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Røyseth V, Hurysz BM, Kaczorowska AK, Dorawa S, Fedøy AE, Arsın H, Serafim MSM, Myers SA, Werbowy O, Kaczorowski T, Stokke R, O’Donoghue AJ, Steen IH. Activation mechanism and activity of globupain, a thermostable C11 protease from the Arctic Mid-Ocean Ridge hydrothermal system. Front Microbiol 2023; 14:1199085. [PMID: 37405169 PMCID: PMC10315481 DOI: 10.3389/fmicb.2023.1199085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 05/26/2023] [Indexed: 07/06/2023] Open
Abstract
Deep-sea hydrothermal vents offer unique habitats for heat tolerant enzymes with potential new enzymatic properties. Here, we present the novel C11 protease globupain, which was prospected from a metagenome-assembled genome of uncultivated Archaeoglobales sampled from the Soria Moria hydrothermal vent system located on the Arctic Mid-Ocean Ridge. Sequence comparisons against the MEROPS-MPRO database showed that globupain has the highest sequence identity to C11-like proteases present in human gut and intestinal bacteria. Successful recombinant expression in Escherichia coli of the wild-type zymogen and 13 mutant substitution variants allowed assessment of residues involved in maturation and activity of the enzyme. For activation, globupain required the addition of DTT and Ca2+. When activated, the 52kDa proenzyme was processed at K137 and K144 into a 12kDa light- and 32kDa heavy chain heterodimer. A structurally conserved H132/C185 catalytic dyad was responsible for the proteolytic activity, and the enzyme demonstrated the ability to activate in-trans. Globupain exhibited caseinolytic activity and showed a strong preference for arginine in the P1 position, with Boc-QAR-aminomethylcoumarin (AMC) as the best substrate out of a total of 17 fluorogenic AMC substrates tested. Globupain was thermostable (Tm activated enzyme = 94.51°C ± 0.09°C) with optimal activity at 75°C and pH 7.1. Characterization of globupain has expanded our knowledge of the catalytic properties and activation mechanisms of temperature tolerant marine C11 proteases. The unique combination of features such as elevated thermostability, activity at relatively low pH values, and ability to operate under high reducing conditions makes globupain a potential intriguing candidate for use in diverse industrial and biotechnology sectors.
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Affiliation(s)
- Victoria Røyseth
- Department of Biological Sciences, Center for Deep Sea Research, University of Bergen, Bergen, Norway
| | - Brianna M. Hurysz
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA, United States
| | - Anna-Karina Kaczorowska
- Collection of Plasmids and Microorganisms | KPD, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
| | - Sebastian Dorawa
- Laboratory of Extremophiles Biology, Department of Microbiology, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
| | - Anita-Elin Fedøy
- Department of Biological Sciences, Center for Deep Sea Research, University of Bergen, Bergen, Norway
| | - Hasan Arsın
- Department of Biological Sciences, Center for Deep Sea Research, University of Bergen, Bergen, Norway
| | - Mateus Sá M. Serafim
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA, United States
- Department of Microbiology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Samuel A. Myers
- La Jolla Institute for Immunology, La Jolla, CA, United States
| | - Olesia Werbowy
- Laboratory of Extremophiles Biology, Department of Microbiology, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
| | - Tadeusz Kaczorowski
- Laboratory of Extremophiles Biology, Department of Microbiology, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
| | - Runar Stokke
- Department of Biological Sciences, Center for Deep Sea Research, University of Bergen, Bergen, Norway
| | - Anthony J. O’Donoghue
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA, United States
| | - Ida Helene Steen
- Department of Biological Sciences, Center for Deep Sea Research, University of Bergen, Bergen, Norway
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2
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Røyseth V, Hurysz BM, Kaczorowska A, Dorawa S, Fedøy AE, Arsin H, Serafim M, Werbowy O, Kaczorowski T, Stokke R, O'Donoghue AJ, Steen IH. Activation mechanism and activity of globupain, a thermostable C11 protease from the Arctic Mid-Ocean Ridge hydrothermal system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.04.535519. [PMID: 37066400 PMCID: PMC10104074 DOI: 10.1101/2023.04.04.535519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Deep-sea hydrothermal vent systems with prevailing extreme thermal conditions for life offer unique habitats to source heat tolearant enzymes with potential new enzymatic properties. Here, we present the novel C11 protease globupain , prospected from a metagenome-assembled genome of uncultivated Archaeoglobales sampled from the Soria Moria hydrothermal vent system located on the Arctic Mid- Ocean Ridges. By sequence comparisons against the MEROPS-MPRO database, globupain showed highest sequence identity to C11-like proteases present in human gut and intestinal bacteria,. Successful recombinant expression in Escherichia coli of the active zymogen and 13 mutant substitution variants allowed assesment of residues involved in maturation and activity of the enzyme. For activation, globupain required the addition of DTT and Ca²⁺. When activated, the 52 kDa proenzyme was processed at Lys 137 and Lys 144 into a 12 kDa light- and 32 kDa heavy chain heterodimer. A structurally conserved His 132 /Cys 185 catalytic dyad was responsible for the proteolytic activity, and the enzyme demonstrated the ability to activate in-trans . Globupain exhibited caseinolytic activity and showed a strong preference for arginine in the P1 position, with Boc-QAR- aminomethylcoumarin (AMC) as the best substrate out of a total of 17 fluorogenic AMC substrates tested. Globupain was thermostable (T m activated enzyme = 94.51 ± 0.09°C) with optimal activity at 75 °C and pH 7.1. By characterizing globupain, our knowledge of the catalytic properties and activation mechanisms of temperature tolerant marine C11 proteases have been expanded. The unique combination of features such as elevated thermostability, activity at relatively low pH values, and ability to operate under high reducing conditions makes globupain a potential intriguing candidate for use in diverse industrial and biotechnology sectors.
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3
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Gophna U, Altman-Price N. Horizontal Gene Transfer in Archaea-From Mechanisms to Genome Evolution. Annu Rev Microbiol 2022; 76:481-502. [PMID: 35667126 DOI: 10.1146/annurev-micro-040820-124627] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Archaea remains the least-studied and least-characterized domain of life despite its significance not just to the ecology of our planet but also to the evolution of eukaryotes. It is therefore unsurprising that research into horizontal gene transfer (HGT) in archaea has lagged behind that of bacteria. Indeed, several archaeal lineages may owe their very existence to large-scale HGT events, and thus understanding both the molecular mechanisms and the evolutionary impact of HGT in archaea is highly important. Furthermore, some mechanisms of gene exchange, such as plasmids that transmit themselves via membrane vesicles and the formation of cytoplasmic bridges that allows transfer of both chromosomal and plasmid DNA, may be archaea specific. This review summarizes what we know about HGT in archaea, and the barriers that restrict it, highlighting exciting recent discoveries and pointing out opportunities for future research. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Uri Gophna
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; ,
| | - Neta Altman-Price
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; , .,Department of Natural and Life Sciences, The Open University of Israel, Raanana, Israel
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4
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Li XG, Tang HZ, Zhang WJ, Qi XQ, Qu ZG, Xu J, Wu LF. Thermococcus aciditolerans sp. nov., a piezotolerant, hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent chimney in the Southwest Indian Ridge. Int J Syst Evol Microbiol 2021; 71. [PMID: 34343062 DOI: 10.1099/ijsem.0.004934] [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: 11/18/2022] Open
Abstract
A hyperthermophilic, strictly anaerobic archaeon, designated strain SY113T, was isolated from a deep-sea hydrothermal vent chimney on the Southwest Indian Ridge at a water depth of 2770 m. Enrichment and isolation of strain SY113T were performed at 85 °C at 0.1 MPa. Cells of strain SY113T were irregular motile cocci with peritrichous flagella and generally 0.8-2.4 µm in diameter. Growth was observed at temperatures between 50 and 90 °C (optimum at 85 °C) and under hydrostatic pressures of 0.1-60 MPa (optimum, 27 MPa). Cells of SY113T grew at pH 4.0-9.0 (optimum, pH 5.5) and a NaCl concentration of 0.5-5.5 % (w/v; optimum concentration, 3.0 % NaCl). Strain SY113T was an anaerobic chemoorganoheterotroph and grew on complex proteinaceous substrates such as yeast extract and tryptone, as well as on maltose and starch. Elemental sulphur stimulated growth, but not obligatory for its growth. The G+C content of the genomic DNA was 55.0 mol%. Phylogenetic analysis of the 16S rRNA sequence of strain SY113T showed that the novel isolate belonged to the genus Thermococcus. On the basis of physiological characteristics, average nucleotide identity values and in silico DNA-DNA hybridization results, we propose a novel species, named Thermococcus aciditolerans sp. nov. The type strain is SY113T (=MCCC 1K04190T=JCM 39083T).
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Affiliation(s)
- Xue-Gong Li
- Laboratory of Deep-Sea Microbial Cell Biology, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China.,International Associated Laboratory of Evolution and Development of Magnetotactic Multicellular Organisms, CNRS-Marseille/ CAS- Sanya, PR China.,CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China
| | - Hong-Zhi Tang
- Laboratory of Deep-Sea Microbial Cell Biology, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China.,University of Chinese Academy of Sciences, Beijing, PR China
| | - Wei-Jia Zhang
- Laboratory of Deep-Sea Microbial Cell Biology, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China.,International Associated Laboratory of Evolution and Development of Magnetotactic Multicellular Organisms, CNRS-Marseille/ CAS- Sanya, PR China.,CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China
| | - Xiao-Qing Qi
- Laboratory of Deep-Sea Microbial Cell Biology, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China.,International Associated Laboratory of Evolution and Development of Magnetotactic Multicellular Organisms, CNRS-Marseille/ CAS- Sanya, PR China.,CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China
| | - Zhi-Guo Qu
- Laboratory of Deep-sea Information Technology, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, PR China
| | - Jun Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Long-Fei Wu
- International Associated Laboratory of Evolution and Development of Magnetotactic Multicellular Organisms, CNRS-Marseille/ CAS- Sanya, PR China.,Aix Marseille Univ, CNRS, LCB, IMM, IM2B, Marseille, France
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5
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Courtine D, Vince E, Maignien L, Philippon X, Gayet N, Shao Z, Alain K. Thermococcus camini sp. nov., a hyperthermophilic and piezophilic archaeon isolated from a deep-sea hydrothermal vent at the Mid-Atlantic Ridge. Int J Syst Evol Microbiol 2021; 71. [PMID: 34236955 DOI: 10.1099/ijsem.0.004853] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A coccoid-shaped, strictly anaerobic, hyperthermophilic and piezophilic organoheterotrophic archaeon, strain Iri35cT, was isolated from a hydrothermal chimney rock sample collected at a depth of 2300 m at the Mid-Atlantic Ridge (Rainbow vent field). Cells of strain Iri35cT grew at NaCl concentrations ranging from 1-5 % (w/v) (optimum 2.0 %), from pH 5.0 to 9.0 (optimum 7.0-7.5), at temperatures between 50 and 90 °C (optimum 75-80 °C) and at pressures from 0.1 to at least 50 MPa (optimum: 10-30 MPa). The novel isolate grew on complex organic substrates, such as yeast extract, tryptone, peptone or beef extract, preferentially in the presence of elemental sulphur or l-cystine; however, these molecules were not necessary for growth. Its genomic DNA G+C content was 54.63 mol%. The genome has been annotated and the metabolic predictions are in accordance with the metabolic characteristics of the strain and of Thermococcales in general. Phylogenetic analyses based on 16S rRNA gene sequences and concatenated ribosomal protein sequences showed that strain Iri35cT belongs to the genus Thermococcus, and is closer to the species T. celericrescens and T. siculi. Average nucleotide identity scores and in silico DNA-DNA hybridization values between the genome of strain Iri35cT and the genomes of the type species of the genus Thermococcus were below the species delineation threshold. Therefore, and considering the phenotypic data presented, strain Iri35cT is suggested to represent a novel species, for which the name Thermococcus camini sp. nov. is proposed, with the type strain Iri35cT (=UBOCC M-2026T=DSM 111003T).
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Affiliation(s)
- Damien Courtine
- Univ Brest, CNRS, Ifremer, Laboratoire de Microbiologie des Environnements Extrêmes LM2E, IUEM, Rue Dumont d'Urville, F-29280 Plouzané, France.,IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China.,Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | - Erwann Vince
- Univ Brest, CNRS, Ifremer, Laboratoire de Microbiologie des Environnements Extrêmes LM2E, IUEM, Rue Dumont d'Urville, F-29280 Plouzané, France.,IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China
| | - Loïs Maignien
- Univ Brest, CNRS, Ifremer, Laboratoire de Microbiologie des Environnements Extrêmes LM2E, IUEM, Rue Dumont d'Urville, F-29280 Plouzané, France.,IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China
| | - Xavier Philippon
- Univ Brest, CNRS, Ifremer, Laboratoire de Microbiologie des Environnements Extrêmes LM2E, IUEM, Rue Dumont d'Urville, F-29280 Plouzané, France.,IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China
| | | | - Zongze Shao
- IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China.,Key Laboratory of Marine Genetic Resources, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, PR China
| | - Karine Alain
- Univ Brest, CNRS, Ifremer, Laboratoire de Microbiologie des Environnements Extrêmes LM2E, IUEM, Rue Dumont d'Urville, F-29280 Plouzané, France.,IRP 1211 MicrobSea, Sino-French Laboratory of Deep-Sea Microbiology, LM2E (Plouzané, France)-KLAMBR, Xiamen, PR China
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6
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Lim JK, Kim YJ, Yang JA, Namirimu T, Yang SH, Park MJ, Kwon YM, Lee HS, Kang SG, Lee JH, Kwon KK. Thermococcus indicus sp. nov., a Fe(III)-reducing hyperthermophilic archaeon isolated from the Onnuri Vent Field of the Central Indian Ocean ridge. J Microbiol 2020; 58:260-267. [DOI: 10.1007/s12275-020-9424-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 09/30/2019] [Accepted: 01/23/2020] [Indexed: 02/04/2023]
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7
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Speijer D. What can we infer about the origin of sex in early eukaryotes? Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0530. [PMID: 27619694 DOI: 10.1098/rstb.2015.0530] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2016] [Indexed: 12/21/2022] Open
Abstract
Current analysis shows that the last eukaryotic common ancestor (LECA) was capable of full meiotic sex. The original eukaryotic life cycle can probably be described as clonal, interrupted by episodic sex triggered by external or internal stressors. The cycle could have started in a highly flexible form, with the interruption of either diploid or haploid clonal growth determined by stress signals only. Eukaryotic sex most likely evolved in response to a high mutation rate, arising from the uptake of the endosymbiont, as this (proto) mitochondrion generated internal reactive oxygen species. This is consistent with the likely development of full meiotic sex from a diverse set of existing archaeal (the host of the endosymbiont) repair and signalling mechanisms. Meiotic sex could thus have been one of the fruits of symbiogenesis at the basis of eukaryotic origins: a product of the merger by which eukaryotic cells arose. Symbiogenesis also explains the large-scale migration of organellar DNA to the nucleus. I also discuss aspects of uniparental mitochondrial inheritance and mitonuclear interactions in the light of the previous analysis.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Dave Speijer
- Department of Medical Biochemistry, Academic Medical Center (AMC), University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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8
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Shalev Y, Turgeman-Grott I, Tamir A, Eichler J, Gophna U. Cell Surface Glycosylation Is Required for Efficient Mating of Haloferax volcanii. Front Microbiol 2017; 8:1253. [PMID: 28725221 PMCID: PMC5496957 DOI: 10.3389/fmicb.2017.01253] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/21/2017] [Indexed: 01/30/2023] Open
Abstract
Halophilic archaea use a fusion-based mating system for lateral gene transfer across cells, yet the molecular mechanisms involved remain unknown. Previous work implied that cell fusion involves cell-cell recognition since fusion occurs more efficiently between cells from the same species. Long believed to be restricted only to Eukarya, it is now known that cells of all three domains of life perform N-glycosylation, the covalent attachment of glycans to select target asparagine residues in proteins, and that this post-translational modification is common for archaeal cell surface proteins. Here, we show that differences in glycosylation of the Haloferax volcanii surface-layer glycoprotein, brought about either by changing medium salinity or by knocking out key glycosylation genes, reduced mating success. Thus, different glycosylation patterns are likely to underlie mating preference in halophilic archaea, contributing to speciation processes.
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Affiliation(s)
- Yarden Shalev
- School of Molecular and Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv UniversityTel Aviv, Israel
| | - Israela Turgeman-Grott
- School of Molecular and Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv UniversityTel Aviv, Israel
| | - Adi Tamir
- Department of Life Sciences, Ben-Gurion University of the NegevBeersheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the NegevBeersheva, Israel
| | - Uri Gophna
- School of Molecular and Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv UniversityTel Aviv, Israel
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9
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Speijer D. Birth of the eukaryotes by a set of reactive innovations: New insights force us to relinquish gradual models. Bioessays 2016; 37:1268-76. [PMID: 26577075 DOI: 10.1002/bies.201500107] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Of two contending models for eukaryotic evolution the "archezoan" has an amitochondriate eukaryote take up an endosymbiont, while "symbiogenesis" states that an Archaeon became a eukaryote as the result of this uptake. If so, organelle formation resulting from new engulfments is simplified by the primordial symbiogenesis, and less informative regarding the bacterium-to-mitochondrion conversion. Gradualist archezoan visions still permeate evolutionary thinking, but are much less likely than symbiogenesis. Genuine amitochondriate eukaryotes have never been found and rapid, explosive adaptive periods characteristic of symbiogenetic models explain this. Mitochondrial proteomes, encoded by genes of "eukaryotic origin" not easily linked to host or endosymbiont, can be understood in light of rapid adjustments to new evolutionary pressures. Symbiogenesis allows "expensive" eukaryotic inventions via efficient ATP generation by nascent mitochondria. However, efficient ATP production equals enhanced toxic internal ROS formation. The synergistic combination of these two driving forces gave rise to the rapid evolution of eukaryotes. Also watch the Video Abstract.
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Affiliation(s)
- Dave Speijer
- Department of Medical Biochemistry, Academic Medical Centre (AMC), University of Amsterdam, Amsterdam, The Netherlands
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10
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Martin WF, Garg S, Zimorski V. Endosymbiotic theories for eukaryote origin. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140330. [PMID: 26323761 PMCID: PMC4571569 DOI: 10.1098/rstb.2014.0330] [Citation(s) in RCA: 280] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2015] [Indexed: 11/12/2022] Open
Abstract
For over 100 years, endosymbiotic theories have figured in thoughts about the differences between prokaryotic and eukaryotic cells. More than 20 different versions of endosymbiotic theory have been presented in the literature to explain the origin of eukaryotes and their mitochondria. Very few of those models account for eukaryotic anaerobes. The role of energy and the energetic constraints that prokaryotic cell organization placed on evolutionary innovation in cell history has recently come to bear on endosymbiotic theory. Only cells that possessed mitochondria had the bioenergetic means to attain eukaryotic cell complexity, which is why there are no true intermediates in the prokaryote-to-eukaryote transition. Current versions of endosymbiotic theory have it that the host was an archaeon (an archaebacterium), not a eukaryote. Hence the evolutionary history and biology of archaea increasingly comes to bear on eukaryotic origins, more than ever before. Here, we have compiled a survey of endosymbiotic theories for the origin of eukaryotes and mitochondria, and for the origin of the eukaryotic nucleus, summarizing the essentials of each and contrasting some of their predictions to the observations. A new aspect of endosymbiosis in eukaryote evolution comes into focus from these considerations: the host for the origin of plastids was a facultative anaerobe.
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Affiliation(s)
- William F Martin
- Institute for Molecular Evolution, Universität Düsseldorf, Universitätsstraße 1, Düsseldorf 40225, Germany
| | - Sriram Garg
- Institute for Molecular Evolution, Universität Düsseldorf, Universitätsstraße 1, Düsseldorf 40225, Germany
| | - Verena Zimorski
- Institute for Molecular Evolution, Universität Düsseldorf, Universitätsstraße 1, Düsseldorf 40225, Germany
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11
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Mora M, Bellack A, Ugele M, Hopf J, Wirth R. The temperature gradient-forming device, an accessory unit for normal light microscopes to study the biology of hyperthermophilic microorganisms. Appl Environ Microbiol 2014; 80:4764-70. [PMID: 24858087 PMCID: PMC4148812 DOI: 10.1128/aem.00984-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 05/17/2014] [Indexed: 12/29/2022] Open
Abstract
To date, the behavior of hyperthermophilic microorganisms in their biotope has been studied only to a limited degree; this is especially true for motility. One reason for this lack of knowledge is the requirement for high-temperature microscopy-combined, in most cases, with the need for observations under strictly anaerobic conditions-for such studies. We have developed a custom-made, low-budget device that, for the first time, allows analyses in temperature gradients up to 40°C over a distance of just 2 cm (a biotope-relevant distance) with heating rates up to ∼5°C/s. Our temperature gradient-forming device can convert any upright light microscope into one that works at temperatures as high as 110°C. Data obtained by use of this apparatus show how very well hyperthermophiles are adapted to their biotope: they can react within seconds to elevated temperatures by starting motility-even after 9 months of storage in the cold. Using the temperature gradient-forming device, we determined the temperature ranges for swimming, and the swimming speeds, of 15 selected species of the genus Thermococcus within a few months, related these findings to the presence of cell surface appendages, and obtained the first evidence for thermotaxis in Archaea.
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Affiliation(s)
- Maximilian Mora
- Institute of Microbiology and Archaea-Centre, University of Regensburg, Regensburg, Germany
| | - Annett Bellack
- Institute of Microbiology and Archaea-Centre, University of Regensburg, Regensburg, Germany
| | - Matthias Ugele
- Institute of Microbiology and Archaea-Centre, University of Regensburg, Regensburg, Germany
| | - Johann Hopf
- Electronic Workshop at the Faculty of Biology, University of Regensburg, Regensburg, Germany
| | - Reinhard Wirth
- Institute of Microbiology and Archaea-Centre, University of Regensburg, Regensburg, Germany
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12
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Gorlas A, Croce O, Oberto J, Gauliard E, Forterre P, Marguet E. Thermococcus
nautili sp. nov., a hyperthermophilic archaeon isolated from a hydrothermal deep-sea vent. Int J Syst Evol Microbiol 2014; 64:1802-1810. [DOI: 10.1099/ijs.0.060376-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Thermococcus nautili, strain 30-1T (formerly reported as Thermococcus nautilus), was isolated from a hydrothermal chimney sample collected from the East Pacific Rise at a depth of 2633 m on the ‘La chainette PP57’ area. Cells were motile, irregular cocci with a polar tuft of flagella (0.8–1.5 µm) and divided by constriction. The micro-organism grew optimally at 87.5 °C (range 55–95 °C), at pH 7 (range pH 4–9) and with 2 % NaCl (range 1–4 %). Doubling time was 64 min in Zillig’s broth medium under optimal conditions. Growth was strictly anaerobic. It grew preferentially in the presence of elemental sulfur or cystine, which are reduced to H2S, on complex organic substrates such as yeast extract, tryptone, peptone, Casamino acids and casein. Slow growth was observed on starch and pyruvate. Strain 30-1T was resistant to chloramphenicol and tetracyclin (at 100 µg ml−1) but sensitive to kanamycin and rifampicin. The G+C content of the genomic DNA was 54 mol%. Strain 30-1T harboured three plasmids named pTN1, pTN2 and pTN3 and produced membrane vesicles that incorporate pTN1 and pTN3. As determined by 16S rRNA gene sequence analysis, strain 30-1T is related most closely to Thermococcus sp. AM4 (99.3 % similarity) and
Thermococcus gammatolerans
DSM 15229T (99.2 %). DNA–DNA hybridization values (in silico) with these two closest relatives were below the threshold value of 70 % (33 % with Thermococcus sp. AM4 and 32 % with
T. gammatolerans
DSM 15229T) and confirmed that strain 30-1 represents a novel species. On the basis of the data presented, strain 30-1T is considered to represent a novel species of the genus
Thermococcus
, for which the name Thermococcus nautili sp. nov. is proposed. The type strain is 30-1T ( = CNCM 4275 = JCM 19601).
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Affiliation(s)
- Aurore Gorlas
- Institut de Génétique et Microbiologie, Université Paris-Sud, CNRS UMR8621, 91405 Orsay Cedex, France
| | - Olivier Croce
- Université Aix-Marseille, Faculté de médecine, CNRS UMR7278, Marseille, France
| | - Jacques Oberto
- Institut de Génétique et Microbiologie, Université Paris-Sud, CNRS UMR8621, 91405 Orsay Cedex, France
| | - Emilie Gauliard
- Institut de Génétique et Microbiologie, Université Paris-Sud, CNRS UMR8621, 91405 Orsay Cedex, France
| | - Patrick Forterre
- Institut de Génétique et Microbiologie, Université Paris-Sud, CNRS UMR8621, 91405 Orsay Cedex, France
| | - Evelyne Marguet
- Institut de Génétique et Microbiologie, Université Paris-Sud, CNRS UMR8621, 91405 Orsay Cedex, France
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Amenábar MJ, Flores PA, Pugin B, Boehmwald FA, Blamey JM. Archaeal diversity from hydrothermal systems of Deception Island, Antarctica. Polar Biol 2012. [DOI: 10.1007/s00300-012-1267-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Zeng X, Zhang X, Jiang L, Alain K, Jebbar M, Shao Z. Palaeococcus pacificus sp. nov., an archaeon from deep-sea hydrothermal sediment. Int J Syst Evol Microbiol 2012; 63:2155-2159. [PMID: 23104364 DOI: 10.1099/ijs.0.044487-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A hyperthermophilic, anaerobic, piezophilic archaeon (strain DY20341(T)) was isolated from a sediment sample collected from an East Pacific Ocean hydrothermal field (1° 37' S 102° 45' W) at a depth of 2737 m. The cells were irregular cocci, 0.8-1.5 µm in diameter. Growth was observed between 50 and 90 °C (optimum 80 °C), pH 5.0 and 8.0 (optimum pH 7.0), 1% and 7% (w/v) sea salts (Sigma, optimum 3%), 1% and 4% (w/v) NaCl (optimum 3%) and 0.1 and 80 MPa (optimum 30 MPa). The minimum doubling time was 66 min at 30 MPa and 80 °C. The isolate was an obligate chemoorganoheterotroph, capable of utilizing complex organic compounds and organic acids including yeast extract, peptone, tryptone, casein, starch, Casamino acids, citrate, lactate, acetate, fumarate, propanoate and pyruvate for growth. It was strictly anaerobic and facultatively dependent on elemental sulfur or sulfate as electron acceptors, but did not reduce sulfite, thiosulfate, Fe(III) or nitrate. The presence of elemental sulfur enhanced growth. The G+C content of the genomic DNA was 43.6 ± 1 mol%. 16S rRNA gene sequence analysis revealed that the closest relative of the isolated organism was Palaeococcus ferrophilus DMJ(T) (95.7% 16S rRNA gene similarity). On the basis of its physiological properties and phylogenetic analyses, the isolate is considered to represent a novel species, for which the name Palaeococcus pacificus sp. nov. is proposed. The type strain is strain DY20341(T) (=JCM 17873(T)=DSM 24777(T)).
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Affiliation(s)
- Xiang Zeng
- Key Laboratory of Marine Biogenetic Resources, The Third Institute of Oceanography SOA, Xiamen, Fujian 361005, PR China
| | - Xiaobo Zhang
- Key Laboratory of Marine Biogenetic Resources, The Third Institute of Oceanography SOA, Xiamen, Fujian 361005, PR China
| | - Lijing Jiang
- Key Laboratory of Marine Biogenetic Resources, The Third Institute of Oceanography SOA, Xiamen, Fujian 361005, PR China
| | - Karine Alain
- CNRS, UMR 6197-Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France.,Université de Bretagne Occidentale, UMR 6197-Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France
| | - Mohamed Jebbar
- CNRS, UMR 6197-Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France.,Université de Bretagne Occidentale, UMR 6197-Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France
| | - Zongze Shao
- Key Laboratory of Marine Biogenetic Resources, The Third Institute of Oceanography SOA, Xiamen, Fujian 361005, PR China
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15
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Complete genome sequence of Thermococcus sp. strain 4557, a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent area. J Bacteriol 2011; 193:5544-5. [PMID: 21914870 DOI: 10.1128/jb.05851-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermococcus sp. strain 4557 is a hyperthermophilic anaerobic archaeon isolated from the deep-sea hydrothermal vent Guaymas Basin site in the Gulf of California at a depth of 2,000 m. Here, we present the complete genome sequence of Thermococcus sp. 4557, which consists of a single circular chromosome of 2,011,320 bp with a G+C content of 56.08%.
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16
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The falsifiability of the models for the origin of eukaryotes. Curr Genet 2011; 57:367-90. [DOI: 10.1007/s00294-011-0357-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 09/29/2011] [Accepted: 09/30/2011] [Indexed: 01/13/2023]
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17
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Kuwabara T, Kawasaki A, Uda I, Sugai A. Thermosipho globiformans sp. nov., an anaerobic thermophilic bacterium that transforms into multicellular spheroids with a defect in peptidoglycan formation. Int J Syst Evol Microbiol 2011; 61:1622-1627. [DOI: 10.1099/ijs.0.025106-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An anaerobic rod-shaped thermophile was isolated from a hydrothermal vent at Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean, and was named strain MN14T. The rods were Gram-negative-staining, non-motile without flagella, 2–4 µm long and 0.5 µm wide, and divided by binary fission in the mid-exponential phase. The cells were surrounded by a sheath-like structure (toga) and occurred singly or in chains. Spheroids containing multiple cells were observed not only in the stationary phase, as previously observed for species of the order Thermotogales, but also from the early exponential phase. Transmission electron microscopy revealed that the peptidoglycan in rods partly disintegrated in the early growth phases and that the outer membrane of the spheroids was not completely lined with peptidoglycan. These findings suggested that the spheroids were formed from rods by the disintegration of peptidoglycan and subsequent inflation of the outer membrane. The spheroids eventually generated tiny cells in the periplasmic space, indicating a viviparous mode of proliferation in addition to binary fission. Strain MN14T grew at 40–75 °C, pH 5.0–8.2 and with 0.25–5.20 % (w/v) NaCl, with optimal growth occurring at 68 °C, pH 6.8 and with 2.5 % NaCl. The shortest doubling time was 24 min, assuming that the strain propagated only by binary fission. Elemental sulfur enhanced growth, but was not essential. Thiosulfate was not an electron acceptor for growth. The strain was a chemo-organotroph that grew on yeast extract as the sole growth substrate. Tryptone and starch supported its growth in the presence of yeast extract. The G+C content of the genomic DNA was 31.7 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that this strain belonged to the genus Thermosipho. No significant DNA–DNA hybridization was observed between the genomic DNA of strain MN14T and phylogenetically related species of the genus Thermosipho. Based on this evidence, strain MN14T is proposed to represent a novel species, named Thermosipho globiformans sp. nov. The species epithet globiformans reflects the formation of multicellular and reproductive spheroids by the novel strain. The type strain of this species is MN14T ( = JCM 15059T = DSM 19918T).
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Affiliation(s)
- Tomohiko Kuwabara
- College of Biological Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Akitomo Kawasaki
- College of Biological Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Ikuko Uda
- Division of Chemistry, College of Liberal Arts and Sciences, Kitasato University, Sagamihara 228-8555, Japan
| | - Akihiko Sugai
- Division of Chemistry, College of Liberal Arts and Sciences, Kitasato University, Sagamihara 228-8555, Japan
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18
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Kim KP, Cho SS, Lee KK, Youn MH, Kwon ST. Improved thermostability and PCR efficiency of Thermococcus celericrescens DNA polymerase via site-directed mutagenesis. J Biotechnol 2011; 155:156-63. [PMID: 21723333 DOI: 10.1016/j.jbiotec.2011.06.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 06/11/2011] [Accepted: 06/17/2011] [Indexed: 11/26/2022]
Abstract
The Thermococcus celericrescens (Tcel) DNA polymerase gene, which contains a 2328-bp open reading frame that encodes 775 amino acid residues, was expressed in the Escherichia coli strain Rosetta(DE3)pLysS. The expressed enzyme was purified through heat treatment, HisTrap™ HP column chromatography and then HiTrap™ SP HP column chromatography. Tcel DNA polymerase has poor thermostability and PCR efficiency compared to those of other family B DNA polymerases. To improve thermostability and PCR efficiency, mutant Tcel DNA polymerases were created via site-directed mutagenesis. Specifically, we targeted the A752 residue for enhanced thermostability and the N213 residue for improved PCR efficiency. The mutant Tcel DNA polymerases all showed enhanced PCR efficiency and thermostability compared to those of the wild-type Tcel DNA polymerase. Specifically, the double mutant TcelA752K/N213D DNA polymerase had an approximately three-fold increase in thermostability over that of the wild-type enzyme and amplified a long 10-kb PCR product in an extension time of 2min. However, there was a small change in the 3'→5' exonuclease activity compared with that of the wild-type Tcel DNA polymerase, even though the mutation is in the ExoII motif. The double mutant TcelA752K/N213D DNA polymerase had a 2.6-fold lower error rate compared to that of Taq DNA polymerase. It seems that the double mutant TcelA752K/N213D DNA polymerase can be used in LA (long and accurate) PCR.
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Affiliation(s)
- Kee Pum Kim
- Department of Genetic Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Republic of Korea
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19
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Pettit RK. Culturability and secondary metabolite diversity of extreme microbes: expanding contribution of deep sea and deep-sea vent microbes to natural product discovery. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2011; 13:1-11. [PMID: 20437069 DOI: 10.1007/s10126-010-9294-y] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 04/14/2010] [Indexed: 05/29/2023]
Abstract
Microbes from extreme environments do not necessarily require extreme culture conditions. Perhaps the most extreme environments known, deep-sea hydrothermal vent sites, support an incredible array of archaea, bacteria, and fungi, many of which have now been cultured. Microbes cultured from extreme environments have not disappointed in the natural products arena; diverse bioactive secondary metabolites have been isolated from cultured extreme-tolerant microbes, extremophiles, and deep-sea microbes. The contribution of vent microbes to our arsenal of natural products will likely grow, given the culturability of vent microbes; their metabolic, physiologic, and phylogenetic diversity; numerous reports of bioactive natural products from microbes inhabiting high acid, high temperature, or high pressure environments; and the recent isolation of new chroman derivatives and siderophores from deep-sea hydrothermal vent bacteria.
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Affiliation(s)
- Robin K Pettit
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-2404, USA.
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20
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A molecular and physiological survey of a diverse collection of hydrothermal vent Thermococcus and Pyrococcus isolates. Extremophiles 2009; 13:905-15. [PMID: 19763742 DOI: 10.1007/s00792-009-0278-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
Strains of hyperthermophilic anaerobic hydrothermal vent archaea maintained in the culture collection assembled by Holger Jannasch at the Woods Hole Oceanographic Institution between 1984 and 1998 were identified and partially characterized by Denaturing Gradient Gel Electrophoresis, 16S rRNA gene sequencing, and by growth tests at different temperatures and on different organic carbon and nitrogen sources. All strains were members of the genera Thermococcus and Pyrococcus. The greatest phylogenetic diversity was found in strains from a single Guaymas Basin core isolated by serial dilution from four different depth horizons of heated sediment incubated at the corresponding in situ temperatures. In contrast, geographically distinct vent locations and sample materials yielded a lower diversity of isolates when enriched under uniform temperature regimes and without prior dilution of the source material.
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21
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Zhou H, Li J, Peng X, Meng J, Wang F, Ai Y. Microbial diversity of a sulfide black smoker in main endeavour hydrothermal vent field, Juan de Fuca Ridge. J Microbiol 2009; 47:235-47. [PMID: 19557339 DOI: 10.1007/s12275-008-0311-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 03/10/2009] [Indexed: 11/28/2022]
Abstract
Submarine hydrothermal vents are among the least-understood habitats on Earth but have been the intense focus of research in the past 30 years. An active hydrothermal sulfide chimney collected from the Dudley site in the Main Endeavour vent Field (MEF) of Juan de Fuca Ridge was investigated using mineralogical and molecular approaches. Mineral analysis indicated that the chimney was composed mainly of Fe-, Zn-and Cu-rich sulfides. According to phylogenetic analysis, within the Crenarchaeota, clones of the order Desulfurococcales predominated, comprising nearly 50% of archaeal clones. Euryarchaeota were composed mainly of clones belonging to Thermococcales and deep-sea hydrothermal vent Euryarchaeota (DHVE), each of which accounted for about 20% of all clones. Thermophilic or hyperthermophilic physiologies were common to the predominant archaeal groups. More than half of bacterial clones belonged to epsilon-Proteobacteria, which confirmed their prevalence in hydrothermal vent environments. Clones of Proteobacteria (gamma-, delta-, beta-), Cytophaga-Flavobacterium-Bacteroides (CFB) and Deinococcus-Thermus occurred as well. It was remarkable that methanogens and methanotrophs were not detected in our 16S rRNA gene library. Our results indicated that sulfur-related metabolism, which included sulfur-reducing activity carried out by thermophilic archaea and sulfur-oxidizing by mesophilic bacteria, was common and crucial to the vent ecosystem in Dudley hydrothermal site.
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Affiliation(s)
- Huaiyang Zhou
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
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22
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Abstract
Thermophilic anaerobes are Archaea and Bacteria that grow optimally at temperatures of 50 degrees C or higher and do not require the use of O(2) as a terminal electron acceptor for growth. The prokaryotes with this type of physiology are studied for a variety of reasons, including (a) to understand how life can thrive under extreme conditions, (b) for their biotechnological potential, and (c) because anaerobic thermophiles are thought to share characteristics with the early evolutionary life forms on Earth. Over 300 species of thermophilic anaerobes have been described; most have been isolated from thermal environments, but some are from mesobiotic environments, and others are from environments with temperatures below 0 degrees C. In this overview, the authors outline the phylogenetic and physiological diversity of thermophilic anaerobes as currently known. The purpose of this overview is to convey the incredible diversity and breadth of metabolism within this subset of anaerobic microorganisms.
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Affiliation(s)
- Isaac D Wagner
- 212 Biological Sciences Building, 1000 Cedar Street, University of Georgia, Athens, GA 30602-2605, USA
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Wang S, Lu Z, Lu M, Qin S, Liu H, Deng X, Lin Q, Chen J. Identification of archaeon-producing hyperthermophilic alpha-amylase and characterization of the alpha-amylase. Appl Microbiol Biotechnol 2008; 80:605-14. [PMID: 18587570 DOI: 10.1007/s00253-008-1561-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 05/29/2008] [Accepted: 05/30/2008] [Indexed: 10/21/2022]
Abstract
The extremely thermophilic anaerobic archaeon strain, HJ21, was isolated from a deep-sea hydrothermal vent, could produce hyperthermophilic alpha-amylase, and later was identified as Thermococcus from morphological, biochemical, and physiological characteristics and the 16S ribosomal RNA gene sequence. The extracellular thermostable alpha-amylase produced by strain HJ21 exhibited maximal activity at pH 5.0. The enzyme was stable in a broad pH range from pH 5.0 to 9.0. The optimal temperature of alpha-amylase was observed at 95 degrees C. The half-life of the enzyme was 5 h at 90 degrees C. Over 40% and 30% of the enzyme activity remained after incubation at 100 degrees C for 2 and 3 h, respectively. The enzyme did not require Ca(2+) for thermostability. This alpha-amylase gene was cloned, and its nucleotide sequence displayed an open reading frame of 1,374 bp, which encodes a protein of 457 amino acids. Analysis of the deduced amino acid sequence revealed that four homologous regions common in amylases were conserved in the HJ21 alpha-amylase. The molecular weight of the mature enzyme was calculated to be 51.4 kDa, which correlated well with the size of the purified enzyme as shown by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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Affiliation(s)
- Shujun Wang
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China
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