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Thompson TP, Megaw J, Kelly SA, Hopps J, Gilmore BF. Microbial communities of halite deposits and other hypersaline environments. ADVANCES IN APPLIED MICROBIOLOGY 2022; 120:1-32. [PMID: 36243451 DOI: 10.1016/bs.aambs.2022.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Large regions of Earth's surface are underlain by salt deposits that evaporated from ancient oceans and are populated by extreme halophilic microbes. While the microbiology of ancient evaporites has been well studied, the ecology of halite deposits and more recently formed NaCl "salticle" stalactite structures (speleothems) in a Triassic halite mine are less well characterized. The microbiome of Kilroot Salt Mine was profiled using conventional and enhanced culturing techniques. From this, 89 halophilic archaeal isolates from six known genera, and 55 halophilic or halotolerant bacterial isolates from 18 genera were obtained. Culture-independent metagenomic approaches also revealed that culturing techniques were inadvertently biased toward specific taxa, and the need for optimized isolation procedures are required to enhance cultivation diversity. Speleothems formed from saturated brines are unique structures that have the potential to entomb haloarchaea cells for thousands of years within fluid inclusions. The presence of such fluid inclusions, alongside the high abundance of genes related to glycerol metabolism, biofilm formation, and persister cell formation is highly suggestive of an environmental niche that could promote longevity and survivability. Finally, previous studies reporting the discovery of novel biocatalysts from the Kilroot mine microbiome, suggests that this environment may be an untapped source of chemical diversity with high biodiscovery potential.
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Affiliation(s)
- Thomas P Thompson
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, United Kingdom.
| | - Julianne Megaw
- School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Stephen A Kelly
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, United Kingdom
| | - Jason Hopps
- Irish Salt Mining & Exploration Company Ltd., Carrickfergus, United Kingdom
| | - Brendan F Gilmore
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, United Kingdom
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2
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Stewart KN, Domaille DW. A one-pot biocatalytic and organocatalytic cascade delivers high titers of 2-ethyl-2-hexenal from n-butanol. REACT CHEM ENG 2022. [DOI: 10.1039/d1re00568e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Combining an organocatalyst with isolated alcohol oxidase or a whole-cell biocatalyst delivers 2-ethyl-2-hexenal in a one-pot, two-step biocatalytic/organocatalytic cascade.
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Affiliation(s)
- Kelsey N. Stewart
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Dylan W. Domaille
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
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3
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Growth optimization and identification of an ω-transaminase by a novel native PAGE activity staining method in a Bacillus sp. strain BaH isolated from Iranian soil. AMB Express 2021; 11:46. [PMID: 33759017 PMCID: PMC7988029 DOI: 10.1186/s13568-021-01207-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/15/2021] [Indexed: 01/09/2023] Open
Abstract
ω-Transaminases’ (ω-TAs) importance for synthesizing chiral amines led to the development of different methods to quickly identify and characterize new sources of these enzymes. Here we describe the optimization of growth and induction of such an enzyme in a wild type strain of Bacillus sp. strain BaH (IBRC-M 11337) isolated from Iranian soil in shaking flasks by the response surface methodology (RSM). Optimum conditions were set in a multiplexed bench-top bioreactor system (Sixfors). ω-TA activity of obtained biomass was checked by an innovative efficient colorimetric assay for localizing ω-TAs in crude extracts on acrylamide gel by using ortho-xylylenediamine (OXD) as amino donor. The application of the established OXD assay is thereby expanded from high-throughput activity screenings and colony-based screenings of heterologously expressed mutants to a direct identification of ω-TAs in wild-type strains: This assay can be used to detect the protein band of the respective enzyme in crude extracts of novel isolates by visual inspection of native PAGEs without any upstream protein purification, thus enabling subsequent further investigations of a newly discovered enzyme directly from the crude extract.
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4
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Characterization of a novel halotolerant esterase from Chromohalobacter canadensis isolated from salt well mine. 3 Biotech 2020; 10:430. [PMID: 32983823 DOI: 10.1007/s13205-020-02420-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/31/2020] [Indexed: 12/13/2022] Open
Abstract
A esterase gene was characterized from a halophilic bacterium Chromohalobacter canadensis which was originally isolated from a salt well mine. Sequence analysis showed that the esterase, named as EstSHJ2, contained active site serine encompassed by a conserved pentapeptide motif (GSSMG). The EstSHJ2 was classified into a new lipase/esterase family by phylogenetic association analysis. Molecular weight of EstSHJ2 was 26 kDa and the preferred substrate was p-NP butyrate. The EstSHJ2 exhibited a maximum activity at 2.5 M NaCl concentration. Intriguingly, the optimum temperature, pH and stability of EstSHJ2 were related to NaCl concentration. At 2.5 M NaCl concentration, the optimum temperature and pH of EstSHJ2 were 65 ℃ and pH 9.0, and enzyme remained 81% active after 80 ℃ treatment for 2 h. Additionally, the EstSHJ2 showed strong tolerance to metal ions and organic solvents. Among these, 10 mM K+, Ca2+ , Mg2+ and 30% hexane, benzene, toluene has significantly improved activity of EstSHJ2. The EstSHJ2 was the first reported esterase from Chromohalobacter canadensis, and may carry considerable potential for industrial applications under extreme conditions.
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Kelly SA, Mix S, Moody TS, Gilmore BF. Transaminases for industrial biocatalysis: novel enzyme discovery. Appl Microbiol Biotechnol 2020; 104:4781-4794. [PMID: 32300853 PMCID: PMC7228992 DOI: 10.1007/s00253-020-10585-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/18/2020] [Accepted: 03/24/2020] [Indexed: 12/04/2022]
Abstract
Transaminases (TAms) are important enzymes for the production of chiral amines for the pharmaceutical and fine chemical industries. Novel TAms for use in these industries have been discovered using a range of approaches, including activity-guided methods and homologous sequence searches from cultured microorganisms to searches using key motifs and metagenomic mining of environmental DNA libraries. This mini-review focuses on the methods used for TAm discovery over the past two decades, analyzing the changing trends in the field and highlighting the advantages and drawbacks of the respective approaches used. This review will also discuss the role of protein engineering in the development of novel TAms and explore possible directions for future TAm discovery for application in industrial biocatalysis. KEY POINTS: • The past two decades of TAm enzyme discovery approaches are explored. • TAm sequences are phylogenetically analyzed and compared to other discovery methods. • Benefits and drawbacks of discovery approaches for novel biocatalysts are discussed. • The role of protein engineering and future discovery directions is highlighted.
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Affiliation(s)
- Stephen A Kelly
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland
| | - Stefan Mix
- Department of Biocatalysis & Isotope Chemistry, Almac, 20 Seagoe Industrial Estate, Craigavon, UK
| | - Thomas S Moody
- Department of Biocatalysis & Isotope Chemistry, Almac, 20 Seagoe Industrial Estate, Craigavon, UK
- Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co. Roscommon, Ireland
| | - Brendan F Gilmore
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland.
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Covalent immobilization of recombinant Citrobacter koseri transaminase onto epoxy resins for consecutive asymmetric synthesis of L-phosphinothricin. Bioprocess Biosyst Eng 2020; 43:1599-1607. [DOI: 10.1007/s00449-020-02351-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 04/11/2020] [Indexed: 12/16/2022]
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Megaw J, Kelly SA, Thompson TP, Skvortsov T, Gilmore BF. Profiling the microbial community of a Triassic halite deposit in Northern Ireland: an environment with significant potential for biodiscovery. FEMS Microbiol Lett 2019; 366:5645231. [DOI: 10.1093/femsle/fnz242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/26/2019] [Indexed: 12/25/2022] Open
Abstract
ABSTRACTKilroot salt mine, a Triassic halite deposit located in County Antrim, Northern Ireland, is the only permanent hypersaline environment on the island of Ireland. In this study, the microbiome of this unstudied environment was profiled for the first time using conventional and enhanced culturing techniques, and culture independent metagenomic approaches. Using both conventional isolation plates and iChip devices, 89 halophilic archaeal isolates from six known genera, and 55 halophilic or halotolerant bacterial isolates from 18 genera were obtained, based on 16S rRNA gene sequencing. The archaeal isolates were similar to those previously isolated from other ancient halite deposits, and as expected, numerous genera were identified in the metagenome which were not represented among the culturable isolates. Preliminary screening of a selection of isolates from this environment identified antimicrobial activities against a panel of clinically important bacterial pathogens from 15 of the bacterial isolates and one of the archaea. This, alongside previous studies reporting the discovery of novel biocatalysts from the Kilroot mine microbiome, suggests that this environment may be a new, untapped source of of chemical diversity with high biodiscovery potential.
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Affiliation(s)
- Julianne Megaw
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Stephen A Kelly
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Thomas P Thompson
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Timofey Skvortsov
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Brendan F Gilmore
- Biofilm Research Group, School of Pharmacy, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
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Screening and Comparative Characterization of Microorganisms from Iranian Soil Samples Showing ω-Transaminase Activity toward a Plethora of Substrates. Catalysts 2019. [DOI: 10.3390/catal9100874] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In this study, soil microorganisms from Iran were screened for ω-transaminase (ω-TA) activity based on growth on minimal media containing (rac)-α-methylbenzylamine (rac-α-MBA) as a sole nitrogen source. Then, for the selection of strains with high enzyme activity, a colorimetric o-xylylendiamine assay was conducted. The most promising strains were identified by 16S rDNA sequencing. Five microorganisms showing high ω-TA activity were subjected to determine optimal conditions for ω-TA activity, including pH, temperature, co-solvent, and the specificity of the ω-TA toward different amine donors and acceptors. Among the five screened microorganisms, Bacillus halotolerans turned out to be the most promising strain: Its cell-free extract showed a highly versatile amino donor spectrum toward aliphatic, aromatic chiral amines and a broad range of pH activity. Transaminase activity also exhibited excellent solvent tolerance, with maximum turnover in the presence of 30% (v/v) DMSO.
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Kelly SA, Moody TS, Gilmore BF. Biocatalysis in seawater: Investigating a halotolerant ω-transaminase capable of converting furfural in a seawater reaction medium. Eng Life Sci 2019; 19:721-725. [PMID: 32624965 DOI: 10.1002/elsc.201900053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/05/2019] [Accepted: 08/07/2019] [Indexed: 11/07/2022] Open
Abstract
The increasing demand for freshwater and the continued depletion of available resources has led to a deepening global water crisis. Significant water consumption required by many biotechnological processes contributes to both the environmental and economic cost of this problem. Relatively few biocatalytic processes have been developed to utilize the more abundant supply of seawater, with seawater composition and salinity limiting its use with many mesophilic enzymes. We recently reported a salt tolerant ω-transaminase enzyme, Ad2-TAm, isolated from the genome of a halophilic bacterium, Halomonas sp. CSM-2, from a Triassic period salt mine. In this study we aimed to demonstrate its applicability to biocatalytic reactions carried out in a seawater-based medium. Ad2-TAm was examined for its ability to aminate the industrially relevant substrate, furfural, in both seawater and freshwater-based reaction systems. Furfural was aminated with 53.6% conversion in a buffered seawater system, displaying improved function versus freshwater. Ad2-TAm outperformed the commonly employed commercial ω-TAms from Chromobacterium violaceum and Vibrio fluvialis, both of which showed decreased conversion in seawater. Given the increasingly precarious availability of global freshwater, such applications of enzymes from halophiles have the ability to reduce demand for freshwater in large-scale industrial processes, delivering considerable environmental and economic benefits.
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Affiliation(s)
| | - Thomas S Moody
- Almac Department of Biocatalysis & Isotope Chemistry Craigavon UK.,Arran Chemical Company Limited Athlone Roscommon Ireland
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Asymmetric synthesis of l-phosphinothricin using thermostable alpha-transaminase mined from Citrobacter koseri. J Biotechnol 2019; 302:10-17. [PMID: 31201835 DOI: 10.1016/j.jbiotec.2019.06.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/30/2019] [Accepted: 06/11/2019] [Indexed: 11/22/2022]
Abstract
α-Transaminase (α-TA) responsible for catalyzing the reversible transfer of amino groups between amine donors and amine acceptors, is applicable to enzymatic route for asymmetric synthesis of herbicide l-phosphinothricin (l-PPT). In the search for α-TAs with better catalysis performance, three α-TAs were discovered by genome mining approach using a known sequence encoding Escherichia coli tyrosine TA (TyrB) as probe. Through detailed comparison of their expression amount, activities and characteristics, Citrobacter koseri TA (CkTA) exhibited better activity and thermostability, which retain 65.9% of initial activity after incubation at 57 °C for 4 h. The Km and kcat/Km values of CkTA were 36.75 mM and 34.29 mM-1 min-1, respectively. In addition, recombinant CkTA cells were immobilized onto Celite 545 using tris(hydroxymethyl)phosphine as crosslinker. During five repetitive asymmetric synthesis of l-PPT from 20 g/L prostereogenic ketone using l-Glu as amine donor, all the yields of l-PPT reached up to 91.2% (>99% ee). These characteristics made CkTA a valuable addition to the currently scarce α-TA library for stereospecific synthesis of l-PPT.
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11
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Kelly SA, Magill DJ, Megaw J, Skvortsov T, Allers T, McGrath JW, Allen CCR, Moody TS, Gilmore BF. Characterisation of a solvent-tolerant haloarchaeal (R)-selective transaminase isolated from a Triassic period salt mine. Appl Microbiol Biotechnol 2019; 103:5727-5737. [PMID: 31123770 PMCID: PMC6597733 DOI: 10.1007/s00253-019-09806-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 03/26/2019] [Accepted: 03/29/2019] [Indexed: 12/11/2022]
Abstract
Transaminase enzymes (TAms) are becoming increasingly valuable in the chemist’s toolbox as a biocatalytic route to chiral amines. Despite high profile successes, the lack of (R)-selective TAms and robustness under harsh industrial conditions continue to prove problematic. Herein, we report the isolation of the first haloarchaeal TAm (BC61-TAm) to be characterised for the purposes of pharmaceutical biocatalysis. BC61-TAm is an (R)-selective enzyme, cloned from an extremely halophilic archaeon, isolated from a Triassic period salt mine. Produced using a Haloferax volcanii–based expression model, the resulting protein displays a classic halophilic activity profile, as well as thermotolerance (optimum 50 °C) and organic solvent tolerance. Molecular modelling predicts the putative active site residues of haloarchaeal TAms, with molecular dynamics simulations providing insights on the basis of BC61-TAm’s organic solvent tolerance. These results represent an exciting advance in the study of transaminases from extremophiles, providing a possible scaffold for future discovery of biocatalytic enzymes with robust properties.
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Affiliation(s)
| | - Damian J Magill
- School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | - Julianne Megaw
- School of Pharmacy, Queen's University Belfast, Belfast, UK
| | | | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - John W McGrath
- School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | | | - Thomas S Moody
- Almac, Department of Biocatalysis & Isotope Chemistry, 20 Seagoe Industrial Estate, Craigavon, UK
- Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co. Roscommon, Ireland
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12
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Zeifman YS, Boyko KM, Nikolaeva AY, Timofeev VI, Rakitina TV, Popov VO, Bezsudnova EY. Functional characterization of PLP fold type IV transaminase with a mixed type of activity from Haliangium ochraceum. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:575-585. [PMID: 30902765 DOI: 10.1016/j.bbapap.2019.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/01/2019] [Accepted: 03/16/2019] [Indexed: 12/11/2022]
Abstract
Pyridoxal-5'-phosphate (PLP)-dependent transaminases are industrially important enzymes catalyzing the stereoselective amination of ketones and keto acids. Transaminases of PLP fold type IV are characterized by (R)- or (S)-stereoselective transfer of amino groups, depending on the substrate profile of the enzyme. PLP fold type IV transaminases include branched-chain amino acid transaminases (BCATs), D-amino acid transaminases and (R)-amine:pyruvate transaminases. Recently, transaminases with a mixed type of activity were identified and characterized. Here, we report biochemical and structural characterization of a transaminase from myxobacterium Haliangium ochraceum (Hoch3033), which is active towards keto analogs of branched-chain amino acids (specific substrates for BCATs) and (R)-(+)-α-methylbenzylamine (specific substrate for (R)-amine:pyruvate transaminases). The enzyme is characterized by an alkaline pH optimum (pH 10.0-10.5) and a tolerance to high salt concentrations (up to 2 M NaCl). The structure of Hoch3033 was determined at 2.35 Å resolution. The overall fold of the enzyme was similar to those of known enzymes of PLP fold type IV. The mixed type of activity of Hoch3033 was implemented within the BCAT-like active site. However, in the active site of Hoch3033, we observed substitutions of specificity-determining residues that are important for substrate binding in canonical BCATs. We suggest that these changes result in the loss of activity towards α-ketoglutarate and increase the affinity towards (R)-(+)-α-methylbenzylamine. These results complement our knowledge of the catalytic diversity of transaminases and indicate the need for further research to understand the structural basis of substrate specificity in these enzymes.
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Affiliation(s)
- Yulia S Zeifman
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, bld. 2, 119071 Moscow, Russian Federation; Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation.
| | - Konstantin M Boyko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, bld. 2, 119071 Moscow, Russian Federation; Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation
| | - Alena Yu Nikolaeva
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, bld. 2, 119071 Moscow, Russian Federation; Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation
| | - Vladimir I Timofeev
- Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation; FSRC «Crystallography and Photonics» RAS, Leninskiy Prospekt 59, 119333 Moscow, Russian Federation
| | - Tatiana V Rakitina
- Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation; Shemyakin&Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya str. 16/10, 117997 Moscow, Russian Federation
| | - Vladimir O Popov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, bld. 2, 119071 Moscow, Russian Federation; Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova sqr 1, 123182 Moscow, Russian Federation
| | - Ekaterina Yu Bezsudnova
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, bld. 2, 119071 Moscow, Russian Federation
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Draft Genome Sequence of Halomonas sp. CSM-2, a Moderately Halophilic Bacterium Isolated from a Triassic Salt Mine. Microbiol Resour Announc 2018; 7:MRA00836-18. [PMID: 30533871 PMCID: PMC6211355 DOI: 10.1128/mra.00836-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/26/2018] [Indexed: 11/20/2022] Open
Abstract
Here, we report the draft genome sequence of Halomonas sp. CSM-2. Here, we report the draft genome sequence of Halomonas sp. CSM-2. This moderately halophilic bacterium was isolated from a brine sample obtained from a Triassic salt mine.
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14
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Kelly SA, Skvortsov T, Magill D, Quinn DJ, McGrath JW, Allen CCR, Moody TS, Gilmore BF. Characterization of a novel ω-transaminase from a Triassic salt mine metagenome. Biochem Biophys Res Commun 2018; 503:2936-2942. [PMID: 30119883 DOI: 10.1016/j.bbrc.2018.08.073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 08/08/2018] [Indexed: 01/08/2023]
Abstract
Chiral amines are valuable building blocks for the pharmaceutical industry, and are increasingly synthesized by transaminase-mediated (TAm) synthesis. Currently available TAms, primarily isolated from the genomes of cultured mesophilic bacteria, often suffer from a number of drawbacks, including poor substrate range and an inability to tolerate the harsh conditions often demanded by industrial processes. These characteristics have, in part, driven the search for novel biocatalysts from both metagenomic sources and extreme environments. Herein, we report the isolation and characterization of an ω-TAm from a metagenome of a Triassic salt mine in Kilroot, N. Ireland, an extremely hypersaline environment formed circa 220-250 mya. The gene sequence was identified based on homology with existing bacterial TAms, synthesized within a pET28a(+) plasmid and expressed in E. coli BL21 DE3 cells. The resultant 49 kDa protein accepted (S)-methylbenzylamine (MBA) as amino donor and had a specific activity of 0.54 U/mg using α-ketoglutarate (ΑKG) as substrate. Molecular modeling and substrate docking indicated the presence of key residues, conserved in a number of other TAms. Despite the hypersaline environment from which it was isolated, the enzyme displayed low halotolerance, highlighting that not all biocatalysts will demonstrate the extreme characteristics associated with their source environment. This study does however reinforce the viability of mining metagenomic datasets as a means of discovering novel and functional biocatalysts, and adds to a currently scant list of such examples in the field of TAms.
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Affiliation(s)
- Stephen A Kelly
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Timofey Skvortsov
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Damian Magill
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Derek J Quinn
- Almac, Department of Biocatalysis & Isotope Chemistry, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, N. Ireland, UK
| | - John W McGrath
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Christopher C R Allen
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Thomas S Moody
- Almac, Department of Biocatalysis & Isotope Chemistry, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, N. Ireland, UK; Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co. Roscommon, Ireland
| | - Brendan F Gilmore
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK.
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