteria (SRB) of genus Desulfovibrio are a group of prokaryotes associated with autism spectrum disorders (ASD). The connection between the elevated numbers of Desulfovibrio in the gut of children with ASD compared with healthy children remains unresolved. A conceivable consequence of SRB overgrowth in the gut is the conversion of bioavailable iron into low-soluble crystalline iron sulphides, causing iron deficiency in the organism. In this study, we report the draft genome sequence and physiological features of the first cultivable isolate from a patient with ASD, Desulfovibrio desulfuricans strain AY5.The capability of the strain to produce crystalline iron sulphides was studied under different pH conditions. The most notable greigite(Fe3S4) and pyrite (FeS2) formation was revealed at pH 6.0, which suggests that the iron loss due to insoluble sulphide formation may occur in the proximal part of the gastrointestinal tract. Strain AY5 was adapted to grow under nitrogen-limiting conditions by N2 fixation. The urease found in the strain’s genome may play a role in resistance to acidic pH.
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Hailemariam S, Zhao S, He Y, Wang J. Urea transport and hydrolysis in the rumen: A review. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2021; 7:989-996. [PMID: 34738029 PMCID: PMC8529027 DOI: 10.1016/j.aninu.2021.07.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 07/02/2021] [Accepted: 07/08/2021] [Indexed: 11/29/2022]
Abstract
Inefficient dietary nitrogen (N) conversion to microbial proteins, and the subsequent use by ruminants, is a major research focus across different fields. Excess bacterial ammonia (NH3) produced due to degradation or hydrolyses of N containing compounds, such as urea, leads to an inefficiency in a host's ability to utilize nitrogen. Urea is a non-protein N containing compound used by ruminants as an ammonia source, obtained from feed and endogenous sources. It is hydrolyzed by ureases from rumen bacteria to produce NH3 which is used for microbial protein synthesis. However, lack of information exists regarding urea hydrolysis in ruminal bacteria, and how urea gets to hydrolysis sites. Therefore, this review describes research on sites of urea hydrolysis, urea transport routes towards these sites, the role and structure of urea transporters in rumen epithelium and bacteria, the composition of ruminal ureolytic bacteria, mechanisms behind urea hydrolysis by bacterial ureases, and factors influencing urea hydrolysis. This review explores the current knowledge on the structure and physiological role of urea transport and ureolytic bacteria, for the regulation of urea hydrolysis and recycling in ruminants. Lastly, underlying mechanisms of urea transportation in rumen bacteria and their physiological importance are currently unknown, and therefore future research should be directed to this subject.
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Affiliation(s)
- Samson Hailemariam
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
- Dilla University, College of Agriculture and Natural Resource, Dilla P. O. Box 419, Ethiopia
| | - Shengguo Zhao
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yue He
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Jiaqi Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
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10
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Hoffmann TD, Paine K, Gebhard S. Genetic optimisation of bacteria-induced calcite precipitation in Bacillus subtilis. Microb Cell Fact 2021; 20:214. [PMID: 34794448 PMCID: PMC8600894 DOI: 10.1186/s12934-021-01704-1] [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: 08/18/2021] [Accepted: 11/06/2021] [Indexed: 11/25/2022] Open
Abstract
Background Microbially induced calcite precipitation (MICP) is an ancient property of bacteria, which has recently gained considerable attention for biotechnological applications. It occurs as a by-product of bacterial metabolism and involves a combination of chemical changes in the extracellular environment, e.g. pH increase, and presence of nucleation sites on the cell surface or extracellular substances produced by the bacteria. However, the molecular mechanisms underpinning MICP and the interplay between the contributing factors remain poorly understood, thus placing barriers to the full biotechnological and synthetic biology exploitation of bacterial biomineralisation. Results In this study, we adopted a bottom-up approach of systematically engineering Bacillus subtilis, which has no detectable intrinsic MICP activity, for biomineralisation. We showed that heterologous production of urease can induce MICP by local increases in extracellular pH, and this can be enhanced by co-expression of urease accessory genes for urea and nickel uptake, depending on environmental conditions. MICP can be strongly enhanced by biofilm-promoting conditions, which appeared to be mainly driven by production of exopolysaccharide, while the protein component of the biofilm matrix was dispensable. Attempts to modulate the cell surface charge of B. subtilis had surprisingly minor effects, and our results suggest this organism may intrinsically have a very negative cell surface, potentially predisposing it for MICP activity. Conclusions Our findings give insights into the molecular mechanisms driving MICP in an application-relevant chassis organism and the genetic elements that can be used to engineer de novo or enhanced biomineralisation. This study also highlights mutual influences between the genetic drivers and the chemical composition of the surrounding environment in determining the speed, spatial distribution and resulting mineral crystals of MICP. Taken together, these data pave the way for future rational design of synthetic precipitator strains optimised for specific applications. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01704-1.
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Affiliation(s)
- Timothy D Hoffmann
- Department of Biology and Biochemistry, Milner Centre for Evolution, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Kevin Paine
- Department of Architecture and Civil Engineering, BRE Centre for Innovative Construction Materials, University of Bath, Bath, BA2 7AY, United Kingdom
| | - Susanne Gebhard
- Department of Biology and Biochemistry, Milner Centre for Evolution, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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11
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Hagström Å, Zweifel UL, Sundh J, Osbeck CMG, Bunse C, Sjöstedt J, Müller-Karulis B, Pinhassi J. Composition and Seasonality of Membrane Transporters in Marine Picoplankton. Front Microbiol 2021; 12:714732. [PMID: 34650527 PMCID: PMC8507841 DOI: 10.3389/fmicb.2021.714732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/24/2021] [Indexed: 11/13/2022] Open
Abstract
In this study, we examined transporter genes in metagenomic and metatranscriptomic data from a time-series survey in the temperate marine environment of the Baltic Sea. We analyzed the abundance and taxonomic distribution of transporters in the 3μm–0.2μm size fraction comprising prokaryotes and some picoeukaryotes. The presence of specific transporter traits was shown to be guiding the succession of these microorganisms. A limited number of taxa were associated with the dominant transporter proteins that were identified for the nine key substrate categories for microbial growth. Throughout the year, the microbial taxa at the level of order showed highly similar patterns in terms of transporter traits. The distribution of transporters stayed the same, irrespective of the abundance of each taxon. This would suggest that the distribution pattern of transporters depends on the bacterial groups being dominant at a given time of the year. Also, we find notable numbers of secretion proteins that may allow marine bacteria to infect and kill prey organisms thus releasing nutrients. Finally, we demonstrate that transporter proteins may provide clues to the relative importance of biogeochemical processes, and we suggest that virtual transporter functionalities may become important components in future population dynamics models.
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Affiliation(s)
- Åke Hagström
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden
| | - Ulla Li Zweifel
- Swedish Institute for the Marine Environment, Gothenburg University, Gothenburg, Sweden
| | - John Sundh
- Department of Biochemistry and Biophysics, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Christofer M G Osbeck
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden
| | - Carina Bunse
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden.,Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Oldenburg, Germany
| | - Johanna Sjöstedt
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden.,Department of Biology, Aquatic Ecology, Lund University, Lund, Sweden
| | | | - Jarone Pinhassi
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden
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12
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Rakitin AL, Ermakova AY, Beletsky AV, Petrova M, Mardanov AV, Ravin NV. Genome Analysis of Acinetobacter lwoffii Strains Isolated from Permafrost Soils Aged from 15 Thousand to 1.8 Million Years Revealed Their Close Relationships with Present-Day Environmental and Clinical Isolates. BIOLOGY 2021; 10:871. [PMID: 34571748 PMCID: PMC8472584 DOI: 10.3390/biology10090871] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 01/21/2023]
Abstract
Microbial life can be supported at subzero temperatures in permafrost up to several million years old. Genome analysis of strains isolated from permafrost provides a unique opportunity to study microorganisms that have not previously come into contact with the human population. Acinetobacter lwoffii is a typical soil bacterium that has been increasingly reported as hospital pathogens associated with bacteremia. In order to identify the specific genetic characteristics of ancient permafrost-conserved strains of A. lwoffii and their differences from present-day clinical isolates, we carried out a genome-wide analysis of five strains of A. lwoffii isolated from permafrost aged from 15 thousand to 1.8 million years. Surprisingly, we did not identify chromosomal genetic determinants that distinguish permafrost strains from clinical A. lwoffii isolates and strains from other natural habitats. Phylogenetic analysis based on whole genome sequences showed that permafrost strains do not form a separate cluster and some of them are most closely related to clinical isolates. The genomes of clinical and permafrost strains contain similar mobile elements and prophages, which indicates an intense horizontal transfer of genetic material. Comparison of plasmids of modern and permafrost strains showed that plasmids from the modern strains are enriched with antibiotic resistance genes, while the content of genes for resistance to heavy metals and arsenic is nearly the same. The thawing of permafrost caused by global warming could release new potentially pathogenic strains of Acinetobacter.
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Affiliation(s)
- Andrey L. Rakitin
- Research Center of Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, 119071 Moscow, Russia; (A.L.R.); (A.Y.E.); (A.V.B.); (A.V.M.)
| | - Alexandra Y. Ermakova
- Research Center of Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, 119071 Moscow, Russia; (A.L.R.); (A.Y.E.); (A.V.B.); (A.V.M.)
| | - Alexey V. Beletsky
- Research Center of Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, 119071 Moscow, Russia; (A.L.R.); (A.Y.E.); (A.V.B.); (A.V.M.)
| | - Mayya Petrova
- Institute of Molecular Genetics of National Research Centre “Kurchatov Institute”, 123098 Moscow, Russia;
| | - Andrey V. Mardanov
- Research Center of Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, 119071 Moscow, Russia; (A.L.R.); (A.Y.E.); (A.V.B.); (A.V.M.)
| | - Nikolai V. Ravin
- Research Center of Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, 119071 Moscow, Russia; (A.L.R.); (A.Y.E.); (A.V.B.); (A.V.M.)
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13
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Yang P, Chen Y, Gong AD. Development of a defined medium for Corynebacterium glutamicum using urea as nitrogen source. 3 Biotech 2021; 11:405. [PMID: 34471588 DOI: 10.1007/s13205-021-02959-6] [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: 04/20/2021] [Accepted: 08/05/2021] [Indexed: 11/28/2022] Open
Abstract
Corynebacterium glutamicum has been widely used for bulk and fine chemicals fermentation these years. In this study, we developed a defined medium for this bacteria based on the widely used CGXII minimal medium. We evaluated the effects of different components in CGXII on cell growth of C. glutamicum ATCC 13032 and improved the medium through single-factor experiment and central composite design (CCD). Urea, K2HPO4 and MgSO4 were found to be significant factors. 7 out of the total 15 components were modified. (NH4)2SO4, KH2PO4, and protocatechuic acid were eliminated. Amounts of urea and MgSO4 were increased, and concentrations of biotin and glucose were reduced. The resulting R2 medium was proved to be more suitable for cell growth, plasmid amplification and protein production than the original recipe. Remarkably, cell biomass accumulation in R2 increased by 54.36% than CGXII. Transcriptome analysis revealed alteration of carbon metabolism, cation transport and energy synthesis, which might be beneficial for cell growth in R2. Considering the high nitrogen content and availability of urea, the new medium is simplified and cost effective, which holds attractive potential for future study. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s13205-021-02959-6.
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Affiliation(s)
- Peng Yang
- College of Life Science, Xinyang Normal University, Xinyang, 464000 People's Republic of China
| | - Yanan Chen
- College of Life Science, Xinyang Normal University, Xinyang, 464000 People's Republic of China
| | - An-Dong Gong
- College of Life Science, Xinyang Normal University, Xinyang, 464000 People's Republic of China
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14
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Paredes GF, Viehboeck T, Lee R, Palatinszky M, Mausz MA, Reipert S, Schintlmeister A, Maier A, Volland JM, Hirschfeld C, Wagner M, Berry D, Markert S, Bulgheresi S, König L. Anaerobic Sulfur Oxidation Underlies Adaptation of a Chemosynthetic Symbiont to Oxic-Anoxic Interfaces. mSystems 2021; 6:e0118620. [PMID: 34058098 PMCID: PMC8269255 DOI: 10.1128/msystems.01186-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/20/2021] [Indexed: 11/23/2022] Open
Abstract
Chemosynthetic symbioses occur worldwide in marine habitats, but comprehensive physiological studies of chemoautotrophic bacteria thriving on animals are scarce. Stilbonematinae are coated by thiotrophic Gammaproteobacteria. As these nematodes migrate through the redox zone, their ectosymbionts experience varying oxygen concentrations. However, nothing is known about how these variations affect their physiology. Here, by applying omics, Raman microspectroscopy, and stable isotope labeling, we investigated the effect of oxygen on "Candidatus Thiosymbion oneisti." Unexpectedly, sulfur oxidation genes were upregulated in anoxic relative to oxic conditions, but carbon fixation genes and incorporation of 13C-labeled bicarbonate were not. Instead, several genes involved in carbon fixation were upregulated under oxic conditions, together with genes involved in organic carbon assimilation, polyhydroxyalkanoate (PHA) biosynthesis, nitrogen fixation, and urea utilization. Furthermore, in the presence of oxygen, stress-related genes were upregulated together with vitamin biosynthesis genes likely necessary to withstand oxidative stress, and the symbiont appeared to proliferate less. Based on its physiological response to oxygen, we propose that "Ca. T. oneisti" may exploit anaerobic sulfur oxidation coupled to denitrification to proliferate in anoxic sand. However, the ectosymbiont would still profit from the oxygen available in superficial sand, as the energy-efficient aerobic respiration would facilitate carbon and nitrogen assimilation. IMPORTANCE Chemoautotrophic endosymbionts are famous for exploiting sulfur oxidization to feed marine organisms with fixed carbon. However, the physiology of thiotrophic bacteria thriving on the surface of animals (ectosymbionts) is less understood. One longstanding hypothesis posits that attachment to animals that migrate between reduced and oxic environments would boost sulfur oxidation, as the ectosymbionts would alternatively access sulfide and oxygen, the most favorable electron acceptor. Here, we investigated the effect of oxygen on the physiology of "Candidatus Thiosymbion oneisti," a gammaproteobacterium which lives attached to marine nematodes inhabiting shallow-water sand. Surprisingly, sulfur oxidation genes were upregulated under anoxic relative to oxic conditions. Furthermore, under anoxia, the ectosymbiont appeared to be less stressed and to proliferate more. We propose that animal-mediated access to oxygen, rather than enhancing sulfur oxidation, would facilitate assimilation of carbon and nitrogen by the ectosymbiont.
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Affiliation(s)
- Gabriela F. Paredes
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Tobias Viehboeck
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Raymond Lee
- Washington State University, School of Biological Sciences, Pullman, Washington, USA
| | - Marton Palatinszky
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Michaela A. Mausz
- University of Warwick, School of Life Sciences, Coventry, United Kingdom
| | - Siegfried Reipert
- University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Vienna, Austria
| | - Arno Schintlmeister
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- University of Vienna, Center for Microbiology and Environmental Systems Science, Large-Instrument Facility for Environmental and Isotope Mass Spectrometry, Vienna, Austria
| | - Andreas Maier
- University of Vienna, Faculty of Geosciences, Geography, and Astronomy, Department of Geography and Regional Research, Geoecology, Vienna, Austria
| | - Jean-Marie Volland
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Claudia Hirschfeld
- University of Greifswald, Institute of Pharmacy, Department of Pharmaceutical Biotechnology, Greifswald, Germany
| | - Michael Wagner
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- Aalborg University, Department of Chemistry and Bioscience, Aalborg, Denmark
| | - David Berry
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
| | - Stephanie Markert
- University of Greifswald, Institute of Pharmacy, Department of Pharmaceutical Biotechnology, Greifswald, Germany
| | - Silvia Bulgheresi
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Lena König
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
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15
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Prell C, Busche T, Rückert C, Nolte L, Brandenbusch C, Wendisch VF. Adaptive laboratory evolution accelerated glutarate production by Corynebacterium glutamicum. Microb Cell Fact 2021; 20:97. [PMID: 33971881 PMCID: PMC8112011 DOI: 10.1186/s12934-021-01586-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 04/26/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The demand for biobased polymers is increasing steadily worldwide. Microbial hosts for production of their monomeric precursors such as glutarate are developed. To meet the market demand, production hosts have to be improved constantly with respect to product titers and yields, but also shortening bioprocess duration is important. RESULTS In this study, adaptive laboratory evolution was used to improve a C. glutamicum strain engineered for production of the C5-dicarboxylic acid glutarate by flux enforcement. Deletion of the L-glutamic acid dehydrogenase gene gdh coupled growth to glutarate production since two transaminases in the glutarate pathway are crucial for nitrogen assimilation. The hypothesis that strains selected for faster glutarate-coupled growth by adaptive laboratory evolution show improved glutarate production was tested. A serial dilution growth experiment allowed isolating faster growing mutants with growth rates increasing from 0.10 h-1 by the parental strain to 0.17 h-1 by the fastest mutant. Indeed, the fastest growing mutant produced glutarate with a twofold higher volumetric productivity of 0.18 g L-1 h-1 than the parental strain. Genome sequencing of the evolved strain revealed candidate mutations for improved production. Reverse genetic engineering revealed that an amino acid exchange in the large subunit of L-glutamic acid-2-oxoglutarate aminotransferase was causal for accelerated glutarate production and its beneficial effect was dependent on flux enforcement due to deletion of gdh. Performance of the evolved mutant was stable at the 2 L bioreactor-scale operated in batch and fed-batch mode in a mineral salts medium and reached a titer of 22.7 g L-1, a yield of 0.23 g g-1 and a volumetric productivity of 0.35 g L-1 h-1. Reactive extraction of glutarate directly from the fermentation broth was optimized leading to yields of 58% and 99% in the reactive extraction and reactive re-extraction step, respectively. The fermentation medium was adapted according to the downstream processing results. CONCLUSION Flux enforcement to couple growth to operation of a product biosynthesis pathway provides a basis to select strains growing and producing faster by adaptive laboratory evolution. After identifying candidate mutations by genome sequencing causal mutations can be identified by reverse genetics. As exemplified here for glutarate production by C. glutamicum, this approach allowed deducing rational metabolic engineering strategies.
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Affiliation(s)
- Carina Prell
- Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - Tobias Busche
- Technology Platform Genomics, Center for Biotechnology (CeBiTec), Bielefeld University, Sequenz 1, 33615 Bielefeld, Germany
| | - Christian Rückert
- Technology Platform Genomics, Center for Biotechnology (CeBiTec), Bielefeld University, Sequenz 1, 33615 Bielefeld, Germany
| | - Lea Nolte
- Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, TU Dortmund University, Emil-Figge-Str. 70, 44227 Dortmund, Germany
| | - Christoph Brandenbusch
- Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, TU Dortmund University, Emil-Figge-Str. 70, 44227 Dortmund, Germany
| | - Volker F. Wendisch
- Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany
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16
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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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17
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Santolin L, Waldburger S, Neubauer P, Riedel SL. Substrate-Flexible Two-Stage Fed-Batch Cultivations for the Production of the PHA Copolymer P(HB- co-HHx) With Cupriavidus necator Re2058/pCB113. Front Bioeng Biotechnol 2021; 9:623890. [PMID: 33829008 PMCID: PMC8020817 DOI: 10.3389/fbioe.2021.623890] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
Recent studies of the impact and dimension of plastic pollution have drawn the attention to finding more sustainable alternatives to fossil-based plastics. Microbially produced polyhydroxyalkanoates (PHAs) biopolymers are strong candidates to replace conventional plastic materials, due to their true biodegradability and versatile properties. However, widespread use of these polymers is still hindered by their high cost of production. In the present study, we target high yields of the PHA copolymer poly(hydroxybutyrate-co-hydroxyhexanoate) [P(HB-co-HHx)] using a substrate-flexible two-stage fed-batch approach for the cultivation of the recombinant Cupriavidus necator strain Re2058/pCB113. A more substrate-flexible process allows to cope with constant price fluctuations and discontinuous supply of feedstocks on the market. Utilizing fructose for biomass accumulation and rapeseed oil for polymer production resulted in a final biomass concentration of 124 g L-1 with a polymer content of 86 wt% holding 17 mol% of HHx. Productivities were further optimized by operating the biomass accumulation stage in a "drain and fill" modus where 10% of the culture broth was recycled for semi-continuous biomass accumulation, after transferring 90% to a second bioreactor for PHA production. This strategy succeeded in shortening process times rising productivity yields to ∼1.45 g L-1 h-1.
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Affiliation(s)
- Lara Santolin
- Chair of Bioprocess Engineering, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Saskia Waldburger
- Chair of Bioprocess Engineering, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Peter Neubauer
- Chair of Bioprocess Engineering, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Sebastian L Riedel
- Chair of Bioprocess Engineering, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
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18
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Pedebos C, Smith IPS, Boags A, Khalid S. The hitchhiker's guide to the periplasm: Unexpected molecular interactions of polymyxin B1 in E. coli. Structure 2021; 29:444-456.e2. [PMID: 33577754 DOI: 10.1016/j.str.2021.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/11/2020] [Accepted: 01/21/2021] [Indexed: 12/19/2022]
Abstract
The periplasm of Gram-negative bacteria is a complex, highly crowded molecular environment. Little is known about how antibiotics move across the periplasm and the interactions they experience. Here, atomistic molecular dynamics simulations are used to study the antibiotic polymyxin B1 within models of the periplasm, which are crowded to different extents. We show that PMB1 is likely to be able to "hitchhike" within the periplasm by binding to lipoprotein carriers-a previously unreported passive transport route. The simulations reveal that PMB1 forms both transient and long-lived interactions with proteins, osmolytes, lipids of the outer membrane, and the cell wall, and is rarely uncomplexed when in the periplasm. Furthermore, it can interfere in the conformational dynamics of native proteins. These are important considerations for interpreting its mechanism of action and are likely to also hold for other antibiotics that rely on diffusion to cross the periplasm.
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Affiliation(s)
- Conrado Pedebos
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Iain Peter Shand Smith
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Alister Boags
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
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19
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Tan KY, Dutta A, Tan TK, Hari R, Othman RY, Choo SW. Comprehensive genome analysis of a pangolin-associated Paraburkholderia fungorum provides new insights into its secretion systems and virulence. PeerJ 2020; 8:e9733. [PMID: 32953261 PMCID: PMC7474880 DOI: 10.7717/peerj.9733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/25/2020] [Indexed: 12/26/2022] Open
Abstract
Background Paraburkholderia fungorum (P. fungorum) is a Gram-negative environmental species that has been commonly used as a beneficial microorganism in agriculture as an agent for biocontrol and bioremediation. Its use in agriculture is controversial as many people believe that it could harm human health; however, there is no clear evidence to support. Methodology The pangolin P. fungorum (pangolin Pf) genome has a genomic size of approximately 7.7 Mbps with N50 of 69,666 bps. Our study showed that pangolin Pf is a Paraburkholderia fungorum supported by evidence from the core genome SNP-based phylogenetic analysis and the ANI analysis. Functional analysis has shown that the presence of a considerably large number of genes related to stress response, virulence, disease, and defence. Interestingly, we identified different types of secretion systems in the genome of pangolin Pf, which are highly specialized and responsible for a bacterium’s response to its environment and in physiological processes such as survival, adhesion, and adaptation. The pangolin Pf also shared some common virulence genes with the known pathogenic member of the Burkholderiales. These genes play important roles in adhesion, motility, and invasion. Conclusion This study may provide better insights into the functions, secretion systems and virulence of this pangolin-associated bacterial strain. The addition of this genome sequence is also important for future comparative analysis and functional work of P. fungorum.
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Affiliation(s)
- Ka Yun Tan
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Avirup Dutta
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: The Novo Nordisk Foundation Center for Basic Metabolic Research, Human Genomics and Metagenomics in Metabolism, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tze King Tan
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Ranjeev Hari
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Rofina Y Othman
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Centre for Research in Biotechnology for Agriculture (CEBAR), Level 3, Research Management & Innovation Complex, Universiti Malaya, Copenhagen, Kuala Lumpur, Malaysia
| | - Siew Woh Choo
- College of Science and Technology, Wenzhou-Kean University, Wenzhou, Zhejiang Province, China
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20
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Hailemariam S, Zhao S, Wang J. Complete Genome Sequencing and Transcriptome Analysis of Nitrogen Metabolism of Succinivibrio dextrinosolvens Strain Z6 Isolated From Dairy Cow Rumen. Front Microbiol 2020; 11:1826. [PMID: 33013723 PMCID: PMC7507024 DOI: 10.3389/fmicb.2020.01826] [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] [Received: 03/30/2020] [Accepted: 07/10/2020] [Indexed: 02/02/2023] Open
Abstract
The unclassified Succinivibrionaceae lineages are abundant in high yielding multiparous cows, and their presence is positively correlated with milk yield and fat percentage and reduces methane emissions. However, it is still unclear which species are associated with the most efficient feed nutrient utilization and productivity. Here, we used integrated whole genome sequencing and matrix-assisted laser desorption/ionization mass spectrometry, coupled with phenotypic and chemotaxonomic analysis, to characterize S. dextrinosolvens Z6, a species in Succinivibrionaceae isolated from the rumen. To assess the role of S. dextrinosolvens Z6 in nitrogen metabolism, cells grown in different nitrogen sources were analyzed by RNA sequencing. The whole genome sequence result revealed a genome size of 3.47 Mbp with 38.9% of G + C content. A total of 2993 encoding sequences account for 98%. The genes for regulating carbohydrate (10.6%) and amino acid (9%) transport and metabolism were the most abundant. ANI (Average nucleotide identity) showed that SD-Z6 was most closely related to SD-22B (99.96%). The whole genome alignment of SD-Z6 with SD-22B showed a more than 0.34 Mb nucleotide difference. Growth of SD-Z6 occurred at a temperature 36–42°C with an optimum at 39.7°C, pH 6–8; the optimum pH was 6.9 and with 0–1% (w/v) NaCl. The maximum growth (OD600 0.825 ± 0.12) and microbial crude protein (MCP) (178.2 μg/ml) were observed in cells grown in amino acid. The maximum concentration of ammonia (3.96 ± 1.2) was observed in urea containing media and 1.06 mM (26.7% of the produced) remained after 24 h incubation. Activities of urease and glutamine synthase (P < 0.01) and glutamate dehydrogenase (P < 0.05) were significantly different in nitrogen and growth phase. Glutamate synthetase (P < 0.01) was significantly different only at different growth phases. In total, 1246 differentially expressed genes (DEGs) were identified in all nitrogen. Among DEGs, 33 were related to nitrogen metabolism. Their expression correlated with nitrogen sources and the intensity of enzyme activity. This result enhances our understanding of the roles of Succinivibrionaceae in the efficient nitrogen utilization and on environmental protection.
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Affiliation(s)
- Samson Hailemariam
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shengguo Zhao
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jiaqi Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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Proteomic investigation of interhyphal interactions between strains of Agaricus bisporus. Fungal Biol 2020; 124:579-591. [PMID: 32448449 DOI: 10.1016/j.funbio.2020.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/17/2020] [Accepted: 02/19/2020] [Indexed: 11/23/2022]
Abstract
Hyphae of filamentous fungi undergo polar extension, bifurcation and hyphal fusion to form reticulating networks of mycelia. Hyphal fusion or anastomosis, a ubiquitous process among filamentous fungi, is a vital strategy for how fungi expand over their substrate and interact with or recognise self- and non-self hyphae of neighbouring mycelia in their environment. Morphological and genetic characterisation of anastomosis has been studied in many model fungal species, but little is known of the direct proteomic response of two interacting fungal isolates. Agaricus bisporus, the most widely cultivated edible mushroom crop worldwide, was used as an in vitro model to profile the proteomes of interacting cultures. The globally cultivated strain (A15) was paired with two distinct strains; a commercial hybrid strain and a wild isolate strain. Each co-culture presented a different interaction ranging from complete vegetative compatibility (self), lack of interactions, and antagonistic interactions. These incompatible strains are the focus of research into disease-resistance in commercial crops as the spread of intracellular pathogens, namely mycoviruses, is limited by the lack of interhyphal anastomosis. Unique proteomic responses were detected between all co-cultures. An array of cell wall modifying enzymes, plus fungal growth and morphogenesis proteins were found in significantly (P < 0.05) altered abundances. Nitrogen metabolism dominated in the intracellular proteome, with evidence of nitrogen starvation between competing, non-compatible cultures. Changes in key enzymes of A. bisporus morphogenesis were observed, particularly via increased abundance of glucanosyltransferase in competing interactions and certain chitinases in vegetative compatible interactions only. Carbohydrate-active enzyme arsenals are expanded in antagonistic interactions in A. bisporus. Pathways involved in carbohydrate metabolism and genetic information processing were higher in interacting cultures, most notably during self-recognition. New insights into the differential response of interacting strains of A. bisporus will enhance our understanding of potential barriers to viral transmission through vegetative incompatibility. Our results suggest that a differential proteomic response occurs between A. bisporus at strain-level and findings from this work may guide future proteomic investigation of fungal anastomosis.
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Recent advances of pH homeostasis mechanisms in Corynebacterium glutamicum. World J Microbiol Biotechnol 2019; 35:192. [PMID: 31773365 DOI: 10.1007/s11274-019-2770-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022]
Abstract
Corynebacterium glutamicum is generally regarded as a safe microorganism, and widely used in the large-scale production of various amino acids and organic acids, such as L-glutamate, L-lysine and succinic acid. During the process of industrial fermentation, C. glutamicum is usually exposed to varying environmental stresses, such as variations in pH, salinity, temperature, and osmolality. Among them, pH fluctuations are regarded as one of the most frequent environmental stresses in microbial fermentation. In this review, we summarize the current knowledge of pH homeostasis mechanisms adopted by C. glutamicum for coping with low acidic pH and high alkaline pH stresses. Facing with low pH environments, C. glutamicum develops a variety of strategies to maintain intracellular pH homeostasis, such as lowering intracellular reactive oxygen species, the improvement of potassium transport, the regulation of mycothiol-related pathways, as well as the repression of sulfur assimilation. While during alkaline pH stresses, the Mrp-type Na+/H+ antiporters are shown to play a dominant role in conferring C. glutamicum cells resistance to alkaline pH. Furthermore, we also discuss the general strategies and prospects on metabolic engineering of C. glutamicum to improve alkaline or acid resistance.
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Moeller FU, Webster NS, Herbold CW, Behnam F, Domman D, Albertsen M, Mooshammer M, Markert S, Turaev D, Becher D, Rattei T, Schweder T, Richter A, Watzka M, Nielsen PH, Wagner M. Characterization of a thaumarchaeal symbiont that drives incomplete nitrification in the tropical sponge Ianthella basta. Environ Microbiol 2019; 21:3831-3854. [PMID: 31271506 PMCID: PMC6790972 DOI: 10.1111/1462-2920.14732] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 06/14/2019] [Accepted: 06/17/2019] [Indexed: 12/25/2022]
Abstract
Marine sponges represent one of the few eukaryotic groups that frequently harbour symbiotic members of the Thaumarchaeota, which are important chemoautotrophic ammonia-oxidizers in many environments. However, in most studies, direct demonstration of ammonia-oxidation by these archaea within sponges is lacking, and little is known about sponge-specific adaptations of ammonia-oxidizing archaea (AOA). Here, we characterized the thaumarchaeal symbiont of the marine sponge Ianthella basta using metaproteogenomics, fluorescence in situ hybridization, qPCR and isotope-based functional assays. 'Candidatus Nitrosospongia ianthellae' is only distantly related to cultured AOA. It is an abundant symbiont that is solely responsible for nitrite formation from ammonia in I. basta that surprisingly does not harbour nitrite-oxidizing microbes. Furthermore, this AOA is equipped with an expanded set of extracellular subtilisin-like proteases, a metalloprotease unique among archaea, as well as a putative branched-chain amino acid ABC transporter. This repertoire is strongly indicative of a mixotrophic lifestyle and is (with slight variations) also found in other sponge-associated, but not in free-living AOA. We predict that this feature as well as an expanded and unique set of secreted serpins (protease inhibitors), a unique array of eukaryotic-like proteins, and a DNA-phosporothioation system, represent important adaptations of AOA to life within these ancient filter-feeding animals.
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Affiliation(s)
- Florian U. Moeller
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Nicole S. Webster
- Australian Institute of Marine ScienceTownsvilleQueenslandAustralia
- Australian Centre for Ecogenomics, School of Chemistry and Molecular BiosciencesUniversity of QueenslandSt LuciaQueenslandAustralia
| | - Craig W. Herbold
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Faris Behnam
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Daryl Domman
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Mads Albertsen
- Center for Microbial Communities, Department of Chemistry and BioscienceAalborg University9220AalborgDenmark
| | - Maria Mooshammer
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Stephanie Markert
- Institute of Marine Biotechnology e.VGreifswaldGermany
- Institute of Pharmacy, Pharmaceutical BiotechnologyUniversity of GreifswaldGreifswaldGermany
| | - Dmitrij Turaev
- Centre for Microbiology and Environmental Systems Science, Division of Computational Systems BiologyUniversity of ViennaAustria
| | - Dörte Becher
- Institute of Microbiology, Microbial ProteomicsUniversity of GreifswaldGreifswaldGermany
| | - Thomas Rattei
- Centre for Microbiology and Environmental Systems Science, Division of Computational Systems BiologyUniversity of ViennaAustria
| | - Thomas Schweder
- Institute of Marine Biotechnology e.VGreifswaldGermany
- Institute of Pharmacy, Pharmaceutical BiotechnologyUniversity of GreifswaldGreifswaldGermany
| | - Andreas Richter
- Centre for Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem ResearchUniversity of ViennaAustria
| | - Margarete Watzka
- Centre for Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem ResearchUniversity of ViennaAustria
| | - Per Halkjaer Nielsen
- Center for Microbial Communities, Department of Chemistry and BioscienceAalborg University9220AalborgDenmark
| | - Michael Wagner
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
- Center for Microbial Communities, Department of Chemistry and BioscienceAalborg University9220AalborgDenmark
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Bishai WR, Timmins GS. Potential for breath test diagnosis of urease positive pathogens in lung infections. J Breath Res 2019; 13:032002. [DOI: 10.1088/1752-7163/ab2225] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Lu K, Liu Z, Dai R, Gardner WS. Urea dynamics during Lake Taihu cyanobacterial blooms in China. HARMFUL ALGAE 2019; 84:233-243. [PMID: 31128808 DOI: 10.1016/j.hal.2019.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 01/04/2019] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
Lake Taihu, the third largest freshwater lake in China, suffers from harmful cyanobacteria blooms caused by Microcystis spp., which do not fix nitrogen (N). Reduced N (i.e., NH4+, urea and other labile organic N compounds) is an important factor affecting the growth of Microcystis. As the world use of urea as fertilizer has escalated during the past decades, an understanding of how urea cycling relates to blooms of Microcystis is critical to predicting, controlling and alleviating the problem. In this study, the cycling rates of urea-N in Lake Taihu ranged from non-detectable to 1.37 μmol N L-1 h-1 for regeneration, and from 0.042 μmol N L-1 h-1 to 2.27 μmol N L-1 h-1 for potential urea-N removal. The fate of urea-N differed between light and dark incubations. Increased 15NH4+ accumulated and higher quantities of the removed urea-15N remained in the 15NH4+ form were detected in the dark than in the light. A follow-up incubation experiment with 15N-urea confirmed that Microcystis can grow on urea but its effects on urea dynamics were minor, indicating that Microcystis was not the major factor causing the observed fates of urea under different light conditions in Lake Taihu. Bacterial community composition and predicted functional gene data suggested that heterotrophic bacteria metabolized urea, even though Microcystis spp. was the dominant bloom organism.
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Affiliation(s)
- Kaijun Lu
- The University of Texas at Austin, Marine Science Institute, Port Aransas, TX, 78373, USA.
| | - Zhanfei Liu
- The University of Texas at Austin, Marine Science Institute, Port Aransas, TX, 78373, USA
| | - Ruihua Dai
- Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Wayne S Gardner
- The University of Texas at Austin, Marine Science Institute, Port Aransas, TX, 78373, USA
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Ullrich SR, Poehlein A, Levicán G, Mühling M, Schlömann M. Iron targeted transcriptome study draws attention to novel redox protein candidates involved in ferrous iron oxidation in “Ferrovum” sp. JA12. Res Microbiol 2018; 169:618-627. [DOI: 10.1016/j.resmic.2018.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/17/2018] [Accepted: 05/25/2018] [Indexed: 11/28/2022]
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Onetto CA, Grbin PR, McIlroy SJ, Eales KL. Genomic insights into the metabolism of ‘CandidatusDefluviicoccus seviourii’, a member ofDefluviicoccuscluster III abundant in industrial activated sludge. FEMS Microbiol Ecol 2018; 95:5210054. [DOI: 10.1093/femsec/fiy231] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/24/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Cristobal A Onetto
- Department of Wine & Food Science, University of Adelaide, Adelaide 5064, Australia
| | - Paul R Grbin
- Department of Wine & Food Science, University of Adelaide, Adelaide 5064, Australia
| | - Simon J McIlroy
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia 4072, Brisbane, Australia
| | - Kathryn L Eales
- Department of Wine & Food Science, University of Adelaide, Adelaide 5064, Australia
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Dittberner H, Ohlmann N, Acquisti C. Stoichio-Metagenomics of Ocean Waters: A Molecular Evolution Approach to Trace the Dynamics of Nitrogen Conservation in Natural Communities. Front Microbiol 2018; 9:1590. [PMID: 30072968 PMCID: PMC6058095 DOI: 10.3389/fmicb.2018.01590] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/26/2018] [Indexed: 11/21/2022] Open
Abstract
Nitrogen is crucially limiting in ocean surface waters, and its availability varies substantially with coastal regions typically richer in nutrients than open oceans. In a biological stoichiometry framework, a parsimonious strategy of nitrogen allocation predicts nitrogen content of proteins to be lower in communities adapted to open ocean than to coastal regions. To test this hypothesis we have directly interrogated marine microbial communities, using a series of metagenomics datasets with a broad geographical distribution from the Global Ocean Sampling Expedition. Analyzing over 20 million proteins, we document a ubiquitous signal of nitrogen conservation in open ocean communities, both in membrane and non-membrane proteins. Efficient nitrogen allocation is expected to specifically target proteins that are expressed at high rate in response to nitrogen starvation. Furthermore, in order to preserve protein functional efficiency, economic nitrogen allocation is predicted to target primarily the least functionally constrained regions of proteins. Contrasting the NtcA-induced pathway, typically up-regulated in response to nitrogen starvation, with the arginine anabolic pathway, which is instead up-regulated in response to nitrogen abundance, we show how both these predictions are fulfilled. Using evolutionary rates as an informative proxy of functional constraints, we show that variation in nitrogen allocation between open ocean and coastal communities is primarily localized in the least functionally constrained regions of the genes triggered by NtcA. As expected, such a pattern is not detectable in the genes involved in the arginine anabolic pathway. These results directly link environmental nitrogen availability to different adaptive strategies of genome evolution, and emphasize the relevance of the material costs of evolutionary change in natural ecosystems.
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Affiliation(s)
- Hannes Dittberner
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Niklas Ohlmann
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Claudia Acquisti
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
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Shiffman ME, Soo RM, Dennis PG, Morrison M, Tyson GW, Hugenholtz P. Gene and genome-centric analyses of koala and wombat fecal microbiomes point to metabolic specialization for Eucalyptus digestion. PeerJ 2017; 5:e4075. [PMID: 29177117 PMCID: PMC5697889 DOI: 10.7717/peerj.4075] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/31/2017] [Indexed: 01/09/2023] Open
Abstract
The koala has evolved to become a specialist Eucalyptus herbivore since diverging from its closest relative, the wombat, a generalist herbivore. This niche adaptation involves, in part, changes in the gut microbiota. The goal of this study was to compare koala and wombat fecal microbiomes using metagenomics to identify potential differences attributable to dietary specialization. Several populations discriminated between the koala and wombat fecal communities, most notably S24-7 and Synergistaceae in the koala, and Christensenellaceae and RF39 in the wombat. As expected for herbivores, both communities contained the genes necessary for lignocellulose degradation and urea recycling partitioned and redundantly encoded across multiple populations. Secondary metabolism was overrepresented in the koala fecal samples, consistent with the need to process Eucalyptus secondary metabolites. The Synergistaceae population encodes multiple pathways potentially relevant to Eucalyptus compound metabolism, and is predicted to be a key player in detoxification of the koala's diet. Notably, characterized microbial isolates from the koala gut appear to be minor constituents of this habitat, and the metagenomes provide the opportunity for genome-directed isolation of more representative populations. Metagenomic analysis of other obligate and facultative Eucalyptus folivores will reveal whether putatively detoxifying bacteria identified in the koala are shared across these marsupials.
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Affiliation(s)
- Miriam E. Shiffman
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Rochelle M. Soo
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Paul G. Dennis
- School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Australia
| | - Mark Morrison
- The University of Queensland Diamantina Institute, Translational Research Institute, The University of Queensland, Brisbane, Australia
| | - Gene W. Tyson
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
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Brown NM, Mueller RS, Shepardson JW, Landry ZC, Morré JT, Maier CS, Hardy FJ, Dreher TW. Structural and functional analysis of the finished genome of the recently isolated toxic Anabaena sp. WA102. BMC Genomics 2016; 17:457. [PMID: 27296936 PMCID: PMC4907049 DOI: 10.1186/s12864-016-2738-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 05/12/2016] [Indexed: 11/29/2022] Open
Abstract
Background Very few closed genomes of the cyanobacteria that commonly produce toxic blooms in lakes and reservoirs are available, limiting our understanding of the properties of these organisms. A new anatoxin-a-producing member of the Nostocaceae, Anabaena sp. WA102, was isolated from a freshwater lake in Washington State, USA, in 2013 and maintained in non-axenic culture. Results The Anabaena sp. WA102 5.7 Mbp genome assembly has been closed with long-read, single-molecule sequencing and separately a draft genome assembly has been produced with short-read sequencing technology. The closed and draft genome assemblies are compared, showing a correlation between long repeats in the genome and the many gaps in the short-read assembly. Anabaena sp. WA102 encodes anatoxin-a biosynthetic genes, as does its close relative Anabaena sp. AL93 (also introduced in this study). These strains are distinguished by differences in the genes for light-harvesting phycobilins, with Anabaena sp. AL93 possessing a phycoerythrocyanin operon. Biologically relevant structural variants in the Anabaena sp. WA102 genome were detected only by long-read sequencing: a tandem triplication of the anaBCD promoter region in the anatoxin-a synthase gene cluster (not triplicated in Anabaena sp. AL93) and a 5-kbp deletion variant present in two-thirds of the population. The genome has a large number of mobile elements (160). Strikingly, there was no synteny with the genome of its nearest fully assembled relative, Anabaena sp. 90. Conclusion Structural and functional genome analyses indicate that Anabaena sp. WA102 has a flexible genome. Genome closure, which can be readily achieved with long-read sequencing, reveals large scale (e.g., gene order) and local structural features that should be considered in understanding genome evolution and function. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2738-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nathan M Brown
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, 97331, OR, USA
| | - Ryan S Mueller
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, 97331, OR, USA
| | - Jonathan W Shepardson
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, 97331, OR, USA
| | - Zachary C Landry
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, 97331, OR, USA
| | - Jeffrey T Morré
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, 97331, OR, USA
| | - Claudia S Maier
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, 97331, OR, USA
| | - F Joan Hardy
- Office of Environmental Public Health Sciences, Washington State Department of Health, Olympia, 98504, WA, USA
| | - Theo W Dreher
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, 97331, OR, USA. .,Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA.
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Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus Nitrospira. Proc Natl Acad Sci U S A 2015; 112:11371-6. [PMID: 26305944 DOI: 10.1073/pnas.1506533112] [Citation(s) in RCA: 273] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrospira are a diverse group of nitrite-oxidizing bacteria and among the environmentally most widespread nitrifiers. However, they remain scarcely studied and mostly uncultured. Based on genomic and experimental data from Nitrospira moscoviensis representing the ubiquitous Nitrospira lineage II, we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate, with or without concomitant nitrite oxidation, using oxygen, nitrate, or both compounds as terminal electron acceptors. Compared with Nitrospira defluvii from lineage I, N. moscoviensis shares the Nitrospira core metabolism but shows substantial genomic dissimilarity including genes for adaptations to elevated oxygen concentrations. Reciprocal feeding and metabolic versatility, including the participation in different nitrogen cycling processes, likely are key factors for the niche partitioning, the ubiquity, and the high diversity of Nitrospira in natural and engineered ecosystems.
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Anaerobic growth of Corynebacterium glutamicum via mixed-acid fermentation. Appl Environ Microbiol 2015; 81:7496-508. [PMID: 26276118 DOI: 10.1128/aem.02413-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 08/11/2015] [Indexed: 01/01/2023] Open
Abstract
Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions.
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Dmytrenko O, Russell SL, Loo WT, Fontanez KM, Liao L, Roeselers G, Sharma R, Stewart FJ, Newton ILG, Woyke T, Wu D, Lang JM, Eisen JA, Cavanaugh CM. The genome of the intracellular bacterium of the coastal bivalve, Solemya velum: a blueprint for thriving in and out of symbiosis. BMC Genomics 2014; 15:924. [PMID: 25342549 PMCID: PMC4287430 DOI: 10.1186/1471-2164-15-924] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 09/23/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Symbioses between chemoautotrophic bacteria and marine invertebrates are rare examples of living systems that are virtually independent of photosynthetic primary production. These associations have evolved multiple times in marine habitats, such as deep-sea hydrothermal vents and reducing sediments, characterized by steep gradients of oxygen and reduced chemicals. Due to difficulties associated with maintaining these symbioses in the laboratory and culturing the symbiotic bacteria, studies of chemosynthetic symbioses rely heavily on culture independent methods. The symbiosis between the coastal bivalve, Solemya velum, and its intracellular symbiont is a model for chemosynthetic symbioses given its accessibility in intertidal environments and the ability to maintain it under laboratory conditions. To better understand this symbiosis, the genome of the S. velum endosymbiont was sequenced. RESULTS Relative to the genomes of obligate symbiotic bacteria, which commonly undergo erosion and reduction, the S. velum symbiont genome was large (2.7 Mb), GC-rich (51%), and contained a large number (78) of mobile genetic elements. Comparative genomics identified sets of genes specific to the chemosynthetic lifestyle and necessary to sustain the symbiosis. In addition, a number of inferred metabolic pathways and cellular processes, including heterotrophy, branched electron transport, and motility, suggested that besides the ability to function as an endosymbiont, the bacterium may have the capacity to live outside the host. CONCLUSIONS The physiological dexterity indicated by the genome substantially improves our understanding of the genetic and metabolic capabilities of the S. velum symbiont and the breadth of niches the partners may inhabit during their lifecycle.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Jonathan A Eisen
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, 4081 Biological Laboratories, Cambridge, MA 02138, USA.
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Kwak MJ, Jeong H, Madhaiyan M, Lee Y, Sa TM, Oh TK, Kim JF. Genome information of Methylobacterium oryzae, a plant-probiotic methylotroph in the phyllosphere. PLoS One 2014; 9:e106704. [PMID: 25211235 PMCID: PMC4161386 DOI: 10.1371/journal.pone.0106704] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/31/2014] [Indexed: 11/19/2022] Open
Abstract
Pink-pigmented facultative methylotrophs in the Rhizobiales are widespread in the environment, and many Methylobacterium species associated with plants produce plant growth-promoting substances. To gain insights into the life style at the phyllosphere and the genetic bases of plant growth promotion, we determined and analyzed the complete genome sequence of Methylobacterium oryzae CBMB20T, a strain isolated from rice stem. The genome consists of a 6.29-Mb chromosome and four plasmids, designated as pMOC1 to pMOC4. Among the 6,274 coding sequences in the chromosome, the bacterium has, besides most of the genes for the central metabolism, all of the essential genes for the assimilation and dissimilation of methanol that are either located in methylotrophy islands or dispersed. M. oryzae is equipped with several kinds of genes for adaptation to plant surfaces such as defense against UV radiation, oxidative stress, desiccation, or nutrient deficiency, as well as high proportion of genes related to motility and signaling. Moreover, it has an array of genes involved in metabolic pathways that may contribute to promotion of plant growth; they include auxin biosynthesis, cytokine biosynthesis, vitamin B12 biosynthesis, urea metabolism, biosorption of heavy metals or decrease of metal toxicity, pyrroloquinoline quinone biosynthesis, 1-aminocyclopropane-1-carboxylate deamination, phosphate solubilization, and thiosulfate oxidation. Through the genome analysis of M. oryzae, we provide information on the full gene complement of M. oryzae that resides in the aerial parts of plants and enhances plant growth. The plant-associated lifestyle of M. oryzae pertaining to methylotrophy and plant growth promotion, and its potential as a candidate for a bioinoculant targeted to the phyllosphere and focused on phytostimulation are illuminated.
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Affiliation(s)
- Min-Jung Kwak
- Department of Systems Biology, and Division of Life Sciences, Yonsei University, Seodaemun-gu, Seoul, Republic of Korea
- Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea
- Biosystems and Bioengineering Program, University of Science and Technology, Yuseong-gu, Daejeon, Republic of Korea
| | - Haeyoung Jeong
- Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea
| | - Munusamy Madhaiyan
- Department of Agricultural Chemistry, Chungbuk National University, Heungdeok-gu, Cheongju, Republic of Korea
- Biomaterials and Biocatalysts Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Yi Lee
- Department of Industrial Plant Science and Technology, Chungbuk National University, Heungdeok-gu, Cheongju, Republic of Korea
| | - Tong-Min Sa
- Department of Agricultural Chemistry, Chungbuk National University, Heungdeok-gu, Cheongju, Republic of Korea
| | - Tae Kwang Oh
- Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea
- 21C Frontier Microbial Genomics and Applications Center, Yuseong-gu, Daejeon, Republic of Korea
| | - Jihyun F. Kim
- Department of Systems Biology, and Division of Life Sciences, Yonsei University, Seodaemun-gu, Seoul, Republic of Korea
- Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea
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Hoffmann J, Altenbuchner J. Hyaluronic acid production with Corynebacterium glutamicum: effect of media composition on yield and molecular weight. J Appl Microbiol 2014; 117:663-78. [PMID: 24863652 DOI: 10.1111/jam.12553] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/19/2014] [Accepted: 05/19/2014] [Indexed: 02/02/2023]
Abstract
AIMS Corynebacterium glutamicum was tested as an alternative host for heterologous production of hyaluronic acid (HA). METHODS AND RESULTS A set of expression vectors containing hasA, encoding HA synthase from Streptococcus equi subsp. zooepidemicus, alone or in combination with genes encoding enzymes for HA precursor production (hasB, hasC, glmU from Pseudomonas putida KT2440) or bacterial haemoglobin (vgb from Vitreoscilla sp.) was constructed. Recombinant Coryne. glutamicum strains were cultivated in two different minimal media, CGXII and MEK700. HA was isolated from the culture broth by ethanol precipitation or ultrafiltration. Analyses of the isolated HA revealed that overall production was higher in CGXII medium (1241 mg l(-1)) than in MEK700 medium (363 mg l(-1)), but molecular weight of the product was higher in MEK700 (>1·4 MDa) than in CGXII (<270 kDa). Coexpression of hasB, hasC or glmU had no effect on HA yield and did not improve molecular weight of the product. Coexpression of vgb lowered HA yield about 1·5-fold and did not affect molecular weight of the product. Microscopy of negative-stained cultures revealed that Coryne. glutamicum produces no distinct HA capsule. CONCLUSIONS Regulation of cell growth and gene expression level of hasA are reasonable starting points for controlling the molecular weight of HA produced by Coryne. glutamicum. SIGNIFICANCE AND IMPACT OF THE STUDY Corynebacterium glutamicum has a great potential as an alternative production host for HA. The fact that Coryne. glutamicum produces no distinct HA capsule facilitates HA isolation and improves overall yield.
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Affiliation(s)
- J Hoffmann
- Institute of Industrial Genetics, University of Stuttgart, Stuttgart, Germany
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Abstract
Urea is exploited as a nitrogen source by bacteria, and its breakdown products, ammonia and bicarbonate, are employed to counteract stomach acidity in pathogens such as Helicobacter pylori. Uptake in the latter is mediated by UreI, a UAC (urea amide channel) family member. In the present paper, we describe the structure and function of UACBc, a homologue from Bacillus cereus. The purified channel was found to be permeable not only to urea, but also to other small amides. CD and IR spectroscopy revealed a structure comprising mainly α-helices, oriented approximately perpendicular to the membrane. Consistent with this finding, site-directed fluorescent labelling indicated the presence of seven TM (transmembrane) helices, with a cytoplasmic C-terminus. In detergent, UACBc exists largely as a hexamer, as demonstrated by both cross-linking and size-exclusion chromatography. A 9 Å (1 Å=0.1 nm) resolution projection map obtained by cryo-electron microscopy of two-dimensional crystals shows that the six protomers are arranged in a planar hexameric ring. Each exhibits six density features attributable to TM helices, surrounding a putative central channel, while an additional helix is peripherally located. Bioinformatic analyses allowed individual TM regions to be tentatively assigned to the density features, with the resultant model enabling identification of residues likely to contribute to channel function.
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Hasselt K, Rankl S, Worsch S, Burkovski A. Adaptation of AmtR-controlled gene expression by modulation of AmtR binding activity in Corynebacterium glutamicum. J Biotechnol 2011; 154:156-62. [DOI: 10.1016/j.jbiotec.2010.09.930] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 09/06/2010] [Accepted: 09/10/2010] [Indexed: 11/28/2022]
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Poetsch A, Haussmann U, Burkovski A. Proteomics of corynebacteria: From biotechnology workhorses to pathogens. Proteomics 2011; 11:3244-55. [PMID: 21674800 DOI: 10.1002/pmic.201000786] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/07/2011] [Accepted: 03/08/2011] [Indexed: 11/09/2022]
Abstract
Corynebacteria belong to the high G+C Gram-positive bacteria (Actinobacteria) and are closely related to Mycobacterium and Nocardia species. The best investigated member of this group of almost seventy species is Corynebacterium glutamicum, a soil bacterium isolated in 1957, which is used for the industrial production of more than two million tons of amino acids per year. This review focuses on the technical advances made in proteomics approaches during the last years and summarizes applications of these techniques with respect to C. glutamicum metabolic pathways and stress response. Additionally, selected proteome applications for other biotechnologically important or pathogenic corynebacteria are described.
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Affiliation(s)
- Ansgar Poetsch
- Lehrstuhl Biochemie der Pflanzen, Ruhr-Universität Bochum, Germany
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Cretenet M, Nouaille S, Thouin J, Rault L, Stenz L, François P, Hennekinne JA, Piot M, Maillard MB, Fauquant J, Loubière P, Le Loir Y, Even S. Staphylococcus aureus virulence and metabolism are dramatically affected by Lactococcus lactis in cheese matrix. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:340-351. [PMID: 23761280 DOI: 10.1111/j.1758-2229.2010.00230.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In complex environments such as cheeses, the lack of relevant information on the physiology and virulence expression of pathogenic bacteria and the impact of endogenous microbiota has hindered progress in risk assessment and control. Here, we investigated the behaviour of Staphylococcus aureus, a major foodborne pathogen, in a cheese matrix, either alone or in the presence of Lactococcus lactis, as a dominant species of cheese ecosystems. The dynamics of S. aureus was explored in situ by coupling a microbiological and, for the first time, a transcriptomic approach. Lactococcus lactis affected the carbohydrate and nitrogen metabolisms and the stress response of S. aureus by acidifying, proteolysing and decreasing the redox potential of the cheese matrix. Enterotoxin expression was positively or negatively modulated by both L. lactis and the cheese matrix itself, depending on the enterotoxin type. Among the main enterotoxins involved in staphylococcal food poisoning, sea expression was slightly favoured in the presence of L. lactis, whereas a strong repression of sec4 was observed in cheese matrix, even in the absence of L. lactis, and correlated with a reduced saeRS expression. Remarkably, the agr system was downregulated by the presence of L. lactis, in part because of the decrease in pH. This study highlights the intimate link between environment, metabolism and virulence, as illustrated by the influence of the cheese matrix context, including the presence of L. lactis, on two major virulence regulators, the agr system and saeRS.
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Affiliation(s)
- Marina Cretenet
- INRA, UMR1253 STLO, 85 rue de Saint Brieuc, F-35000 Rennes, France. Agrocampus Ouest, UMR1253 STLO, 85 rue de Saint Brieuc, F-35000 Rennes, France. Université de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France. INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France. CNRS, UMR5504, F-31400 Toulouse, France. Genomic Research Laboratory, University of Geneva Hospitals, Rue Gabrielle-Perret-Gentil, 4 CH-1211 Geneva 14, Switzerland. University Medical Center, Department of Microbiology and Molecular Medicine, CH-1211 Geneva 4, Switzerland. Laboratory for Study and Research on Quality of Food and on Food Processes, French Agency for Food Safety (AFSSA-lerqap), National and Community Reference Laboratory, 94704 Maisons-Alfort cedex, France
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Pedrosa FO, Monteiro RA, Wassem R, Cruz LM, Ayub RA, Colauto NB, Fernandez MA, Fungaro MHP, Grisard EC, Hungria M, Madeira HMF, Nodari RO, Osaku CA, Petzl-Erler ML, Terenzi H, Vieira LGE, Steffens MBR, Weiss VA, Pereira LFP, Almeida MIM, Alves LR, Marin A, Araujo LM, Balsanelli E, Baura VA, Chubatsu LS, Faoro H, Favetti A, Friedermann G, Glienke C, Karp S, Kava-Cordeiro V, Raittz RT, Ramos HJO, Ribeiro EMSF, Rigo LU, Rocha SN, Schwab S, Silva AG, Souza EM, Tadra-Sfeir MZ, Torres RA, Dabul ANG, Soares MAM, Gasques LS, Gimenes CCT, Valle JS, Ciferri RR, Correa LC, Murace NK, Pamphile JA, Patussi EV, Prioli AJ, Prioli SMA, Rocha CLMSC, Arantes OMN, Furlaneto MC, Godoy LP, Oliveira CEC, Satori D, Vilas-Boas LA, Watanabe MAE, Dambros BP, Guerra MP, Mathioni SM, Santos KL, Steindel M, Vernal J, Barcellos FG, Campo RJ, Chueire LMO, Nicolás MF, Pereira-Ferrari L, Silva JLDC, Gioppo NMR, Margarido VP, Menck-Soares MA, Pinto FGS, Simão RDCG, Takahashi EK, Yates MG, Souza EM. Genome of Herbaspirillum seropedicae strain SmR1, a specialized diazotrophic endophyte of tropical grasses. PLoS Genet 2011; 7:e1002064. [PMID: 21589895 PMCID: PMC3093359 DOI: 10.1371/journal.pgen.1002064] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 03/18/2011] [Indexed: 01/28/2023] Open
Abstract
The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme--GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species.
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Abstract
Urea transport proteins were initially proposed to exist in the kidney in the late 1980s when studies of urea permeability revealed values in excess of those predicted by simple lipid-phase diffusion and paracellular transport. Less than a decade later, the first urea transporter was cloned. Currently, the SLC14A family of urea transporters contains two major subgroups: SLC14A1, the UT-B urea transporter originally isolated from erythrocytes; and SLC14A2, the UT-A group with six distinct isoforms described to date. In the kidney, UT-A1 and UT-A3 are found in the inner medullary collecting duct; UT-A2 is located in the thin descending limb, and UT-B is located primarily in the descending vasa recta; all are glycoproteins. These transporters are crucial to the kidney's ability to concentrate urine. UT-A1 and UT-A3 are acutely regulated by vasopressin. UT-A1 has also been shown to be regulated by hypertonicity, angiotensin II, and oxytocin. Acute regulation of these transporters is through phosphorylation. Both UT-A1 and UT-A3 rapidly accumulate in the plasma membrane in response to stimulation by vasopressin or hypertonicity. Long-term regulation involves altering protein abundance in response to changes in hydration status, low protein diets, adrenal steroids, sustained diuresis, or antidiuresis. Urea transporters have been studied using animal models of disease including diabetes mellitus, lithium intoxication, hypertension, and nephrotoxic drug responses. Exciting new animal models are being developed to study these transporters and search for active urea transporters. Here we introduce urea and describe the current knowledge of the urea transporter proteins, their regulation, and their role in the kidney.
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Affiliation(s)
- Janet D Klein
- Renal Division, Department of Medicine, Emory University, Atlanta, Georgia, USA
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Eitinger T, Rodionov DA, Grote M, Schneider E. Canonical and ECF-type ATP-binding cassette importers in prokaryotes: diversity in modular organization and cellular functions. FEMS Microbiol Rev 2011; 35:3-67. [PMID: 20497229 DOI: 10.1111/j.1574-6976.2010.00230.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Thomas Eitinger
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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Rehm N, Georgi T, Hiery E, Degner U, Schmiedl A, Burkovski A, Bott M. l-Glutamine as a nitrogen source for Corynebacterium glutamicum: derepression of the AmtR regulon and implications for nitrogen sensing. Microbiology (Reading) 2010; 156:3180-3193. [DOI: 10.1099/mic.0.040667-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Corynebacterium glutamicum, a Gram-positive soil bacterium employed in the industrial production of various amino acids, is able to use a number of different nitrogen sources, such as ammonium, urea or creatinine. This study shows that l-glutamine serves as an excellent nitrogen source for C. glutamicum and allows similar growth rates in glucose minimal medium to those in ammonium. A transcriptome comparison revealed that the nitrogen starvation response was elicited when glutamine served as the sole nitrogen source, meaning that the target genes of the global nitrogen regulator AmtR were derepressed. Subsequent growth experiments with a variety of mutants defective in nitrogen metabolism showed that glutamate synthase is crucial for glutamine utilization, while a putative glutaminase is dispensable under the experimental conditions used. The gltBD operon encoding the glutamate synthase is a member of the AmtR regulon. The observation that the nitrogen starvation response was elicited at high intracellular l-glutamine levels has implications for nitrogen sensing. In contrast with other Gram-positive and Gram-negative bacteria such as Bacillus subtilis, Salmonella enterica serovar Typhimurium and Klebsiella pneumoniae, a drop in glutamine concentration obviously does not serve as a nitrogen starvation signal in C. glutamicum.
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Affiliation(s)
- Nadine Rehm
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Tobias Georgi
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Eva Hiery
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Ursula Degner
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Alfred Schmiedl
- Lehrstuhl für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Andreas Burkovski
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Michael Bott
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
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Schröder J, Tauch A. Transcriptional regulation of gene expression inCorynebacterium glutamicum: the role of global, master and local regulators in the modular and hierarchical gene regulatory network. FEMS Microbiol Rev 2010; 34:685-737. [DOI: 10.1111/j.1574-6976.2010.00228.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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45
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Selengut JD, Rusch DB, Haft DH. Sites Inferred by Metabolic Background Assertion Labeling (SIMBAL): adapting the Partial Phylogenetic Profiling algorithm to scan sequences for signatures that predict protein function. BMC Bioinformatics 2010; 11:52. [PMID: 20102603 PMCID: PMC3098086 DOI: 10.1186/1471-2105-11-52] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 01/26/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Comparative genomics methods such as phylogenetic profiling can mine powerful inferences from inherently noisy biological data sets. We introduce Sites Inferred by Metabolic Background Assertion Labeling (SIMBAL), a method that applies the Partial Phylogenetic Profiling (PPP) approach locally within a protein sequence to discover short sequence signatures associated with functional sites. The approach is based on the basic scoring mechanism employed by PPP, namely the use of binomial distribution statistics to optimize sequence similarity cutoffs during searches of partitioned training sets. RESULTS Here we illustrate and validate the ability of the SIMBAL method to find functionally relevant short sequence signatures by application to two well-characterized protein families. In the first example, we partitioned a family of ABC permeases using a metabolic background property (urea utilization). Thus, the TRUE set for this family comprised members whose genome of origin encoded a urea utilization system. By moving a sliding window across the sequence of a permease, and searching each subsequence in turn against the full set of partitioned proteins, the method found which local sequence signatures best correlated with the urea utilization trait. Mapping of SIMBAL "hot spots" onto crystal structures of homologous permeases reveals that the significant sites are gating determinants on the cytosolic face rather than, say, docking sites for the substrate-binding protein on the extracellular face. In the second example, we partitioned a protein methyltransferase family using gene proximity as a criterion. In this case, the TRUE set comprised those methyltransferases encoded near the gene for the substrate RF-1. SIMBAL identifies sequence regions that map onto the substrate-binding interface while ignoring regions involved in the methyltransferase reaction mechanism in general. Neither method for training set construction requires any prior experimental characterization. CONCLUSIONS SIMBAL shows that, in functionally divergent protein families, selected short sequences often significantly outperform their full-length parent sequence for making functional predictions by sequence similarity, suggesting avenues for improved functional classifiers. When combined with structural data, SIMBAL affords the ability to localize and model functional sites.
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Affiliation(s)
- Jeremy D Selengut
- J, Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850, USA.
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Godara G, Smith C, Bosse J, Zeidel M, Mathai J. Functional characterization of Actinobacillus pleuropneumoniae urea transport protein, ApUT. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1268-73. [PMID: 19144751 DOI: 10.1152/ajpregu.90726.2008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Urea transporters (UTs) effect rapid flux of urea across biological membranes. In the mammalian kidney, UT activity is essential for effective urine concentration. In bacteria, UT-mediated urea uptake permits intracellular urease to degrade urea to ammonia and CO(2), a process that either buffers acid loads or provides nutrient nitrogen. We have characterized the urea transport channel protein ApUT from Actinobacillus pleuropneumoniae. Kinetic analysis of bacterial inside-out membranes enriched in ApUT showed approximately 28-fold increase in urea permeability (3.3 +/- 0.4 x 10(-4) cm/s) compared with control vesicles (0.11 +/- 0.02 x 10(-4) cm/s). In addition to urea, ApUT also conducts water. Urea and water transport across the channel was phloretin and mercury inhibitable, and the site of inhibition may be located on the cytoplasmic side of the protein. Glycerol and urea analogs, such as methylamine, dimethylurea, formamide, acetamide, methylurea, propanamide, and ethylamine did not permeate across ApUT.
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Affiliation(s)
- Geeta Godara
- Beth Israel Deaconess Medical Center, Cambridge, MA 02139, USA
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47
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Buchinger S, Strösser J, Rehm N, Hänssler E, Hans S, Bathe B, Schomburg D, Krämer R, Burkovski A. A combination of metabolome and transcriptome analyses reveals new targets of the Corynebacterium glutamicum nitrogen regulator AmtR. J Biotechnol 2008; 140:68-74. [PMID: 19041910 DOI: 10.1016/j.jbiotec.2008.10.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Revised: 09/30/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
Abstract
The effects of a deletion of the amtR gene, encoding the master regulator of nitrogen control in Corynebacterium glutamicum, were investigated by metabolome and transcriptome analyses. Compared to the wild type, different metabolite patterns were observed in respect to glycolysis, pentose phosphate pathway, citric acid cycle, and most amino acid pools. Not all of these alterations could be attributed to changes at the level of mRNA and must be caused by posttranscriptional regulatory processes. However, subsequently carried out transcriptome analyses, which were confirmed by gel retardation experiments, revealed two new targets of AmtR, the dapD gene, encoding succinylase involved in m-diaminopimelate synthesis, and the mez gene, coding for malic enzyme. The regulation of dapD connects the AmtR-dependent nitrogen control with l-lysine biosynthesis, the regulation of mez with carbon metabolism. An increased l-glutamine pool in the amtR mutant compared to the wild type was correlated with deregulated expression of the AmtR-regulated glnA gene and an increased glutamine synthetase activity. The glutamate pool was decreased in the mutant and also glutamate excretion was impaired.
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48
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Li L, Wada M, Yokota A. Cytoplasmic proteome reference map for a glutamic acid-producing Corynebacterium glutamicum ATCC 14067. Proteomics 2008; 7:4317-22. [PMID: 18040983 DOI: 10.1002/pmic.200700269] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We constructed a cytoplasmic proteome reference map for a glutamic acid producing Corynebacterium glutamicum ATCC 14067 by 2-DE and protein identification by MALDI-TOF-MS and PMF using genome database of the type strain ATCC 13032. The map allowed us to identify 166 protein spots representing 139 different proteins. A considerable strain difference was observed in the proteomic images between strains ATCC 14067 and ATCC 13032 grown under the glutamic acid production conditions, suggesting the importance of strain-specific reference map for proteomic analysis.
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Affiliation(s)
- Liyuan Li
- Laboratory of Microbial Physiology, Division of Applied Bioscience, Research Faculty of Agriculture, Hokkaido University, Hokkaido, Japan
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49
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Tauch A, Trost E, Tilker A, Ludewig U, Schneiker S, Goesmann A, Arnold W, Bekel T, Brinkrolf K, Brune I, Götker S, Kalinowski J, Kamp PB, Lobo FP, Viehoever P, Weisshaar B, Soriano F, Dröge M, Pühler A. The lifestyle of Corynebacterium urealyticum derived from its complete genome sequence established by pyrosequencing. J Biotechnol 2008; 136:11-21. [PMID: 18367281 DOI: 10.1016/j.jbiotec.2008.02.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 12/11/2007] [Accepted: 02/07/2008] [Indexed: 01/11/2023]
Abstract
Corynebacterium urealyticum is a lipid-requiring, urealytic bacterium of the human skin flora that has been recognized as causative agent of urinary tract infections. We report the analysis of the complete genome sequence of C. urealyticum DSM7109, which was initially recovered from a patient with alkaline-encrusted cystitis. The genome sequence was determined by a combination of pyrosequencing and Sanger technology. The chromosome of C. urealyticum DSM7109 has a size of 2,369,219bp and contains 2024 predicted coding sequences, of which 78% were considered as orthologous with genes in the Corynebacterium jeikeium K411 genome. Metabolic analysis of the lipid-requiring phenotype revealed the absence of a fatty acid synthase gene and the presence of a beta-oxidation pathway along with a large repertoire of auxillary genes for the degradation of exogenous fatty acids. A urease locus with the gene order ureABCEFGD may play a pivotal role in virulence of C. urealyticum by the alkalinization of human urine and the formation of struvite stones. Multidrug resistance of C. urealyticum DSM7109 is mediated by transposable elements, conferring resistances to macrolides, lincosamides, ketolides, aminoglycosides, chloramphenicol, and tetracycline. The complete genome sequence of C. urealyticum revealed a detailed picture of the lifestyle of this opportunistic human pathogen.
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Affiliation(s)
- Andreas Tauch
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany.
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Characterization and regulation of PiDur3, a permease involved in the acquisition of urea by the ectomycorrhizal fungus Paxillus involutus. Fungal Genet Biol 2008; 45:912-21. [PMID: 18313954 DOI: 10.1016/j.fgb.2008.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 01/08/2008] [Accepted: 01/13/2008] [Indexed: 11/20/2022]
Abstract
Urea, which is known to be a source of nitrogen for the growth of many organisms, represents an important fertilizer in forest soils. Since most trees form symbiotic associations with ectomycorrhizal fungi, the capacities of these symbionts to take up and assimilate urea would determine the efficiency of urea nitrogen salvaging by plants. We showed that Paxillusinvolutus, an ectomycorrhizal basidiomycete, is capable of using urea as sole nitrogen source. We report the molecular characterization of an active urea transporter (PiDur3) isolated from this fungus. We demonstrated that the import of urea is a minor event on ammonium condition, since the expression of PiDUR3 is repressed by the high intracellular glutamine pool. Interestingly, on urea nutritive condition, the uptake of urea is rather mediated by the intracellular urea pool and particularly by urease efficiency.
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