1
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Coker JA. 'All About' Extremophiles. Fac Rev 2023; 12:27. [PMID: 38027090 PMCID: PMC10630985 DOI: 10.12703/r/12-27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023] Open
Abstract
Despite common perception, most of Earth is what is often referred to as an 'extreme environment.' Yet to the organisms that call these places home, it is simply that (home). They have adapted to thrive in these environments and, in the process, have evolved many unique adaptations at the molecular- and 'omic-level. Scientists' interest in these organisms has typically been in how they and their products can be harnessed for biotechnological applications and the environments where they are found, while the general public's veers more toward a fascination with their deviation from the 'norm'. However, these organisms have so much more to tell us about Life and the myriad ways there are to perform 'simple' biological processes.
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Affiliation(s)
- James A Coker
- Center for Biotechnology Education, Advanced Academic Programs, Krieger School of Arts and Sciences, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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2
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Couto-Rodríguez RL, Koh J, Chen S, Maupin-Furlow JA. Insights into the Lysine Acetylome of the Haloarchaeon Haloferax volcanii during Oxidative Stress by Quantitative SILAC-Based Proteomics. Antioxidants (Basel) 2023; 12:1203. [PMID: 37371933 PMCID: PMC10294847 DOI: 10.3390/antiox12061203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/23/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
Oxidative stress adaptation strategies are important to cell function and are linked to cardiac, neurodegenerative disease, and cancer. Representatives of the Archaea domain are used as model organisms based on their extreme tolerance to oxidants and close evolutionary relationship with eukaryotes. A study of the halophilic archaeon Haloferax volcanii reveals lysine acetylation to be associated with oxidative stress responses. The strong oxidant hypochlorite: (i) stimulates an increase in lysine acetyltransferase HvPat2 to HvPat1 abundance ratios and (ii) selects for lysine deacetylase sir2 mutants. Here we report the dynamic occupancy of the lysine acetylome of glycerol-grown H. volcanii as it shifts in profile in response to hypochlorite. These findings are revealed by the: (1) quantitative multiplex proteomics of the SILAC-compatible parent and Δsir2 mutant strains and (2) label-free proteomics of H26 'wild type' cells. The results show that lysine acetylation is associated with key biological processes including DNA topology, central metabolism, cobalamin biosynthesis, and translation. Lysine acetylation targets are found conserved across species. Moreover, lysine residues modified by acetylation and ubiquitin-like sampylation are identified suggesting post-translational modification (PTM) crosstalk. Overall, the results of this study expand the current knowledge of lysine acetylation in Archaea, with the long-term goal to provide a balanced evolutionary perspective of PTM systems in living organisms.
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Affiliation(s)
- Ricardo L. Couto-Rodríguez
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA;
| | - Jin Koh
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610, USA; (J.K.); (S.C.)
| | - Sixue Chen
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610, USA; (J.K.); (S.C.)
- Genetics Institute, University of Florida, Gainesville, FL 32610, USA
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- Department of Biology, The University of Mississippi, Oxford, MS 38677, USA
| | - Julie A. Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA;
- Genetics Institute, University of Florida, Gainesville, FL 32610, USA
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3
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Wu JH, McGenity TJ, Rettberg P, Simões MF, Li WJ, Antunes A. The archaeal class Halobacteria and astrobiology: Knowledge gaps and research opportunities. Front Microbiol 2022; 13:1023625. [PMID: 36312929 PMCID: PMC9608585 DOI: 10.3389/fmicb.2022.1023625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 09/07/2022] [Indexed: 09/19/2023] Open
Abstract
Water bodies on Mars and the icy moons of the outer solar system are now recognized as likely being associated with high levels of salt. Therefore, the study of high salinity environments and their inhabitants has become increasingly relevant for Astrobiology. Members of the archaeal class Halobacteria are the most successful microbial group living in hypersaline conditions and are recognized as key model organisms for exposure experiments. Despite this, data for the class is uneven across taxa and widely dispersed across the literature, which has made it difficult to properly assess the potential for species of Halobacteria to survive under the polyextreme conditions found beyond Earth. Here we provide an overview of published data on astrobiology-linked exposure experiments performed with members of the Halobacteria, identifying clear knowledge gaps and research opportunities.
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Affiliation(s)
- Jia-Hui Wu
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Terry J. McGenity
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Petra Rettberg
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
| | - Marta F. Simões
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
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4
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Duprey A, Groisman EA. The regulation of DNA supercoiling across evolution. Protein Sci 2021; 30:2042-2056. [PMID: 34398513 PMCID: PMC8442966 DOI: 10.1002/pro.4171] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/04/2021] [Accepted: 08/04/2021] [Indexed: 11/11/2022]
Abstract
DNA supercoiling controls a variety of cellular processes, including transcription, recombination, chromosome replication, and segregation, across all domains of life. As a physical property, DNA supercoiling alters the double helix structure by under- or over-winding it. Intriguingly, the evolution of DNA supercoiling reveals both similarities and differences in its properties and regulation across the three domains of life. Whereas all organisms exhibit local, constrained DNA supercoiling, only bacteria and archaea exhibit unconstrained global supercoiling. DNA supercoiling emerges naturally from certain cellular processes and can also be changed by enzymes called topoisomerases. While structurally and mechanistically distinct, topoisomerases that dissipate excessive supercoils exist in all domains of life. By contrast, topoisomerases that introduce positive or negative supercoils exist only in bacteria and archaea. The abundance of topoisomerases is also transcriptionally and post-transcriptionally regulated in domain-specific ways. Nucleoid-associated proteins, metabolites, and physicochemical factors influence DNA supercoiling by acting on the DNA itself or by impacting the activity of topoisomerases. Overall, the unique strategies that organisms have evolved to regulate DNA supercoiling hold significant therapeutic potential, such as bactericidal agents that target bacteria-specific processes or anticancer drugs that hinder abnormal DNA replication by acting on eukaryotic topoisomerases specialized in this process. The investigation of DNA supercoiling therefore reveals general principles, conserved mechanisms, and kingdom-specific variations relevant to a wide range of biological questions.
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Affiliation(s)
- Alexandre Duprey
- Department of Microbial PathogenesisYale School of MedicineNew HavenConnecticutUSA
| | - Eduardo A. Groisman
- Department of Microbial PathogenesisYale School of MedicineNew HavenConnecticutUSA
- Yale Microbial Sciences InstituteWest HavenConnecticutUSA
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5
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Evans JJ, Gygli PE, McCaskill J, DeVeaux LC. Divergent Roles of RPA Homologs of the Model Archaeon Halobacterium salinarum in Survival of DNA Damage. Genes (Basel) 2018; 9:genes9040223. [PMID: 29677156 PMCID: PMC5924565 DOI: 10.3390/genes9040223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/08/2018] [Accepted: 04/12/2018] [Indexed: 01/23/2023] Open
Abstract
The haloarchaea are unusual in possessing genes for multiple homologs to the ubiquitous single-stranded DNA binding protein (SSB or replication protein A, RPA) found in all three domains of life. Halobacterium salinarum contains five homologs: two are eukaryotic in organization, two are prokaryotic and are encoded on the minichromosomes, and one is uniquely euryarchaeal. Radiation-resistant mutants previously isolated show upregulation of one of the eukaryotic-type RPA genes. Here, we have created deletions in the five RPA operons. These deletion mutants were exposed to DNA-damaging conditions: ionizing radiation, UV radiation, and mitomycin C. Deletion of the euryarchaeal homolog, although not lethal as in Haloferax volcanii, causes severe sensitivity to all of these agents. Deletion of the other RPA/SSB homologs imparts a variable sensitivity to these DNA-damaging agents, suggesting that the different RPA homologs have specialized roles depending on the type of genomic insult encountered.
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Affiliation(s)
- Jessica J Evans
- South Dakota School of Mines and Technology, Biomedical Engineering Program, Rapid City, SD 57701, USA.
| | - Patrick E Gygli
- Idaho State University Department of Biological Sciences, Pocatello, ID 83209, USA.
| | - Julienne McCaskill
- Idaho State University Department of Biological Sciences, Pocatello, ID 83209, USA.
| | - Linda C DeVeaux
- New Mexico Institute of Mining and Technology, Department of Biology, Socorro, NM 87801, USA.
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6
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McMillan LJ, Hwang S, Farah RE, Koh J, Chen S, Maupin-Furlow JA. Multiplex quantitative SILAC for analysis of archaeal proteomes: a case study of oxidative stress responses. Environ Microbiol 2017; 20:385-401. [PMID: 29194950 DOI: 10.1111/1462-2920.14014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/27/2017] [Accepted: 11/28/2017] [Indexed: 01/08/2023]
Abstract
Stable isotope labelling of amino acids in cell culture (SILAC) is a quantitative proteomic method that can illuminate new pathways used by cells to adapt to different lifestyles and niches. Archaea, while thriving in extreme environments and accounting for ∼20%-40% of the Earth's biomass, have not been analyzed with the full potential of SILAC. Here, we report SILAC for quantitative comparison of archaeal proteomes, using Haloferax volcanii as a model. A double auxotroph was generated that allowed for complete incorporation of 13 C/15 N-lysine and 13 C-arginine such that each peptide derived from trypsin digestion was labelled. This strain was found amenable to multiplex SILAC by case study of responses to oxidative stress by hypochlorite. A total of 2565 proteins was identified by LC-MS/MS analysis (q-value ≤ 0.01) that accounted for 64% of the theoretical proteome. Of these, 176 proteins were altered at least 1.5-fold (p-value < 0.05) in abundance during hypochlorite stress. Many of the differential proteins were of unknown function. Those of known function included transcription factor homologs related to oxidative stress by 3D-homology modelling and orthologous group comparisons. Thus, SILAC is found to be an ideal method for quantitative proteomics of archaea that holds promise to unravel gene function.
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Affiliation(s)
- Lana J McMillan
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.,Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| | - Sungmin Hwang
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Rawan E Farah
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Jin Koh
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Sixue Chen
- Genetics Institute, University of Florida, Gainesville, FL 32611, USA.,Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA.,Department of Biology, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.,Genetics Institute, University of Florida, Gainesville, FL 32611, USA
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7
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Jones DL, Baxter BK. DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea. Front Microbiol 2017; 8:1882. [PMID: 29033920 PMCID: PMC5626843 DOI: 10.3389/fmicb.2017.01882] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/14/2017] [Indexed: 12/31/2022] Open
Abstract
Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV) radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a "first line of defense," and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.
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Affiliation(s)
| | - Bonnie K. Baxter
- Department of Biology, Great Salt Lake Institute, Westminster College, Salt Lake City, UT, United States
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Williams TJ, Liao Y, Ye J, Kuchel RP, Poljak A, Raftery MJ, Cavicchioli R. Cold adaptation of the Antarctic haloarchaea
Halohasta litchfieldiae
and
Halorubrum lacusprofundi. Environ Microbiol 2017; 19:2210-2227. [DOI: 10.1111/1462-2920.13705] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 01/17/2017] [Accepted: 02/08/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Timothy J. Williams
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydney New South Wales2052 Australia
| | - Yan Liao
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydney New South Wales2052 Australia
| | - Jun Ye
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydney New South Wales2052 Australia
- Centre for Marine Bio‐InnovationThe University of New South WalesSydney New South Wales2052 Australia
| | - Rhiannon P. Kuchel
- Electron Microscopy UnitThe University of New South WalesSydney New South Wales2052 Australia
| | - Anne Poljak
- Bioanalytical Mass Spectrometry FacilityThe University of New South WalesSydney New South Wales2052 Australia
| | - Mark J. Raftery
- Bioanalytical Mass Spectrometry FacilityThe University of New South WalesSydney New South Wales2052 Australia
| | - Ricardo Cavicchioli
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydney New South Wales2052 Australia
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9
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Impact of a homing intein on recombination frequency and organismal fitness. Proc Natl Acad Sci U S A 2016; 113:E4654-61. [PMID: 27462108 DOI: 10.1073/pnas.1606416113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inteins are parasitic genetic elements that excise themselves at the protein level by self-splicing, allowing the formation of functional, nondisrupted proteins. Many inteins contain a homing endonuclease (HEN) domain and rely on its activity for horizontal propagation. However, successful invasion of an entire population will make this activity redundant, and the HEN domain is expected to degenerate quickly under these conditions. Several theories have been proposed for the continued existence of the both active HEN and noninvaded alleles within a population. However, to date, these models were not directly tested experimentally. Using the natural cell fusion ability of the halophilic archaeon Haloferax volcanii we were able to examine this question in vivo, by mating polB intein-positive [insertion site c in the gene encoding DNA polymerase B (polB-c)] and intein-negative cells and examining the dispersal efficiency of this intein in a natural, polyploid population. Through competition between otherwise isogenic intein-positive and intein-negative strains we determined a surprisingly high fitness cost of over 7% for the polB-c intein. Our laboratory culture experiments and samples taken from Israel's Mediterranean coastline show that the polB-c inteins do not efficiently take over an inteinless population through mating, even under ideal conditions. The presence of the HEN/intein promoted recombination when intein-positive and intein-negative cells were mated. Increased recombination due to HEN activity contributes not only to intein dissemination but also to variation at the population level because recombination tracts during repair extend substantially from the homing site.
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Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics. Appl Environ Microbiol 2016; 82:3165-73. [PMID: 26994078 DOI: 10.1128/aem.00473-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 03/12/2016] [Indexed: 01/23/2023] Open
Abstract
UNLABELLED Deep Lake in the Vestfold Hills is hypersaline and the coldest system in Antarctica known to support microbial growth (temperatures as low as -20°C). It represents a strong experimental model because the lake supports a low-complexity community of haloarchaea, with the three most abundant species totaling ∼72%. Moreover, the dominant haloarchaea are cultivatable, and their genomes are sequenced. Here we use metaproteomics linked to metagenome data and the genome sequences of the isolates to characterize the main pathways, trophic strategies, and interactions associated with resource utilization. The dominance of the most abundant member, Halohasta litchfieldiae, appears to be predicated on competitive utilization of substrates (e.g., starch, glycerol, and dihydroxyacetone) produced by Dunaliella, the lake's primary producer, while also possessing diverse mechanisms for acquiring nitrogen and phosphorus. The second most abundant member, strain DL31, is proficient in degrading complex proteinaceous matter. Hht. litchfieldiae and DL31 are inferred to release labile substrates that are utilized by Halorubrum lacusprofundi, the third most abundant haloarchaeon in Deep Lake. The study also linked genome variation to specific protein variants or distinct genetic capacities, thereby identifying strain-level variation indicative of specialization. Overall, metaproteomics revealed that rather than functional differences occurring at different lake depths or through size partitioning, the main lake genera possess major trophic distinctions, and phylotypes (e.g., strains of Hht. litchfieldiae) exhibit a more subtle level of specialization. This study highlights the extent to which the lake supports a relatively uniform distribution of taxa that collectively possess the genetic capacity to effectively exploit available nutrients throughout the lake. IMPORTANCE Life on Earth has evolved to colonize a broad range of temperatures, but most of the biosphere (∼85%) exists at low temperatures (≤5°C). By performing unique roles in biogeochemical cycles, environmental microorganisms perform functions that are critical for the rest of life on Earth to survive. Cold environments therefore make a particularly important contribution to maintaining healthy, stable ecosystems. Here we describe the main physiological traits of the dominant microorganisms that inhabit Deep Lake in Antarctica, the coldest aquatic environment known to support life. The hypersaline system enables the growth of halophilic members of the Archaea: haloarchaea. By analyzing proteins of samples collected from the water column, we determined the functions that the haloarchaea were likely to perform. This study showed that the dominant haloarchaea possessed distinct lifestyles yet formed a uniform community throughout the lake that was collectively adept at using available light energy and diverse organic substrates for growth.
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Stantial N, Dumpe J, Pietrosimone K, Baltazar F, Crowley DJ. Transcription-coupled repair of UV damage in the halophilic archaea. DNA Repair (Amst) 2016; 41:63-68. [DOI: 10.1016/j.dnarep.2016.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/22/2016] [Accepted: 03/21/2016] [Indexed: 12/01/2022]
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Aliyu H, De Maayer P, Cowan D. The genome of the Antarctic polyextremophileNesterenkoniasp. AN1 reveals adaptive strategies for survival under multiple stress conditions. FEMS Microbiol Ecol 2016; 92:fiw032. [DOI: 10.1093/femsec/fiw032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2016] [Indexed: 01/18/2023] Open
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13
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Leuko S, Domingos C, Parpart A, Reitz G, Rettberg P. The Survival and Resistance of Halobacterium salinarum NRC-1, Halococcus hamelinensis, and Halococcus morrhuae to Simulated Outer Space Solar Radiation. ASTROBIOLOGY 2015; 15:987-997. [PMID: 26539978 DOI: 10.1089/ast.2015.1310] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
UNLABELLED Solar radiation is among the most prominent stress factors organisms face during space travel and possibly on other planets. Our analysis of three different halophilic archaea, namely Halobacterium salinarum NRC-1, Halococcus morrhuae, and Halococcus hamelinensis, which were exposed to simulated solar radiation in either dried or liquid state, showed tremendous differences in tolerance and survivability. We found that Hcc. hamelinensis is not able to withstand high fluences of simulated solar radiation compared to the other tested organisms. These results can be correlated to significant differences in genomic integrity following exposure, as visualized by random amplified polymorphic DNA (RAPD)-PCR. In contrast to the other two tested strains, Hcc. hamelinensis accumulates compatible solutes such as trehalose for osmoprotection. The addition of 100 mM trehalose to the growth medium of Hcc. hamelinensis improved its survivability following exposure. Exposure of cells in liquid at different temperatures suggests that Hbt. salinarum NRC-1 is actively repairing cellular and DNA damage during exposure, whereas Hcc. morrhuae exhibits no difference in survival. For Hcc. morrhuae, the high resistance against simulated solar radiation may be explained with the formation of cell clusters. Our experiments showed that these clusters shield cells on the inside against simulated solar radiation, which results in better survival rates at higher fluences when compared to Hbt. salinarum NRC-1 and Hcc. hamelinensis. Overall, this study shows that some halophilic archaea are highly resistant to simulated solar radiation and that they are of high astrobiological significance. KEY WORDS Halophiles-Solar radiation-Stress resistance-Survival.
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Affiliation(s)
- S Leuko
- 1 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Luft- und Raumfahrtmedizin , Abteilung Strahlenbiologie, Arbeitsgruppe Astrobiologie, Köln, Germany
| | - C Domingos
- 2 Faculty of Sciences, University of Lisbon , Lisbon, Portugal
| | - A Parpart
- 1 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Luft- und Raumfahrtmedizin , Abteilung Strahlenbiologie, Arbeitsgruppe Astrobiologie, Köln, Germany
| | - G Reitz
- 1 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Luft- und Raumfahrtmedizin , Abteilung Strahlenbiologie, Arbeitsgruppe Astrobiologie, Köln, Germany
| | - P Rettberg
- 1 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Luft- und Raumfahrtmedizin , Abteilung Strahlenbiologie, Arbeitsgruppe Astrobiologie, Köln, Germany
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Bioengineering radioresistance by overproduction of RPA, a mammalian-type single-stranded DNA-binding protein, in a halophilic archaeon. Appl Microbiol Biotechnol 2013; 98:1737-47. [PMID: 24292079 PMCID: PMC4096848 DOI: 10.1007/s00253-013-5368-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 10/21/2013] [Accepted: 10/25/2013] [Indexed: 10/26/2022]
Abstract
Halobacterium sp. NRC-1 is a wild-type extremophilic microbe that is naturally tolerant to high levels of ionizing radiation. Mutants of strain NRC-1 with even higher levels of resistance to ionizing radiation, named RAD, were previously isolated after selecting survival to extremely high doses of ionizing radiation. These RAD mutants displayed higher transcription levels for the rfa3 operon, coding two subunits of the RPA-like putative single-stranded binding protein, rfa3 and rfa8, and a third downstream gene, ral. In order to bioengineer cells with increased tolerance to ionizing radiation and further explore the genetic basis of the RAD phenotype, we placed the rfa3 operon under control of the gvpA promoter in a Halobacterium expression plasmid, pDRK1. When pDRK1 was introduced into the wild-type NRC-1 strain, overproduction of the Rfa3 and Rfa8 proteins was observed by Western blotting and proteomic analysis. The Halobacterium strains expressing Rfa3 and Rfa8 also displayed improved survival after exposure to ionizing radiation, similar to the RAD mutants, when compared to wild-type strain NRC-1. The Rfa3 and Rfa8 proteins co-purified by affinity chromatography on single-stranded DNA cellulose columns, confirming the ability of the proteins to bind to single-stranded DNA as well as their relative abundance in the wild-type, RAD mutants, and rfa3 operon overexpression strains. These results clearly establish that overexpression of haloarchaeal RPA promotes ionizing radiation resistance in Halobacterium sp. NRC-1 and that the Rfa3 and Rfa8 subunits bind single-stranded DNA. Bioengineering cells with increased levels of ionizing radiation resistance may have potential value in medical and environmental applications.
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15
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Trigui H, Masmoudi S, Brochier-Armanet C, Maalej S, Dukan S. Survival of extremely and moderately halophilic isolates of Tunisian solar salterns after UV-B or oxidative stress. Can J Microbiol 2011; 57:923-33. [PMID: 22017705 DOI: 10.1139/w11-087] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adaptation to a solar saltern environment requires mechanisms providing tolerance not only to salinity but also to UV radiation (UVR) and to reactive oxygen species (ROS). We cultivated prokaryote halophiles from two different salinity ponds: the concentrator M1 pond (240 g·L(-1) NaCl) and the crystallizer TS pond (380 g·L(-1) NaCl). We then estimated UV-B and hydrogen peroxide resistance according to the optimal salt concentration for growth of the isolates. We observed a higher biodiversity of bacterial isolates in M1 than in TS. All strains isolated from TS appeared to be extremely halophilic Archaea from the genus Halorubrum. Culturable strains isolated from M1 included extremely halophilic Archaea (genera Haloferax, Halobacterium, Haloterrigena, and Halorubrum) and moderately halophilic Bacteria (genera Halovibrio and Salicola). We also found that archaeal strains were more resistant than bacterial strains to exposure to ROS and UV-B. All organisms tested were more resistant to UV-B exposure at the optimum NaCl concentration for their growth, which is not always the case for H(2)O(2). Finally, if these results are extended to other prokaryotes present in a solar saltern, we could speculate that UVR has greater impact than ROS on the control of prokaryote biodiversity in a solar saltern.
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Affiliation(s)
- Hana Trigui
- Aix-Marseille Université, Laboratoire de chimie bactérienne, Institut de microbiologie de la Méditerranée, Centre national de la recherche scientifique, France
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16
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Capes MD, Coker JA, Gessler R, Grinblat-Huse V, DasSarma SL, Jacob CG, Kim JM, DasSarma P, DasSarma S. The information transfer system of halophilic archaea. Plasmid 2010; 65:77-101. [PMID: 21094181 DOI: 10.1016/j.plasmid.2010.11.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 11/08/2010] [Accepted: 11/15/2010] [Indexed: 10/18/2022]
Abstract
Information transfer is fundamental to all life forms. In the third domain of life, the archaea, many of the genes functioning in these processes are similar to their eukaryotic counterparts, including DNA replication and repair, basal transcription, and translation genes, while many transcriptional regulators and the overall genome structure are more bacterial-like. Among halophilic (salt-loving) archaea, the genomes commonly include extrachromosomal elements, many of which are large megaplasmids or minichromosomes. With the sequencing of genomes representing ten different genera of halophilic archaea and the availability of genetic systems in two diverse models, Halobacterium sp. NRC-1 and Haloferax volcanii, a large number of genes have now been annotated, classified, and studied. Here, we review the comparative genomic, genetic, and biochemical work primarily aimed at the information transfer system of halophilic archaea, highlighting gene conservation and differences in the chromosomes and the large extrachromosomal elements among these organisms.
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Affiliation(s)
- Melinda D Capes
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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Osburne MS, Holmbeck BM, Frias-Lopez J, Steen R, Huang K, Kelly L, Coe A, Waraska K, Gagne A, Chisholm SW. UV hyper-resistance in Prochlorococcus MED4 results from a single base pair deletion just upstream of an operon encoding nudix hydrolase and photolyase. Environ Microbiol 2010; 12:1978-88. [PMID: 20345942 PMCID: PMC2955971 DOI: 10.1111/j.1462-2920.2010.02203.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 01/28/2010] [Indexed: 12/01/2022]
Abstract
Exposure to solar radiation can cause mortality in natural communities of pico-phytoplankton, both at the surface and to a depth of at least 30 m. DNA damage is a significant cause of death, mainly due to cyclobutane pyrimidine dimer formation, which can be lethal if not repaired. While developing a UV mutagenesis protocol for the marine cyanobacterium Prochlorococcus, we isolated a UV-hyper-resistant variant of high light-adapted strain MED4. The hyper-resistant strain was constitutively upregulated for expression of the mutT-phrB operon, encoding nudix hydrolase and photolyase, both of which are involved in repair of DNA damage that can be caused by UV light. Photolyase (PhrB) breaks pyrimidine dimers typically caused by UV exposure, using energy from visible light in the process known as photoreactivation. Nudix hydrolase (MutT) hydrolyses 8-oxo-dGTP, an aberrant form of GTP that results from oxidizing conditions, including UV radiation, thus impeding mispairing and mutagenesis by preventing incorporation of the aberrant form into DNA. These processes are error-free, in contrast to error-prone SOS dark repair systems that are widespread in bacteria. The UV-hyper-resistant strain contained only a single mutation: a 1 bp deletion in the intergenic region directly upstream of the mutT-phrB operon. Two subsequent enrichments for MED4 UV-hyper-resistant strains from MED4 wild-type cultures gave rise to strains containing this same 1 bp deletion, affirming its connection to the hyper-resistant phenotype. These results have implications for Prochlorococcus DNA repair mechanisms, genome stability and possibly lysogeny.
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Affiliation(s)
- Marcia S Osburne
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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