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Genomic Insights into Omega-3 Polyunsaturated Fatty Acid Producing Shewanella sp. N2AIL from Fish Gut. BIOLOGY 2022; 11:biology11050632. [PMID: 35625360 PMCID: PMC9138089 DOI: 10.3390/biology11050632] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/09/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022]
Abstract
The genus Shewanella is widely distributed in niches ranging from an aquatic environment to spoiled fish and is loaded with various ecologically and commercially important metabolites. Bacterial species under this genus find application in bioelectricity generation and bioremediation due to their capability to use pollutants as the terminal electron acceptor and could produce health-beneficial omega-3 fatty acids, particularly eicosapentaenoic acid (EPA). Here, the genome sequence of an EPA-producing bacterium, Shewanella sp. N2AIL, isolated from the gastrointestinal tract of Tilapia fish, is reported. The genome size of the strain was 4.8 Mb with a GC content of 46.3% containing 4385 protein-coding genes. Taxonogenomic analysis assigned this strain to the genus Shewanella on the basis of average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH), phylogenetically most closely related with S. baltica NCTC 10735T. The comparative genome analysis with the type strain of S. baltica revealed 693 unique genes in the strain N2AIL, highlighting the variation at the strain level. The genes associated with stress adaptation, secondary metabolite production, antibiotic resistance, and metal reduction were identified in the genome suggesting the potential of the bacterium to be explored as an industrially important strain. PUFA synthase gene cluster of size ~20.5 kb comprising all the essential domains for EPA biosynthesis arranged in five ORFs was also identified in the strain N2AIL. The study provides genomic insights into the diverse genes of Shewanella sp. N2AIL, which is particularly involved in adaptation strategies and prospecting secondary metabolite potential, specifically the biosynthesis of omega-3 polyunsaturated fatty acids.
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Li Y, Sun XM, Dang YR, Liu NH, Qin QL, Zhang YQ, Zhang XY. Genomic analysis of Marinomonas profundi M1K-6T reveals its adaptation to deep-sea environment of the Mariana Trench. Mar Genomics 2022; 62:100935. [DOI: 10.1016/j.margen.2022.100935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 11/26/2022]
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Shen L, Zhang S, Chen G. Regulated strategies of cold-adapted microorganisms in response to cold: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:68006-68024. [PMID: 34648167 DOI: 10.1007/s11356-021-16843-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
There are a large number of active cold-adapted microorganisms in the perennial cold environment. Due to their high-efficiency and energy-saving catalytic properties, cold-adapted microorganisms have become valuable natural resources with potential in various biological fields. In this study, a series of cold response strategies for microorganisms were summarized. This mainly involves the regulation of cell membrane fluidity, synthesis of cold adaptation proteins, regulators and metabolic changes, energy supply, and reactive oxygen species. Also, the potential of biocatalysts produced by cold-adapted microorganisms including cold-active enzymes, ice-binding proteins, polyhydroxyalkanoates, and surfactants was introduced, which provided a guidance for expanding its application values. Overall, new insights were obtained on response strategies of microorganisms to cold environments in this review. This will deepen the understanding of the cold tolerance mechanism of cold-adapted microorganisms, thus promoting the establishment and application of low-temperature biotechnology.
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Affiliation(s)
- Lijun Shen
- College of Life Sciences, Jilin Agricultural University, Changchun, China
- Key Laboratory of Straw Biology and Utilization, The Ministry of Education, Changchun, China
| | - Sitong Zhang
- College of Life Sciences, Jilin Agricultural University, Changchun, China.
- Key Laboratory of Straw Biology and Utilization, The Ministry of Education, Changchun, China.
| | - Guang Chen
- College of Life Sciences, Jilin Agricultural University, Changchun, China.
- Key Laboratory of Straw Biology and Utilization, The Ministry of Education, Changchun, China.
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Biotechnological and Ecological Potential of Micromonospora provocatoris sp. nov., a Gifted Strain Isolated from the Challenger Deep of the Mariana Trench. Mar Drugs 2021; 19:md19050243. [PMID: 33923039 PMCID: PMC8146288 DOI: 10.3390/md19050243] [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: 03/30/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/24/2022] Open
Abstract
A Micromonospora strain, isolate MT25T, was recovered from a sediment collected from the Challenger Deep of the Mariana Trench using a selective isolation procedure. The isolate produced two major metabolites, n-acetylglutaminyl glutamine amide and desferrioxamine B, the chemical structures of which were determined using 1D and 2D-NMR, including 1H-15N HSQC and 1H-15N HMBC 2D-NMR, as well as high resolution MS. A whole genome sequence of the strain showed the presence of ten natural product-biosynthetic gene clusters, including one responsible for the biosynthesis of desferrioxamine B. Whilst 16S rRNA gene sequence analyses showed that the isolate was most closely related to the type strain of Micromonospora chalcea, a whole genome sequence analysis revealed it to be most closely related to Micromonospora tulbaghiae 45142T. The two strains were distinguished using a combination of genomic and phenotypic features. Based on these data, it is proposed that strain MT25T (NCIMB 15245T, TISTR 2834T) be classified as Micromonospora provocatoris sp. nov. Analysis of the genome sequence of strain MT25T (genome size 6.1 Mbp) revealed genes predicted to responsible for its adaptation to extreme environmental conditions that prevail in deep-sea sediments.
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Whole Genome Sequence of Dermacoccus abyssi MT1.1 Isolated from the Challenger Deep of the Mariana Trench Reveals Phenazine Biosynthesis Locus and Environmental Adaptation Factors. Mar Drugs 2020; 18:md18030131. [PMID: 32106586 PMCID: PMC7143476 DOI: 10.3390/md18030131] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 12/21/2022] Open
Abstract
Dermacoccus abyssi strain MT1.1T is a piezotolerant actinobacterium that was isolated from Mariana Trench sediment collected at a depth of 10898 m. The organism was found to produce ten dermacozines (A‒J) that belonged to a new phenazine family and which displayed various biological activities such as radical scavenging and cytotoxicity. Here, we report on the isolation and identification of a new dermacozine compound, dermacozine M, the chemical structure of which was determined using 1D and 2D-NMR, and high resolution MS. A whole genome sequence of the strain contained six secondary metabolite-biosynthetic gene clusters (BGCs), including one responsible for the biosynthesis of a family of phenazine compounds. A pathway leading to the biosynthesis of dermacozines is proposed. Bioinformatic analyses of key stress-related genes provide an insight into how the organism adapted to the environmental conditions that prevail in the deep-sea.
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Lemaire ON, Méjean V, Iobbi-Nivol C. The Shewanella genus: ubiquitous organisms sustaining and preserving aquatic ecosystems. FEMS Microbiol Rev 2020; 44:155-170. [DOI: 10.1093/femsre/fuz031] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 01/09/2020] [Indexed: 12/16/2022] Open
Abstract
ABSTRACT
The Gram-negative Shewanella bacterial genus currently includes about 70 species of mostly aquatic γ-proteobacteria, which were isolated around the globe in a multitude of environments such as surface freshwater and the deepest marine trenches. Their survival in such a wide range of ecological niches is due to their impressive physiological and respiratory versatility. Some strains are among the organisms with the highest number of respiratory systems, depending on a complex and rich metabolic network. Implicated in the recycling of organic and inorganic matter, they are important components of organism-rich oxic/anoxic interfaces, but they also belong to the microflora of a broad group of eukaryotes from metazoans to green algae. Examples of long-term biological interactions like mutualism or pathogeny have been described, although molecular determinants of such symbioses are still poorly understood. Some of these bacteria are key organisms for various biotechnological applications, especially the bioremediation of hydrocarbons and metallic pollutants. The natural ability of these prokaryotes to thrive and detoxify deleterious compounds explains their use in wastewater treatment, their use in energy generation by microbial fuel cells and their importance for resilience of aquatic ecosystems.
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Affiliation(s)
- Olivier N Lemaire
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
| | - Vincent Méjean
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
| | - Chantal Iobbi-Nivol
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
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Pankowski JA. Use of essential gene, encoding prophobilinogen deaminase from extreme psychrophilic Colwellia sp. C1, to generate temperature-sensitive strain of Francisella novicida. Lett Appl Microbiol 2017; 63:124-30. [PMID: 27248501 DOI: 10.1111/lam.12598] [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: 04/04/2016] [Revised: 05/25/2016] [Accepted: 05/31/2016] [Indexed: 11/28/2022]
Abstract
UNLABELLED Previously, several essential genes from psychrophilic bacteria have been substituted for their homologues in mesophilic bacterial pathogens to make the latter temperature sensitive. It has been noted that an essential ligA gene from an extreme psychrophile, Colwellia sp. C1, yielded a gene product that is inactivated at 27°C, the lowest that has been observed for any psychrophilic enzyme, and hypothesized that other essential proteins of that strain would also have low inactivation temperatures. This work describes the partial sequencing of the genome of Colwellia sp. C1 strain and the identification of 24 open reading frames encoding homologues of highly conserved bacterial essential genes. The gene encoding porphobilinogen deaminase (hemC), which is involved in the pathway of haem synthesis, has been tested for its ability to convert Francisella novicida into a temperature-sensitive strain. The hybrid strain carrying the C1-derived hemC gene exhibited a temperature-sensitive phenotype with a restrictive temperature of 36°C. These results support the conclusion that Colwellia sp. C1 is a rich source of heat-labile enzymes. SIGNIFICANCE AND IMPACT OF THE STUDY The issue of biosafety is often raised when it comes to work with pathogenic organisms. The main concern is caused by the risk of researchers being exposed to infectious doses of dangerous microbes. This paper analyses essential genes identified in partial genomic sequence of the psychrophilic bacterium Collwelia sp. C1. These sequences can be used as a mean of generating temperature-sensitive strains of pathogenic bacteria. Such strains are incapable of surviving at the temperature of human body. This means they could be applied as vaccines or for safer work with dangerous organisms.
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Affiliation(s)
- J A Pankowski
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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Koh HY, Park H, Lee JH, Han SJ, Sohn YC, Lee SG. Proteomic and transcriptomic investigations on cold-responsive properties of the psychrophilic Antarctic bacterium Psychrobacter sp. PAMC 21119 at subzero temperatures. Environ Microbiol 2016; 19:628-644. [PMID: 27750393 DOI: 10.1111/1462-2920.13578] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/12/2016] [Indexed: 11/28/2022]
Abstract
Psychrobacter sp. PAMC 21119, isolated from Antarctic permafrost soil, grows and proliferates at subzero temperatures. However, its major mechanism of cold adaptation regulation remains poorly understood. We investigated the transcriptomic and proteomic responses of this species to cold temperatures by comparing profiles at -5°C and 20°C to understand how extreme microorganisms survive under subzero conditions. We found a total of 2,906 transcripts and 584 differentially expressed genes (≥ twofold, P <0.005) by RNA-seq. Genes for translation, ribosomal structure and biogenesis were upregulated, and lipid transport and metabolism was downregulated at low temperatures. A total of 60 protein spots (≥ 1.8 fold, P < 0.005) showed differential expression on two-dimensional gel electrophoresis and the proteins were identified by mass spectrometry. The most prominent upregulated proteins in response to cold were involved in metabolite transport, protein folding and membrane fluidity. Proteins involved in energy production and conversion, and heme protein synthesis were downregulated. Moreover, isoform exchange of cold-shock proteins was detected at both temperatures. Interestingly, pathways for acetyl-CoA metabolism, putrescine synthesis and amino acid metabolism were upregulated. This study highlights some of the strategies and different physiological states that Psychrobacter sp. PAMC 21119 has developed to adapt to the cold environment in Antarctica.
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Affiliation(s)
- Hye Yeon Koh
- Unit of Polar Genomics Korea Polar Research Institute, Incheon, South Korea.,Department of Marine Molecular Biotechnology, Gangneung-Wonju National University, Gangneung, South Korea
| | - Hyun Park
- Unit of Polar Genomics Korea Polar Research Institute, Incheon, South Korea.,Department of Polar Sciences, University of Science and Technology, Incheon, South Korea
| | - Jun Hyuck Lee
- Unit of Polar Genomics Korea Polar Research Institute, Incheon, South Korea.,Department of Polar Sciences, University of Science and Technology, Incheon, South Korea
| | - Se Jong Han
- Unit of Polar Genomics Korea Polar Research Institute, Incheon, South Korea.,Department of Polar Sciences, University of Science and Technology, Incheon, South Korea
| | - Young Chang Sohn
- Department of Marine Molecular Biotechnology, Gangneung-Wonju National University, Gangneung, South Korea
| | - Sung Gu Lee
- Unit of Polar Genomics Korea Polar Research Institute, Incheon, South Korea.,Department of Polar Sciences, University of Science and Technology, Incheon, South Korea
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Gundlapally SR, Ara S, Sisinthy S. Draft genome of Kocuria polaris CMS 76or(T) isolated from cyanobacterial mats, McMurdo Dry Valley, Antarctica: an insight into CspA family of proteins from Kocuria polaris CMS 76or(T). Arch Microbiol 2015; 197:1019-26. [PMID: 26238095 DOI: 10.1007/s00203-015-1138-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/13/2015] [Accepted: 07/18/2015] [Indexed: 11/25/2022]
Abstract
Kocuria polaris strain CMS 76or(T) is a gram-positive, orange-pigmented bacterium isolated from a cyanobacterial mat sample from a pond located in McMurdo Dry Valley, Antarctica. It is psychrotolerant, orange pigmented, hydrolyses starch and Tween 80 and reduces nitrate. We report the 3.78-Mb genome of K. polaris strain CMS 76or(T), containing 3416 coding sequences, including one each for 5S rRNA, 23S rRNA, 16S rRNA and 47 tRNA genes, and the G+C content of DNA is 72.8%. An investigation of Csp family of proteins from K. polaris strain CMS 76or(T) indicated that it contains three different proteins of CspA (peg.319, peg.2255 and 2832) and the length varied from 67 to 69 amino acids. The three different proteins contain all the signature amino acids and two RNA binding regions that are characteristic of CspA proteins. Further, the CspA from K. polaris strain CMS 76or(T) was different from CspA of four other species of the genus Kocuria, Cryobacterium roopkundense and E. coli indirectly suggesting the role of CspA of K. polaris strain CMS 76or(T) in psychrotolerant growth of the bacterium.
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Song W, Lin X, Huang X. Characterization and expression analysis of three cold shock protein (CSP) genes under different stress conditions in the Antarctic bacterium Psychrobacter sp. G. Polar Biol 2012. [DOI: 10.1007/s00300-012-1191-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Overexpression of cold shock protein A of Psychromonas arctica KOPRI 22215 confers cold-resistance. Protein J 2010; 29:136-42. [PMID: 20169403 DOI: 10.1007/s10930-010-9233-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
A polar bacterium was isolated from Arctic sea sediments and identified as Psychromonas artica, based on 16S rDNA sequence. Psychromonas artica KOPRI 22215 has an optimal growth temperature of 10 degrees C and a maximum growth temperature of 25 degrees C, suggesting this bacterium is a psychrophile. Cold shock proteins (Csps) are induced upon temperature downshift by more than 10 degrees C. Functional studies have researched mostly Csps of a mesophilic bacterium Escherichia coli, but not on those of psychrophilic bacteria. In an effort to understand the molecular mechanisms of psychrophilic bacteria that allow it withstand freezing environments, we cloned a gene encoding a cold shock protein from P. artica KOPRI 22215 (CspA(Pa)) using the conserved sequences in csp genes. The 204 bp-long ORF encoded a protein of 68 amino acids, sharing 56% homology to previously reported E. coli CspA protein. When CspA(Pa) was overexpressed in E. coli, it caused cell growth-retardation and morphological elongation. Interestingly, overexpression of CspA(Pa) drastically increased the host's cold-resistance by more than ten times, suggesting the protein aids survival in polar environments.
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Nakashima N, Tamura T. Cell-free protein synthesis using cell extract of Pseudomonas fluorescens and CspA promoter. Biochem Biophys Res Commun 2004; 319:671-6. [PMID: 15178458 DOI: 10.1016/j.bbrc.2004.05.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Indexed: 10/26/2022]
Abstract
We have modified the cell-free coupled transcription/translation system of bacteria. The cell-free extract of Pseudomonas fluorescens was used for translation instead of Escherichia coli. In addition, transcription of the target gene was regulated by CspA promoter with endogenous RNA polymerase instead of by T7 promoter with exogenous T7 RNA polymerase. We could increase the yields of soluble proteins using different combinations of the S30 extract and the promoter and different temperatures for protein synthesis. Increasing the variety of synthesis systems allows production of large quantities of soluble proteins. In order to carry out efficient cell-free protein synthesis, versatile pCop-plasmids carrying CspA promoter were constructed and these plasmids were applicable to expression of recombinant proteins in E. coli cells.
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Affiliation(s)
- Nobutaka Nakashima
- Proteolysis and Protein Turnover Research Group, Research Institute of Genome-based Biofactory, National Institute of Advanced Industrial Science and Technology, Sapporo 062-8517, Japan.
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13
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Serror P, Dervyn R, Ehrlich SD, Maguin E. csp-like genes of Lactobacillus delbrueckii ssp. bulgaricus and their response to cold shock. FEMS Microbiol Lett 2003; 226:323-30. [PMID: 14553929 DOI: 10.1016/s0378-1097(03)00594-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The two csp-like genes from the lactic acid bacterium Lactobacillus delbrueckii ssp. bulgaricus were characterized and designated cspA and cspB. The gene cspA has been identified using a polymerase chain reaction (PCR)-based approach with degenerated primers and further characterized using an inverse PCR strategy. cspA encodes a protein of 65 amino acid residues which displays between 81 and 77% identity with proteins CspL and CspP of Lactobacillus plantarum. cspB has been identified as a cspA ortholog using the partial sequence of the L. bulgaricus ATCC11842. cspB encodes a protein of 69 amino acids which has 42% identity with CspA. Northern blot analyses showed that cspA is transcribed as a single gene and that its transcription increased after a temperature downshift from 42 to 25 degrees C. In contrast, cspB is part of an operon transcribed at constant level irrespective of the temperature. These results indicate that cspA encodes the only Csp-like protein of L. bulgaricus induced by a downshift of temperature.
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Affiliation(s)
- Pascale Serror
- Unité Recherche Laitière et Génétique Appliquée, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
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Ikegami A, Nakasone K, Kato C, Nakamura Y, Yoshikawa I, Usami R, Horikoshi K. Glutamine synthetase gene expression at elevated hydrostatic pressure in a deep-sea piezophilic Shewanella violacea. FEMS Microbiol Lett 2000; 192:91-5. [PMID: 11040434 DOI: 10.1111/j.1574-6968.2000.tb09364.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
A glutamine synthetase gene (glnA) was isolated from a deep-sea piezophilic bacterium, Shewanella violacea strain DSS12. A 7.5-kb SacI fragment containing the complete glnA gene was cloned and sequenced. The glnA gene was found to encode a protein consisting of 469 amino acid residues, showing 75.0% identity to the glutamine synthetase of Escherichia coli. Primer extension analyses revealed two transcription initiation sites in glnA and expression from each site was positively regulated by pressure. Putative promoters recognized by sigma(70) and sigma(54) were identified in the region upstream of glnA. An electrophoretic mobility shift assay demonstrated that S. violacea sigma(54) specifically binds to the promoter region of glnA, suggesting that sigma(54) may play an important role in pressure-regulated transcription in this piezophilic bacterium.
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Affiliation(s)
- A Ikegami
- The DEEPSTAR Group, Japan Marine Science and Technology Center, Yokosuka, Japan
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Ikegami A, Nakasone K, Fujita M, Fujii S, Kato C, Usami R, Horikoshi K. Cloning and characterization of the gene encoding RNA polymerase sigma factor sigma(54) of deep-sea piezophilic Shewanella violacea. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1491:315-20. [PMID: 10760597 DOI: 10.1016/s0167-4781(00)00035-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have recently reported that a sigma(54)-like factor recognizes a DNA element, designated as region A, upstream of a pressure-regulated operon in piezophilic Shewanella violacea strain DSS12 (Nakasone et al., FEMS Microbiology Lett. 176 (1999) 351-356). In this study, we isolated and characterized the rpoN gene of this piezophilic bacterium. The rpoN gene was found to encode a putative protein consisting of 492 amino acid residues with a predicted molecular mass of 55359 Da. Significant homology was evident comparing the rpoN sequence of S. violacea with that of Escherichia coli (62.8% identity), Vibrio anguillarum (61.7% identity) and Pseudomonas putida (57.0% identity). The DNA-binding domain at the C-terminus of sigma(54) is well conserved in the case of the S. violacea rpoN gene product and the helix-turn-helix motif and the RpoN box are also present. In addition, the conserved glutamine-rich domain is present at the N-terminus. sigma(54) in S. violacea was expressed at a relatively constant level under various growth conditions as determined by both primer extension and Western blotting analyses. By means of a recombinant plasmid, a hexahistidine-tagged derivative of the sigma(54) from strain DSS12 was overexpressed in Escherichia coli and purified to near homogeneity. An electrophoretic mobility shift assay demonstrated that the purified sigma(54) protein specifically recognizes region A in the above-mentioned pressure-regulated operon.
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Affiliation(s)
- A Ikegami
- Department of Applied Chemistry, Faculty of Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama, Japan
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